Progress 10/01/19 to 09/30/20
Outputs
Progress Report Objectives (from AD-416): Objective 1: Explore for natural enemies of invasive weeds identified as high priority targets by the ARS Office of National Programs, performing collections, importations and exportations in compliance with local and international regulations. High priority invasive weeds include but are not limited to water hyacinth, water lettuce, Brazilian waterweed, Brazilian peppertree, water primrose and giant salvinia. Objective 2: Explore for natural enemies of invasive insect pests identified as high priority targets by the ARS Office of National Programs, performing collections, importations and exportations in compliance with local and international regulations. High priority pests include but are not limited to black imported fire ant, red imported fire ant, little fire ant, tawny crazy ant, cactus moth, and cactus mealybug. Objective 3: Perform taxonomic and phylogenetic studies as needed to support the development of biological control agents, such as characterizing undescribed or cryptic parasites and herbivores of the targets. Objective 4: Identify the biological and physical parameters that affect the efficacy and safety of potential agents, including climatic conditions, host specificity, effective rearing conditions, and biogeography. Approach (from AD-416): FuEDEI (ex-SABCL) research program Project Plan approved by OSQR in 2010 includes target weeds: Brazilian peppertree (Schinus terebinthifolius), Brazilian waterweed (Egeria densa), water primrose (Ludwigia hexapetala), water lettuce (Pistia stratiotes) and waterhyacinth (Eichhornia crassipes) . Insect targets are cactus moth (Cactoblastis cactorum), little fire ant (Wasmannia auropunctata), Harrisia cactus mealybug (Hypogeococcus pungens) , imported fire ants (Solenopsis invicta and S. richteri) and the water fern (Salvinia molesta) commonly known as giant salvinia. Prior to the collection of their natural enemies, more in depth studies on the biology, ecology, genetics, and/or taxonomy of water primrose, cactus moth and little fire ant are required. These studies are planned as sub-objectives. Target priorities are set by Congressional mandates, as a result of stakeholder workshops, or by hierarchical decision with input from ARS National Program Leaders (NPLs), stakeholders, Laboratory director and ARS scientists. Flexibility in this Project is needed to deal with new pest problems in the U.S., with concurrence of PLs and ARS laboratories. FuEDEI (ex-SABCL) functions as an overseas arm for several U.S.-based biological control programs on invasive pests of South American origin, conducting foreign exploration, collection and evaluation of potential biological control agents to be used in the U.S. Waterhyacinth, Brazilian peppertree and imported fire ants were also targets in the previous Project Plan and, except for Brazilian peppertree, Obj.1 and Obj.2 have already been accomplished; current work is limited to collecting and shipping of selected agents (Obj.3). Brazilian waterweed, water primrose, water lettuce, cactus moth, little fire ants and Harrisia cactus mealybug were added by NPLs during the implementation of the previous Project Plan and investigations are in different stages of progress; for the most recently- added targets (cactus moth, little fire ant and Harrisia cactus mealybug), specific approach and procedures for Obj.2 will be determined as soon as natural enemies are discovered, collected and identified. The general impact of work conducted at FuEDEI (ex-SABCL) includes conservation of non-renewable resources by self-perpetuation of natural enemies; cost-effective suppression of target pests; decreased use of hazardous pesticides; improved environment quality; protection of natural ecosystems from invasive species, favoring biodiversity; sustainable production systems and land use; higher quality food and fiber; higher protection of human health; enhanced scientific understanding of successful biocontrol programs and integrated pest management. Brazilian peppertree (BP). A defoliating sawfly has been studied as a promising biological control agent for BP in Brazil, Hawaii and Florida since late 1990s. Like other members of the sawfly family, this species is known to produce toxic proteins with potential for poisoning wild and domesticated animals that may ingest the insect larvae. However, recent studies revealed that these proteins occurred at low concentrations, so the utilization of this species as a biological control agent for BP is being reconsidered. While conducting BP surveys in southern Brazil, a new species of sawfly larvae was collected feeding on BP. Should outcomes of toxicity and host range testing result positive, it may become a new biological control agent for Brazilian peppertree in the USA. Giant Salvinia (GS). GS is an aquatic fern that is invasive in most tropical and subtropical areas of the world. An aquatic weevil has been used as an effective natural enemy of GS for decades, however, the plant is invading more temperate areas with harsher winters in the US where the weevil is unable to overwinter. FuEDEI has been trying to find cold-hardy weevil strains in the southern range of Salvinia in South America and to explore the southern limits of Salvinia in Argentina, under the assumption that these weevils might survive Louisiana winters and control the plant. During exploration trips another species of weevil was found on a small patch of Salvinia located ca. 250 Km South of Buenos Aires city. Further field and laboratory host range studies are needed to determine the potential of this new species as a biocontrol agent for Salvinia in the USA. Salt Cedar (SC). The invasion of saltcedar in the USA and Argentina, constitutes an opportunity for collaboration on this invasive weed. Biological control of this shrub has been highly successful in the USA after the introduction of four Old World leaf beetles. Piggybacking on the biocontrol program undertaken in the USA constitutes an opportunity for Argentina to reduce costs associated with the exploratory surveys, risk assessments and rearing procedures to implement biological control of SC in the country. We have created a consortium with researchers from the ARS, FuEDEI and other local institutions to develop a classical biological control program against the plant in Argentina. The first objective of the project is to sample local populations of SC and related native plants to obtain a checklist of native and exotic insects that feed on these species. Very few herbivores have been found so far, which are in the process of being identified by specialists. Future efforts will be focused on completing the surveys along the SC invaded area in Argentina and on getting permits to import the leaf beetles form the USA with the help of the USDA-ARS-ISPH lab in Albany, CA. Little fire ant (LFA). Surveys were conducted in central and northern Argentina to collect samples of the invasive LFA. Since there are no