Effects of botanical oil on preference and prey consumption of Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) and Cryptolaemus montrouzieri Mulsant (Coleoptera: Corcinelidae) against the cotton mealybug (Phenacoccus solenopsis; Hemiptera: Pseudococcidae)

Due to serious drawbacks as a result of overreliance on and overuse on insecticides, efforts are being made to develop non-toxic, safe and biodegradable alternatives to synthetic insecticides from biological substances in plants. In this study, the authors investigated the effect of different concentrations of neem oil on the foraging and feeding behavior of the green lacewing [Chrysoperla carnea) Stephens) (Neuroptera: Chrsopidae)] and the mealybug destroyer [Cryptolaemus montrouzieri) Mulsant (Coleoptera: Coccinelidae)]. Neem oil concentrations had different impacts on predator preference and prey consumption. Neem oil at higher concentrations (2%, 2.5%, and 3%) had antifeedant effect on both predator species compared with the control. The percent prey (Phenacoccus solenopsis) consumption by both predator species was significantly lowest at the highest neem oil concentration. The feeding ability of C. carnea and C. montrouzieri decreased by 24% and 20% respectively, on leaves treated with the highest neem oil concentration. Both predators preferred the control treatment (untreated cotton leaves) compared with leaves treated with higher neem oil concentrations. On the average, the generalist predator (C. carnea) spent more time (54%) in the foraging prey compared with time spent by the specialist predator (C.montrouzieri) (42%) on leaves treated with the highest neem oil concentration. The settling response of both predator species decreased (68%) on leaves treated with the highest neem oil concentration. The lower neem oil concentrations (0.5%, 1% and 1.5%) did not influence the preference and prey consumption of both predator species. The present work has shown that neem-based insecticides at appropriate concentration can be incorporated in integrated pest management (IPM) programs.