Effectiveness of long-lasting insecticide netting on Tribolium castaneum is modulated by multiple exposures, biotic, and abiotic factors

Authors: Gerken, Alison; Scully, Erin; Campbell, James - Jim; Morrison, William - Rob

Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/11/2020
Publication Date: 3/1/2021
Citation: Gerken, A.R., Scully, E.D., Campbell, J.F., Morrison III, W.R. 2021. Effectiveness of long-lasting insecticide netting on Tribolium castaneum is modulated by multiple exposures, biotic, and abiotic factors. Pest Management Science. 77(3):1235-1244. https://doi.org/10.1002/ps.6134.
DOI: https://doi.org/10.1002/ps.6134

Interpretive Summary: Because of the low tolerance for insect infestations in food, preventing insects from colonizing food products is critical. Netting material with reduced risk insecticide incorporated into it (long-lasting insecticide netting (LLIN)) can be used as a barrier in food facilities. When dispersing insects contact the netting they are exposed to the insecticide, leading to knockdown and death. Insecticide netting has been used as bed-netting to prevent mosquitoes from transmitting malaria and has recently gained attention in the fight against stored-product pests. Short duration exposure to netting with deltamethrin insecticide can impact dispersal ability but may not be sufficient to cause mortality of stored product insects such as the red flour beetle. In this study, we demonstrated that beetles may recover after a single short exposure to the netting but that repeated short duration exposures had a cumulative effect equivalent to a single longer duration exposure. We also observed that effectiveness of the netting was impacted by different internal and external factors. The proportion of beetles that recovered from knockdown after exposure to the treated netting was greater in the presence of food, when humidity was high and when exposure occurred earlier in the day. Furthermore, older insects were less affected by the insecticide compared to younger insects. This information can be used in developing integrated pest management programs that incorporate insecticide netting as a tool to prevent insect infestations.

Technical Abstract: Prevention is the first line of defense to mitigating losses of post-harvest crops. Long-lasting insecticide treated netting (LLIN) could be used in food facilities to expose insects to insecticide at different areas within a facility. Prior research has shown that single short exposures reduce movement and longer exposures increase mortality for stored-product insect pests, but we do not know how multiple short duration exposures and biotic and abiotic conditions affect insects exposed to LLIN. Here, we repeatedly exposed red flour beetles, Tribolium castaneum, to LLIN to assess cumulative effects. We also examined the effects of beetle age and time of day during exposure and temperature, humidity, and food availability during recovery after a single exposure to LLIN. We found that four repeated 10-minute exposures had similar knockdown as a single 30-min exposure time. We also found that beetles were more affected when they were aged 1–6 d versus 14–20 d or exposed mid- or late-day versus earlier in the day. Higher recovery levels were observed with food and at higher relative humidity. In addition, older beetles were more active than younger beetles during exposure, which could reduce contact time with the netting and partially explain why older beetles tended to be less affected. Thus, some individuals can recover after exposure to LLIN dependent on exposure duration and environmental factors, but our study shows that sublethal effects likely persist and future work should consider the physiology of T. castaneum before, during, and after exposure to the LLIN.