Direct lethality and time-delayed sublethal effects of multiple types of insecticide netting against stored product insects

Authors: RANABHAT, SABITA - Kansas State University; Abshire, Jennifer; JAMES, AVERY - Kansas State University; Scheff, Deanna; BINGHAM, GEORGINA - University Of Nebraska; ZHU, KUN YAN - Kansas State University; Morrison Iii, William

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/21/2025
Publication Date: 6/16/2025
Citation: Ranabhat, S., Abshire, J.L., James, A., Scheff, D.S., Bingham, G.V., Zhu, K., Morrison Iii, W.R. 2025. Direct lethality and time-delayed sublethal effects of multiple types of insecticide netting against stored product insects. Journal of Economic Entomology. https://doi.org/10.1093/jee/toaf059.
DOI: https://doi.org/10.1093/jee/toaf059

Interpretive Summary: Long-lasting insecticide-incorporated netting is a newer tactic being evaluated for integrated pest management programs (IPM) against insects that infest grain after it is harvested from the field. Two main pests to be targeted by insecticide netting are red flour beetle and lesser grain borer, which are both widespread and highly destructive. We sought to 1) evaluate the efficacy of nets containing two different types of insecticides (deltamethrin and alpha-cypermethrin), 2) assess their mobility immediately after exposure and 3) to evaluate the extended effects on mobility from LLINs against both pests. After exposure for 60-min to deltamethrin and alpha-cypermethrin LLIN, mortality for red flour beetle and lesser grain borer was 8.2–8.7-fold and 276–313-fold higher, respectively, when compared to the control netting without insecticide. After immediate exposure to the netting, lesser grain borer movement was elevated even after contact with netting containing no insecticide, but this was not true for red flour beetle. This suggests contact with netting material may impact the mobility of some stored product insects. For both species, there was a reduction in movement after an extended 60-min exposure to both LLINs by 95-98% compared to control netting without insecticide. Overall, this study demonstrates the efficacy of nets containing alpha-cypermethrin and deltamethrin against two cosmopolitan, destructive stored product insects.

Technical Abstract: Long-lasting insecticide-incorporated netting (LLIN) is a newer tactic being evaluated in agriculture as part of holistic integrated pest management (IPM) programs. The aims of the current study were to 1) evaluate the efficacy of the commonly used LLINs (deltamethrin and alpha-cypermethrin) for direct lethality, 2) assess the baseline mobility after exposure and 3) to evaluate the sublethal effects among LLINs against R. dominica and T. castaneum. To accomplish this, we exposed cohorts of both species to 0.4% w/w deltamethrin and 0.34% alpha-cypermethrin for periods of 5, 60, or 120-min in the laboratory, and checked individuals for the condition after a duration of 0, 24, 72, or 168 h. The movement of alive and affected adults were assessed using Ethovision software over 60-min trials after a 5- or 60-min exposure to LLIN immediately or 72 h after exposure. After exposure for 60-min to deltamethrin and alpha-cypermethrin LLIN, mortality for R. dominica and T. castaneum was 8.2–8.7-fold and 276–313-fold higher, respectively, when compared to the controls without insecticide. In the baseline mobility assay, R. dominica netting exhibited a thigmotactic effect on movement, but not for T. castaneum. For both species, the movement was reduced by 77–99% deltamethrin netting above and beyond the thigmotactic effects. There was a sublethal reduction in movement after a 60-min exposure to both LLINs by 95-98% compared to control netting without insecticide. Overall, this study helps delineate the relationship in efficacy between these two active ingredients for two cosmopolitan, destructive stored product insects.