Evaluation of damage to early maturity soybean cultivars and lines caused by stink bugs and caterpillars

The damage of stink bugs and caterpillars was evaluated in soybean cultivar s and lines from two maturity groups, in experiments under field conditions , at the Institute Agronomico, in the Experimental Station of Ribeirao Pret o, SP, Brazil, in the 1995/96 and 1996/97 seasons. The stink bug infestatio n, predominantly Piezodorus guildinii (West.), was more intense in the firs t season. Anticarsia gemmatalis Hub. infested the experiments only in the f irst year. Among the early maturing genotypes with approximately 110 days ( 'IAS 5', 'IAC 17', IAC 90-3395, IAC 93-345 and IAC 93-386), the cultivar IA C 17 showed the lowest defoliation (11.7%) caused by A. gemmatalis, while t he line LAC 90-3395 presented the highest (28.3%). Regarding to the stink b ug damage, as evaluated by three criteria (foliar retention, pod damage and yield), the lines IAC 93-345,IAC 93-386 and IAC 90-3395 and the cultivar I AC 17 presented the highest resistance levels, yielding more than cultivar IAS 5, in the first year. Among the genotypes of 120-days maturity group (' IAC 15', 'IAC 18', 'IAC 100', IAC 93-2277, IAC 93-2738, IAC 93-3335), the c ultivar IAC 100 and the line IAC 93-3335 were the most resistant to A. gemm atalis. The cultivar IAC 15 was susceptible to that insect and to the stink bugs. The cultivar IAC 18 ranked as one of the highest yielding genotypes in spite of its high foliar retention, maintaining stable average yields ov er years. Among the lines, IAC 93-3335 showed the lowest defoliation by A. gemmatalis, and presented low pod damage and good yield, similar to cultiva r IAC 18.