Source: UNIVERSITY OF CALIFORNIA, RIVERSIDE submitted to NRP
INVASIVE INSECT PESTS AND BIOLOGICAL CONTROL AGENTS IN CALIFORNIA: IMPACT ON AGRICULTURE AND CONSERVATION
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
HATCH
Reporting Frequency
Annual
Accession No.
0194617
Grant No.
(N/A)
Cumulative Award Amt.
(N/A)
Proposal No.
(N/A)
Multistate No.
(N/A)
Project Start Date
Oct 1, 2012
Project End Date
Sep 30, 2017
Grant Year
(N/A)
Program Code
[(N/A)]- (N/A)
Recipient Organization
UNIVERSITY OF CALIFORNIA, RIVERSIDE
(N/A)
RIVERSIDE,CA 92521
Performing Department
Entomology, Riverside
Non Technical Summary
Situation California experiences yearly a large number of new insect pests that affect both agriculture and natural habitats. Over the period 1955 -1988 a total of 208 exotic invertebrates established in California. With the increase in worldwide shipping this rate of new arrivals is expected only to increase in the foreseeable future. These pests affect agriculture, either because they inflict direct damage to crops, or because their presence causes the imposition of quarantine measures. Particularly damaging are pest species that are the vectors of different plant pathogens. Many of our natural habitats are also affected by the arrival of invasive species. The total cost of just the agriculturally important invasive pests is estimated to be $ 3 billion annually in California alone, while nationally it is estimated to be at least $13.9 billion Purpose This project applies various DNA based techniques to help in the early recognition of invasive species and to pin-point the origin of the invasive population. Once we know where the invasive species originated we can collect natural enemies from the same area and apply them to control the pest in the area where it invaded. In addition we study the genetic factors that correlate with the success of natural enemies. This work will help in a more rapid control of pest insects once they are established.
Animal Health Component
(N/A)
Research Effort Categories
Basic
(N/A)
Applied
(N/A)
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
2113110113030%
2124010113030%
2153110113040%
Knowledge Area
212 - Pathogens and Nematodes Affecting Plants; 211 - Insects, Mites, and Other Arthropods Affecting Plants; 215 - Biological Control of Pests Affecting Plants;

Subject Of Investigation
4010 - Bacteria; 3110 - Insects;

Field Of Science
1130 - Entomology and acarology;
Goals / Objectives
Objective 1. Determine the geographical origin and/ or biotype identity of invasive species and species/biotype identity of natural enemies. California acquires yearly at least 6 new insect pests. The goal of our research is to determine from where in the native range these exotics originated and collect natural enemies from that area for biological control in the invasive range. Outputs: Methods for rapid identification of invasive species and their natural enemies. Objective 2. Determine the factors important in improving biological control using natural enemies. Natural enemies have been used in biological control for over 100 years. Little research has been done to determine how important the within species genetic variation is for the success of biological control introductions. In addition, life-history traits that may affect the success of different genotypes in biological control have not been studied either. In this part of the project we will test a large number of genetically different lines both in the laboratory for life-history traits and in the field for their ability to find and parasitize hosts. In addition, we will test the effect of the Wolbachia symbiont that induces parthenogenesis in its parasitoid host on its effectiveness as a biological control agent. Outputs: Rules for the best practices to maintain genetic quality of natural enemies during the mass rearing phase of biological control programs. Objective 3. Monitoring the genetic change in insect-vectored plant pathogens during the vector invasion. The ability of plant pathogens to evolve a level of virulence is a function of the transmission frequency of the pathogen, and the chance that new genetic forms of the pathogen can be created. In California the invasion of the Glassy Winged Sharp Shooter and its enormous population growth, has created an environment with a much higher frequency of transmission of the plant pathogen Xylella fastidiosa. In addition, several different subspecies of this pathogen are present. With the high Glassy Winged Sharp Shooter densities these subspecies will now co-occur much more frequently either in the same insect or in the same host plant, thus allowing for an increased rate of recombination between subspecies. The goal of this research is to monitor the emergence of different strains of the Xyllela fastidiosa through recombination and to monitor these strains for virulence. Outputs: Methods for the rapid identification of different pathogen strains.
Project Methods
For most of these studies we apply various DNA techniques. For determining the origin of invasive species we use both microsatellite DNA markers and DNA sequences of mitochondrial genes to compare the genetic make-up of the invasive population with that of the species in its native range. For the determination if different collections of an insect are likely to belong to the same species we use the DNA sequence of various mitochondrial genes and several nuclear genes such as the ribosomal 28S D2 sequence. In order to create molecular keys to easily distinguish related pest insect we generally rely on the sequence of internally transcribed spaces of the ribosomal cistron, and use differences between the species to design sets of primers that will allow the individual species to be identified in a single multiplex PCR reaction. In our study to determine factor of importance for the success of biological control we use different genetic lines of the species Trichogramma pretiosum. Individuals belonging to different lines can be recognized using microsatellite markers. This will allow us to release known numbers of several different lines simultaneously in the same release plot and determine their relative performance by placing host egg cards in the field. These host eggs are collected and the wasps emerging from parasitized eggs are subsequently analyzed using the microsatellite markers to assign them to one of the released lines. We also compare PI Wolbachia infected lines with the same line but now cured of their Wolbachia infection. In this case we have to also use a Wolbachia DNA marker to distinguish the infected from the uninfected wasps. Life-history traits that will be determined in the laboratory will include longevity, fecundity, walking behavior, offsprig sex -ratio etc. In our study of the genetics of Xyllela fastidiosa we have developed a series of PCR primers to amplify different genes in the Xyllela genome. These DNA sequences have been used to develop a Multi Locus Sequence Typing system for this plant pathogen. This system allows us to determine from each collected strain to which sequence type it belongs. Isolates with the same sequence type are assumed to be the same. Different sequence types are tested for their plant host range and their virulence on a panel of host plants. To be able to recognize South American subspecies of this plant pathogen, we will also include them in our MLST system. This will allow us to quickly recognize these very damaging isolates such as the Citrus Variegated Chlorosis variant.

