Efficacy of two alternative insecticide-impregnated nets with new active ingredients against four major stored product beetle species

Authors: VALLI, ELENI - University Of Thessaly; SAKKA, MARIA - University Of Thessaly; RUMBOS, CHRISTOS - University Of Thessaly; RANABHAT, SABITA - Kansas State University; Morrison Iii, William; ATHANASSIOU, CHRISTOS - University Of Thessaly

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/2/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: Netting incorporated with insecticides can be used to protect grain and grain-based products from stored product insect infestations after harvest from the field. The majority of these long-lasting insecticide nets (LLINs) use alpha-cypermethrin or deltamethrin as insecticides. However, resistance to deltamethrin has been reported in some stored product insects and thus, there is an interest in using new active ingredients in LLINs. In this study, two different LLINs, one with 8% etofenprox and one with 2% permethrin, were tested against adults of four stored product insects, including larger grain borer, maize weevil, red flour beetle, and granary weevil. Short, 15 min exposures to the LLIN resulted in immediate knockdown of all four species, but insects could recover after an initial knockdown. Increasing exposure times to LLIN to the nets reduced recovery and increased mortality. The amount of exposure time required to achieve mortality varied among the four species, with granary weevil being the most susceptible and requiring the lowest exposure times to achieve mortality and the larger grain borer being the most resistant. Our data underline the efficacy of impregnated nets with new active ingredients and their potential for further use in stored product protection strategies.

Technical Abstract: The majority of long-lasting insecticide nets (LLINs) use alpha-cypermethrin or deltamethrin after harvest. However, there is interest in including long-lasting insecticide nets in integrated pest management (IPM) programs at food facilities with new active ingredients against stored product insects. In this study, two impregnated nets, one with etofenprox and one with permethrin, were tested against adults of four stored product insects, i.e. Prostephanus truncatus, Sitophilus zeamais, Tribolium castaneum, and Sitophilus granarius. Among the tested species, S. granarius was the most susceptible, while in most cases there were no differences in the efficacy level between the two nets. Short exposures resulted in immediate knockdown of all species, while increasing exposure to the nets decreased knockdown and increased adult mortality. When all adults were removed from the treated substrate and transferred to untreated dishes, previous exposure to both nets caused a considerable increase in delayed mortality 3 or 7 days later. Our data underline the efficacy of impregnated nets with new active ingredients and their potential for further use in stored product protection strategies.