Resistência de cultivares de soja à Spodoptera cosmioides (Lepidoptera: Noctuidae)

Abstract

The soybean stands out as the most important crop for Brazil, but several pests, if not controlled, have the potential to reduce their productivity. The caterpillar Spodoptera cosmioides (Lepidoptera: Noctuidae) has been outstanding due to the damages caused to this crop in its vegetative and reproductive phases of the plant. The objective of this work was to evaluate the resistance of soybean cultivars to Spodoptera cosmioides. The experiments carried out in the laboratory used the following soybean varieties: Anta 82 RR, BMX Challenge RR, BMX Power RR, BRS 397, BRS GO 6970 IPRO, BRS 7270 IPRO, BRS 7470 IPRO, BRS 8170 IPRO, BRS 8482, BRS GO 7460, IP 747 IPRO, PI 227682 and PI 22768. It was evaluated the attractiveness and non-preference for feeding with 3rd instar caterpillars, determining the number of caterpillars attracted per leaf disc at different times, food consumption and the attractiveness index in tests with and without choice, oviposition and colorimetric indexes. Also, the antibiosis effect of the varieties on the caterpillar was evaluated. The evaluated variables were: period and larval, pupal and total viability, larval and pupal weight, adult longevity and sexual ratio. The varieties IAC 100, PI 227682 and PI 227687 showed antioxenic resistance to S. cosmioides. The causes of resistance: trichome density and leaf color of the soybean plant are associated with the antioxenia to S. cosmioides. These varieties can be used in soy breeding programs aimed at incorporating sources of resistance to this pest. The moderate resistance variety M 7739 IPRO can be used by soybean producers as a strategy in the control of S. cosmioides. The colorimetric indexes L * and b * are fully correlated with the oviposition of the moths of S. cosmioides, since high values of these variables in shades of foliage of soybean plants tend to repel the selection for oviposition of these butterflies. The varieties PI 227682, PI 227687, IAC 100 and BRS 7270 IPRO showed antibiosis resistance. The varieties Anta 82, BMX Challenge, BMX Power, BRS 397, BRS 6970 IPRO, BRS 7470 IPRO, BRS 8170 IPRO, BRS 8482, BRS GO Jataí, BRS GO 7460, M 7739 IPRO, NA 5909, NS 7338 IPRO and NS 7447 IPRO are susceptible to S. cosmioides