Progress 10/01/12 to 09/30/17

Outputs
Target Audience:The target audience of our work consists of several groups. First of all growers in California. We have worked on several projects involved with invasive species in different crops: Avocado and Citrus. For these growers we have provided information on the biology of several of the pests they are now facing such as two shot hole borer species belonging to the Euwallacea fornicatus species complex in Avocado and the management of Asian Citrus Psyllid in Citrus. More recently with the expansion of the shot hole borer invasion wildland managers, indian tribes and cities have become part of our target groups. Another group which is informed by our work consists of scientists trying to do biological control of invasive species and need to determine where the invasive species originate and how to manage the genetics of biocontrol agents. Finally students that attend classes offered by me, graduate students and postdoctoral associates that receive training in research, as well as foreign visitors that come to the lab to learn different molecular identification techniques. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Several PhD students have graduated during the period of this project (2 US and 1 foreign). Several other US and foreign PhD students have spenfd a period of time in the laboratory to learn different techniques (1 Brazilian, 1 Croatian, 1 Mexican, 1 Iranian, 1 Pakistani, 2 Spanish) Several post doctoral associates have worked in the laboratory for various amounts of time to learn different techniques (1 US, 1 Israeli, 1Spanish, 1 Tunesian, 1 Italian). In addition we have taught classes on how to use DNA based markers for all the graduate students that come through our department (~10 per year, so for this period about 50 graduate students).? How have the results been disseminated to communities of interest?We have presented numerous talks and field day presentations on the polyphagous shot hole borer invasion of southern California mainly in meetings organized by the California Avocado Commission for Avocado growers, as well as for the CaliforniaAssociation of Pest Control Advisers (CAPCA): Similarly we have given several presentations for the Citrus Research Board on the mass rearing of Tamarixia radiataand biological control of the Asian Citrus Psyllid in Southern California. I have presented talks on biological control and on the phylogeography of the shot hole borers. In addition, we have presented our work at the Entomological Society of America annual meeting, and several international entomological meetings (International Biological Control Organization) What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? During the duration of this project we have worked on determining the origin and geographic distribution of several economically important invasive species that have become pests in Clifornia. These species included the plant pathogen Xylella fastidiosa, and the exotic invasive species Red Palm Weevil and the different species of the Euwallacea fornicatus species complex (Kuroshio Shot Hole Borer and Polyphagous Shot Hole borer), and the native species that have invaded California, such as the Gold Spotted Oak Borer and Walnut Twig Beetle. Our work on the two native invasive beetle species into California: The gold spotted oak borer and the walnut twig beetle has shown that they both came from Arizona/New Mexico/ Colorado. The gold spotted oak borer was most likely brought to California with firewood. Using DNA sequences we identified the most likely source of these beetles as the Dragoon mountain range in Arizona. The origin of the Walnut Twig Beetle, a vector of the thousand cancer disease of walnuts, is more complex. Here our phylogenetic work using several different DNA sequences shows that the form that has now invaded many different states in the USA, most likely came about by a hybridization between two previously isolated populations of this species, one occurring on the east side of the Sierra Madre mountain range in Mexico and the other occurring on the west side of these mountains. The populations stretched down into the USA but did not meet until though planting of walnut trees in the cities allowed the beetles to expand their range and the two forms met and hybridized. Our DNA evidence showed that hybridization has taken place and this form has now invaded both the western and eastern USA and threatens the eastern walnut forest. First of all the Red Palm Weevil which had invaded California was characterized. The invading population appeared to have originated from Indonesia. Interestingly for such a large weevil species, the systematics of this species was rather confused. The two forms earlier recognized as different species had been synonomyzed in the 1990's, however our work showed that these two orginal species were indeed different species and that most of the invasive forms found throughout the world are part of theRhynchophorusferrugineus species, while the population that invaded California was a second speciesRhynchophorus vulneratus. Fortunately this species was exterminated in California. A second species group that had our attention was the cryptic species complex of Euwallacea fornicatus, an invasive species of ambrosia beetle that invaded California in the early part of this century, but did not become known as a pest until 2012 when it was found to attack a backyard avocado tree in the greater Los Angeles area. Initially the specimens collected in 2006 had been identified using morphological characters as Euwallacea fornicatus, also known as the Tea Shot Hole borer, an important pest of tea in mainly Sri Lanka. When we compared the DNA sequences of the specimen invading California with those collected from Sri Lanka, it became clear that they had to be different species. Since there were no obvious morphological differences between the specimens collected in Sri Lanka (Tea Shot Hole Borer (TSHB)) and beetles invading California, we decided to give the CA specimens a new common name to distinguish them from the TSHB, and named them the Polyphagous Shot Hole Borer (PSHB), because we had determined that the PSHB attacked a large number of different tree species. The second species was found in San Diego County where it infested avocado trees and many trees in riparian areas and again this one differed from both the TSHB and from the PSHB. This species was named the Kuroshio Shot Hole Borer. Our extensive work resulted in a publication on the phylogeography of this species complex. This work is now used to try to find natural enemies for these beetles that may be used as biological control agents against these pests. Several other results have come from the study of these invasive shot hole borers. We have tested several different lures to attract these beetles to traps and this work has resulted in an effective trap. In addition we have found an effected deterrent that is capable of reducing trap catches on traps lured with an attractant by 95%. For objective 2 we continue to maintain the genetic quality of Tamarixia radiata used for the biological control of the Asian Citrus Psyllid in California, we maintain the stock cultures and deliver mixtures of these colonies to mass rearing facilities for short term mass rearing and release in the field. A similar approach will be followed once a parasitoid has been identified that is suitable for the control of shot hole borers. For objective 3.For the plant pathogenXylella fastidiosaour work over the last 10 years has shown that the causative agent of the Pierce's disease - Xylella fastidiosa spp fastidiosa- is an invasive plant pathogen that originated from central America and most likely invaded California around 1860. This pathogen then hybridized with some of our native forms of Xylella fastidiosa spp multiplex and created new forms some of which have become pathogens on particular trees (f.i Mulberry). Our work on these pathogens has shown that different forms of these bacteria recombine commonly and can result in novel pathogens infesting host plants that previously were not infested. Some of the South American forms that are pests in Citrus most likely also came about by a recombination between the North American formXylella fastidiosamultiplex with a as yet unknown south American form ofXyllelato form the subspecies that is currently known asXylella fastidiosa spp. pauca. Xylella fastidiosahas recently become a big pest in Europe with the importation there of several pathovars that either originate from the US or from central America. In particular the Olive industry in threatened by the importantion of a Central American pathovar.

Publications

  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Yasin M, Rugman-Jones PF, Wakil W, Stouthamer R. (2016) Genetic variation among populations of Red Palm Weevil Rhyncophorus ferrugineus (Olivier) from Pakistan. Journal of Insect Science 16(1): 100; 17
  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Stouthamer R, Rugman-Jones PF, Thu, P-Q, Eskalen A, Thibault T, Hulcr J, Wang L-J, Jordal B, Chen C-Y, Cooperband M, Lin C-S, Kamata N, Lu S-S, Masuya H, Mendel Z, Rabaglia R, Sanguansub S, Shin S-H, Sittichaya W, Zong S. (2017). Tracing the origin of a cryptic invader: Phylogeography of the Euwallacea fornicatus (Coleoptera: Curculionidae: Scolytinae) species complex. Agricultural and Forest Entomology. DOI: 10.1111/afe.12215
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Skarlinsky TL, Rugman-Jones PF, Funderburk J, Stouthamer R, Sanabria Ujueta C. (2017). Adult identity crisis in Leucothrips (Thysanoptera, Thripidae) associated with the tropical ornamental plant Codiaeum variegatum. Florida Entomologist 100:509-514
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Lindsey ARI, Stouthamer R (2017). Penetrance of symbiont-mediated parthenogenesis is driven by reproductive rate in a parasitoid wasp. PeerJ doi.org/10.7717/peerj.3505
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Lara-Artiga J, Rugman-Jones PF, Stouthamer R, Hoddle MS. (2017) Population genetics of Oligonychus perseae (Acari: Tetranychidae) collected from avocados in Mexico and California. Florida Entomologist 100:616-626
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Rugman-Jones PF, Kharrat S, Hoddle MS, Stouthamer R (2017) The invasion of Tunisia by Rhynchophorus ferrugineus (Coleoptera: Curculionidae): crossing an ocean or crossing a sea? Florida Entomologist 100:262-265.
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Dodge C, Coolidge J, Cooperband M, Coss� A, Carrillo D, Stouthamer R. (2017) Quercivorol as a lure for the polyphagous and Kuroshio shot hole borers, Euwallacea spp. nr. fornicatus (Coleoptera: Scolytinae), vectors of Fusarium dieback. PeerJ doi.org/10.7717/peerj.3656
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Lindsey ARI, Stouthamer R (2017) The effects of outbreeding on a parasitoid wasp fixed for infection with a parthenogenesis-inducing Wolbachia symbiont. Heredity doi: 10.1038/hdy.2017.53


Progress 10/01/15 to 09/30/16

Outputs
Target Audience:The target audience of our work consists of several groups. First of all growers in California. We have worked on several projects involved with invasive species in different crops: Avocado and Citrus. For these growers we have provided information on the biology of several of the pests they are now facing such as two shot hole borer species belonging to the Euwallacea fornicatus species complex in Avocado and the management of Asian Citrus Psyllid in Citrus. More recently with the expansion of the shot hole borer invasion wildland managers, indian tribes and cities have become part of our target groups. Another group which is informed by our work consists of scientists trying to do biological control of invasive species and need to determine where the invasive species originate and how to manage the genetics of biocontrol agents. Finally students that attend classes offered by me, as well as postdoctoral associates that receive training in research. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?I have continued to teach my biological control classes. In addition we teach all graduate students in our program the use of molecular markers to resolve entomological questions. We have contiued training students in the application of molecualr techniques to help in the identificaton of insects.During the reporting period I was the major professor for four graduate students at UCR. We have participated in many meetings organized by the Avocado Commission and the Citrus Research board to disseminate the results of our work to growers and interested scientists. We have given extensive training to both the USDA and the CDFA in the mass rearing Tamarixia parasitoids for the control of the Asian CItrus Psyllid. How have the results been disseminated to communities of interest?We have presented numerous talks and field day presentations on the polyphagous shot hole borer invasion of southern California mainly in meetings organized by the California Avocado Commission for Avocado growers, Similarly we have given several presentations for the Citrus Research Board on the mass rearing of Tamarixia radiata and biological control of the Asian Citrus Psyllid in Southern California. I have presented talks on biological control and on the phylogeography of the shot hole borers. In addition, we have presented our work at the Entomological Society of America annual meeting What do you plan to do during the next reporting period to accomplish the goals?Objective 1. During the next reporting period we will do additional foreign exploration trips to find additional natural enemies for the Polyphagous Shot Hole Borer in Taiwan. We have already obtained colonies of entomopathogenic nematodes that we are studying at present to determine their effect on the beeltes that they have been found to be associated with. We will be trying to culture parasitoids from Taiwan in our insectary so that we next may test their specificity for the invasive Euwallacea species found in the US. In addition, we are will continue our research on effective trapping methods for both for the beetles and their natural enemies. Objective 2. The mass rearing of the Tamarixia lines will be continued. In addition we hope to set up a similar breeding system for the natural enemies of the shot hole borers. Objective 3. We will study the effect of different microbes found in the Polyphagous shot hole borer on the maintenance of the fungal gardens inside galleries of the beetles. We hope to find microbes that may be used to influence the infection rates by the fungi. This project is still ongoing and bacterial symbionts have been identified.

