Searching and Feeding Behavior ofNephaspis oculatusandDelphastus catalinae(Coleoptera: Coccinellidae), Predators ofBemisia argentifolii(Homoptera: Aleyrodidae)

Abstract

The coccinellids Nephaspis oculatus (Blatchley) and Delphastus catalinae (LeConte) [formerly D. pusillus (LeConte)] are predators of whiteflies (Homoptera: Aleyrodidae), and have shown potential for biological control of Bemisia argentifolii Bellows & Perring in greenhouses. We observed the searching and feeding behavior of N. oculatus and D. catalinae on hibiscus ( Hibiscus rosa-sinensis L.). D. catalinae larvae maintained the entire body in contact with the substrate while moving, whereas N. oculatus larvae planted the uropod on the substrate and swept the body in an arc while searching. Estimated movement rates of all stages of D. catalinae were greater than the corresponding stages of N. oculatus. However, the searching areas by different larval stages of D. catalinae were significantly smaller than those by the corresponding larval stages of N. oculatus, which the larvae sweep around while searching. The adults of both coccinellid species traveled in a similar pattern; therefore, D. catalinae, moving at a greater rate, searched a greater area than that of N. oculatus, moving at a slower rate. Larvae and adults of both coccinellid species responded to prey only after contacting prey with their mouthparts or front legs. Younger larvae took significantly longer to consume prey than older larvae or adults. Larvae and adults of the smaller N. oculatus consumed whiteflies at a significantly slower rate than did corresponding stages of D. catalinae.