Trichogrammatid egg parasitoids (Hymenoptera: Trichogrammatidae) of rice leaf folder and cabbage caterpillars in Sri Lanka

Abstract

Use of egg parasitoids is an effective option available for managing lepidopteran pest species through augmentation and release of the parasitoids, particularly the locally available species. As the local egg parasitoids in Sri Lanka are poorly studied, an investigation was conducted to identify the egg parasitoids associated with rice leaf folder (Cnaphalocrocis medinalis Guenee) and cabbage semilooper (Trichoplusia ni Hubner). The host eggs were collected in different geographical locations for different durations in rice (Oryza sativa L.) and cabbage (Brassica oleracea L.) fields. The eggs were incubated until the emergence of host larvae or the adult parasitoid. Emerged parasitoids were preserved in 70% ethanol and subsequently dissected for male genitalia and the permanent slides were prepared using Canada balsam as the mounting media. Identification of specimens was done using taxonomic keys and related literature. Identities were confirmed by the Natural History Museum, London. Two species namely, Trichogramma chilonis Ishhi and T. achaeae Nagaraja and Nagarkatti were found parasitizing T. ni at Dodangolla and Thalatuoya regions in Sri Lanka. The record of T. achaeae is the first country report and T. chilonis had been recorded previously in Sri Lanka. The morphology of male genitalia was described and compared with the original description. Trichogrammatoidea bactrae Nagaraja and T. nana Zehnter were found parasitizing C. medinalis eggs at six sampling sites. The male genitalia of these two species were characterized and compared with the original descriptions.