known macroscopic effective natural enemies of LFA that can be used in a biological control program, we are exploring for useful microorganisms, such as viruses. Samples from 39 colonies were collected, preserved in ARN/DNA shield and later sent to CMAVE, ARS-USDA. Metagenomics and next generation sequencing will be employed to discover natural enemies (virus) of the LFA in its native (Argentina) and introduced (US and Australia) ranges. RNA quantity was satisfactory to conduct the analyses. Experiments were also conducted to analyze if the thermal and desiccation tolerance of LFA can explain its current and potential geographical distribution. As expected, colonies from regions with colder climates had higher cold tolerance and recovered faster from chill coma (recovery time) than colonies from warmer regions. Unexpectedly, colonies from drier regions showed a slightly higher cuticular permeability (higher loss of water) than colonies from wetter sites, suggesting that susceptibility to desiccation could be a more limiting factor than vulnerability to temperature and competition for this species. Cactus moth (CM). This species, native to South America, gregariously feeds, damages and threatens prickly pear crops and native cacti from North America. CM physically damages the plants by eating its inner tissues during larval development, causing decreased plant longevity and fruit production. However, losses in the fruit production have not been quantified. Estimation of the effect of CM on prickly pear production was evaluated in a commercial plantation for the first time, resulting in drastic fruit loss as pest density increased. This information supports the need to continue with the biological control program of this pest in North America and advance in the studies for the release of a small wasp that is the most specific and potential biocontrol agent known to date. This wasp is being mass reared at quarantine at DPI-FDACS, FL. Research and specificity tests continue, as well as mass rearing of the parasitoid. Additionally, the evaluation of a second parasitoid and potential biocontrol agent has started with laboratory and semi-field experiments. This parasitoid is used in inundative biocontrol programs against several pests of pome fruits with great success in Argentina. The effectiveness of a pheromone monitoring trap as an estimator of moth abundance in naturally attacked plantations continues to be evaluated. Population structures of native populations of the cactus moth, as well as of related species, are being assessed with next-generation DNA sequencing. Huanglongbing (HLB): Xylella fastidiosa, the bacterium that causes HLB also causes several plant diseases of economic importance: grapevine Pierce's disease; citrus variegated chlorosis; peach phony disease; plum leaf scald, olive scorch; as well as leaf scorch diseases on almond, coffee, oleander, pecan, and several berry species. This bacterium is vectored by a leafhopper known as Asian citrus psyllid. Our objective is to genetically characterize the populations of the vector⿿s main parasitoid in Argentina through the study of their population structure and correlation with the known population structure of the disease vector. We are also screening other native leafhopper species that might vector the disease. Several molecular and preservation techniques were compared to find the best technique to achieve this knowledge. Next step is to acquire more samples for another combination of primers to improve the sequencing techniques. Tawny crazy ant (TCA). TCA is an invasive ant in Central and North America, both in natural and urban areas. Our research has revealed the existence of species complexes within the genus (Nylanderia). In addition, the two invasive species in the U.S. have cryptic workers. Due to these difficulties to determine which species is which, we are carrying out a species delimitation study in the native range, through which we found that invasive TCA populations belong to a single lineage. New explorations in the native range are aimed at collecting TCA decapitating phorid flies to carry out phylogenetic analyses that will confirm if there is only one or more species parasitizing both lineages. Finally, studies of a bacterium, Wolbachia, which infects all lineages, suggests these bacteria are not driving speciation within the TCA species complex. Harrisia cactus mealybug (HCM): this mealybug is devastating native cacti in Puerto Rico and threatening cactus diversity in the Caribbean and North America. In fact, the California Department of Food and Agriculture has detected and eradicated six times the Puerto Rican pest from nurseries and gardens in California. The cacti pest is an undescribed species of the HCM species complex, constituted by at least 5 species. FuEDEI discovered and reared two parasitoid species that attack HCM populations. Laboratory host range testing was conducted in Argentina to predict post-release impacts on the pest in Puerto Rico. We tested five populations of mealybugs of the same genus as the Puerto Rico cacti pest, plus two species from other genera, and the results of this study indicate that both parasitoids are specific to the pest genus, such that other, non-pestiferous, mealybugs would not be at risk. When travel from South America to Puerto Rico is resumed, a shipment will be made to restart colonies of both parasitoid species and specificity tests on 10 non-target Puerto Rican mealybugs. This shipment was ready by early 2020, but due to the CoV shutdown, the shipment is estimated to be sent toward the end of 2020. Genetic studies indicate that the origin of the Puerto Rican cactus pest is in Brazil, and that the mealybug detected on cacti in California belongs to the same species. The mealybug collected on Amaranthaceae and/or Portulacaceae in Puerto Rico and the continental United States is another member of the HCM complex. These findings suggested two independent invasion events of two different mealybug species in Puerto Rico and the continental United States. Accomplishments 01 Brazilian peppertree - BP. The discovery of a new phytophagous insect associated with S. terebinthifolia that resulted in the description of a new sawfly species, Heteroperreyia kava Smith. 02 Water hyacinth - WH. A documentary about biological control of the plant and community engagement in a nearby lake is now online. This documentary explains the invasion of the plant, the operation of the biological control program, and the role of the community, particularly the educational sector, in the project. 03 Giant salvinia - GS. A population of the weevil T. parvulus was found in temperate, southern areas, opening possibilities for a new, cold- resistant, biocontrol agent for this aquatic weed. 04 Little fire ant - LFA. The thermal and desiccation tolerance of population of W. auropunctata distributed along temperature and rainfall gradients were characterized which could allow predicting its current and potential spread in the Americas.
