Progress 07/01/02 to 09/30/06
Outputs
The last phase for this project was to focus our study on the recovery of entomopathogenic nematodes. For this, a survey for entomopathogenic nematodes was conducted in oak-juniper woodlands of four mountain ranges (Santa Rita, Santa Catalina, Pinaleno and Chiricahuas), in southeastern Arizona. From a total of 120 soil samples, 23.3% were EPN-positive. Of them 78.5% were positive for Steinernema spp. and 21.5% were positive for Heterorhabditis spp. An integrated approach, combining both traditional (morphological) and molecular methods, was used for examining the diversity of species of these entomopathogenic nematodes. Two named-species S. oregonense and S. riobrave are reported for the first time in Arizona, expanding their currently-known geographic range. In addition to this, three undescribed Steinernema and two Heterorhabditis spp. were recovered. Insular evolution, in part, could account for the geographic distribution of entomopathogenic nematodes in Arizona.
Impacts
Until now only a few EPN species have been isolated from desert or semi-desert habitats worldwide.In the US, only one EPN species, S. riobrave, has been recovered from a semi-arid environment.The present study provided the first data regarding the diversity and distribution of these nematodes in the southeastern Arizona.The geographic distribution of two named-species, S. riobrave and S. oregonense, is expanded. S. riobrave was originally found in Texas and more recently its geographic range was extended to the North of Mexico (Tamaulipas)Steinernema oregonense was originally recovered in Oregon, and was subsequently found in California. The three Heterorhabditis isolates found represent two new undescribed species. Two of these isolates were recovered in the Santa Rita mountains and the third one was collected in the Chiricahua mountain range.odlands, therefore confining and isolating EPN upland and to a particular sky island. EPN populations recovered in this study
represent new germplasm that is now available for a wide range of studies. Moreover, these new species may offer a more suitable alternative for inundative release against a variety of native and/or introduced pests in southwestern USA. This aspect is of particular interest in desert or semi-desert habitats where hot and dry weather conditions coupled with intensive agricultural systems and conventional pest control practices, contribute to periodic and often unpredictable outburst in insect pest populations.
Publications
- Gassmann, A., J. Stock, S. P., Carriere, Y. and Tabashnik, B. T. 2006. Effect of Entomopathogenic Nematodes on the Fitness Cost of Resistance to Bt Toxin Cry1Ac in the Pink Bollworm (Lepidoptera: Gelechiidae). J. Econ. Entomol. 99 (3): 920-926.
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Progress 01/01/05 to 12/31/05
Outputs
A survey for entomopathogenic nematodes was conducted in oak-juniper woodlands of four mountain ranges (Santa Rita, Santa Catalina, Pinaleno and Chiricahuas), in southeastern Arizona. From a total of 120 soil samples, 23.3% were EPN-positive. Of them 78.5% were positive for Steinernema spp. and 21.5% were positive for Heterorhabditis spp. An integrated approach, combining both traditional (morphological) and molecular methods, was used for examining the diversity of species of these entomopathogenic nematodes. Two named-species S. oregonense and S. riobrave are reported for the first time in Arizona, expanding their currently-known geographic range. In addition to this, three undescribed Steinernema and two Heterorhabditis spp. were recovered. Insular evolution, in part, could account for the geographic distribution of entomopathogenic nematodes in Arizona.
Impacts
The present study provides the first data regarding the diversity and distribution of these nematodes in the southeastern Arizona. dlands, therefore confining and isolating EPN upland and to a particular sky island. EPN populations recovered in this study represent new germplasm that is now available for a wide range of studies. Moreover, these new species may offer a more suitable alternative for inundative release against a variety of native and/or introduced pests in southwestern USA. This aspect is of particular interest in desert or semi-desert habitats where hot and dry weather conditions coupled with intensive agricultural systems and conventional pest control practices, contribute to periodic and often unpredictable outburst in insect pest populations.
