A dilute solution of potassium chloride and magnesium sulfate induces oviposition in artificial eggs by the egg parasitoids Trichogramma pretiosum and T. minutum. The ability to obtain large numbers of eggs through the use of this inexpensive solution is a major advance toward the development of diets and the large-scale production of Trichogramma spp. in vitro.

K +, Mg 2+, CI-, and 5042" were important components eliciting oviposition by Trichogramma pretiosum in aqueous solutions in wax eggs. Ca 2+ inhibited oviposition in a KCI-MgSO~ solution. The solutions most active in stimulating oviposition were 124.7--36.5 and 83.1--24.3 mM, respectively, of KCI-MgSO~.

The predaceous larvae of Chrysoperla rufilabris (Burmeister) exhibited some success-motivated searching, particularly when feeding on Heliothis virescens (F.) eggs, but handling time did not decrease with experience. Handling time for H. virescens larvae was more than twice that for eggs. H. virescens larvae were preferred to cotton aphids (Aphis gossypii (F.)) while aphids were preferred to H. virescens eggs. C. rufilabris larvae exhibited a linear functional response to the three prey types tested, over the prey densities tested.

No abstract

Three methods, which are more efficient than previously reported techniques, are described for in vitro production of Trichogramma pretiosum Riley in numbers ranging from a few to thousands. Several antibiotics with concentrations as high as 0.5% were not toxic to the parasitoids, reduced microbial growth, and permitted the successful rearing to the pupal stage of T. pretiosum on artificial diet composed of insect hemolymph, egg yolk, and milk. The likelihood that Trichogramma can be mass produced efficiently in vitro has been significantly increased, but it is essential that the cost and nutritional quality of the artificial diet be significantly improved.