Impacts
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Publications
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Progress 10/01/18 to 09/30/19
Outputs
Progress Report Objectives (from AD-416): Objective 1: Explore for natural enemies of invasive weeds identified as high priority targets by the ARS Office of National Programs, performing collections, importations and exportations in compliance with local and international regulations. High priority invasive weeds include but are not limited to water hyacinth, water lettuce, Brazilian waterweed, Brazilian peppertree, water primrose and giant salvinia. Objective 2: Explore for natural enemies of invasive insect pests identified as high priority targets by the ARS Office of National Programs, performing collections, importations and exportations in compliance with local and international regulations. High priority pests include but are not limited to black imported fire ant, red imported fire ant, little fire ant, tawny crazy ant, cactus moth, and cactus mealybug. Objective 3: Perform taxonomic and phylogenetic studies as needed to support the development of biological control agents, such as characterizing undescribed or cryptic parasites and herbivores of the targets. Objective 4: Identify the biological and physical parameters that affect the efficacy and safety of potential agents, including climatic conditions, host specificity, effective rearing conditions, and biogeography. Approach (from AD-416): FuEDEI (ex-SABCL) research program Project Plan approved by OSQR in 2010 includes target weeds: Brazilian peppertree (Schinus terebinthifolius), Brazilian waterweed (Egeria densa), water primrose (Ludwigia hexapetala), water lettuce (Pistia stratiotes) and waterhyacinth (Eichhornia crassipes) . Insect targets are cactus moth (Cactoblastis cactorum), little fire ant (Wasmannia auropunctata), Harrisia cactus mealybug (Hypogeococcus pungens) , imported fire ants (Solenopsis invicta and S. richteri) and the water fern (Salvinia molesta) commonly known as giant salvinia. Prior to the collection of their natural enemies, more in depth studies on the biology, ecology, genetics, and/or taxonomy of water primrose, cactus moth and little fire ant are required. These studies are planned as sub-objectives. Target priorities are set by Congressional mandates, as a result of stakeholder workshops, or by hierarchical decision with input from ARS National Program Leaders (NPLs), stakeholders, Laboratory director and ARS scientists. Flexibility in this Project is needed to deal with new pest problems in the U.S., with concurrence of PLs and ARS laboratories. FuEDEI (ex-SABCL) functions as an overseas arm for several U.S.-based biological control programs on invasive pests of South American origin, conducting foreign exploration, collection and evaluation of potential biological control agents to be used in the U.S. Waterhyacinth, Brazilian peppertree and imported fire ants were also targets in the previous Project Plan and, except for Brazilian peppertree, Obj.1 and Obj.2 have already been accomplished; current work is limited to collecting and shipping of selected agents (Obj.3). Brazilian waterweed, water primrose, water lettuce, cactus moth, little fire ants and Harrisia cactus mealybug were added by NPLs during the implementation of the previous Project Plan and investigations are in different stages of progress; for the most recently- added targets (cactus moth, little fire ant and Harrisia cactus mealybug), specific approach and procedures for Obj.2 will be determined as soon as natural enemies are discovered, collected and identified. The general impact of work conducted at FuEDEI (ex-SABCL) includes conservation of non-renewable resources by self-perpetuation of natural enemies; cost-effective suppression of target pests; decreased use of hazardous pesticides; improved environment quality; protection of natural ecosystems from invasive species, favoring biodiversity; sustainable production systems and land use; higher quality food and fiber; higher protection of human health; enhanced scientific understanding of successful biocontrol programs and integrated pest management. Brazilian peppertree: Brazilian peppertree is a sprawling shrub or small tree that has been introduced to California, Texas, Hawaii, Arizona, Nevada, Louisiana and Florida. Planted originally as an ornamental outside of its native range, Brazilian pepper has become widespread and is considered an invasive species in many subtropical regions. The release petition for a sawfly with a restricted host range as a control agent for BP was delayed to assess whether the insect is toxic to wildlife and livestock. Field and laboratory host range studies are being conducted with previously untested species. Giant salvinia: This aquatic fern, an important fern in the US, has an effective natural enemy in a weevil. However, it is invading areas with harsher winters where the weevil cannot establish. The aim is to find cold-hardy strains of the weevil from Argentina and Uruguay. The southern limits of Salvinia were explored in Argentina, south of Buenos Aires city, where the weevil is not known to thrive. Floating pennywort: Floating pennywort is an aquatic creeper that blocks the surface of water bodies affecting the health and use of fresh water bodies in its invasive range in Europe and Australia. A species of weevil that impacts native pennywort populations heavily in its native range has been studied quite intensively as a biocontrol candidate and was introduced in quarantine facilities in the UK for specificity and impact tests. Problems with exportation permits from Argentina have made it very difficult to ship enough live material to perform these tests. Export permits were obtained from Paraguay, and a fresh batch of field- collected weevils were hand carried to UK to complete specificity studies on Old World plant species. Waterhyacinth (WH): WH is an aquatic floating plant that invades and covers entire water bodies, changing both structure and diversity of macrophyte communities, increasing fish mortality, degrading wetlands and water bodies. This invasive species is currently spreading to higher latitudes than historically recorded, probably as a result of global warming. WH sites in South Africa and Argentina were sampled for morphological and demographic plant features to compare invaded sites in the exotic range and invaded and natural sites in the native range. Data is used to calibrate different climate change models for the weed. A Community Engagement Biocontrol Program was devised in which students from an agricultural school are now mass rearing a weevil and a planthopper to control WH in the local lake. Water primrose: WP is an aggressive invader that reproduces by seed and vegetatively, and is a serious threat to the stability of aquatic ecosystems in the USA and Europe. Neither chemical nor mechanical control provide long term results. In their native range these species tend to grow in small patches and are usually mixed with other native plants. Promising biocontrol agents are being evaluated from among the 19 insect species found in association with the plant in its native range in Argentina. Morphological and molecular studies as well as biological and host specificity studies of a very damaging flea beetle are being carried out. Little fire ant: We evaluated interference competition of LFA with 3 invasive species: red fire ant (RFA), Argentine ant and tawny crazy ant, to determine their hierarchy in the southernmost limit where all coexist. Species supremacy varied according to daily and seasonal temperature in each region. RFA was dominant over the 3 species. LFA was less cold- tolerant showing it cannot continue invading further south in Argentina. Leaf-cutting ants (LCA): LCA are important forestry pests. Willow and poplar plantations were studied for 5 years to determine preference and defoliation damage in new forestations. Coexistence of both LCA species in this region was analyzed. For