Publications
- Stock, S. P and Gress, J. C. 2006. Diversity and phylogenetic relationships of entomopathogenic nematodes from the Sky Islands of southern Arizona. Journal of Invertebrate Pathology (In Press)
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Progress 01/01/04 to 12/31/04
Outputs
Until now, only a few EPN species have been isolated from desert or semi-desert habitats worldwide. Many of these species appear to posses unique traits that enable their survival in unique environments; and these traits can be exploited in novel pest management strategies. In this regard, there is a heighten interest to search for new EPN species/strains that are adapted to high temperatures and low moisture levels, so they can be considered in pest management programs in xerophitic regions. Our survey of EPN in Arizona provides the first record of the diversity and distribution of these nematodes in the southwestern US. In this study, oak woodlands were selected as the habitat sampled because results from a previous survey conducted in California demonstrated oak woodlands were the most resourceful for the recovery of EPN. Indeed, from a total of 148 soil samples taken from oak woodlands from different mountain ranges in Arizona ( 25 percent were EPN-positive. Of
them 75 percent were positive for Steinernema spp. and 25 percent were positive for Heterorhabditis spp. Identification of recovered isolates was conducted using a combination of molecular markers and classic morphological diagnostic tools. Four new EPN species, three Steinernema and one Heterorhabditis, are currently being identified, representing new germplasm available for a wide range of studies. The evolutionary relationships of these new species is also being studied using sequence data from two nuclear rDNA genes, 28S and ITS (including ITS1, 5.8S and ITS2). Phylogenetic trees will be inferred from both data sets separately and combined, using maximum parsimony and maximum likelihood criteria. Moreover, rDNA sequence analysis is also being used as a tools for delimitation of taxa considering the phylogenetic species concept criteria.
Impacts
The ongoing research project relates to the National Pest Management Alternatives Program which main goal is to identify new alternatives for management of pests without some of the most widely used chemical pesticides. The use the native Arizonan EPN in controlling arthropod and plant pests in urban and agricultural areas in the Southwestern USA will not only provided a non-chemical alternative for this region but also for other areas with similar climatic and pest characteristics.
Publications
- No publications reported this period
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Progress 01/01/03 to 12/31/03
Outputs
During the first year of this period 12 isolates of Steinernema spp. and 9 isolates of Heterorhabditis spp. were recovered. These entomopathogenic nematodes isolates were collected from three out of the four mountain ranges that were sampled: Santa Catalina Mts., Chiricahua Mts. and Santa Rita Mts. All isolates were recovered from oak woodlands or mixed oak/juniper woodlands at an average elevation of 6000ft. Soil parameters such as pH, organic matter content (5), and soil texture were taken into account. Steinernmatid strains were more likely to be found in sandy-loam soils soils with a pH of 7.2-8.04, 3.2-4.5% of organic matter content. Heterorhabditids were collected from sandy to sandy loam soils with a pH of 6.98-7.7, and an organic matter content of 1.8-2.99%. Using molecular diagnostic tools (28S and ITS rDNA sequence analysis) we have identified 2 Heterorhabditis species and 4 Steinernema species, some of them being new undescribed species. Morphological
(light and scanning electron microscopy) studies are currently undergoing to further characterize these species. Two of the isolates (two Steinernema spp.) are currently being tested in the laboratory for host, temperature and moisture range, which are basic (but much needed) assays for assessing the potential of these EPN for biological control practices.
Impacts
The ongoing research project relates to the National Pest Management Alternatives Program which main goal is to identify new alternatives for management of pests without some of the most widely used chemical pesticides. The use the native Arizonan EPN in controlling arthropod and plant pests in urban and agricultural areas in the Southwestern USA will not only provided a non-chemical alternative for this region but also for other areas with similar climatic and pest characteristics.
Publications
- Stock, S. P. and Reid, A. P. 2003. Biosystematics of entomopathogenic nematodes (Steinernematidae, Heterorhabditidae): current status and future directions. In: Cook, R. & Hunt, D.J. (Eds). Proceedings of the Fourth International Congress of Nematology, 8 - 13 June 2002, Tenerife, Spain. Nematology Monographs and Perspectives 2, 435-446.
- Stock, S. P. and Koppenhofer, A. M. 2003. Steinernema scarabaei n. sp. (Rhabditida: Steinernematidae), a natural pathogen of scarab beetle larvae (Coleoptera: Scarabaeidae) from New Jersey. Nematology 5: 191-204.
- Hazir, S., Kaya, H.K, Stock, S.P. and Keskin, N. 2003. Entomopathogenic nematodes(Steinernematidae and Heterorhabditidae)for biological control of soil pests. Turkish Journal of Biology 27: 181-202.
- Cutler, C. G. and Stock, S. P. 2003. Steinernema websteri n. sp. (Rhabditida: Steinermeatidae),a new entomopathogenic nematode from China. Nematologia Mediterranea 31: 215-224.
- Campbell, J. F., Lewis, E. E., Stock, S. P., Nadler, S. A. and H. K. Kaya. 2003. Evolution of host search strategies in entomopathogenic nematodes (Nematoda: Steinernematidae). Journal of Nematology 35: 142-145.
- Ruiz-Vega, J., Aquino-Bolanos, T, Kaya, H. K. and Stock, S. P. 2003. Colecta y evaluacion de nematodos entomopatogenos para el control de gallinas ciegas, Phyllophaga vetula (Horn) en Oaxaca, Mexico. Folia Entomologica Mexicana 42: 169-175.
