Plodia interpunctella and Trogoderma variabile larval penetration and invasion of untreated and methoprene-treated foil packaging

Authors: Scheff, Deanna; SUBRAMANYAM, BHADRIRAJU - Kansas State University; Arthur, Franklin; DOGAN, HULYA - Kansas State University

Submitted to: Journal of Stored Products Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2018
Publication Date: 6/15/2018
Citation: Scheff, D.S., Subramanyam, B., Arthur, F.H., Dogan, H. 2018. Plodia interpunctella and Trogoderma variabile larval penetration and invasion of untreated and methoprene-treated foil packaging. Journal of Stored Products Research. 78:74-82. https://doi.org/10.1016/j.jspr.2018.05.002.
DOI: https://doi.org/10.1016/j.jspr.2018.05.002

Interpretive Summary: The warehouse beetle, Trogoderma variabile Ballion, and the Indian meal moth, Plodia interpunctella (Hübner), are diverse feeding stored-product insects found in stored grain, processing facilities, retail stores, and consumer pantries. Both species are capable of chewing through packaging materials or entering through defective packaging and infesting the food inside. Impregnating the insect growth regulator methoprene between layers of packaging material may be an effective method of preventing insects from packaged food products. The methoprene-treated packaging prevented the warehouse beetle larvae from chewing through the material or entering the packaging through a pinhole. The Indian meal moth did not chew through the treated packaging, but could invade the package when pinholes in the package were present. Our results reveal that defect free methoprene-treated packaging prevented insects from chewing through the packaging material and infesting the food product inside. However if a defect is present in the packaging, such as a hole or rip, insects are capable of entering the packaging regardless of the methoprene treatment.

Technical Abstract: Packaged food products inside retail stores and food warehouses are susceptible to infestation by stored-product insects. The insect growth regulator methoprene can be impregnated onto packaging to help limit stored-product insect population development and prevent infestations. The objectives of this study were to determine the effect of methoprene-treated foil packaging on egg hatchability and the penetration and invasion ability of the warehouse beetle, Trogoderma variabile Ballion, and the Indian meal moth Plodia interpunctella (Hübner). Twenty-five eggs of each species were added to Petri dishes containing untreated or methoprene-treated packaging at 0.1, 0.25, and 0.5% of active ingredient, and percent hatchability was calculated. Additionally, a 6 cm by 8 cm food packages were created from untreated and methoprene-treated packaging and placed into 0.18-L vials. First or third instars of each species were introduced into vials containing diet or no diet, to determine penetration ability after 21 and 42 d. In a separate experiment, packages were pierced with pinholes, and first instar T. variable or P. interpunctella were introduced and observed after 21 and 42 d for package invasion. The foil packaging had no significant effect on egg hatchability of either species. T. variabile were unable to penetrate or invade any foil packages. P. interpunctella invaded all packages containing pinholes. The methoprene-treated packaging reduced the adult emergence of P. interpunctella and caused pupal and adult deformations in T. variabile. Methoprene-treated packaging presents a valuable option for food manufacturers to prevent insect infestations and maintain integrity of packaged food products.