Impacts
What was accomplished under these goals? During this reporting period we have finished off several projects on determining the area of origin of various invasive species: A major project has been the phylogeography of the cryptic species of the Euwallacea fornicates species complex. Two of these cryptic species have invaded California : Kuroshio Shot Hole Borer and the Polypahagous Shot Hole Borer, while both Hawaii and Florida have been invaded by the Tea Shot Hole Borer. Knowledge of the phylogeography of these cryptic species has informed us where to look for potential natural enemies against these species. This knowledge has been used for a targetgted search of natural enemies in Taiwan where we discovered several species of natural enemies (parasitoids) that will be imported and tested for non-target effects. For objective 2 we continue to maintain the genetic quality of Tamarixia radiata used for the biological control of the Asian Citrus Psyllid in California, we maintain the stock cultures and deliver mixtures of these colonies to mass rearing facilities for short term mass rearing and release in the field. A similar approach will be followed once a parasitoid has been identified that is suitable for the control of shot hole borers. Objective 3. We have continued our work on Xylella fastidiosa pathovars and our identification system based on Multi Locus Sequence Typing -with data bases available online- is now used by many labs for the identification of these bacteria. In addition, we have been working on a invasive species complex in California, the polyphagous shot hole borer to determine its area of origin, recent work has shown that we have two species of the species complex in California one most likely originating from Vietnam or Southern China, while the other came from either Taiwan or Okinawa. These beetles are transmitting plant pathogenic fungi.

Publications

  • Type: Journal Articles Status: Published Year Published: 2015 Citation: Lynch SC, Twizeyimana M, Wang DH, Mayorquin JS, Na F, Kayim M, Kasson MT, Bateman C, Hulcr J, Pham TQ, Stouthamer R, Rugman-Jones PF, Eskalen A (2015) Identification, pathogenicity, and abundance of Acremonium pembeum sp. nov. and Graphium euwallaceum sp. nov.- two newly discovered mycangial associates of the polyphagous shot hole borer (Euwallacea sp.) in California. Mycologia doi:10.3852/15-063
  • Type: Journal Articles Status: Published Year Published: 2015 Citation: Sumer-Ercan F, Kodan M, Oztemiz S, Rugman-Jones PF, Stouthamer R (2015) Identifying the Trichogramma spp. parasitizing Archips rosana (L.), an important pest of fruit trees in Turkey. Journal of Biotechnology Research 1: 8-11, 08-2015.
  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Almeida RP, Stouthamer R (2015) ITS-2 sequences-based identification of Trichogramma species in South America. Brazilian Journal of Biology 75: 974-982
  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Berry D, Selby RD, Horvath JC, Cameron RH, Porqueras D, Stouthamer R (2016) A modular system of 3D printed traps for studying the biology of shot hole borers and other Scolytinae. Journal of Economic Entomology: doi: 10.1093/jee/tov407
  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Cooperband M, Stouthamer R, Carrillo D, Eskalen A, Thibault T, Coss� A, Castrillo L, Vandenberg J, Rugman-Jones P (2016) Biology of two members of the Euwallacea fornicatus species complex, recently invasive in the USA, reared on an ambrosia beetle artificial diet. Agricultural and Forest Entomology. 10.1111/afe.12155


Progress 10/01/14 to 09/30/15

Outputs
Target Audience:The target audience of our work consists of several groups. First of all growers in California. We have worked on several projects involved with invasive species in different crops: Avocado and Citrus. For these growers we have provided information on the biology of several of the pests they are now facing such as twoshot hole borer species belonging to theEuwallacea fornicatus species complex in Avocado and the management of Asian Citrus Psyllid in Citrus. Another group which is informed by our work consists of scientists trying to do biological control of invasive species and need to determine where the invasive species originate and how to manage the genetics of biocontrol agents. Finally students that attend classes offered by me, as well as postdoctoral associates that receive training in research. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?I have continued to teach my biological control classes. In addition we teach all graduate students in our program the use of molecular markers to resolve entomological questions. During the reporting period I was the major professor for five graduate students at UCR. We have participated in many meetings organized by the Avocado Commission and the Citrus Research board to disseminate the results of our work to growers and interested scientists. We have given extensive training to both the USDA and the CDFA in the mass rearing Tamarixia parasitoids for the control of the Asian CItrus Psyllid. How have the results been disseminated to communities of interest?I have presented numerous talks and field day presentations on the polyphagous shot hole borer invasion of southern California mainly in meetings organized by the California Avocado Commission for Avocado growers, Similarly we have given several presentations for the Citrus Research Board on the mass rearing of Tamarixia radiata and biological control of the Asian Citrus Psyllid in Southern California. In southeast Asia during our field work there for the polyphagous shot hole borer, I have presented talks on biological control and on the phylogeography of the shot hole borers. In addition, we have presented our work at the Entomological Society of America annual meeting What do you plan to do during the next reporting period to accomplish the goals?Objective 1. During the next reporting period we will do additional foreign exploration trips to find potential natural enemies for the Polyphagous Shot Hole Borer in Vietnam, Taiwan. From Vietnam we will obtain colonies of entomopathogenic nematodes that they have in culture there, and we will testtheir efficiency against the shot hole borers in California. We have found a parasitoid killing shot hole borers in Taiwan and hope to establish cultures of these wasps in our quarantine facility to determine their suitability for the biological control of the shothole borer species that have invaded California.In addition, we are working on effective trapping methods both for the beetles and their natural enemies. Objective 2. The mass rearing of the Tamarixia lines will be continued. In addition we hope to set up a similar breeding system for the natural enemies of the shot hole borers.Objective 3. We will study the effect of different microbes found in the Polyphagous shot hole borer on the maintenance of the fungal gardens inside galleries of the beetles. We hope to find microbes that may be used to influence the infection rates by the fungi. This project is still ongoing and bacterial symbionts have been identified.

Impacts
What was accomplished under these goals? During this reporting period we have finished off several projects on determining the area of originof various invasive species: A major project has been the phylgeography of the walnut twig beetle, where we found that the species identified as the walnut twig beetle appears to consist of two forms that may have interbred in Colorado, and that signature of this interbreeding are still foundin some of the populations that have invaded other states. Potentially indicating that either a hybridization in between these forms was involved in generating the invasive form. The two forms may in the past have been isolated from each other because their geographical ranges did not overlap, but in more recent times - potentially because of planting walnut trees in areas between the two previously isolated populations - the two populations became sympatric and this allowed them to hybridize. Methods for the identification of the two different forms have been developed. Similarly, we worked on trying to determine the native range of another invasive species in California the gold spotted oak borer. This species is also a native species to the US and is found commonly in the mountain ranges in Arizona. Material collected from those areas was studied and although we could not identify one particular range as the source of the California invasion it is most likely that the beetles originated from Arizona. Methods for identifying the Gold Spotted Oak Borer have been developed and we are regularly asked to identify larval forms of this species. For objective 2 we continue to maintain the genetic quality of Tamarixia radiata used for the biological control of the Asian Citrus Psyllid in California, we maintain the stock cultures and deliver mixtures of these colonies to mass rearing facilities for short term mass rearing and release in the field. Objective 3. We have continued our work on Xylella fastidiosa pathovars and our identification system based on Multi Locus Sequence Typing -with data bases available online-is now used by many labs for the identification of these bacteria. In addition, we have been working on a invasive species complex in California, the polyphagous shot hole borer to determine its area of origin, recent work has shown that we have two species of the species complex in California one most likely originating from Vietnam or Southern China, while the other came from either Taiwan or Okinawa. These beetles are transmitting plant pathogenic fungi.

Publications

  • Type: Journal Articles Status: Published Year Published: 2014 Citation: Lopez VM, Rugman-Jones PF, Coleman TW, Hoddle MS, Stouthamer R (2014) Population genetics of goldspotted oak borer, Agrilus auroguttatus Schaeffer (Coleoptera: Buprestidae): investigating the origin of an invasive pest of native oaks in California. Biological Invasions 16:2392-2402
  • Type: Journal Articles Status: Published Year Published: 2014 Citation: Nunney L, Ortiz B, Russell SA, Ruiz S�nchez R, Stouthamer R (2014) The complex biogeography of the plant pathogen Xylella fastidiosa: genetic evidence of introductions and subspecific introgression in Central America. PLoS ONE 9(11): e112463. doi:10.1371/journal.pone.0112463
  • Type: Journal Articles Status: Published Year Published: 2014 Citation: Lynch SC, Wang DH, Rugman-Jones PF, Mayorquin JS, Stouthamer R, Eskalen A. (2014) Foamy bark canker: A new disease on coast live oak, in association with Pseudopithyophthorus pubipennis in California. Phytopathology 104: 182.
  • Type: Journal Articles Status: Published Year Published: 2015 Citation: Rugman-Jones PF, Seybold SJ, Graves AD, Stouthamer R (2015) Phylogeography of the Walnut Twig Beetle, Pityophthorus juglandis, the vector of Thousand Cankers Disease in North American walnut trees. PlosOne DOI: 10.1371/journal.pone.0118264
  • Type: Journal Articles Status: Published Year Published: 2015 Citation: Carrillo D, Narvaez T, Cosse AA, Stouthamer R, Cooperband M. (2015) Attraction of Euwallacea near fornicatus to lures containing querciverol. Florida Entomologist 98: 780-782


