Evaluation of prethroid insecticides and insect growth regulators applied to different surfaces for control of Trogoderma granarium (Coleoptera: Dermestidae) the khapra beetle

Authors: Arthur, Franklin; GHIMIRE, MUKTI - Animal And Plant Health Inspection Services (APHIS), National Wildlife Center; MYERS, SCOTT - Animal And Plant Health Inspection Services (APHIS), National Wildlife Center; PHILLIPS, THOMAS - Kansas State University

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/26/2018
Publication Date: 4/2/2018
Citation: Arthur, F.H., Ghimire, M.N., Myers, S.W., Phillips, T.W. 2018. Evaluation of prethroid insecticides and insect growth regulators applied to different surfaces for control of Trogoderma granarium (Coleoptera: Dermestidae) the khapra beetle. Journal of Economic Entomology. 111(2):612-619. https://doi.org/10.1093/jee/toy040.
DOI: https://doi.org/10.1093/jee/toy040

Interpretive Summary: The khapra beetle is a quarantined pest should it be detected by USDA-APHIS inspectors at seaports, airports, and border crossings, and there is increasing concerns regarding potential establishment in the USA. When infestations are detected the most effective treatment may be fumigation using methyl bromide, but this is costly and its application may be limited in certain areas. One alternative to fumigation is residual insecticide treatments but it is essential these treatments are applicable to a range of environments and provide high levels of efficacy across life stages and larval size classes. There are no studies of new reduced-risk insecticides that are currently on the market that could be used for control of the khapra beetle on different types of surfaces found in indoor habitats. In laboratory tests exposing young and old khapra beetle larvae on different surfaces treated with contact pyrethroid insecticides there was less mortality of larvae on concrete, painted wood and floor tile compared to metal and wood, and mortality on concrete and floor tile declined as residues aged. Young larvae were much more susceptible than large larvae. When concrete, metal, and wood were treated with insect growth regulator insecticides young larvae were more susceptible than large larvae. Results of these experiments show the potential efficacy of these new reduced-risk insecticides in management programs applied when and if khapra beetle infestations are detected in the USA.

Technical Abstract: The khapra beetle, Trogoderma granarium Everts, is a serious pest of stored products and is the only stored products pest that triggers a quarantine response when it is found in the United States. The larvae of T. granarium feed on a wide range of dry food products of plant and animal origin including cereals, dried fish and museum specimens. In this study, we evaluated the residual efficacy of two pyrethroid insecticides, deltamethrin and beta-cyfluthrin applied on concrete, wood, painted-wood, vinyl flooring tile, and metal surfaces using small and large T. granarium larvae. Residual efficacy of two insect growth regulators, methoprene and pyriproxyfen was also evaluated on concrete, metal and wood surfaces. In both studies larvae were exposed with provision of a food source on the treated surfaces and residual assays were conducted at 0 (1-d), 30, 60, and 90 d post-treatment times. In general, both of the pyrethroids provided a high level of control of T. granarium larvae, though small larvae were much more susceptible than large larvae. The IGRs were comparatively less effective, with more larval survival and adult emergence of exposed larvae. Residues of the pyrethroids and IGRs were most persistent on the metal surface. Results can be used to help to control and eradicate infestations of T. granarium when they are detected in the USA.