The performance of soybean cultivars and lines belonging to two maturity groups (110-125 and 140-160 days of cycle) was evaluated in two experiments under field conditions in relation to the attack of stink bugs and defoliators. The criterion used to estimate the defoliation was the PAFC (percentage of eaten leaf area). Three criteria were used to evaluate the damage caused by stink bugs: percentage of foliar retention, index of percent pod damage and yield. Among genotypes of the early maturity group (IAC 100, IAC 17, IAC Holambra Stuart-2, IAS 5 and IAC 83-311) no difference in resistance to the defoliators (predominantly Anticarsia gemmatalis Hübner) was observed. However, in relation to stink bugs [Nezara viridula (L.), Euschistus heros (Fabr.) and, predominantly Piezodorus guildinii (West.)] different levels of resistance could be detected. Regarding pod damage and foliar retention ratings, genotypes IAC 83-311 and IAS 5 were the most damaged, while IAS 5 was the only genotype rated susceptible as to yield criterion. The genotypes of longer cycle (145-160 days) comprised eleven lines of the soybean breeding program carried out at the IAC and three cultivars (IAC 14, IAC 8 and IAC PL-1). In this group significant differences among the treatments in relation to defoliators were observed: line IAC 78-2318, with multiple insect resistance, confirmed its behavior while cultivar IAC PL-l was the most defoliated, showing high susceptibility. Genotypes of this maturity group could also be ranked as to resistance to stink bugs; considering yield, most of the breeding lines showed good performance, yielding higher than the three cultivars.
Insecta; Pentatomidae; Anticarsia gemmatalis; varietal resistance; Glycine max