Progress 10/01/13 to 09/30/14

Outputs
Target Audience: The target audience of our work consists of several groups. FIrst of all growers in California. We have worked on several projects involved with invasive species in different crops: Avocado and Citrus. For these growers we have provided information on the biology of several of the pests they are now facing such as the polyphagous shot hole borer Euwallacea fornicatus in Avocado and the management of Asian Citrus Psyllid in Citrus. Another group which is informed by our work consists of scientists trying to do biological control of invasive species and need to determine where the invasive species originate and how to manage the genetics of biocontrol agents. Finally students that attend classes offered by me, as well as postdoctoral associates that receive training in research. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? I have continued to teach my biological control classes. In addition we teach all graduate students in our program the use of molecular markers to resolve entomological questions. During the reporting period I was the major professor for five graduate students at UCR, housed during part of the year two international graduate students (Mexico, Brazil). We have participated in many meetings organized by the Avocado Commission and the Citrus Research board to disseminate the results of our work to growers and interested scientists. We have given extensive training to both the USDA and the CDFA in the mass rearing Tamarixia parasitoids for the control of the Asian CItrus Psyllid. How have the results been disseminated to communities of interest? I have presented numerous talks and field day presentations on the polyphagous shot hole borer invasion of southern California mainly in meetings organized by the California Avocado Commission for Avocado growers, Similarly we have given many presentations for the Citrus Research Board on the mass rearing of Tamarixia radiata and biological control of the Asian Citrus Psyllid in Southern California. Presentaions have also been given at the national and regional Entomological Society of America meetings What do you plan to do during the next reporting period to accomplish the goals? Objective 1. During the next reporting period we will do additional foreign exploration trips to find potential natural enemies for the Polyphagous Shot Hole Borer in Vietnam, Taiwan and China. In addition we are working on effective trapping methods both for the beetles and their natural enemies. Objective 2. The mass rearing of the Tamarixia lines will be continued and additional tests will be done to determine the importance of wasp size on the field success of Tamarixia. Objective 3. We will study the effect of different microbes found in the Polyphagous shot hole borer on the maintenance of the fungal gardens inside galleries of the beetles. We hope to find microbes that may be used to influence the infection rates by the fungi.

Impacts
What was accomplished under these goals? Objective 1. During this period we determined that the population of the ambrosia beetle (Euwallacea fornicatus) that has invaded California consists of two seperate invasions, the invasion in the Los Angeles area consists of beetles with a genetic finger print that is similar to beetles collected in the Northern part of Vietnam and southern China, while the invasion in San Diego county has a genetic finger print that is similar to beetles collected from Taiwan. In February 2014 we did a foreign exploration trip to Vietnam to determine if natural enemies were present. Several potential natural enemies were identified and our cooperator in Vietnam will try to rear them. In addition we analysed all our samples of the beetles that are morphologically identified as Euwallacea fornicatus and our analysis shows that this species consists of 4 cryptic species, California has been invaded by two of those, while Florida and Hawaii have been invaded by a third species. Objective 2. We have instituted a mass rearing scheme through which we 1)maintain the genetic variation of Tamarixia radiata a parasitoid of the Asian Citrus Psyllid and 2) avoid domestication of these cultures. The wasps maintained by us in this way are subsequently supplied to mass rearing facilities where the lines are mixed and are used for a limited number of generations to produce high quality wasps for release in the field. In addition, we have published a paper on the feasibility of tracking the release of a "better" genetic line in an already established population. With the presence of many molecular population genetic tools, the idea has been floated several times to follow the spread of these "better" lines in already established populations. Unfortunately we show through modelling in our publication that this is only possible under very limiting conditions. Obejctive 3. In the work on the insect transmitted plant pathogen X. fastidiosa we have shown that recombination is taking place between different subspecies of the pathogen and that some of these recombinant forms may infect host plants that were previously in infected. This pattern illustrates the danger ofmixing different subspecies of plant pathogens through international trade.

Publications

  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Nunney L, Vickerman D, Bromley RE, Russell SE, Hartman J, Morano LD, & Stouthamer R (2013) Recent evolutionary radiation and host plant specialization in the Xylella fastidiosa subspecies native to the United States. Applied and Environmental Microbiology 79: 2189-2200.
  • Type: Journal Articles Status: Published Year Published: 2014 Citation: Stouthamer R, Nunney L (2014) Can neutral molecular markers be used to determine the success of an introduction of a better strain into an established population of a biocontrol parasitoid? J. Econ Entomology 107:483-495.
  • Type: Journal Articles Status: Published Year Published: 2014 Citation: Lynch SC, Wang DH, Mayorquin JS, Rugman-Jones PF, Stouthamer R, Eskalen A (2014) First Report of Geosmithia pallida causing foamy bark canker, a new disease on Coast Live Oak (Quercus agrifolia), in association with Pseudopityophthorus pubipennis in California. Plant Disease 98: 1276
  • Type: Journal Articles Status: Published Year Published: 2014 Citation: Nunney L, Schuenzel EL, Scally M, Bromley RE, Stouthamer R (2014). Large-scale intersubspecific recombination in the plant-pathogenic bacterium Xylella fastidiosa is associated with the host shift to Mulberry. AEM80: 3025-3033
  • Type: Journal Articles Status: Published Year Published: 2014 Citation: Gonz�lez-Cabrera J, Arredondo-Bernal HC, Stouthamer R (2014) Evaluaci�n de calidad del parasitoide tricograma (Trichogramma spp.) proveniente de seis insectarios mexicanos. Agrociencia 48 (3), 321-329
  • Type: Journal Articles Status: Published Year Published: 2014 Citation: Nunney L, Hopkins DL, Morano LD, Russell SE, Stouthamer R (2014) Intersubspecific recombination in Xylella fastidiosa strains native to the United States: infection of novel hosts associated with an unsuccessful invasion. AEM 80: 1159-1169
  • Type: Journal Articles Status: Published Year Published: 2014 Citation: del Pino M, Hern�ndez-Su�rez E, Cabello T, Rugman-Jones P, Stouthamer R & Polaszek A. (2013),Trichogramma canariensis (Insecta: Hymenoptera: Trichogrammatidae) a parasitoid of eggs of the twin-spot moth Chrysodeixis chalcites (Lepidoptera: Noctuidae) in the Canary Islands. Arthropod Systematics & Phylogeny 71:169-179
  • Type: Journal Articles Status: Published Year Published: 2014 Citation: Uelese A, Ridland PM, Stouthamer R, He Y, Ang G, Zalucki MP, Furlong MJ. (2014). Trichogramma chilonis: A potential biocontrol agent of Crocidolomia pavonana in Samoa: Biological Control 73: 31-38.


Progress 01/01/13 to 09/30/13

Outputs
Target Audience: The target audience of our work consists of several groups. FIrst of all growers in California. We have worked on several projects involved with invasive species in different crops: Avocado and Citrus. For these growers we have provided information on the biology of several of the pests they are now facing such as the polyphagous shot hole borer Euwallacea fornicatus in Avocado and the management of Asian Citrus Psyllid in Citrus. Another group which is informed by our work consists of scientists trying to do biological control of invasive species and need to determine where the invasive species originate and how to manage the genetics of biocontrol agents. Finally students that attend classes offered by me, as well as postdocatoral associates that receive training in research Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? I have continued to teach my biological control classes. During the reporting period I was the major professor for three graduate students at UCR, housed during prt of the year two international graduate students (Mexico, Brazil). We have participated in several meetings organized by the Avocado Commission and the Citrus Research board to disseminate the results of our work to growers and interested scientists. We have given extensive training to both the USDA and the CDFA in the mass rearing Tamarixia parasitoids for the control of the Asian CItrus Psyllid. Organized and participated in a meeting at the Huntington Library and Gardens on the thread of invasive species to public gardens (August 2013). How have the results been disseminated to communities of interest? I have presented numerous talks of the polyphagous shot hole borer invasion of southern California mainly in meetings organized by the California Avocado Commission for Avocado growers, Similarly we have given many presentations for the Citrus Research Board on the mass rearing of Tamarixia radiate and biological control of the Asian Citrus Psyllid in Southern California. I have organized and given talks in the work shop organized by the Huntington Library and Gardens titled ” Dialogue on emergent plant pests and diseases impacting California's fields, forests, and landscapes” What do you plan to do during the next reporting period to accomplish the goals? The main focus in the next period will be: For the Asian Citrus Psyllid Biological Control project, to fully establish a genetically variable population of the parasitoid Tamrixia radiata of the Asian CItrus Psyllid. In addition we will work on trying to find natural enemies of the Polyphagous shot hole borer and do further studies of their life history. In the Xyllela project we will further analyse a number of different Xylella isolates through genomic analysis.. In addition we plan to finish our study of the Walnut Twig Beetle genetic variation and possilbe origin of the invasive form of this species that spreads the Thousand Cancers Disease throughout the US.

