Dalbulus maidis (DeLong & Wolcott) is a primary pest in Brazil, as the vector of maize stunting pathogens e.g. the corn stunt spiroplama, Spiroplasma kunkelii. Although the main control strategy for this pest is chemical, few studies have investigated the efficacy of insecticides in preventing leafhopper feeding and transmission of these pathogens. In this study, we evaluated the effect of insecticides in seed treatment (ST) and foliar spray (PS) on D. maidis feeding and mortality rates, as well as on S. kunkelii transmission. All tested insecticides, both in ST and PS, significantly reduced the feeding rate of D. maidis in relation to the control (without insecticide). In ST, plants treated with Chlorantraniliprole and Imidacloprid + Thiodicarb allowed a higher feeding rate, than on plants treated with Thiamethoxam and Clothianidin. In PS, there was a higher feeding rate on plants treated with Chlorpyrifos than with other insecticides (Thiamethoxam, Imidacloprid, Methomyl, Thiamethoxam + Lambda-cyhalothrin, Imidacloprid + Beta-cyfluthrin and Lambda-cyhalothrin + Sulfoxaflor). Of the insecticides tested in the transmission experiment, only in plants treated with Chlorpyrifos (PS) and Chlorantraniliprole (ST), in addition to the control (without insecticide), there was transmission of S. kunkelii. In a complementary experiment, the mortality rates of D. maidis did not differ between infective and non-infective insects, after 24, 72 and 120 h of exposure to plants treated with Thiamethoxam (ST) or Methomyl (PS). The results show that some insecticides are useful for managing S. kunkelii by successfully reducing vector feeding and transmission rates.
