Effects of Leptoglossus occidentalis Heidemann (Heteroptera Coreidae) egg age on the indigenous parasitoid Ooencyrtus pityocampae Mercet (Hymenoptera Encyrtidae)

Abstract

Leptoglossus occidentalis is a Nearctic polyphagous coreid capable to feed on cones and seeds of many coniferous plants. In Italy this pest threatens pine nut commercial production and represents a serious concern in protected areas where control by chemicals is restricted. For this reason, new strategies of biological control against L. occidentalis are under investigation. Ooencyrtus pityocampae, an indigenous egg parasitoid of the lepidopter Thaumetopoea pityocampae was recently found to parasitize L. occidentalis eggs. However low parasitization rates in the field were reported. Host egg age is often regarded as a key element in determining host acceptance and parasitoid capacity to exploit host eggs. Therefore, in the current work, the effects of host egg age on parasitization O. pityocampae were evaluated by exposing eggs ranging in age from < 24h to within a day of hatching. O. pityocampae. Results showed that number of parasitized eggs and sex ratio were not significantly influenced by the age of the host eggs. In contrast, female development time resulted to be longer in older eggs. O. pityocampae appeared to be not only flexible to adapt to the new host but also cable to efficiently exploit L. occidentalis eggs containing fully developed nymphs.