Impacts
What was accomplished under these goals? Objective 1. We have finished our work on determining the area of origin of the red palm weevil that has an so far unsuccessful invasion of California. After the initial discovery of specimens of the Red Palm Weevil in Laguna Beach California no more specimens have been detected in this area. Based on genetic analysis that we did of the extensive collections made of this beetle by Dr. M. Hoddle throughout the world, we have concluded that the individuals that formed the invasive population in Laguna Beach originated somewhere in the Indonesian archipelago. Furthermore in the process of doing this analysis we have clarified the taxonomic relationships between the two forms of this species that have undergone frequent taxonomic renaming,and we can now clearly distinguish between these taxa. Our work has made it clear that two species hide behind the common name of Red Palm Weevil: Rhynchophorus vulneratus and R.ferrugineus. In addition we have narrowed down the area of origin of another recent invader into California Euwallacea fornicatus (Polyphagous Shot Hole Borer). This species name also appears to comprise two genetic species,the polyphagous shot hole borer with a native range from Northern Thailand to the southern islands of Japan. This species is a serious pest in Avocado in Israel and is now also spreading through the urban forest in Southern California towards commercial avocado groves. The second form (The tea shot hole borer) occurs more southernly in Sri Lanka, Southern Thailand, Indonesia, Papua New Guinea and Australia, and is invasive in Florida and Hawaii. Objective 2. We have continued to maintain the genetic variation in the population of the parasitoid Tamarixia radiate, a parasitoid used in the classical biological control for the Asian Citrus Psyllid. We supply mass rearing groups of the CDFA with starting material so that they can maintain the genetic variation in the mass reared population. Maintaining this variation is particularly important for classical biological control applications, more so than for inundative applications. In classical biological control genetic quality cannot be compensated for with quantity. In addition we have optimized the mass rearing procedure for this parasitoid by including a host feeding step which has improved the raised the parasitization percentage in our mass rearing from about 40% to around 70-80%. The effects of low genetic variation of offspring production in the lab has been tested using Trichogramma pretiosum wasps, and experiments have shown that the fitness parameters of inbred lines can vary substantially, with the best line being 4 times more fit than the worst line. This also illustrate how important it is to start a classical biological control project with a lot of genetic variation otherwise the project may end up with one of the worst lines and mistakingly conclude that a particular parasitoid is not suitable for biocontrol. Objective 3. We have continued analyzing the various genetic forms of the plant pathogen Xylella fastidiosa though our Multilocus Sequence Typing system. This work in the last year has shown that the native form of this plant pathogen (X, fastidiosa multiplex) consists of two types: the assumed native type and the type that came about by recombination between the Xylella fastidiosa fastidiosa originating from Central America and our native form. The new recombinant form appears to be infecting some host species that have not been found to be hosts for the native form of this pathogen. Illustrating the danger that the importation of different forms of a plant pathogen may cause to our agriculture, not only can some of the exotic forms infest our crops but through recombination entirely different forms may be created

Publications

  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Segoli, M., Stouthamer, R., Stouthamer, C. M., Rugman?Jones, P., & Rosenheim, J. A. (2013). The effect of Wolbachia on the lifetime reproductive success of its insect host in the field. Journal of evolutionary biology, 26(12), 2716-2720.
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Eskalen A, Stouthamer R, Lynch SC, Rugman-Jones PF, Twizeyimana M, Gonzalez A, Thibault T (2013). Host range of fusarium dieback and its ambrosia beetle (Coleoptera: Scolytinae) vector in southern California. Plant Disease 97:938-951
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Pino, M., Rugman-Jones, P., Hern�ndez-Su�rez, E., Polaszek, A., & Stouthamer, R. (2013). Rapid molecular identification of five species of Trichogramma occurring in the Canary Islands with notes on their distribution in banana groves. BioControl, 58(4), 515-524.
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Guzm�n?Larralde, A., Cerna?Ch�vez, E., Rodr�guez?Campos, E., Loyola?Licea, J. C., & Stouthamer, R. (2013). Genetic variation and the performance of a mass?reared parasitoid, Trichogramma pretiosum (Hymenoptera: Trichogrammatidae), in laboratory trials. Journal of Applied Entomology.DOI: 10.1111/jen.12073
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Rugman-Jones, P. F., Hoddle, C. D., Hoddle, M. S., & Stouthamer, R. (2013). The Lesser of Two Weevils: Molecular-Genetics of Pest Palm Weevil Populations Confirm Rhynchophorus vulneratus (Panzer 1798) as a Valid Species Distinct from R. ferrugineus (Olivier 1790), and Reveal the Global Extent of Both. PloS one, 8(10), e78379.


Progress 01/01/12 to 12/31/12

Outputs
OUTPUTS: We have continued working on determining the area origin of several invasive species (Walnut Twig Beetle, Gold spotted Oakborer, Polyphagous Shot Hole Borer, Red Palm Weevil) . The work on goldspotted oakborer has narrowed down the location in Arizona where the beetles most likely originated to a particular mountain range in the center of the state. We have continued our genetic work on the parasitoid Tamarixia radiata to have tools to determine if the recovered parasitoids from the field indeed are the same species as the one we have mass reared and released. A new project that we have become involved in is the recent invasion of Southern California by the Ambrosia Beetle Euwallacea fornicatus (polyphagous SHot Hole Borer). Over the summer we have samples >300 tree species to determine the plant host range of this beetle, and have determined which species can function as reproductive hosts for the beetle. More than 20 species are host and these include Avocado. A very worrisome aspect of this beetle is the fact that they are able to reproduce in more than 25% of the street tree specimens planted in Southern California. Events: We have presented our work at several times to the California Avocado growers, the Southern California Nursery Organization, The Citrus Research Board. In addition we participated in the Invasive Ambrosia Beetle meeting at Riverside, and work on thrips and walnut Twig Beetles was presented at the International Congress of Entomology in Korea. PARTICIPANTS: Richard Stouthamer, PI, design of experiments, development of methods, analysis of results and writing manuscripts. Paul Rugman-Jones Associate Project Scientist development of dna finger printing methods, analysis of data and writing manuscripts. Holly Hills PhD Candidate involved in the experiments on the negative effects of mass rearing on natural enemies. Amelia Lindsey, PhD candidate involved in the research on the genome of Trichogramma pretiosum and its associated Wolbachia. Aviva Goldmann, PhD student involved with the research on predation of the Asian Citrus Psyllid. We have collaborated with scientists in Japan on the influence of symbionts on the crossing compatibility between different Orius species and with colleagues from Iran and Spain on the identification and biocontrol using Trichogramma parasitoids TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
The keys that we developed in our research are applied in the identification of several pest species. The Tamarixia radiata wasps that we have mass reared are established in Southern California from the Asian Citrus Psyllid in the field, and hopefully will contribute to the control of this pest.

Publications

  • Coleman T., V. Lopez, P.F. Rugman-Jones, R. Stouthamer, S.J. Seybold, R. Reardon, M.S. Hoddle. 2011. Can the destruction of California's oak woodlands be prevented Potential for biological control of the goldspotted oak borer, Agrilus auroguttatus. BioControl 57:211-225
  • Rugman-Jones P.F., M.S. Hoddle, P.A. Phillips, G. Jeong, R. Stouthamer. (2012) Strong genetic structure among populations of the avocado lace bug Pseudacysta perseae (Heidemann) (Hemiptera: Tingidae) reveals the source of introduced populations. Biological Invasions 14:1079-1100
  • Nunney, L., Elfekih, S, Stouthamer, R. (2012).The importance of multilocus sequence typing: cautionary tales from the bacterium Xylella fastidiosa. Phytopathology 102:456-460
  • Nunney, L, X. Yuan, R.E. Bromley, and R.Stouthamer. (2012). Detecting genetic introgression: high levels of inter-subspecific recombination found in Xylella fastidiosa in Brazil. Applied and Environmental Microbiology. 78:4702-4714.
  • Rugman-Jones P.F., M.S. Hoddle, R. Amrich, J.M. Heraty, C.E. Stouthamer-Ingel and R. Stouthamer (2012). Phylogeographic structure, outbreeding depression, and reluctant virgin oviposition in the bean thrips, Caliothrips fasciatus (Pergande) (Thysanoptera: Thripidae), in California. Bulletin of Entomological Research, 102: 698-709


