MATTHEW J. GRIESHOP,  PAUL W. FLINN, JAMES R. NECHOLS, MATTHIAS SCHÖLLER  (2007)

Host-Foraging Success of Three Species of Trichogramma (Hymenoptera: Trichogrammatidae) in a Simulated Retail Environment

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Abstract

Three species of trichogrammatid egg parasitoids (Trichogramma deion Pinto & Oatman,

Trichogramma ostriniae Pang & Chen, and Trichogramma pretiosum Riley) (Hymenoptera:

Trichogrammatidae) were evaluated under laboratory conditions as potential biological control agents

for the Indianmeal moth, Plodia interpunctella (Hu¨ bner) (Lepidoptera: Pyralidae), on retail shelves.

Asingle shelving unit was used in each trial and a grid of sentinel egg disks was used to evaluate foraging

success. The shelving consisted of pallet units with Þve shelves that were either bare or stocked with

empty cereal boxes. In each replicate, 500 female Trichogramma were released at the center of the

shelving unit and allowed to forage for 48 h. Percentage of egg parasitism and percentage of host egg

mortality were recorded after 7 d. Foraging success as well as the spatial pattern of parasitism differed

signiÞcantlyamongthe three Trichogramma species. Percentage of egg parasitism was4 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 efÞciency of T. ostriniae and T. pretiosum but not T. deion. Based on these Þndings, 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.