Author
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Hagler, James |
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Blackmer, Felisa |
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Submitted to: Ecological Entomology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 1/2/2013 Publication Date: 5/7/2013 Citation: Hagler, J.R., Blackmer, F. 2013. Identifying inter-and intraguild predator feeding activity of an anthropod predator assemblage. Ecological Entomology. 38:258-271. Interpretive Summary: Arthropod predators play an important role in controlling insect populations. Unfortunately, most predators are generalist feeders, and thus, they feed on both pests and other natural enemies. As such, understanding predator—prey interactions of the arthropod predator community in any given ecosystem is essential in pinpointing the ecosystem services provided by natural enemies. A suite of prey-specific molecular assays were developed, optimized, and then used to analyze the gut contents of the cotton predator community. The targeted prey included two notorious cotton pests and two common predators. A field study was conducted to quantify the demography of the cotton predator assemblage and to assess the frequencies of predation on the targeted prey. A total of 1,794 predators, representing 17 insect and spider families, were collected over two seasons from cotton fields using both sweepnet and whole plant sampling procedures. The predator gut analyses showed that there was substantial and moderate predation occurring on the pests, silverleaf whitefly and lygus bug, respectively. In addition moderate and little predation was occurring on the predators, big-eyed bug and collops beetle, respectively. The gut assays also revealed that the targeted pest remains were found more frequently in insect predators than spiders; whereas there were no significant differences in predation between the predatory insects and spiders for the targeted beneficial insects. Finally, there was a significantly higher frequency of predation events recorded for whitefly, lygus and big-eyed bug from the sweepnet samples. This indicates that the method of collection might influence the interpretation of the gut assay results. Technical Abstract: Understanding predator—prey interactions of the arthropod predator community in any given ecosystem is essential in pinpointing the ecosystem services provided by natural enemies. A suite of prey-specific PCR assays were developed, optimized, and then used to analyze the gut contents of the cotton predator community. The targeted prey included two cotton herbivores and two predator species. Prior to the field study, prey retention tests were conducted to determine how long a single prey item could be detected in a predator after ingestion. The assays yielded highly variable inter-assay (between assay types) and intra-assay (among predator species) prey detection efficiencies. A multifaceted field study was then conducted to identify members the cotton predator assemblage and to assess the frequencies of predation on the targeted prey. A total of 1,794 predators, representing 17 insect and spider families, were collected over two seasons from cotton fields using both sweepnet and whole plant sampling procedures. The predator gut analyses showed that there was substantial interguild predation occurring on the herbivore, Bemisia tabaci (Gennadius); moderate intraguild predation on the omnivores, Lygus spp. and Geocoris spp.; and very little intraguild predation on the carnivore, Collops vittatus (Say). The gut assays also revealed that the targeted pests, B. tabaci and Lygus spp. remains were found more frequently in insect predators than spiders; whereas there were no significant differences in predation between the predatory insects and spiders for the targeted beneficial insects, Geocoris spp. and C. vittatus. Finally, there was a significantly higher frequency of predation events recorded for B. tabaci, Lygus spp., and Geocoris spp. in the sweepnet samples. This indicates that the method of collection might influence the interpretation of the gut assay results. |
