Revealing the diet of generalist insect predators in strawberry fields: not only pests, but other predators beware

Authors: Krey, Karol; Cooper, William - Rodney; RENKEMA, JUSTIN - Agriculture And Agri-Food Canada

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/11/2020
Publication Date: 11/2/2020
Citation: Krey, K.L., Cooper, W.R., Renkema, J.M. 2020. Revealing the diet of generalist insect predators in strawberry fields: not only pests, but other predators beware. Environmental Entomology. 49(6):1300-1306. https://doi.org/10.1093/ee/nvaa125.
DOI: https://doi.org/10.1093/ee/nvaa125

Interpretive Summary: Generalist insect predators are major contributors to pest management in agriculture crops such as strawberry. While many generalist predators can be captured or observed in strawberry fields, it remains unknown whether those predators readily consume insects pests that damage berries. Researchers at the USDA-ARS in Wapato Washington, University of Florida, and Agriculture and Agri-Food Canada, captured generalist insect predators from commercial organic Florida strawberry fields and performed molecular gut content analysis on those predators to identify what insects they had previously fed upon. All of the predators tested had fed upon pests of strawberries including fruit flies, but had also fed upon other predators and non-pest insects. The consumption of non-pest insects, including other predators, may help retain the predators within strawberry fields when pest populations are low. Results of this study provide a better understanding of predator food webs and contribute to the improvement of the use of biological control as a cost-effective pest management tactic for organic strawberry production

Technical Abstract: Generalist invertebrate predators contribute to pest management in agriculture, providing an important ecosystem service, particularly in organically managed fields. DNA-based methods to study food webs and feeding interactions in unrestricted field conditions have transformed dietary analysis of generalist predators. In this study, we used MiSeq next-generation sequencing (NGS) technology and universal arthropod primers to investigate the diet of several generalist insect predators collected in commercial organic Florida strawberry fields from November 2017 to March 2018. Of 12 predator insect taxa, Geocoris spp. (Say) (Hemiptera: Geocoridae) was the most abundant early in the growing season (November) and was collected consistently until the end of the season (early March). DNA sequences from 105 predator samples were matched to 44 arthropod families, and of these, 17 were categorized as pest families, 10 as nonpest or nonpredator families, and 17 as predator families. Drosophilidae was the most detected pest family, and Dolichopodidae was the most detected predator family. Prey diversity differed among the predators. Chrysoperla spp. (Neuroptera: Chrysopidae) consumed more prey earlier in the season than did other predators, whereas the other predators consumed a greater diversity of other predators regardless of month. Our results showed a high amount of intraguild predation, but also that predators are contributing to pest suppression in organic strawberries and providing an important biological control service in Florida organic strawberries