Sublethal exposure of Trogoderma granarium Everts (Coleoptera: Dermestidae) to insecticide-treated netting alters thigmotactic arrestment and olfactory-mediated anemotaxis

Authors: DOMINGUE, MICHAEL - Kansas State University; Scheff, Deanna; Arthur, Franklin; MYERS, SCOTT - Animal And Plant Health Inspection Service (APHIS)

Submitted to: Pesticide Biochemistry and Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/3/2020
Publication Date: 1/15/2021
Citation: Domingue, M.J., Scheff, D.S., Arthur, F.H., Myers, S.W. 2021. Sublethal exposure of Trogoderma granarium Everts (Coleoptera: Dermestidae) to insecticide-treated netting alters thigmotactic arrestment and olfactory-mediated anemotaxis. Pesticide Biochemistry and Physiology. 171:104742. https://doi.org/10.1016/j.pestbp.2020.104742.
DOI: https://doi.org/10.1016/j.pestbp.2020.104742

Interpretive Summary: Long-lasting insecticide treated netting (LLIN), which has the insecticide deltamethrin incorporated into it, can be used as a barrier to prevent movement by stored product insects and ultimately infestation of stored food. This netting could potentially be used in the management of the khapra beetle (Trogoderma granarium) a widespread pest of many agricultural commodities and a quarantine pest in the US. We found that brief exposures of larvae to LLIN, for less than 30 minutes, decreases the chance of eventual adult emergence compared to larvae exposed on untreated netting. Next, we observed that short ten minute exposures to the LLIN, such as might occur when a dispersing insect has a brief encounter with the netting, had little reduction in adult emergence but did have effects on movement and response to volatile cues. Insects not exposed to netting showed increased likelihood of walking upwind if a pheromone or food based lure was provided, as expected. However, when LLIN was used, the insects became more likely to move and there was a baseline increase in the likelihood of moving upwind. However, upwind walking was no longer related to attractants being presented. These observations suggest that particular care should be used in relation to the airflow patterns and chemical landscape in settings in where LLIN are deployed.

Technical Abstract: Long-lasting insecticide treated netting (LLIN) has a number of potential uses for the control of insect pests. Using such netting, stored products may be protected from insects including the khapra beetle (Trogoderma granarium Everts, Coleoptera: Dermestidae) a widespread pest of many agricultural commodities. Here we first examined whether brief exposures of larvae to LLIN, for less than 30 minutes, decreases the chance of eventual adult emergence compared to larvae exposed on untreated netting. Next, we observed the responses of larvae that were either not exposed to any netting, exposed to untreated netting, or exposed to LLIN for ten minutes and then placed in a wind tunnel and monitored for movement towards a stimulus. The wind-tunnel assay was performed either with or without a lure containing kairomones and pheromones known to be attractive to larvae of this species. There was little effect of the LLIN on adult emergence. However, there were interacting effects of untreated netting and LLIN relating to thigmotaxis and anemotaxis. Insects not exposed to netting showed increased likelihood of walking upwind if the semiochemical lure was provided, as expected. A similar pattern was observed when the control netting was used, but the insects became more likely to remain stationary in the assay after acclimating to the net. When LLIN was used, the insects became more likely to move and there was a baseline increase in the likelihood of moving upwind. However, upwind walking was no longer related to semiochemical presentation. These observations suggest that particular care should be used in relation to the airflow patterns and semiochemical landscape of the warehouse settings in which LLIN are deployed.