the first time, the level of economic damage and threshold of action were determined for LCA. Tawny crazy ant (TCA): TCA is an ant species from southern South America introduced in Central and North America. It affects native ant biodiversity and hinders urban environments and agriculture. A phorid fly that attacks TCA was found in Buenos Aires and Misiones provinces, and confirmed by a phylogenetic study to be a single species. Samples in the native range showed four distinct groups of haplotypes. The sympatric distribution of two of these groups that represent TCA populations suggest that the species is going through a speciation process. Studies show that there is a mixed reproductive system: sexual and clonal reproduction as well as diploid males in populations of Argentina. Population analysis showed that TCA has a super colonial structure in the US with colonies up to 2000 km wide, while in the native range, super- colonies seem to be much smaller (5 km). In the introduced range, hundreds of reproductive queens were found, each mated by a single male, but only a maximum of nine queens and dozens of males were found in native nests. Harrisia cactus mealybug (HCM): This mealybug from South America is a serious threat to native and endemic cacti from Puerto Rico and continental U.S. Laboratory host range testing is being conducted to predict post-release impacts on the two parasitoids shipped from South America to Puerto Rico. We tested five populations of mealybugs closely related to the Puerto Rico cacti pest, plus two non-target mealybug species. The results of this study continue to be promising; both parasitoids, as occurs in the field in the native range, are specific to the cacti pest genera. Specificity tests are soon to be completed in Argentina and Puerto Rico after which we will apply for the release of these biological control organisms. Identity of the mealybug species that invaded Puerto Rico is also under study. Evidence suggests that HCM is not a single species, rather a species complex. Preliminary results indicate that the complex could comprise the cacti pest of Puerto Rico plus 4-5 different species. These results were supported by genetics and biological studies. We also found that the Puerto Rican cacti pest is the result of only one invasive event. Cactus moth: This moth is native to Southern South America, and it threatens several crop and vulnerable cacti from North America. Research continues on the mass rearing of a parasitoid that is a potential biocontrol agent for cactus moth. The fluctuations in field parasitism rates of the parasitoid were evaluated, as well as the effect of the cactus moth on fruit production of prickly pears in the native range. Genetic analyses have started to shed light on population structures of the cactus moth and related species regarding their host plants. Bellyache bush: Bellyache bush is a major weed of rangelands and riparian zones in dry tropical Australia. Biological control is considered the most economically viable and long-term management solution for this widespread invader. Native range surveys have come up with two undescribed leaf-feeding gall midges that cause shoot-tip dieback and terminal galls. Host specificity tests were performed on species of economic significance, and to date the results of these no choice trials are promising. Silverleaf nightshade: Silverleaf nightshade is one of the worst invasive plants worldwide. New explorations in the native range are ongoing to study and develop a biological control program against this invasive weed in Australia. The main objective is to explore the native range of the weed in Argentina and look for potential biocontrol agents. Several natural enemies are being evaluated, including a mite, a leaf beetle, a rust and a lace bug. Cabomba: Cabomba is a submerged plant native to the Americas, common in the acidic, clear waters of the Iberá wetlands in northeastern Argentina. It is invasive in Australia, southeast Asia, China, India, and parts of Europe and North America. It affects water use in all its forms, as well as native aquatic flora and fauna. Efforts are devoted to the collection, study and rearing of an aquatic weevil which develops on cabomba during its larval stage inside stem mines and as an adult by feeding on the tips and laying its eggs on the leaves. Specificity tests indicate this weevil is probably specific enough to be used as a biocontrol agent where the plant is invasive. Accomplishments 01 Brazilian pepper tree. In July, the ARS lab in Florida released the first biological control agent of the invasive weed Brazilian peppertree: a leaf-feeding thrips that reduces the growth and reproduction of this noxious weed. A lab in Argentina has been cooperating on the BP project since 2005, conducting extensive exploratory surveys and host range studies of this thrips in South America. 02 Little Fire Ant. Competitive interactions among four highly invasive ant species were studied in connection with ambient temperature. This could allow to predict their hierarchy of dominance depending on the daily and seasonal temperatures of the region in the world where they are able to coexist. 03 Leaf cutting ants. Results related to the natural history of two sympatric species of LCA provide relevant information for their management and control in forest plantations. Economic damage and action thresholds were estimated for the first time in Argentina and for an Acromyrmex species. These values are important for management and a fundamental requirement to obtain a forestry certification (FSC- Forest Stewardship Council) in the Lower Delta of the Paraná River, and other forestry regions of South America 04 Tawny crazy ants. We are beginning to understand which Nylanderia species are present in southern South America, the distribution of the invasive ant N. fulva, and its parasitoid fly, a potential biocontrol agent. Evidence of clonal reproduction and diploid males were found in populations from Argentina. 05 Harrisia Cactus Mealybug. In May 2019, mealybug parasitoids and their hosts were collected in Paraguay. Exportation permits were obtained to ship two mealybug parasitoids to the quarantine facilities in Puerto Rico. Field host range studies and preliminary laboratory host specificity tests with the two parasitoids indicate that both species are restricted to the mealybug. We found the Brazilian origin of the HCM population pest present in Puerto Rico. The cacti pest of Puerto Rico was also found as a pest on Cactaceae in California, U.S. It is a new species restricted to cacti. 06 Bellyache bush. The gall midge collected on this plant was originally identified as the pest species Prodiplosis longifila, yet after testing several crops known to host this gall midge, results show that the Paraguay species is different from the pest species. The rejection of crop species as hosts makes this gall midge a promising candidate for biological control of bellyache bush. 07 Giant Salvinia. A new population of Salvinia weevil was located in temperate, southern areas, opening possibilities for new, cold- resistant, agents for this floating weed. 08 Water hyacinth. The biological control program carried out at the Agricultural School in San Vicente was declared of Scientific and Cultural Interest by the Municipality of San Vicente and by the Congress of the Province of Buenos Aires. The Municipality of San Vicente, the Ministry of Education of the Province of Buenos Aires and FuEDEI signed a cooperation agreement in November 2018. "Biological Control Environment" is now part of the curriculum of the school. 09 Water primrose. A colony of a thrips as biocontrol of water primrose was exported and established at the ARS lab in Albany, California. 10 Cabomba. We managed to complete the life cycle of the cabomba weevil (a probable biocontrol agent) in small tanks under controlled conditions. This is the first time this goal was achieved. Although a mass rearing colony is not established yet, recent results are promising.
