Effects of Pea Aphid (Homoptera: Aphididae) Honeydew on Longevity and Fecundity of the Alfalfa Weevil (Coleoptera: Curculionidae) Parasitoid Bathyplectes curculionis (Hymenoptera: Ichneumonidae)

Abstract

The ability of parasitoids to attack their hosts may be influenced by the availability of adult food sources such as homopteran honeydew. To test this hypothesis for the wasp Bathyplectes curculionis (Thomson), a parasitoid of the alfalfa weevil, Hypera postica (Gyllenhal), we performed laboratory experiments to determine whether availability of pea aphid, Acyrthosiphon pisum (Harris), honeydew influenced adult longevity and fecundity of the wasp. Adult wasps caged with alfalfa, Medicago sativa L., and pea aphids fed on the aphid honeydew and lived a50% longer than wasps caged with alfalfa alone. In a related experiment, newly emerged, unmated B. curculionis females were allowed to feed for 2 d on pea aphid honeydew, sucrose dissolved in water, or water alone, and were then dissected to determine the number of eggs in a lateral oviduct. Egg production was slightly (11–15%) but significantly greater in females with access to pea aphid honeydew or sugar water than in females with access to water only. These results suggest that availability of pea aphid honeydew in alfalfa fields may enhance the realized fecundity of B. curculionis . Hence, the presence of pea aphids in moderate numbers may be beneficial for biological control of the alfalfa weevil.