Control failure of deltamethrin in Colombian populations of Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae)

Abstract

Rhyzopertha dominica (F.) is a major pest in stored cereals in Colombia, which causes significant lossesin production. Chemical control is the main tool used in the country, and despite the common use ofinsecticides such as deltamethrin, resistance has been observed in some Colombian populations but isa worldwide problem. The objective of this work was to evaluate the efficacy of deltamethrin and thecombination of deltamethrin and piperonyl butoxide in Colombian populations of R. dominica. Failureto control and survival tests showed that the recommended doses on product labels were insufficient toprotect the grain from this pest. Failure control demonstrated that mortality did not exceed 80 percent inthe populations studied. Differences in susceptibility were observed between populations, with El Espinaland Neiva highlighted as less susceptible and Pore as the most sensitive to the action of insecticides.The combination of deltamethrin and piperonyl butoxide reduced insect survival but did not effectivelycontrol it (0–20%). These results suggest that R. dominica may be developing resistance to insecticides,as has been found in other countries. This underscores the importance of conducting toxicological studies and the need to investigate molecules with diverse modes of action, contributing to the strengthening ofchemical management strategies. To achieve effective control, it is necessary to implement IntegratedPest Management (IPM) with a focus on alternative methods to chemical control.