Impacts
(N/A)
Publications
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Progress 10/01/16 to 09/30/17
Outputs
Progress Report Objectives (from AD-416): Objective 1: Explore for natural enemies of invasive weeds identified as high priority targets by the ARS Office of National Programs, performing collections, importations and exportations in compliance with local and international regulations. High priority invasive weeds include but are not limited to water hyacinth, water lettuce, Brazilian waterweed, Brazilian peppertree, water primrose and giant salvinia. Objective 2: Explore for natural enemies of invasive insect pests identified as high priority targets by the ARS Office of National Programs, performing collections, importations and exportations in compliance with local and international regulations. High priority pests include but are not limited to black imported fire ant, red imported fire ant, little fire ant, tawny crazy ant, cactus moth, and cactus mealybug. Objective 3: Perform taxonomic and phylogenetic studies as needed to support the development of biological control agents, such as characterizing undescribed or cryptic parasites and herbivores of the targets. Objective 4: Identify the biological and physical parameters that affect the efficacy and safety of potential agents, including climatic conditions, host specificity, effective rearing conditions, and biogeography. Approach (from AD-416): FuEDEI (ex-SABCL) research program Project Plan approved by OSQR in 2010 includes target weeds: Brazilian peppertree (Schinus terebinthifolius), Brazilian waterweed (Egeria densa), water primrose (Ludwigia hexapetala), water lettuce (Pistia stratiotes) and waterhyacinth (Eichhornia crassipes) . Insect targets are cactus moth (Cactoblastis cactorum), little fire ant (Wasmannia auropunctata), Harrisia cactus mealybug (Hypogeococcus pungens) , imported fire ants (Solenopsis invicta and S. richteri) and the water fern (Salvinia molesta) commonly known as giant salvinia. Prior to the collection of their natural enemies, more in depth studies on the biology, ecology, genetics, and/or taxonomy of water primrose, cactus moth and little fire ant are required. These studies are planned as sub-objectives. Target priorities are set by Congressional mandates, as a result of stakeholder workshops, or by hierarchical decision with input from ARS National Program Leaders (NPLs), stakeholders, Laboratory director and ARS scientists. Flexibility in this Project is needed to deal with new pest problems in the U.S., with concurrence of PLs and ARS laboratories. FuEDEI (ex-SABCL) functions as an overseas arm for several U.S.-based biological control programs on invasive pests of South American origin, conducting foreign exploration, collection and evaluation of potential biological control agents to be used in the U.S. Waterhyacinth, Brazilian peppertree and imported fire ants were also targets in the previous Project Plan and, except for Brazilian peppertree, Obj.1 and Obj.2 have already been accomplished; current work is limited to collecting and shipping of selected agents (Obj.3). Brazilian waterweed, water primrose, water lettuce, cactus moth, little fire ants and Harrisia cactus mealybug were added by NPLs during the implementation of the previous Project Plan and investigations are in different stages of progress; for the most recently- added targets (cactus moth, little fire ant and Harrisia cactus mealybug), specific approach and procedures for Obj.2 will be determined as soon as natural enemies are discovered, collected and identified. The general impact of work conducted at FuEDEI (ex-SABCL) includes conservation of non-renewable resources by self-perpetuation of natural enemies; cost-effective suppression of target pests; decreased use of hazardous pesticides; improved environment quality; protection of natural ecosystems from invasive species, favoring biodiversity; sustainable production systems and land use; higher quality food and fiber; higher protection of human health; enhanced scientific understanding of successful biocontrol programs and integrated pest management. Water primrose. Native to South America,19 species of specialized insects were found in Argentina. A thrips described as a new species was selected for further studies. In new surveys in the islands of the Parana River delta, a different species of Liothrips was found on Ludwigia peruviana. It has not yet been identified. Waterhyacinth. Studies were focused on one promising biological control agent, the planthopper Taosa longula, specifically its field reproductive biology, and its relationship with physical and chemical features of the host plant. These studies took two years, and were performed in the insect�s native range in northern Argentina. There was an apparent increase of gravid females during summer associated with plant �leaf toughness and nitrogen content, which is now being investigated in a biological station (CECOAL) in Northeastern Argentina in large field cages. Also, the FUEDEI team is following the development of waterhyacinth populations in two lakes where the plant is invasive. One is in the porvince of La Rioja (150 ha) where the plant was reported as invasive 50 years ago, and biological control was implemented 42 years ago with the release of the waterhyacinth weevil. The weevils reduced plant cover from the full 150 ha to less than 1 ha. In the second lake (30 ha) the BC program was begun recently (less than 3 years ago). The data show a reduction in biomass and density of almost 50 % coincidental with a weevil population increase, suggesting it is probably a consequence of the weevils we added to the system. Alligator weed. Native to South America its characteristics and natural enemies have been studied at FuEDEI for several years. According to a predictive model for weed distribution, the main environmental variables are temperature, seasonality and precipitation of the warmest quarter. Ploidy levels affect the impact of biocontrol agents and were determined for 20 populations from the whole range of the plant. Sampling for natural enemies on AW populations will continue for another year. Some organisms are pending identification. Specialist insects collected were the known thrips and five flea beetles. Floating pennywort. This plant grows on slow water bodies preventing light penetration, producing eutrophication, oxygen depletion, local species extinctions and water fouling, affecting water use and quality. Tests show the weevil Listronotus elongatus to be a likely biocontrol agent as it is specialized on floating pennywort, but quarantine tests in UK suggest the European native, marsh pennywort, may be at risk. Lab tests showed that the South American native Hydrocotyle modesta could sustain high adult feeding, but in natural settings this did not occur. We carried out two-way tests between floating pennywort and H. modesta together with similar tests performed at CABI, UK, between floating and marsh pennywort. After two weeks no survival was observed in the H. modesta pots. All the feeding damage occurred within the first 10 days. Ovipositions observed did not prosper because the leaf petioles cannot take the oviposition damage. Also, oviposition was around twenty-fold higher