|Arthur, Franklin - Frank|
Submitted to: Journal of Stored Products Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/27/2017
Publication Date: 4/4/2017
Citation: Ghimire, M.N., Myers, S.W., Arthur, F.H., Phillips, T.W. 2017. Susceptibility of Trogoderma granarium Everts and Trogoderma inclusum LeConte (Coleoptera: Dermestidae) to residual contact insecticides. Journal of Stored Products Research. 72: 75-82. doi: 10.1016/j.jspr.2017.02.006. Interpretive Summary: The khapra beetle is the only stored-product insect that is classified as a quarantine pest in the USA, and the USDA-APHIS is reporting increased interceptions of this pest at ports of entry. It is a member of the family dermestidae, and is similar in biology and habits to other members of that family. We conducted a study to determine susceptibility of larvae to insecticides, and also to determine if the larger cabinet beetle, another stored product dermestid beetle that is a resident pest, can serve as substitute species for evaluations. Larvae of both species recovered from short-term exposures to three registered insecticides and were able to emerge as adults, but the cabinet beetle larvae were less susceptible than the khapra beetle. In a second test evaluating two strains of khapra beetle, larvae of a field strain were more tolerant compared to a lab strain, but for both strains adults were far more susceptible to the insecticides than larvae. Results show that control measures for khapra beetle and other dermestids must account for the greater tolerance of larvae compared to adults. USDA-APHIS can utilize our results in planning revised control procedures for khapra beetle when infestations of this pest are detected.
Technical Abstract: Two pyrethroid insecticides were evaluated on concrete arenas for their efficacy against Trogoderma granarium and T. inclusum larvae. Ten larvae of either species were exposed to treated arenas for 1, 2, 3, and 7 d then transferred into 175 ml cups with diet for 30 d to evaluate delayed mortality. In a subsequent study, efficacy of three contact insecticides, ß-cyfluthrin, deltamenthrin, and chlorfenapyr were evaluated at 0, 2, 4, 8, and 12 wk post-treatment assays against laboratory and field strains of T. granarium. Ten adults or larvae of either strain were exposed to treated arenas. Mortality was assessed after 4 and 30 d of exposure for adults and larvae, respectively. Delayed mortality of T. granarium and T. inclusum larvae was low (< 26%) with two pyrethroid products, and T. inclusum larvae were less susceptible than T. granarium. Adult mortality was high (90-100%) for both strains of T. granarium across post-treatment assays irrespective of insecticide treatment and no difference was observed between strains. All three insecticides provided high larval mortality (100%) for the first two post-treatment assays then efficacy declined, with field strain larvae more tolerant than lab strain larvae. T. granarium and T. inclusum larvae were not killed in short exposures. Larvae were more tolerant than adults and required longer exposure to insecticides.