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

Abstract

AbstractBACKGROUNDPrevention is the first line of defense in mitigating losses of post‐harvest crops. Long‐lasting insecticide treated (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 the 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.RESULTSWe found that four repeated 10‐min exposures had similar knockdown effects as a single 30‐min exposure. We also found that beetles were more affected when aged 1–6 days versus 14–20 days or were exposed at mid‐ or late in the 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 time in contact with netting and partially explain why older beetles tended to be less affected.CONCLUSIONSome 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 LLIN. Published 2020. This article is a U.S. Government work and is in the public domain in the USA