Danos de Melanagromyza sojae (Diptera: agromyzidae) em soja

Abstract

The soybean stem fly, Melanagromyza sojae Zehntner (Diptera: Agromyzidae), an important soybean pest in East Asia, has recently invaded and colonized the major soybean producing countries of South America. Management strategies for this pest remain largely undeveloped due to lack of information regarding its damaging potential in Brazil and neighbouring countries. The objective of this study was to quantify soybean yield reduction caused by M. sojae damage. Two experiments were carried out during the 2019/2020 (experiment A) and 2020/2021 (experiment B) cropping seasons. The experimental design was completely randomized with eight treatments and ten replicates for experiment A and seven treatments and ten replicates for experiment B, representing different levels of coexistence between the target pest and soybean plants. Number of grains, 1000-grain weight, grain yield and number of pods were quantified for lower, middle and upper canopy segments of the plants. In experiment A, each 1% of injured stem in the lower, middle and upper canopy segments reduced (p<0.0001), respectively: 1.41, 0.71 and 0.75 grains/plant; 2.45, 3.10 and 3.36 g of 1000-grain weight; and 0.43, 0.24 and 0.23 g of yield/plant. Considering the three segments, yield reduction reached 0.9 g/plant (p<0.0001) for each 1% of injured stem. The findings from this study point to a high damaging potential of M. sojae under Brazilian growing conditions and highlight the need to develop management strategies for this pest in soybean crops.