Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 27, 2013
Publication Date: February 7, 2014
Citation: Kharel, K., Arthur, F.H., Zhu, K., Campbell, J.F., Subramanyam, B. 2014. Evaluation of synergized pyrethrin aerosol for control of Tribolium castaneum and Tribolium confusum (Coleoptera: Tenebrionidae). Journal of Economic Entomology. 107(1):462-468. DOI: http://dx.doi.org/10.1603/EC13355. Interpretive Summary: Aerosol insecticides are used to control flour beetles in milling facilities, and there are areas within flour mills where food spillage can accumulate and provide harborage sites for insect infestations. There is a need for information regarding the effect of food material on aerosol effectiveness. When the insects were directly exposed to the aerosol, mortality was high, but when they were exposed with flour, or exposed in the treated flour, mortality was greatly reduced. Larvae of both species were less susceptible to the pyrethrin aerosol in the presence of flour compared to adults and pupae, possibly because they were able to burrow into the flour and escape exposure. Results of this study show that sanitation and cleaning in conjunction with aerosol application may yield increased control of flour beetle populations in milling and food storage facilities.
Technical Abstract: Aerosol insecticides have been used in flour mill pest management programs, but there is limited information on their efficacy on different insect life stages. In this study, we evaluated the efficacy of synergized pyrethrin applied as an aerosol against eggs, larvae, pupae, and adults of the red flour beetle, Tribolium castaneum (Herbst), and the confused flour beetle, Tribolium confusum Jacquelin du Val. Effects of direct and indirect exposure were evaluated by exposing each life stage to the aerosol and then transferring to untreated flour, transferring untreated insects to treated flour, or exposing both the insects and the flour to the aerosol. The aerosol was effective against both species and all life stages when insects were directly treated with it, irrespective of transferring them to treated or untreated flour, and mortality was generally >88%. The mortality was significantly reduced when insects were either treated together with flour or untreated insects were transferred to treated flour (indirect exposure to the aerosol). Larvae and adults of both species were more tolerant compared to eggs and pupae. Additionally, more moribund adults in indirect exposure treatments were able to recover compared to moribund insects in the direct exposure treatments. Results show the importance of delivering the aerosol to the insects instead of treating flour or surfaces. Good sanitation prior to aerosol application could facilitate direct exposure of insects and thus increase its effectiveness inside flour mills.