Monday, December 11, 2006

Suitability of different lepidopteran hosts for development of Bracon hebetor (Hymenoptera: Braconidae), a larval ecto-parasitoid of stored-product moths

Mukti N. Ghimire, and Thomas W. Phillips, Oklahoma State University, Department of Entomology and Plant Pathology, 127 Noble Research Center, Stillwater, OK

Bracon hebetor Say (Hymenoptera: Braconidae) is a gregarious larval ecto-parasitoid of several species of pyralid moths that attack stored grains, nuts, fruits and other processed food commodities. We investigated host acceptance and suitability for the oviposition and development of B. hebetor on 11 different lepidopteran species: Indianmeal moth, Plodia interpunctella, Mediterranean flour moth, Epesthia kuehniella, almond moth Cadra cautella, rice moth, Corcyra cephalonica, navel orangeworm, Amyelois transitella, greater wax moth, Galleria mellonella, Tobacco budworm, Heliothis virescens, corn earworm, Helicoverpa zea, beet armyworm, Spodoptera exigua, webbing clothes moth, Tineola bisselliella and Angoumois grain moth, Sitotroga cerealella. Experiments were conducted in the laboratory in a no-choice design using Petri-dishes as experimental arenas with a single host larvae. B. hebetor females within 24 hours after emergence were kept with males in a 500 ml glass jar for one day and were provided honey and water. Females were introduced singly into experimental arenas and allowed to sting and oviposit for 5 days with a fresh host given daily. The number of hosts paralyzed and parasitized, number of eggs laid each day on each host, egg-to-adult survivorship, and progeny sex ratio were used as parameters for host suitability. B. hebetor females were able to paralyze and lay eggs on most of the hosts tested except H. zea, H. virrescens, and S. exigua. The egg-to-adult survivorship and progeny sex ratio were significantly affected by the host species. The possible application of these results for biological control of stored product insects is discussed.

Species 1: Hymenoptera Braconidae Bracon hebetor
Species 2: Lepidoptera Pyralidae Plodia interpunctella (Indianmeal moth)
Species 3: Lepidoptera Pyralidae Galleria mellonella (greater wax moth)