Effect of Ephestia kuehniella (Lepidoptera: Pyralidae) larval diet on egg quality and parasitism by Trichogramma brassicae (Hymenoptera: Trichogrammatidae)

Authors: MOGHADDASI, YASAMAN - University Of Tehran; ASHOURI, AHMAD - University Of Tehran; BANDANI, ALIREZA - University Of Tehran; LEPPLA, NORMAN - University Of Florida; Shirk, Paul

Submitted to: Journal of Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/26/2019
Publication Date: 7/18/2019
Citation: Moghaddasi, Y., Ashouri, A., Bandani, A., Leppla, N.C., Shirk, P.D. 2019. Effect of Ephestia kuehniella (Lepidoptera: Pyralidae) larval diet on egg quality and parasitism by Trichogramma brassicae (Hymenoptera: Trichogrammatidae). Journal of Insect Science. 19(4):1-7. https://doi.org/10.1093/jisesa/iez076.
DOI: https://doi.org/10.1093/jisesa/iez076

Interpretive Summary: Parasitoid wasps have been used successfully as biological control agents of pest insects for more than 100 years. Mass rearing of the parasitoids is critical to having them available for augmentive releases for control of lepidopteran pests. Scientists at the University of Tehran and University of Florida collaborated with scientists at USDA-ARS, Center for Medical, Agricultural and Veterinary Entomology, Gainesville, Florida, to assess how food quality for the rearing host affected the quality of the parasitoids produced on them. The results showed that an enriched diet for the moth hosts produced the largest female moths that produced the largest number of eggs. The moth eggs from the enriched food produced the highest quality of parasitoids while a minimal diet produced smaller and fewer parasitoids. This study provides a foundation for understanding the nutritional requirements for producing quality parasitoids for biological control of pest moths.

Technical Abstract: Trichogramma spp., among the most common parasitoids used for augmentation biological control, often are mass-reared on eggs of the Mediterranean flour moth, Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae). To evaluate removal of nutritional components from the E. kuehniella larval diet and reduce production costs, colonies were maintained using one of three diets: a standard diet consisting of eight ingredients, a reduced diet containing whole wheat flour, glycerol and brewer’s yeast, or a third minimal diet of only whole wheat flour. The standard diet sustained the fastest larval development, female pupae with the greatest mass, the highest level of adult emergence, and production of the most eggs per female. Eggs from moths reared as larvae on the standard and reduced diet had equivalent mass, length and percent hatch. Females from larvae fed the minimal diet produced eggs with the least mass that were shorter and had the lowest percent hatch. Eggs from the three E. kuehniella colonies were exposed separately to T. brassicae females to determine their acceptability for oviposition. More of the eggs from the standard diet were parasitized by the females, eggs from the reduced and minimal diets being less acceptable. The percent emergence of the parasitoids was the same regardless of diet, however the largest wasps emerged from the standard diet eggs and a greater proportion of them were females. Consequently, the standard E. kuehniella larval diet resulted in the highest rate of reproduction and robust eggs that produced superior T. brassicae wasps.