The potential for greenhouse biocontrol by generalist predators Hippodamia variegata and Micromus tasmaniae

The predators were reared on a diet of A. craccivora which were used in these experiments as a standard. Development from first instar larva to adult was significantly faster on aphid diets than on other prey species for both predators. Hippodamia variegata that were fed F. occidentalis failed to reach pupation and pre-imaginal survival of M. tasmaniae were significantly lower on a diet of F. occidentalis than on either M. persicae or A. craccivora. Micromus tasmaniae could not complete development on a diet of T. urticae. Both predators may have potential against aphid species whilst M. tasmaniae may awed no effect on H. variegata. Temperature also had a statistically significant effect on mean daily oviposition and pre-oviposition period at 18°C. At the end of the experimental period, the ovaries of all H. variegata held at 25°C were mature while most of the ovaries of the insects held at 18°C were not mature.