Resistance in Common Bean (Phaseolus vulgaris) to Lygus hesperus (Heteroptera: Miridae)

Abstract

Thirty-eight selected acquisitions of Phaseolus vulgaris (L.) were evaluated for resistance to the Lygus bug, Lygus hesperus Knight, a major pest of common beans in the western United States. Estimates of gross increase, ovipositional preference, nymphal development, and survival of Iygus bugs on those cultivars were used as parameters to identify resistant germplasm and general mechanisms involved in resistance. The assessment of resistance was dependent upon counting newly hatched nymphs as a measure of oviposition. Studies were also done to validate this by assessing survivorship of eggs. Counts of first-instar lygus bugs after 12 days of incubation were shown to be a reliable estimate of oviposition. Resistance through ovipositional nonpreference was found in entries ‘BAT 1258’, ‘DOR 42’, ‘Gloria’, ‘BLAN 7644’, ‘Bountiful’, and ‘c 15’. Antibiosis was evidenced by reduced nymphal development rate on entries ‘BAT 1081’, ‘BAT 1258’, ‘BAT 1299’, ‘BAT 1254’, ‘Gloria’, ‘0425’, and ‘CIAT 5979’, as well as by reduced survival on these same entries with the exception of ‘Gloria’ and ‘CIAT 5979’. Significant reduction in survival was also observed in ‘T 39’ and ‘Michigan Improved Cranberry’. These results suggest that at least two general mechanisms function to provide resistance: nonpreference by interference with oviposition and antibiosis by induction of reduced nymphal growth and survival. These findings will help in selection of germplasm for breeding common beans resistant to L. hesperus .