Poder residual do tratamento de sementes de milho com neonicotinoides para controle de Dalbulus maidis (Delong & Wolcott)

Abstract

Corn crops are extremely important in Brazilian agriculture, with a large cultivation area facing challenges, one of which is pest control, such as the corn leafhopper (Dalbulus maidis), a vector of pathogens that can severely impact production. This study aimed to evaluate the residual efficacy of different insecticides applied as seed treatments for the control of D. maidis under greenhouse conditions. The experiments were conducted at the Pest Management Laboratory at UFSCar, using maize plants of the AL Bandeirante variety treated with neonicotinoids. The insecticidal active ingredients tested were clothianidin, thiamethoxam, and a ready-made mixture of thiamethoxam with lambda-cyhalothrin. The seeds were treated with the respective products, sown in pots, and later, plants at 5, 10, 15, 20, 25, and 30 days post-emergence were infested with adult leafhoppers to assess insect mortality over four days. The results indicated that clothianidin and thiamethoxam, both alone and in combination with lambda-cyhalothrin, were effective in controlling D. maidis during the first 15 days post-emergence, with a high insect mortality rate. However, after 20 days, there was a significant decrease in treatment efficacy, becoming almost null by 30 days. These findings highlight the need for additional interventions beyond seed treatment to control D. maidis in maize after 15 days post-sowing.