Cameraria virgulata, a new host record for Pediobius foveolatus (Hymenoptera:Eulophidae) and some more eulophid parasitoids, and their overwintering strategies
摘要
Pediobius foveolatus has been known to parasitize Epilachna spp. and Henosepilachna spp. Here, we report its parasitization on Cameraria virgulata (Lepidoptera: Gracillariidae), a leaf miner infesting Pongamia pinnata (Leguminosae), a rich biodiesel resource. Previously, no parasitoids have been recorded from C. virgulata. Therefore, the first part of our study focused on the exploration of parasitoid fauna from the mines collected from P. pinnata during summer. We found diverse eulophid parasitoids, including P. foveolatus, a new record on the miner. P. foveolatus was observed as ecto/endoparasitoid, solitary/gregarious, primary larval, koinobiont, and generalist. It showed a peak parasitism of 25 to 39% in October (maximum temperature 25–30°C). ANOVA results showed that percentage parasitism varied significantly for summer and sampled trees. However, there were consistencies in seasonal fluctuations over the years. The second part of the study consisted of a search for overwintering hosts of the eulophid parasitoids. Their assemblages, including P. foveolatus, were discovered on immature leaves of Ricinus communis (Leguminosae) located in a particular niche. Consistent presence of P. foveolatus was observed, and the peak population was attained during the coldest part of winter (minimum temp 2–3°C), when none of them were observed on P. pinnata. Thus, R. communis could provide an overwintering habitat that deserves conservation priorities. Such natural populations of P. foveolatus exhibiting cold hardiness, can potentially contribute to selecting strains of the parasitoids with increased cold tolerance and will help improve the biological control practices.