- Hazir, S., Stock, S. P. and Keskin, N. 2003. A new entomopathogenic nematode, Steinernema anatoliense. n. sp. (Rhabditida: Steinernematidae), from Turkey. Systematic Parasitology 55: 211-220.
- Hazir, S., Keskin, N., Stock, S. P. Kaya, H. K. and Ozcan, S. 2003. Diversity and distribution of entomopathogenic nematodes (Rhabditida: Steinernematidae and Heterorhabditidae) in Turkey. Biodiversity and Conservation 12: 375-386.
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Progress 01/01/02 to 12/31/02
Outputs
Soil samples were collected from four mountain ranges(Santa Catalina, Pinaleno, Santa Rita and Chiricahua)in southeastern Arizona.Sampling at each mountain range contemplated the upper Sonoran lifezone (4500-7500 ft elevation),where several oak species (Emory oak, Quercus emoryi; Mexican blue oak, Q. oblongifolia; silverleaf oak, Q. hypoleucoides;desert scrub oak, Q. turbinella and Arizona white oak , Q. arizonica),are the dominant vegetation type. The goal of this sampling was to assess overall nematode diversity in this ecosystem. Free-living and phytophagous nematodes were extracted from mineral soil and litter using a modified Seinhorst mist apparatus. Insect pathogenic nematodes were extracted from soil samples using the modified insect baiting technique (Kaya and Stock, 1997). GPS coordinates, soil parameters (pH,texture, and organic matter content), altitude, date and climate data (precipitation, humidity, minimum and maximum temperature) and associated
invertebrates, were recorded for each site sampled. A combination of molecular (SSU and LSU DNA sequence analysis)and morphological characters are currently being used for diagnosis and characterization of all nematodes recovered. Four trophic groups of nematodes were identified based on morphological features at the generic level: fungivores, bacterivores, phytophages and omnivore-predators. Bacterial feeding nematodes, including those considered entomopathogenic(Steinernematidae and Heterorhabditidae) were dominant. Forty-three percent of the soil samples collected yielded entomopathogenic nematodes(EPN) in the Steinernematidae and Heterorhabditidae. Of them 65 percent yielded Steinernema spp, 20 percent Heterorhabditis spp.(mainly H. bacteriophora) and 15 percent were samples with mixed Steinernema sp. and Heterorhabditis sp. populations. Currently, all EPN isolates are being characterized using a combined molecular (28S rDNA sequence analysis) and morphological approach.
Impacts
This ongoing research project relates to the National Pest Management Alternatives Program which main goal is to identify new alternatives for management of pests without some of the most widely used chemical pesticides. Our preliminary results already indicate the presence of several beneficial native Arizonan nematode species and/or strains that might have potential in controlling insect and plant pests of Arizona's agriculture as well as from other regions where climatic conditions and target pests are similar. Moreover, characterization of nematode communities from oak woodlands in Arizona will provide information on key nematode taxa that could be used as bioindicators of soil health of this ecosystem.
Publications
- Hazir, S., Keskin, N., Stock, S. P., Kaya, H. K. and Ozcan, S. 2002. Diversity and distribution of entomopathogenic nematodes(Rhabditida: Steinernematidae and Heterorhabditidae)in Turkey. Biodiversity and Conservation 12:375-386.
- Stock, S. P., De Ley, I., De Ley, P, Mundo, M., Baldwin, J. G. and Nadler, S. A. 2002. Plectonchus hunti n. sp. and Panagrobelus stammeri Ruhm):Implications of new morphological observations for characterization of these closely related genera (Nematoda: Panagrolaimoidea). Nematology 4:403-419.
- Stock, S. P., Griffin, C. T. and Burnell A. M. 2002. Morphological characterization of three isolates of Heterorhabditis Poinar, from the Irish group (Nematoda: Rhabditida: Heterorhabditidae) and additional evidence supporting their recognition as a distinct species, H. downesi n. sp. Systematic Parasitology 51:95-106.
- Stock, S. P.2002. Entomopathogenic nematode diversity in South America: Opportunities for exploration. In: Proceedings of the 8th International Colloquium on Invertebrate Pathology and Microbial Control. Foz do Iguazu, Brazil.Pp 105-109.
- Stock, S. P.2002. New Trends in Entomopathogenic Nematode Systematics: Impact of molecular biology and phylogenetic reconstruction. In: Monduzzi (ed) Proceedings of the International Conference on Parasitology, Vancouver, Canada. Pp 1-8.
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