Reproduction and feeding behavior of Delphastus pusillus (Coleoptera: Coccinellidae), a predator of Bemisia tabaci (Homoptera: Aleyrodidae)
1993
Hoelmer, K.A. | Osborne, L.S. | Yokomi, R.K.
The development, feeding behavior, fecundity, and longevity of Delphastus pusillus (LeConte) on the whitefly Bemisia tabaci (Gennadius) was studied in the laboratory at 28 +/- 3 degrees C. Developmental time from oviposition to eclosion was 21.0 d. Longevity of adults was 60.5 d for females and 44.8 d for males. Larval and adult beetles fed on all stages of whitefly. The number of prey consumed by adult beetles decreased with increasing age and size of prey; i.e., 167.1 eggs or 11.6 early fourth instars per day. Handling time increased with stage of whitefly, from 31.3 s for eggs to 377.7 s for early fourth instars. Beetle larvae began feeding upon hatching and consumed a mean of 977.5 eggs before pupating. Mated females laid eggs only when reared on diets containing whitefly eggs. When reared exclusively on a diet of eggs, beetles laid 3.0 eggs per day. Mean lifetime egg production was 183.2. Predation on B. tabaci eggs and beetle oviposition was also observed in a greenhouse; mean prey consumption was 51% greater and mean daily oviposition by females was 103% higher than in the laboratory. Between 100 and 150 whitefly eggs per day were required to initiate and sustain oviposition in the laboratory and the greenhouse. The need for large numbers of whitefly eggs in the diet suggests D. pusillus will maintain itself without augmentation only in large populations of B. tabaci.
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