on the weevil�s natural host; larval survival was significant. Giant salvinia. Invasive in tropical and subtropical areas, it is invading more temperate areas with harsher winters. The aquatic weevil, Cyrtobagous salviniae is an effective natural enemy, but it cannot overwinter in temperate areas. We are searching for cold-hardy strains of the weevil in Argentina and Uruguay, studying its abundance and reproductive stages in the southern range of salvinia. Cold tolerant assessments suggest survival at 0�C was greater in the Lower Paran�- Uruguay Delta population compared to the Louisiana population, so the Lower Paran�-Uruguay Delta provenance should be considered for managing the fern in temperate regions. Population dynamics of the weevil is being studied. A lake near Buenos Aires city, mostly covered with the fern, is used to attempt the introduction and establishment of the weevil for experimental purposes. Dome-floating cages containing weevils were installed on the lake and are checked periodically. Cabomba. A South American plant, fanwort grows rooted in mud of stagnant to slow-flowing water. It is a severe weed in temperate North America, and other countries. South America and USA were surveyed for natural enemies; herbivores were found feeding on cabomba, all in Argentina, but only one weevil is likely to be specific to this plant. Tests were run on several submerged plants in the fanwort environment in South America as no other species of Cabombaceae was recorded for Argentina. No-choice testing was shifted to other plant species. Results suggest larvae are highly specific, and unable to feed on any of the other aquatic plants. All the larvae died within 4 or 5 days, but a significant proportion of the larvae could re-enter fresh cabomba stems. As for adult feeding, mortality was not considered since adult weevils can go without food for weeks. But some inconsistent feeding was observed on two species of water lilies. Leaf-cutter ants . LCA are pests in forest plantations and crops in the Neotropics. Much of the original coverage of the Parana River lower Delta was replaced by willow and poplar plantations, the habitat of 2 sympatric species of leafcutter ants. Damage produced by LCA on willow forestations was quantified for 3 years. Daily and annual foraging activity and diet of LCA were studied, and nest density in different habitats is under study to estimate impact on vegetation. Critical temperatures were measured for each species in the lab and these parameters of thermal tolerance compared to field foraging temperature for each LCA species. Foraging preference was studied by offering leaves of willows, poplars, and native plants. Field surveys for LCA were extended to new regions of Argentina. Potential areas of distribution and niche overlap analysis for the most widespread and detrimental LCA were estimated. Preliminary phylogenetic analyses were carried out using sequence fragments of nuclear gene and mitochondrial genes. Tawny crazy ant. A major pest introduced in the US in 2002 from an unknown site in its native range. Nest surveys focused on northeastern Argentina. As in populations introduced in the US, native populations did not show evidence of aggressive behavior between nests. Comparison of sequences from a mitochondrial gene (COI) between the native range and the US showed that the number of mitochondrial haplotypes in the native range was higher and more diverse than in the US. A neighbor joining distance tree recovered three haplogroups: all introduced populations grouped in a single haplogroup containing a haplotype from Misiones (Argentina), Paraguay and Brazil similar to a haplotype in Texas and Louisiana, and a haplotype from Entre Rios (Argentina) which is similar to a haplotype in Florida and Texas and related to the haplotype in Virgin Islands. This suggests that they originated in northeastern Argentina and nearby areas of Paraguay and Brazil, in the Atlantic Forest ecoregion. Population genetic analysis from Argentina revealed that queens were homozygous in more loci than workers, which were mostly heterozygotes. These unusual genotype frequencies could have resulted from a combination of sexual and asexual reproduction, as in other invasive ants. Harrisia cactus mealybug. Until recently identified as Hypogeococcus pungens and now an unknown species of the genus Hypogeococcus, it is a pest of native and endemic columnar cacti in dry districts of Puerto Rico. Molecular identification of the components of the HCM complex, the description of new species, and the re-description of previously studied valid species of all components of the HCM species complex found in Puerto Rico, Brazil, Paraguay and Argentina, continued. HCM and its parasitoids were collected on different host plants in Brazil, Paraguay and Argentina. Two shipments of parasitoids were successfully sent from South America to a quarantine facility in Puerto Rico. Cactus moth. Focus continued on improving mating and rearing of the parasitoid wasp colony and reducing the male biased sex ratio. Newly emerged wasps placed in large cages with larvae feeding on whole cacti pads lead to the wasps� immediate flight and mating of adults in the roof of polyester gauze cages: mating was observed for the first time in laboratory conditions. Field experiments were conducted to compare growth and fruit production in healthy and attacked plants. Attacked cacti produced half the fruit of healthy plants and cladodes decreased with the presence of CM. Brazilian peppertree. A defoliating sawfly was studied as a probable biocontrol agent for BP. Further studies with this insect were delayed due to potential toxicity of the larvae. Given the restricted field and lab host range of the sawfly and its potential as a BP biocontrol agent, additional toxicity studies were carried out to determine the existence of toxic peptides in the larvae. Host plant use in the native range and host specificity studies with untested cashew family species are being conducted. Sawfly larvae from South America were sent to the Royal Belgian Natural Sciences Institute for toxicity studies.The sawfly laid eggs on all tested species including native South American cashew family and economically important pistachio tree. More tests will be carried out in laboratory and natural scenarios. Parasitoid adults were sent to Fundaci�n Lillo for identification. In Brazil, natural enemies were collected and shipped to US quarantine facilities for further studies. Accomplishments 01 We can confirm that the pest in Puerto Rico is not Hypogeococcus pungens sensu stricto, given that this species is restricted to host plants of the family Amaranthaceae. 02 A new species of parasitoids was described from Salta province, Argentina, Anagyrus lapachosus Triapitsyn, Aguirre & Logarzo (Encyrtidae). 03 Waterhyacinth: one of the most stunning results of this work was the discovery, looking for different maturity grades of females, of a mating orifice in Taosa longula, which is open and only visible only in mated females. Females dissected that had the orifice visible were found to be full of eggs, or they had elongated ovariols. In females wihout a visible mating orifice, the ovaries were hard to find, because they were very small and immature.