Progress 01/01/11 to 12/31/11

Outputs
OUTPUTS: Activities:We have continued working on armored scale insects to determine what species of scales are present in California avocado groves and which parasitoids are already present controlling these scales. This in an effort to 1) determine if invasive scales from imported avocado fruit have already established in California and 2) to have a clear insight in the parasitoids already present. We have continued our work on various invasive beetle species including Gold Spotted Oak Borer, the Walnut Twig Borer and the Red Palm Weevil in order to determine the origin of these populations. We Have continued our cooperation with the CDFA on identifying the native species of Trichogramma that parasitize the invasive Light Brown Apple Moth that is spreading rapidly from focal points in Santa Cruz and San Francisco to adjacent areas. And have developed genetic methods to distinguish released Trichogramma platneri from native wasps. Finally we have continued working on the molecular identification of thrips occurring in California and have made an extensive study of the genetic variation present in two native pest species, bean thrips and blue green sharp shooter. Events: We presented our work to California Avocado Growers and at the Entomological Society of America. Services: We have identified Trichogramma species for various parties that send us material. In addition we developed a rapid identification method for parasitoids of the genus Metaphycus, natural enemies of soft scales. We also developed identification methods for invasive slugs, and did an extensive study on the genetic variation present in the plant pathogen Xylella fastidiosa. PARTICIPANTS: Principle investigator: Richard Stouthamer. General lab directions, design experiments and analyse data Paul Rugman-Jones. Associate Specialist. Does most of the work related to projects involving the application of DNA finger printing techniques. Holly Hills. Graduate student involved in the effects of mass on natural enemies. Partner Organizations California department of food and agriculture, California Avocado Commission, Collaborators and contacts Dr. L.Nunney, Dept of Biology, UCR Dr. D.A. Cooksey, Dept of Plant Pathology and Microbiology, UCR Dr. F Sumer-Ercan, Department of Biology, Faculty of Science and Arts, Bozok University, Yozgat, Turkey Dr. S.K. Jalali, National Bureau of Agriculturally Important Insects. Bangalore 560 024, Karnataka, India Dr. J. Karimi. Department of Plant Protection, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran Training or professional development Holly Hills PhD student UCR Jaime Gonzalez, PhD student UCR TARGET AUDIENCES: Target audience includes Avocado Growers of California, border inspectors (CDFA and USDA) for the identification keys we have developed, USDA Pest Risk scientists with regards to the presence of living scales on imported fruit. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
The keys we have developed in our research are applied in the identification of several pest species, in particular thrips of the genus Scirtothrips. Our earlier work on phoresy in scale insects is now being used by the USDA-APHIS to revise the pest risk assessment for scale insects of imported fruit. Our molecular work on gold spotted oak borer has narrowed down the native range of the invasive population now found in CA. The work on the released Trichogramma wasps in the biocontrol of LBAM shows that most of the hosts placed in the release areas were parasitized by the released wasps and they they have a clear impact on the LBAM egg population. Our work on the genetic variation present in Xylella fastidiosa has shown that in contrast to established believe, the causal agent of Pierce's disease is not a native bacterium, rather it has invaded North America from Central America.

Publications

  • Rugman-Jones, P.F., Morse, J.G., Luck R.F., Guereri, E., Monti, M., Stouthamer, R. (2011) Taxon-specific multiplex-PCR for quick, easy, and accurate identification of encyrtid and aphelinid parasitoid species attacking soft scale insects in California citrus groves. BioControl 56:265-275.
  • Ballman E., P.F Rugman-Jones, R. Stouthamer, M. S. Hoddle.(2011) Genetic Analyses of Graphocephala atropunctata (Hemiptera: Cicadellidae) Across its Natural Range in California Reveal Population Isolation by Increasing Distance. Journal of Economic Entomology 104:279-287
  • McDonnell, R.J., P.F. Rugman-Jones, T. Backeljau, K. Breugelmans, K. Jordaens, R. Stouthamer, T. Paine and M. Gormally. (2011). Molecular identification of the exotic slug Arion subfuscus sensu lato (Gastropoda: Pulmonata) in California, with comments on the source location of introduced populations. Biological Invasions 13:61-66
  • Nunney, L., X. Yuan, R.E. Bromley, J.S Hartung, M. Montero-Astua, R. Stouthamer (2010). Population Genomic Analysis of a Bacterial Plant Pathogen: Novel Insight into the Origin of Pierces Disease of Grapevine in the U.S. PlosOne 5(11): e15488


Progress 01/01/10 to 12/31/10

Outputs
OUTPUTS: Activities:We have continued working on armored scale insects to determine the methods used by armored scale crawlers in their dispersal, to better understand the risks involved in the massive importation of scale insects on Avocados. Our research showed that in addition to wind dispersal the scale crawlers also use phoresy for their dispersal. Phoresy can lead to a much more directed and longer dispersal than the dispersal only by wind. In addition we are are still involved in determining the genetic make-up and area of origin of the recent invasion into California of the Golden Spotted Oak Borer, a devastating pest of mature oak trees that is starting to affect Oaks in San Diego county, its area of origin is most likely Arizona. Similarly we are involved in determining the genetic makeup and area of origin of the Walnut twig borer a recent pest of Walnut trees throughout California. We cooperate with the CDFA on identifying the native species of Trichogramma that parasitize the invasive Light Brown Apple Moth that is spreading rapidly from focal points in Santa Cruz and San Francisco to adjacent areas. Finally we have continued working on the molecular identification of thrips occurring in California and discovered that the western flower thrips consists of two genetically isolated forms in California, these forms are most likely different species. Events: We presented our work to California Avocado Growers and at the Entomological Society of America. Services: We have identified Trichogramma species for various parties that send us material. PARTICIPANTS: Magsig-Castillo was trained during this project. She worked on the scale crawler dispersal and after finishing the work here she moved to Germany to do a PhD. Paul Rugman-Jones worked on the different molecular identification methods Britanny Crawford also participated in field studies on the scale insects TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Our research has shown that Scale insect crawlers, at least in the lab, are capable of dispersing by phoresy in contrast to the commonly held belief that they only disperse by wind. Our thrips work has shown that the pest species Frankliniella occidentalis consists of two forms, this has a large impact on studies of this pest species. Many papers have been published for which it is now unclear what form they were. Our work makes it easy to distinguish between these forms.

Publications

  • Rugman-Jones, P.F., J. Andersen, J. Morse, B. Normark & R. Stouthamer. (2010) Molecular Phylogenetic Placement of Abgrallaspis aguacatae Evans, Watson & Miller and Several Congeners (Hemiptera: Diaspididae) Annals of the Entomological Society 103:30-38.
  • Rugman-Jones, P.F., Hoddle, M.S. and Stouthamer, R. (2010). Nuclear-mitochondrial barcoding exposes the global pest Western flower thrips, Frankliniella occidentalis (Thysanoptera: Thripidae) as two sympatric cryptic pest species in its native California. Journal of Economic Entomology 103:877-886.
  • Magsig-Castillo, J., J.G. Morse, G.P. Walker, J.L. Bi, P.F. Rugman-Jones and R. Stouthamer (2010). Phoretic dispersal of armored scale crawlers. Journal of Economic Entomology 103:1172-1179.


Progress 01/01/09 to 12/31/09

Outputs
OUTPUTS: Activities:We have continued working on armored scale insects to develop quick and reliable methods for their identification. In addition we are now studying the methods used by armored scale crawlers in their dispersal, to better understand the risks involved in the massive importation of scale insects on Avocados. In addition we are now also involved in determining the genetic make-up and area of origin of the recent invasion into California of the Golden Spotted Oak Borer, a devastating pest of mature oak trees that is starting to affect Oaks in San Diego county. Similarly we are involved in determining the genetic makeup and area of origin of the Walnut twig borer a recent pest of Walnut trees throughout California. We cooperate with the CDFA on identifying the native species of Trichogramma that parasitize the invasive Light Brown Apple Moth that is spreading rapidly from focal points in Santa Cruz and San Francisco to adjacent areas. Finally we have continued working on the molecular identification of thrips occurring in California. Events: Participated in the International Entomophagous work shop in Minnesota and presented our thrips work in Melbourne at the IX International Symposium on Thysanaptera and Tosposviruses. In addition we presented our work to California Avocado Growers. Services: We have identified Trichogramma species for various parties that send us material. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
We have learned that many of the scales found on Avocado and are not present in North America. Our research has shown that Scale insect crawlers, at least in the lab, are capable of dispersing by phoresy in contrast to the commonly held belief that they only disperse by wind. The Trichogramma species parasitizing LBAM harbored a species not previously detected in the USA, i.e. Trichogramma fasciatum. Golden Spotted Oak Borers show a very high level of genetic variation, indicating that most likely the invading population was large or originated from many different locales

Publications

  • Hansen, A.K., J.T. Trumble, R. Stouthamer, T.D. Paine. 2008. New Huanglongbing (HLB) Candidatus species, C. Liberibacter psyllaurous, found to infect tomato and potato is vectored by the psyllid Bactericerca cockerelli (Sulc). Applied and Environmetal Microbiology 74: 5862-5865
  • McDonnell R.J., T.D. Paine, R. Stouthamer, M.J. Gormally, J.D. Harwood (2008) Molecular and morphological evidence for the occurrence of two new species of invasive slugs in Kentucky, Arion intermedius and Arion hortensis (arionidae: Stylommatophora). J. Kentucky Academy of Sciences 69:117-123.
  • Humeres, E.C., J.G. Morse, R. Stouthamer, W. Roltsch & M. S. Hoddle. (2009) Evaluation of natural enemies and insecticides for control of Pseudacysta perseae (Hemiptera: Tingidae) in Southern California. Florida Entomologist 92: 35-42
  • Morse, J. G., P. F. Rugman-Jones, G. W. Watson, J. L. Bi, L. J. Robinson & R. Stouthamer. (2009). High levels of exotic armored scales on imported avocados raise concerns regarding USDA-APHIS phytosanitary risk assessment. Journal of Economic Entomology 102: 855-867
  • Rugman-Jones, P.F., Morse, J.G., Stouthamer R. (2009) Rapid, molecular identification of armored scale insects (Hemiptera: Diaspididae) on Mexican Hass avocado. Journal of Economic Entomology 102:1948-1953.


