Laboratory and glasshouse evaluation of the green lacewing, Chrysopa pallens (Neuroptera: Chrysopidae) against the western flower thrips, Frankliniella occidentalis (Thysanoptera: Thripidae)

Abstract

Western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), is an important invasive polyphagous pest in vegetable and ornamental crops. The increasing resistance to chemical insecticides in F. occidentalis has resulted in heightened interest in alternative control methods including the generalist entomophagous predator Chrysopa pallens (Rambur) (Neuroptera: Chrysopidae). The first part of this study evaluated the prey capacity of the three larval instars of C. pallens on F. occidentalis larvae, using functional responses. The C. pallens larvae exhibited a type III functional response to the F. occidentalis larvae. When offered 80 thrips larvae, 34–41 were consumed by a single C. pallens larvae within 24 h. The second part examined the effects of releasing C. pallens to control F. occidentalis on glasshouse-cultivated cucumber plants. In comparison with the control, releases of C. pallens larvae at densities of 2, 4, 8, and 16 per plant led to a reduction in F. occidentalis by 11%, 39%, 59%, and 68% of the larvae and 12%, 43%, 58%, and 68% of the adults, respectively, after 5 weeks. Our results suggested that the C. pallens may be an effective biological control agent for use against F. occidentalis.