Influence of Extent and Timing of Colorado Potato Beetle (Coleoptera: Chrysomelidae) Defoliation on Potato Tuber Production in Eastern Virginia

Abstract

A 2-yr field study was done to evaluate tuber production of ‘Superior’ variety potatoes, Solanum tuberosum L., following various levels of defoliation by the Colorado potato beetle, Leptinotarsa decemlineata (Say). Plants were subjected to defoliation during five consecutive plant growth periods, and tuber weights were measured at the end of each period. Additional plants subjected to defoliation were marked with a visual defoliation rating at the end of each period and maintained free of Colorado potato beetle infestation during subsequent growth periods. Tuber weights of these plants were recorded at the end of growth period five. plants were most sensitive to beetle defoliation during the early stages of plant growth up to 60 d after planting. Tuber yield was least affected by beetle feeding damage during later plant growth stages. Up to 100%defoliation during the last plant growth period (75-89 d after planting) did not result in significant reduction in tuber weights, compared with undefoliated plants. Colorado potato beetle counts indicated that plants could tolerate beetle populations well above published threshold levels without a decrease in tuber production, particularly after initiation of bloom.