Effect of methoprene treated polymer packaging on fecundity, egg hatchability, and egg-to-adult emergence of Tribolium castaneum and Trogoderma variabile

Abstract

The fecundity, egg hatchability, and egg-to-adult emergence of the red flour beetle, Tribolium castaneum (Herbst) and warehouse beetle, Trogoderma variabile Ballion, were evaluated on untreated and methoprene-treated polyethylene-to-polyethylene (PE-PE) and polyethylene terephthalate-to-polyethylene (PET-PE) packaging at 27 and 32 °C and 60% r.h. Inside and outside surfaces of the packaging were fit into ∼62 cm2 Petri dishes, and 500 mg of flour (T. castaneum) or vanilla shake mix diet (T. variabile) were added to arenas as food for developing larvae. On methoprene-treated PE-PE packaging, hatchability of added T. castaneum eggs was consistently lower than on untreated packaging. On PET-PE packaging, hatchability of T. castaneum eggs on inside surfaces at both temperatures was significantly lower than on untreated packaging. No consistent trends were observed in T. variabilile hatchability between the packaging types, temperatures, and on inside and outside surfaces of untreated and methoprene-treated packaging. The fecundity of T. variabile was not significantly different between the packaging types. None of the T.castaneum eggs on inside and outside surfaces of the PE-PE methoprene-treated packaging emerged as adults. Methoprene-treated PET-PE packaging reduced fecundity of T. castaneum. Generally, hatchability of eggs laid by both species was not significantly different among the treatment combinations. Only the inside surface of PET-PE packaging gave 100% suppression of egg-to-adult adult emergence of T. castaneum. Development of T. variabile larvae was arrested at the pupal stage at both temperatures on the outside surface of methoprene-treated PE-PE packaging, whereas on the inside surface larvae completed development to adulthood. A 87–97% reduction in egg-to-adult emergence of T. variabile was observed on the inside surface of the PET-PE packaging relative to emergence in corrresponding control treatments at both temperatures. The packaging types evaluated in this study can potentially protect food products stored in these packages from infestations of T. castaneum and T. variable.