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Progress 10/01/15 to 09/30/16
Outputs
Progress Report Objectives (from AD-416): Objective 1: Explore for natural enemies of invasive weeds identified as high priority targets by the ARS Office of National Programs, performing collections, importations and exportations in compliance with local and international regulations. High priority invasive weeds include but are not limited to water hyacinth, water lettuce, Brazilian waterweed, Brazilian peppertree, water primrose and giant salvinia. Objective 2: Explore for natural enemies of invasive insect pests identified as high priority targets by the ARS Office of National Programs, performing collections, importations and exportations in compliance with local and international regulations. High priority pests include but are not limited to black imported fire ant, red imported fire ant, little fire ant, tawny crazy ant, cactus moth, and cactus mealybug. Objective 3: Perform taxonomic and phylogenetic studies as needed to support the development of biological control agents, such as characterizing undescribed or cryptic parasites and herbivores of the targets. Objective 4: Identify the biological and physical parameters that affect the efficacy and safety of potential agents, including climatic conditions, host specificity, effective rearing conditions, and biogeography. Approach (from AD-416): FuEDEI (ex-SABCL) research program Project Plan approved by OSQR in 2010 includes target weeds: Brazilian peppertree (Schinus terebinthifolius), Brazilian waterweed (Egeria densa), water primrose (Ludwigia hexapetala), water lettuce (Pistia stratiotes) and waterhyacinth (Eichhornia crassipes) . Insect targets are cactus moth (Cactoblastis cactorum), little fire ant (Wasmannia auropunctata), Harrisia cactus mealybug (Hypogeococcus pungens) , imported fire ants (Solenopsis invicta and S. richteri) and the water fern (Salvinia molesta) commonly known as giant salvinia. Prior to the collection of their natural enemies, more in depth studies on the biology, ecology, genetics, and/or taxonomy of water primrose, cactus moth and little fire ant are required. These studies are planned as sub-objectives. Target priorities are set by Congressional mandates, as a result of stakeholder workshops, or by hierarchical decision with input from ARS National Program Leaders (NPLs), stakeholders, Laboratory director and ARS scientists. Flexibility in this Project is needed to deal with new pest problems in the U.S., with concurrence of PLs and ARS laboratories. FuEDEI (ex-SABCL) functions as an overseas arm for several U.S.-based biological control programs on invasive pests of South American origin, conducting foreign exploration, collection and evaluation of potential biological control agents to be used in the U.S. Waterhyacinth, Brazilian peppertree and imported fire ants were also targets in the previous Project Plan and, except for Brazilian peppertree, Obj.1 and Obj.2 have already been accomplished; current work is limited to collecting and shipping of selected agents (Obj.3). Brazilian waterweed, water primrose, water lettuce, cactus moth, little fire ants and Harrisia cactus mealybug were added by NPLs during the implementation of the previous Project Plan and investigations are in different stages of progress; for the most recently- added targets (cactus moth, little fire ant and Harrisia cactus mealybug), specific approach and procedures for Obj.2 will be determined as soon as natural enemies are discovered, collected and identified. The general impact of work conducted at FuEDEI (ex-SABCL) includes conservation of non-renewable resources by self-perpetuation of natural enemies; cost-effective suppression of target pests; decreased use of hazardous pesticides; improved environment quality; protection of natural ecosystems from invasive species, favoring biodiversity; sustainable production systems and land use; higher quality food and fiber; higher protection of human health; enhanced scientific understanding of successful biocontrol programs and integrated pest management. Water primrose. A thrips was evaluated by lab and field studies in Argentina as a candidate for biocontrol of water primrose, an invasive plant in California. The thrips was tested following no-choice feeding protocols, testing related plants and species that coexist in the environment. They only developed on two invasive species of water primrose. Damage tests showed that thrips� nymphs and adults affected the development of the plant. Lab tests were complemented with field searches of the thrips in different potential host plants in Argentina; results showed that the thrips was associated only with the target host. Studies should be completed in quarantine facilities in the US on native species. Waterhyacinth. Two ongoing studies are a) biocontrol of waterhyacinth in water bodies of Argentina with native insects to evaluate compatibility and impact in the field; b) search for clues to improve rearing methodologies of a potential biological control agent. In the El Ojo Lake, Buenos Aires, a lake isolated from the natural distribution of the plant, only the weevils Neochetina spp established among four species released. Weevil density had increased exponentially18 months after their release, waterhyacinth biomass diminished to almost half of its original weight (from 15 tons to 8 tons/ha). The search for factors that affect the reproductive behavior of a planthopper in northeastern Argentina continues. Efforts concentrate on the apparition of sperm cells and/or eggs in females in relation to physical and chemical plant characteristics and other environmental clues. Water lettuce. Work on water lettuce is on hold, evaluating effects and interaction of two biocontrol agents on a natural population of Pistia invading a provincial reserve in Buenos Aires. Brazilian waterweed. Experiment underway involving 10 250-liter tubes connected to pumps imitating a tidal system to compare in the lab the reproductive success of the leaf-mining shore fly Hydrellia egeriae on Brazlian waterweed patches with stable water levels (plants always accessible for ovipositing) to their success on patches subjected to a tidal regime (plants periodically inaccessible). Brazilian peppertree. During reporting period July 2015-July 2016, testing of prospective agents and the search for new ones in Argentina continue to be priorities for the Brazilian peppertree (BP) biological control project. Surveys in Argentina and Brazil revealed the presence of several defoliating caterpillars: inchworms and two cryptic moth species. During a 6-day fieldtrip in November 2015, a total of 23 inchworms, 19 Paectes sp. moth and 214 Episimus sp. moth larvae were collected by beating on 236 Brazilian peppertree plants at 14 sites. Parasitism rates of collected moth species were: inchworms 0%; Paectes sp. moth 19% and Episimus sp. moth 18%. The defoliating sawfly, Heteroperreyia hubrichi, has been intensively studied as a prospective biocontrol agent for BP. Further studies with this insect are delayed due to the potential toxicity of the larvae of this species. Considering the restricted host range of the sawfly, additional toxicity studies are conducted to determine the existence of toxic peptides in this species. In an 8-day trip in May 2016, a total of 72 larvae of the sawfly and nine larvae of a closely related species were collected, fixed in 100% ethanol and preserved for subsequent toxicity studies. Giant salvinia. The aquatic salvinia weevil is an effective