Submitted to: Journal of Economic Entomology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/11/2006
Publication Date: 9/1/2007
Citation: Grieshop, M.J., Flinn, P.W., Nechols, J.R., Scholler, M. 2007. Host-foraging success of three species of Trichogramma (Hymenoptera: Trichogrammatidae) in a simulated retail environment. Journal of Economic Entomology 100: 591-598. Interpretive Summary: The Indianmeal moth is a serious pest of raw and finished stored products and attacks both packaged and bulk commodities as well as spillage. Indianmeal moth larvae can infest stored products like bags of grain, cereal, or pet food. Three species of Trichogramma wasp parasitoids were tested to find the best one for biological control of the Indianmeal moth. Indianmeal moth egg parasitism was approximately four times greater for T. deion than for T. ostriniae or T. pretiosum. Based on these findings, Trichogramma deion may be the best-suited candidate for augmentative biological control of Indianmeal moth in retail stores. This could provide a new tool for the retail organic food industry to manage insect pests. Growers have been using Trichogramma wasps for decades to control outdoor pests plaguing cotton and other crops, so the beneficial insects would be readily available to the pest control industry. Harmless and practically invisible, Trichogramma wasps are an environmentally-friendly way to keep food pests in check.
Technical Abstract: Three species of trichogrammatid egg parasitoids (Trichogramma deion Pinto and Oatman, T. ostriniae Pang and Chen, and T. pretiosum Riley) were evaluated as potential biological control agents for the Indianmeal moth (Plodia interpunctella (Hübner)) on retail shelves under laboratory conditions. A single shelving unit was used in each trial and a grid of sentinel egg patches was used to evaluate foraging success. The shelving consisted of pallet units with five shelves that were either bare or stocked with empty cereal boxes. In each replicate, approximately 500 female Trichogramma were released at the center of the shelving unit and allowed to forage for 48 h. Percentage egg parasitism and percentage host egg mortality were recorded after seven days. Foraging success as well as the spatial pattern of parasitism differed significantly among the three Trichogramma species. Percentage egg parasitism was approximately four times greater for T. deion than for T. ostriniae or T. pretiosum. The vertical distribution of parasitism by T. deion was also more uniform than for the other two species. In addition, the presence of packaging affected the foraging efficiency of T. ostriniae and T. pretiosum but not T. deion. Based on these findings, Trichogramma deion may be the best-suited candidate for augmentative biological control of P. interpunctella in retail stores, and a central release point of T. deion will likely provide adequate coverage of products on pallet-type shelving.