Oviposition behavior of Cotesia flavipes and Goniozus indicus, larval parasitoids of the lepidopteran stemborer Chilo partellus

Abstract

Observing the opposition behavior of ingress-and-sting larval parasitoids of lepidopteran stemborers is difficult due to the cryptic feeding behavior of the hosts. A method for observing their opposition behavior was developed. An individual stemborer larva was introduced into a glass tube (0.7 cm in diameter; 7 cm in length) which contained a piece of maize stem (0.5-0.6 cm in diameter; 4-5 cm in length). The larva was allowed 14-20 h to feed on the maize and produce frass before introducing a single adult female parasitoid. Using this method, we observed the endoparasitoid Cotesia flavipes (CAMERON) and the ectoparasitoid Goniozus indicus ASHMEAD ovipositing on the pyralid stemborer Chilo partellus (SWINHOE). On contacting C. partellus larvae, C. flavipes females quickly stung them and immediately left the glass tube. G. indicus females paralyzed the hosts before ovipositing on them, and stayed with the hosts inside the glass tube for a few days after opposition. After stung by either C. flavipes or G. indicus females, C. partellus larvae spat saliva and often aggressively bit the female parasitoids.