natural enemy of Giant salvinia in most tropical and subtropical areas of the world. The plant is invading more temperate areas with harsher winters in the US (Texas and Louisiana), so that the weevil populations cannot get established and overwinter. During the reporting period, July 2015- July 2016, 6 field day-trips were made to study the seasonal abundance and population dynamics of cold-hardy ecotypes/strains of the salvinia weevil at a site in the south of Entre R�os Province, Argentina. A total of 10330 adults of the weevil were collected from 28 kg of dry matter of Salvinia plants in Berlese funnels. The physiological age structure of the salvinia weevil is being studied. A subsample of 20 females from each collection trip is being dissected and their reproductive developmental stage determined. Besides the salvinia weevil, about 30 morphospecies of weevils associated with Giant salvinia have been collected and are being identified. Cactus moth. Focused on improvement of mating, rearing and colony maintenance of a parasitoid; and the reduction of male biased sex ratio of the colony. Experiments conducted to expand on the knowledge of the parasitoid regarding lifetime fecundity, potential fecundity and parasitoid oviposition behavior. A lab colony of the target insect Cactoblastis cactorum was also maintained to supply hosts for the parasitoid. C. cactorum larvae were exposed to the parasitoid under different environmental conditions to standardize the maintenance of the parasitoid colony under the condition producing the highest proportion of females. Potential and actual lifetime fecundity of single mated females of the parasitoid was determined, and parasitoid learning and stimuli recognition was assessed by experiments. Based on various behavioral traits measured, it was determined that C. cactorum larvae that fed on artificial diet, or in the presence of frass from feeding on artificial diet, were significantly unattractive to the parasitoid females, regardless of the previous stimuli presented. Field collected infested C. cactorum larvae are to be shipped or hand-carried to the quarantine facility in Gainesville. Harrisia cactus mealy bug (HCM). Harrisia cactus mealybug, until recently identified as Hypogeococcus pungens and now an unknown species of the genus Hypogeococcus, is a serious pest of native and endemic columnar cacti in the dry districts of southern Puerto Rico. Puerto Rico started a biological control program to search for natural enemies of HCM in its putative native range, South America. The natural enemy selected to manage the Puerto Rico HCM pest depends on the correct identification of the pest. FuEDEI carried out studies on biology, reproductive compatibility of different clades, taxonomy, and molecular genetics in the putative native range of H. pungens to sort out the HCM complex. The species that is a pest of cacti in Puerto Rico is closely related to the Argentine mealybug H. pungens sensu stricto. Genetic studies were insufficient to sort out the identity of this species. Imported fire ants (IFA). 160 IFA colony samples (workers, alate males and females, and queens) were collected in Mendoza, Tucum�n, Misiones and Entre R�os and sent to the Gainesville quarantine. Molecular data generated was included in the fire ant phylogeny, the fire ant species delimitation, and the Gp-9 supergene/genome projects conducted in cooperation with ARS Gainesville. Molecular phylogenies of fire ants and their South American parasitoid flies were obtained. These data allow to establish species relationships and to delimit populations of each known fly species and putative new fly species. Little fire ants (LFA). Life history and biology of LFA within their native range was studied to understand their invasion scenario. LFA was widespread at the southernmost limit of its native distribution range, with higher abundances recorded mainly in anthropic habitats. The social organization was mainly supercolonial in all habitat types. The reproductive system was mainly clonal in anthropic habitats, mixed in partially disturbed sites and floodplains, and sexual in natural sites. LFA had a lower competitive ability than expected, indicating that interspecific competition is not the most important factor associated with its success. The natural expansion to high latitudes, to the south of South America, would have allowed it to adapt to colder climates and seasonality, key to its later establishment in the Mediterranean region. Naturally disturbed environments may have played an important role in the appearance of features such as clonality, supercoloniality (widespread colonies), better competitive abilities, and tolerance to cold, all of which would have favored the dispersal of LFA mainly in anthropic habitats, the key to its dispersal outside its native range. A local grant was obtained to begin physiological and genetic (genomic) studies of this invasive ant. Leaf-cutter ants (LCA). LCA are one of the most important pests in forest plantations and most crops in the Neotropical region. LCA species surveys were conducted in new areas of Argentina. Samples were included in the phylogenetic, delimitation species, and phylogeographical analyses. A species distribution modeling (Maxent) was conducted with occurrence data of some of the most detrimental leaf-cutter ant species. Results showed that two of these species, Acromyrmex lobicornis and A. striatus, were found in two disjunct areas, the Monte ecoregion and the Atlantic Forest ecoregion. Their fragmented distribution could indicate that they are going through a process of genetic differentiation by distance, a typical mechanism of speciation. A. lundi and A. ambiguus were distributed in between these disjunct areas, mainly in the lower basin of the La Plata River slightly overlapping the aforementioned areas. Damage produced by the A. lobicornis and A. striatus in vineyards in San Juan, and by A. lundi and A. ambiguus on willow forestations in the lower basin of La Plata River was quantified. Damage on four commercial clones of poplar forestations is being assessed. Nest density, foraging activity, and diets of the four LCA species are being studied in the field to estimate the magnitude of their impact on vegetation, especially on cultures. Preference studies will be conducted in the lab. An estimation of the loss level was obtained for four commercial clones of willow trees and vineyards in Argentina. Accomplishments 01 Harrisia cactus mealybug (HCM). Biological and taxonomic comparisons of H. pungens sensu stricto and material from Puerto Rico indicate that they are different species. Although we disentangled the H. pungens complex in at least 4-6 species, we were not able to identify HCM from Puerto Rico. We found a match between Brazil and Puerto Rico mealybug populations, both samples collected on cacti. Recently, we found populations of HCM in Argentina which produce the same damage as HCM in Puerto Rico and in Brazil. From the survey of natural enemies conducted in unexplored areas of Argentina, one species of a primary parasitoid was collected. The biology and taxonomy of two species were studied. Colonies of the three species of Anagyrus were successfully established at the FuEDEI facilities. In addition, the survey of natural enemies continues in Argentina, focusing on unexplored areas. 02 Cactus moth (CM). Significant improvement of rearing conditions of A. opuntiarum allowed the establishment of a lab colony for experimental purposes.
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