Effect of Food Resources on Adult Glyptapanteles militaris and Meteorus communis (Hymenoptera: Braconidae), Parasitoids of Pseudaletia unipuncta (Lepidoptera: Noctuidae)

Abstract

Adult parasitoids frequently require access to food and adequate microclimates to maximize host location and parasitization. Realized levels of parasitism in the field can be significantly influenced by the quantity and distribution of extra-host resources. Previous studies have demonstrated a significant effect of landscape structure on parasitism of the armyworm Pseudaletia unipuncta (Haworth) (Lepidoptera: Noctuidae). As a possible mechanism underlying this pattern, we investigated the effect of carbohydrate food sources on the longevity and fecundity of armyworm parasitoids under laboratory conditions of varying temperature, host availability, and mating status. Glyptapanteles militaris (Walsh) (Hymenoptera: Braconidae) adults lived significantly longer when provided with honey as food and when reared at 20°C versus 25°C. Meteorus communis (Cresson) (Hymenoptera: Braconidae) adults also lived significantly longer when provided with honey, although longevity was reduced when females were provided hosts. Honey-fed females of M. communis parasitized significantly more hosts because of their increased longevity, but did not differ in daily oviposition from females provided only water. Mating significantly increased parasitism by honey-fed M. communis, but not those provided water alone. These results indicate that the presence of both carbohydrate resources and moderated microclimates may significantly increase the life span and parasitism of these parasitoids. However, the greater longevity and lower daily rate of oviposition of M. communis suggest that food and microclimate resources are more critical for this species than for the shorter lived, gregarious G. militaris. These findings contribute to our understanding of how these two parasitoids respond to landscape complexity.