Controle e danos de Melanagromyza sojae (Zehntner, 1900) (Diptera: Agromyzidae) em soja

Abstract

Soybean is the main grain crop grown in Brazil, with great importance for world food security. The soybean stem fly (SSF) Melanagromyza sojae (Diptera: Agromyzidae) is an invasive pest recently identified and categorized in Brazil, which has a great potential for damage to the soybean crop, especially in the second soybean crop (sown from December 31th). The damage caused by the SSF is due to its feeding process, as it forms galleries inside the stems of soybean plants, harming the development of the crop. As it is a recent pest in Brazil, there is only one insecticide registered for control via seed treatment. The objective of this work was to evaluate the reduction of damage caused by SSF in soybean, by 15 insecticides registered for soybean crop, regularly recommended for the management of other soybean pests. Two experiments were conducted during the 2021 (first season) and 2022 (second season) growing seasons, under different conditions of rainfall and SSF population pressure. The experimental design used was completely randomized with split plots in time with 16 treatments and 20 replications at 8 time levels in 2021 and 5 time levels in the 2022 season. The results showed that in the two seasons evaluated, the best treatments to reduce SSF damage were chlorpyrifos and cyantraniliprole applied weekly. The lowest levels of protection against SSF damage were registered for the methomyl treatment. The highest yields, in both years, were obtained in the treatments with chlorpyrifos and cyantraniliprole, demonstrating correlation with the damage reduction data by SSF. The results of this study point to a high potential for damage by the soybean stem fly, which can be mitigated by the use of chemical insecticides, as long as they are applied in the early stages of the soy crop