Antibiosis of four insect-resistant soybean genotypes to the soybean looper (Lepidoptera: Noctuidae)

Larvae of the soybean looper, Pseudoplusia includens (Walker), were reared on insect resistant soybean genotypes GATIR 81-26, GATIR 81-306, GATIR 81-327, PI 423968, or the susceptible cultivar "Ransom". Larvae reared on the four resistant genotypes exhibited decreased foliage consumption and decreased pupal weight when compared to larvae reared on "Ransom". Larvae consumed less 81-327 foliage than that of any other genotype. Mortality of larvae was also significantly greater on 81-327 (58.8%) when compared to that on the other soybean genotypes (16-32%). Mean number of days to pupation ranged from 10.7 ("Ransom") to 12.3 (81-327). Adult P. includens oviposited significantly more eggs when reared on "Ransom" foliage, while those reared on 423968, 81-26, and 81-327 produced the fewest numbers of eggs. The soybean genotype 81-327 exhibited the highest degree of antibiosis, with low-to-intermediate levels noted in 81-306, 81-26, and 423968.