Progress 01/01/08 to 12/31/08

Outputs
OUTPUTS: : Several studies have been completed on the scale insects present on imported avocado fruit and presentations have been given to Avocado growers regarding the importance of these findings. A publication on this topic will be published this year in a scientific journal. Several studies have been completed on various factors that may influence the success of biological control and these have been published in scientific journals. We are continuing the work on the Xylella genetic variants found in North America and a large number of isolates have been characterized. This information is made available through a website that is under development : www.xylella.org. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: In this reporting period we have been very active in communicating with the Avocado growers in California PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Our study on the scale insects found on imported avocados shows that several species that are not present in California are imported in large numbers on the fruit. While the official USDA rule on the presence of armored scales on Avocado fruit is that they only pose a small risk of establishment in our orchards, the large number of living scales (>50 million) in 9 months should result in a substantial chance that these species will establish. Several studies on the recognition of pestiferous thrips species belonging to the genus Scirtothrips have been published. One publication clarifies the status of Scirtothrips species infesting avocado in Mexico. For a while many different species were recognized based on morphological features, in this study we show that these features are very variable within the single species S. perseae. This result helps to avoid confusion that may take place if new infestations of S. perseae are found, we can now safely say they are all the same species. Another publication describes molecular methods to identify many of the pest species in the genus Scirtothrips, including species that are present in the US and those that are not yet here but are known to be pests elsewhere in the world. This study helps in the identification of these potentially invasive exotic Scirtothrips species. Two studies were published that show how symbionts may influence the effectiveness of biological control agents. In one we found a correlation between the presence of a bacterial symbiont in the host insect and the rate at which these hosts were parasitized by a parasitoid natural enemy. In the second publication we show how a bacterial symbiont of a wasps species allows it to reproduce by complete parthenogenesis. The mechanism by which this Rickettsial symbiont manipulates the meiosis of the wasp is substantially different from that employed by Wolbachia symbionts that also induce parthenogenesis in their hosts. This study clearly shows how different symbionts can accomplish the same outcome by different manipulations of their host insect.

Publications

  • Hoddle, M.S., L. A. Mound, P. F. Rugman-Jones, and R. Stouthamer 2008. Synonomy of Five Scirtothrips species (Thysanoptera: Thripidae) Described from Avocados (Persea americana) in Mexico. Florida Entomologist 91:16-21
  • Hoddle, M.S., J. M. Heraty, P. F. Rugman-Jones, L. A. Mound, and R. Stouthamer 2008. Relationships Among Species of Scirtothrips Shull 1909 (Thysanoptera: Thripidae, Thripinae) Using Molecular and Morphological Data Ann. Entomol. Soc. Am. 101(3): 491-500
  • Adachi-Hagimori, T., K. Miura, and R. Stouthamer. 2008. New cytogenetic mechanism for bacterial endosymbiont-induced parthenogenesis in Hymenoptera. Proceedings Royal Society 275:2667-2673


Progress 01/01/07 to 12/31/07

Outputs
OUTPUTS: We have been working on several Avocado pest species that have recently invaded CA. Among these are the avocado thrips, and avocado lace bug. In addition we have also been working on scale insects that are imported into California on avocado fruit. For the vocado lace bug we have been determining the DNA sequences of several genes, and have developed a number of microsatellite DNA markers. For the scale insects we have sequenced several genes of 100's of scales collected from imported fruit to determine their species identity. We have participated in two field days in May for the Avocado growers in California " Exotic pests and the California Avocado Grower", where we explained the methods we are using for the identification of the species, as well as the outcomes of this work. In addition we have presented our work on the parasitoids of the Olive Fruitfly at the 9th exotic Fruit Fly Symposium in Fresno California. The work on the fruitfly parasitoids consists of developing molecular markers that can be used to distinguish different species of the Psyttalia species complex. Many different species in this complex are closely related and cannot be confidently distinguished using morphological features. These wasps are candidates for release against the olive fly in California. In the work on identifying different Xylella strains we have continued to add more strains to our Multi Locus Sequence Typing system. This system is developed to have a precise method to communicate about the different Xylella fastidiosa strains. This plant pathogen consists of many different strains that causes scorching diseases in many different plants. PARTICIPANTS: PI/PDs Dr. Joseph Morse, Dept of Entomology, UCR Dr. Mark Hoddle, Dept. of Entomology, UCR Dr. Leonard Nunney, Dept. of Biology, UCR Dr. Frank Wong, Dept of Plant Pathology, UCR Dr. Don Cooksey, Dept of Plant Pathology, UCR Dr. Robert Luck, Dept of Entomology, UCR Partner Organizations California Avocado Commission Professional Developent Dr. Paul Rugman-Jones, post doctoral researcher TARGET AUDIENCES: Several commodity groups such as the Avocado growers and Citrus growers.

Impacts
Our work on invasive species has made us aware that many different species have invaded California and knowing the species identity and the area of origin will help in finding natural enemies for their control. Our work on the scale insect identification has shown that several species not yet present in California are imported now on avocado fruit from abroad. In addition we are determining if parasitoids are present on these scale insects, so that once these new pests do establish in California we can do a directed search for the parasitoids. Thus avoiding having the spray insecticides to economically control these pests.

Publications

  • Gols, R., C. Schutte, R. Stouthamer, M. Dicke. 2007. PCR-based identification of the pathogenic bacterium, Acaricomes phytoseiuli, in the biological control agent Phytoseiulus persimilis (Acari: Phytoseiidae). Biological Control 42: 316-325


Progress 01/01/06 to 12/31/06

Outputs
We have continued several projects on the recognition of natural enemies and pest insects in California. We have determined that several Anagrus collections that are being considered for biological control of the Galssy Winged Sharp Shooter, although morphologically identical, are different species. Consequently these should be tested separately for their potential as biocontrol agents. The Avocado Lace Bug is a new invasive species in California that we have studied and we have developed microsatellite markers for this species, in addition we have determined the DNA sequence of several genes to get a better idea about the origin of the invasive population. Collections from the Caribbean, Florida, Texas and several areas in Mexico have been studied and it appears unlikely that either the Caribbean or Florida are the source of our invasion, based on the DNA sequences of the mitochondrial COI gene our population resembles that from Texas and the area around Vera Cruz in Mexico, however when we used the microsatellites to analyse these specimens it became clear that neither our collection from Texas nor that from Vera Cruz could have been the source of the invasion. Additional collections need to be made in Mexico to get a better idea of the source of our invasion

Impacts
The studies on invasive species help in the determination of the origin of these pests, which may help in the prevention of future invasions from these sources, and can direct us to potential sources of natural enemies that are most suitable for the control of the invasive species. The studies on the identification of the parasitoids of the Glassy Winged Sharp Shooter have helped in making it clear that collections thought to be a single species really consist of several different species. Accurate identification of these species is of paramount importance for their application in biological control.

Publications

  • Rugman-Jones, P. F. , M. S. Hoddle, L.A. Mound, R. Stouthamer. 2006. A molecular key for the pest species of Scirtothirps (Thysanoptera: Thripidae). Journal of Economic Entomology 99:1813-1819.
  • P. F. Rugman-Jones, M. S. Hoddle, R. Stouthamer. 2007. Population genetics of Scirtothrips perseae: tracing the origin of a recently introduced exotic pest of Californian avocado orchards, using mitochondrial and microsatellite DNA markers. Entomologia Experimentalis et Applicata (in press)
  • Triapitsyn, S. V., D. Gonzalez, D. B. Vickerman, J. S. Noyes & E. B. White. 2007. Morphological, biological, and molecular comparisons among the different geographical populations of Anagyrus pseudococci (Hymenoptera: Encyrtidae), parasitoids of Planococcus spp. (Hemiptera: Pseudococcidae), with notes on Anagyrus dactylopii. Biological Control 41 (1): 14-24.


