Trichogramma platneri (Hym.: Trichogrammatidae): host choices between viable and nonviable codling moth, Cydia pomonella, and three-lined leafroller, Pandemis limitata (Lep.: Tortricidae) eggs.

摘要

In laboratory host-preference studies, Trichogramma platneri females, reared on viable Cydia pomonella eggs, parasitized significantly more viable than nonviable C. pomonella eggs produced by cobalt 60 irradiated adults. This ovipositional preference was maintained when competition increased per host egg. Similarly, one, three and five T. platneri females consistently oviposited more eggs into viable versus nonviable host eggs. A single female T. platneri parasitized a similar number of viable C. pomonella and Pandemis limitata eggs. However, as the number of females per host eggs increased, a significantly larger number of C. pomonella versus P. limitata eggs were parasitized. One, three and five Trichogramma females parasitized significantly more P. limitata versus nonviable C. pomonella eggs. Nonviable C. pomonella eggs deflated to less than 25% of their original volume in 4 and 10 days when held under dry and humid conditions, respectively. The blackened prepupal stage of the parasitoid generally occurred in the nonviable C. pomonella eggs 4 days post-parasitization, whereas the parasitized viable eggs blackened zero to one day earlier. Incubation under dry or humid conditions did not appear to influence the number of parasitized eggs that were able to blacken and show evidence of parasitism.