Etofenprox guarding concrete for six weeks: immediate and delayed mortality of three major stored-product coleopterans

This study addresses the residual efficacy of the pyrethroid insecticide etofenprox sprayed on concrete surfaces for the management of Prostephanus truncatus (Horn) (Coleoptera: Bostrychidae) adults, Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) adults, and Trogoderma granarium Everts (Coleoptera: Dermestidae) adults and larvae, through a period of six weeks. Three doses of etofenprox (5 mu g/cm(2), 15 mu g/cm(2), and 45 mu g/cm(2)) were tested to assess immediate (1, 2, 3, and 7 days of exposure) and delayed (7 days post-exposure) mortality. For P. truncatus, after 7 days of exposure, immediate mortality ranged between 35.6% and 53.3% the first week while the sixth week ranged from 12.2% to 27.8% after a gradual decrease the weeks in-between. Similarly, at the same exposure interval, the tested doses of etofenprox killed 36.7-62.2% of R. dominica the first week while 20.0-41.1% the sixth week. Etofenprox provided the highest mortality rates against T. granarium adults reaching 93.3-97.8% the first week. After a progressive decrease, mortalities ranged from 73.3% to 87.8% the sixth week. Regarding T. granarium larvae, 43.3-63.3% of the exposed individuals died the first week but during the last week mortalities decreased to 13.3-32.2%. Delayed mortality of all tested species/developmental stages was elevated the first week, reaching 100.0% for all tested doses against P. truncatus and T. granarium adults. During the last week, 45 mu g/cm(2) killed 100.0% of P. truncatus adults, 67.4% of R. dominica adults, and 42.9% and 31.1% of T. granarium adults and larvae respectively. The results indicate that the efficacy of etofenprox on concrete depends on the pest species/developmental stages that are exposed and/or the time that has passed since the application date.

Automated summary

This study examined the efficacy of etofenprox insecticide on concrete surfaces for controlling Prostephanus truncatus, Rhyzopertha dominica, and Trogoderma granarium adults and larvae over a period of six weeks. The results showed that etofenprox had varying levels of immediate and delayed mortality, with the efficacy dependent on the pest species/developmental stages and the time since application. The highest mortality rates were observed for T. granarium adults in the first week, while mortalities decreased over time for all tested species/stages.