Comparative efficacy of alternative insecticides for Rhyzopertha dominica management in Colombia: Beyond organophosphates and pyrethroids

Abstract

Here, we directly compared the insecticide efficacy of diamides (chlorantraniliprole), neonicotinoids (thiamethoxam), and spinosyns (spinosad and spinetoram) with that of organophosphates (pirimiphos-methyl) and pyrethroids (deltamethrin) in Colombian populations (i.e., Ibagué; El Espinal; Granada; Pore, and Sahagún) of R. dominica. Furthermore, we established the lethal concentrations for spinetoram in our insecticide-susceptible pattern population (Ibagué) and compared this insecticide residual activity against individuals of Ibagué and El Espinal populations. The Ibagué population was most susceptible to deltamethrin and chlorantraniliprole, while Ibagué and El Espinal populations showed higher susceptibility to pirimiphos-methyl and spinetoram. Thiamethoxam exhibited similar toxicity to the Ibagué, Granada, and Sahagún populations, and the susceptibility to spinosad was similar across all populations. The spinetoram exhibited high toxicity (LC₅₀ = 0.221 (0.174–0.287) mg a.i./Kg of grains) and residual activity against individuals from Ibagué and El Espinal populations, reinforcing its potential as alternative molecule for the management of R. dominica. Our findings expanded the insecticide options for controlling R. dominica in Colombia, contributing to avoid undesired effects of pyrethroids and organophosphates.