Facultative egg-larval parasitism of the beet armyworm, Spodoptera exigua (Lepidoptera: Noctuidae) by Cotesia marginiventris (Hymenoptera: Braconidae)

The braconid parasitoid Cotesia marginiventris (Cresson) has long been known to be a larval parasitoid of numerous lepidopteran species. Recent field observations, however, indicated that C. marginiventris is also capable of functioning as an egg-larval parasitoid of the beet armyworm, Spodoptera exigua (Hubner). These field observations were corroborated by laboratory observations, demonstrating that C. marginiventris is capable of ovipositing in S. exigua eggs, and of successfully developing and emerging from host larvae hatching from stung eggs. The mechanisms used by the parasitoids to locate host egg masses in the field were not determined. These results lend support to phylogenetic hypotheses of the Braconidae that indicate a close relationship between the Cheloninae and the microgastroid taxa.