Progress 01/01/05 to 12/31/05

Outputs
The project on the recognition of different species/biotypes of Gonatocerus ashmeadi is concluded with the conclusion that all ashmeadi in the USA indeed are a single species where the different populations are reproductively compatible. We have also completed a project on a closely related group of egg parasitoids Gonatocerus morilli and several species have been discovered by crossing experiments and the use of molecular methods. We have finished the work on the citrus peelminer from the central valley and we have concluded that we cannot prove that the citrus peelminer found in the central valley necessarily originated from Mexico. We have found that the Coachella citrus peelminer differs from the citrus peelminer found in the central valley, but when we extended our search for peelminers to include areas in Arizona, we found that around Yuma the peelminer is of the Coachella type, but around Phoenix, we find the same citrus peelminer as in the central valley and in Mexico. Consequently the range of the central valley peelminer simply extends from Mexico, though Arizona to the central valley of California. We have concluded our work on the impact of Wolbachia on the biocontrol agent Aphytis, most of the wild and insectary populations are infected with this bacterium and little or no negative impact of this bacterium on the biocontrol effectiveness of this scale parasitoid is expected.

Impacts
The studies on invasive species help in the determination of the origin of these pests, which may help in the prevention of future invasions from these sources. For biological control it may also be helpful to know where the pest originated in order to collect the natural enemies. The work on Wolbachia has made it clear that we do not have to take specific precautions when we release insectary reared wasps in field populations. The studies on the identification of the parasitoids of the Glassy Winged Sharp Shooter help in determining which natural enemy may be useful for additional releases to suppress this pest to a non economic level.

Publications

  • Rugman-Jones, P. F., A.R. Weeks, M. S. Hoddle, R. Stouthamer. 2005. Isolation and characterization of microsatellite loci in the avocado thrips Scirtothrips perseae (Thysanoptera: Thripidae). Molecular Ecology Notes 5:644-646.
  • Liu, D., J. T. Trumble and R. Stouthamer. 2005-6. Molecular characterization indicates recent introductions of tomato psyllid (Bactericera cockerelli) into western North America are genetically different from eastern populations. Entomologia Experimentalis et Applicata (Accepted Sept. 2005, 22 ms pp.).
  • Vickerman D. B., M. S. Hoddle, S. Triapitsyn and R. Stouthamer. 2004. Species identity of geographically distinct populations of the glassy-winged sharpshooter parasitoid Gonatocerus ashmeadi: Morphology, DNA sequences and reproductive compatibility. Biological Control 31:338-345


Progress 01/01/04 to 12/31/04

Outputs
A number of new projects on the use f molecular markers for distinguishing different biotypes and species of parasitoids used in biological control have been started. In particular we have done work on the parasitoids that are used for the biological control of the Glassy Winged Sharp Shooter, the insect vector of the Pierces Disease. This work showed that most of the North American strains of the species Gonatocerus aschmeadi belong to the same species and are reproductively compatible. We have continued our work on the invasive Avocado Thrips and have developed an identification key using molecular markers for the pest species in the genus Scirtothrips. In the work on trying to identify the area of origin of the Citrus Peelminer in the central valley of California, we have developed several molecular markers that show that the Peelminer from the central valley is very similar to the peelminer found in Northern Mexico, the area from which the peelminers are thought to have invaded the central valley. Both Mexican and the central vally peelminer differ from the Citrus Peelminer found in the Coachella valley. This year we will determine if the peelminers found in Arizona resemble the ones form the central valley. If that is the case than it will be difficult to make a definitive statement about the origin of the central valley peelminers, however if the Arizona peelminers resemble the Coachella peelminers then it becomes more likely that the central valley peelminers originate from Mexico. In addition we have continued our work on the influence of symbiotic bacteria on the life history of pest insects and their parasitoids. We are now involved in determining if Wolbachia has a negative impact on the biological control agent Aphytis melinus, used for the control of the Citrus Red scale.

Impacts
The studies on the invasive species will help to determine their origin and with that can help in the prevention of future invasions from these sources. In addition it also helps in identifying areas where natural enemies can be collected. The key of thrips species for California will allow fast and unambiguous identification of these difficult to identify insects. Our studies on the Wolbachia may help in creating more efficient biological control agents once we can infect uninfected species, our work has shown that horizontal transmission is possible but is more difficult between species. The study of the Wolbachia in Aphytis will also result in a more efficient use of these parasitoids, and will make the biocontrol of Citrus Red Scale more efficient.

Publications

  • Huigens, M. E., R. P. de Almeida, P. Boons., R. F. Luck, and R. Stouthamer. 2004. Natural interspecific and intraspecific horizontal transfer of parthenogenesis-inducing Wolbachia in Trichogramma wasps. Proceedings of the Royal Society London 271: 509-515
  • Weeks, A. R. and R. Stouthamer. 2004. Increased fecundity associated with infection by a Cytophaga-like intracellular bacterium in the predatory mite, Metaseiulus occidentalis. Proceedings of the Royal Society of London - Series B: Biological Sciences. 271 (Suppl. 4): S193-S195.


Progress 01/01/03 to 12/31/03

Outputs
Several projects were initiated to study the genetics of invasive species including the Avocado Thrips and the Citrus Peelminer. Markers to study the population genetics of these species were developed to help in determining the area of origin of the Avocado Thrips and to determine if the current pest form of the Citrus Peelminer originates from California or is the offspring of an imported population. The large scale analysis of these populations will be done next. In addition we are making a key based on DNA sequences to easily identify different thrip species that are pests in California We have finished a study to help in the identification of the egg parasitoid species Trichogramma minutum and T. platneri. These species are commonly used in biological control of moth pests in orchards in California. They cannot be distinguished using morphological characters. Their correct identification is important because the release of the wrong species (T. minutum) in California could result in a reduction of the biological control exerted by the naturally occurring T. platneri. The method we developed is based on the difference in the DNA sequences between these species. In our studies on heritable factors that influence the offspring sex ratio of parasitoid wasps we are continuing our studies on the bacteria of the genus Wolbachia that are commonly found. We are particularly studying those Wolbachia that are causing their hosts to produce exclusively daughters. They produce only daughters without the need of egg fertilization. These bacteria may be applied to wasps used in biological control programs because infection with these bacteria can lead to a higher population growth rate of the wasps. We have developed methods for egg parasitoids of the genus Trichogramma to transfer the infection, however the results so far show that these infections are difficult to transmit. In addition we have initiated studies of the species Aphytis melinus, an important parasitoid of the citrus red scale in California. This species is infected with another Wolbachia bacterium that can cause sterility in crosses between infected and uninfected forms of this species. We are determining the rate at which this phenomenon occurs in this important biological control species. Recently, a second group of bacteria has been discovered that causes effects similar to those caused by Wolbachia, in order to determine how prevalent these new bacteria are we have done a survey of approximately 200 insect species. Approximately 8% of all these species was infected with these Cytophaga-like bacteria.

Impacts
The studies on the invasive species will help to determine their origin and with that can help in the prevention of future invasions from these sources. The key of thrips species for California will allow fast and unambiguous identification of these difficult to identify insects. The identification method for the Trichogramma will help mass producers sell the correct species for use in California, and will improve the biological control of moth pests in California. Our studies on the Wolbachia may help in creating more efficient biological control agents once we can infect uninfected species. The study of the Wolbachia in Aphytis will also result in a more efficient use of these parasitoids, and will make the biocontrol of Citrus Red Scale more efficient. Finally our knowledge of the common occurrence of the different bacterial symbionts of insects may open new methods for the control of insect pests.

Publications

  • Pinto, J.D., G.R. Platner & R. Stouthamer. (2003) The taxonomic status of Trichogramma minutum Riley and T. platneri Nagarkatti (Hymenoptera: Trichogrammatidae): the evidence from reproductive compatibility and allozymic studies Biological Control 27:167-180
  • van Vugt, J.F.A., M. Salverda, J.H. de Jong and R. Stouthamer (2003).Cytogenetic study on the Paternal Sex Ratio chromosome in the parasitic wasp Trichogramma kaykai. Genome 46: 580-587.
  • Weeks, A.R., R. Velten, R. Stouthamer (2003). Prevalence of a new sex ratio distorting endosymbiotic bacterium among arthropods. Proceedings of the Royal Society London (B).270:1857-1865.
  • Huigens,M.E., R.F. Luck and R. Stouthamer (2003). Reduced competitive ability due to P-I Wolbachia infection in the parasitoid wasp Trichogramma kaykai. Entomologia Experimentalis et Applicata 110: 115-123.
  • De Almeida, R. A. and R. Stouthamer (2003). Molecular identification of Trichogramma cacoeciae Marchal (Hymenoptera: Trichogrammatidae): A new record for Peru. Neotropical Entomology. 32: 269-272.
  • Borghuis, A., J.D. Pinto, G.R. Platner and R. Stouthamer (2003). Molecular identification of Trichogramma minutum and T. platneri. Biological Control (in press)