The larval ectoparasitoid Euplectrus ronnai (Brèthes) is one of the components of a species complex that attacks the armyworm Mythimna (Pseudaletia) sequax Franclemont (Lepidoptera: Noctuidae). No data are available on the fecundity, longevity and host instar preference of E. ronnai, what prompted the conduction of this research. No parasitism occurred on the first and sixth instars of the host, and a positive relationship was found between host instar and the number of parasitoid eggs/host, which ranged from 1.5 on third- instar hosts to 3.6 on fifth instars. Females of E. ronnai showed a preference for either the fourth or fifth instar of M. sequax. There were no significant differences in the developmental time of the parasitoid, sex ratio, mean number of parasitized hosts and percentage of parasitized caterpillars in free-choice tests using fourth- and fifth-instar M. sequax. However significantly more parasitoids/host were found on fifth than on fourth-instar caterpillars. Mean lifetime fecundity was 63.7 eggs/female and each female parasitized an average of 20.3 caterpillars. Oviposition started one day after emergence of the females, which remained reproductively active until one day before death. Females of E. ronnai lived significantly longer when deprived of hosts (187.5 days) in comparison to females kept in ovipositional activity throughout their lifetime (29.7 days).
Insecta; biological control; parasitoid; armyworm; Mythimna sequax
