Levels of resistance to insecticides in Trialeurodes vaporariorum (Westwood) (Homoptera: Aleyrodidae), a pest of beans

Abstract

Adults of the greenhouse whitefly were exposed to the insecticides monocrotophos, methamidophos, profenofos, methomyl, cypermethrin, and deltamethrin. These products were applied in commercial formulations by dipping the foliage of bean plants. Granular carbofuran applied at planting time was also tested. The adult mortality was recorded 24 hours after application. Data were then utilized to calculate LC₅₀ and DL₅₀ values by means of the probit analysis. Moderate levels of resistance to monocrotophos and methamidophos were detected. Highest RRs were found with methamidophos in Fusagasugá race (41X), and with monocro­tophos in Tocotá (33X) and Tenerife (26X) races. RRs values for methomyl in Tenerife and Tocotá races were lower than those calculated for methamidophos and monocro­tophos. No resistance to carbofuran was detected. The Fusagasugá, Rionegro, Tocotá and Otoño races showed resistance to cypermethrin and deltamethrin. RRs values for cypermethrin were similar to those calcu­lated for monocrotophos and methamidophos. Overall, the highest resistance levels were found with deltamethrin (RR values: 47X end 68X).