The effect of two prey species, Chrysomphalusaonidum and Corcyra cephalonica, on the qualityof the predatory thrips, Aleurodothripsfasciapennis, reared in the laboratory

Periodic and augmentative releases of natural enemies are often required to enhance biological control and integrated pest management programs. One requirement for these programs to be practical is that natural enemies can be easily and economically mass-reared. This study assessed the effects of dieton the quality of the F3 and F4laboratory-reared generations of the predatory thrips,Aleurodothrips fasciapennis. Diets were eggs and crawlers of the diaspidid scale Chrysomphalusaonidum and eggs of the pyralid moth Corcyracephalonica. It was found that both the F3 and F4 generations were not viable when reared on the eggs and crawlers of C. aonidum due to very low fecundity and, in the F4 generation, increased larval mortality. In contrast, thrips reared on the eggs of C. cephalonica were viable in both generations but an increase in larval mortality from the F3 to the F4 generation did result in are duction in viability. These results are discussed in terms of genetic, environmental and behavioural factors that may have influenced the quality of the thrips. It is concluded that genetic factors(inbreeding suppression, genetic drift or selection),the behaviour of scale crawlers and the predatory behaviour of thrips were probably of little value in explaining the results. The most likely explanation was that the diet supplied to thrips was of in adequatenutritional quality. It was not possible to distinguish whether this was due to low intrinsic quality of the prey or an indirect effect of experimental conditions on prey quality.