Location: Integrated Cropping Systems ResearchTitle: Molecular determination of the predator community of a cassava whitefly in Colombia: Pest-specific primer development and field validation Author
|Becerra Lopez, Luis|
Submitted to: Journal of Pest Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/14/2013
Publication Date: 3/1/2014
Citation: Lundgren, J.G., Becerra Lopez, L.A., Parsa, S., Wyckhuys, K. 2014. Molecular determination of the predator community of a cassava whitefly in Colombia: Pest-specific primer development and field validation. Journal of Pest Science. 87:125-131. Interpretive Summary: Cassava is an important food crop in the tropics that is afflicted by several severe insect pests, including a complex of cassava whiteflies. In Colombia, Aleurotrachelus socialis is the dominant whitefly, which is primarily controlled using insecticidal sprays. Biological control- using insect predators to control pests- forms the basis of sustainable, non-chemical pest management systems, but little is known regarding the predator complex of cassava whitefly. We developed a test system with which we analyzed the gut contents of predators collected from cassava fields for the presence of whitefly-specific DNA fragments. Eleven percent of the 586 predators analyzed (representing 131 taxa from 29 families) tested positive for whitefly DNA in their stomachs. Of these, a netwing beetle, spider, the Multi-colored Asian Lady Beetle, and two lacewings were the most frequent consumers of whitefly DNA in the field. This work shows that a diverse predator community affects cassava whitefly in southern Colombia, and provides the groundwork for the design of cassava production systems with minimal pesticide inputs.
Technical Abstract: In South America, the whitefly Aleurotrachelus socialis is one of the principal pests of cassava (Manihot esculenta Crantz), reaching high population levels throughout the Andean region. Management of this species is primarily based upon the use of insecticides, while biological control has received limited attention. To date, knowledge of A. socialis natural enemies is restricted to occasional records of predators and parasitoids. In this study, we developed PCR primer sets specific for the cassava whitefly, Aleurotrachelus socialis, to identify their predator community in Colombian cassava. Eleven percent of 586 predator specimens (representing 131 taxa from 29 families) tested positive for cassava whitefly DNA. Of the 21 predator taxa that consumed cassava whiteflies, an unidentified netwing beetle (Lycidae), an unidentified spider species (Araneae), Harmonia axyridis (Coleoptera: Coccinellidae), a Cereaochrysa sp. (Neuroptera: Chrysopidae), and a Leucochrysa sp. (Chrysopidae) were the taxa that consumed cassava whiteflies most frequently under field conditions. Two abundant predators in the system, Delphastus sp. (Coccinellidae) and the long-legged fly, Condylostylus sp. (Diptera: Dolichopodidae), were both positive for whitefly DNA, but did not have the strongest trophic linkage to the pest relative to other predators. This work shows that a diverse predator community affects cassava whitefly in southern Colombia, and provides the groundwork for the design of cassava production systems with minimal pesticide inputs.