Effect of a Seed-Mix Deployment of Cry3A-transgenic and Nontransgenic Potato on the Abundance of Lebia grandis (Coleoptera: Carabidae) and Coleomegilla maculata (Coleoptera: Coccinellidae)

Abstract

We estimated the relative abundance of 2 important natural enemies of the Colorado potato beetle, Leptinotarsa decemlineata (Say), in seed-mixed and pure fields of Cry3A-transgenic and nontransgenic potato. Sampling techniques included sweeping foliage, making timed visual counts of predators on foliage, and by trapping soil-dwelling predators in pitfall traps. Adults of Lebia grandis Hentz were less abundant in seed-mixed and pure 100% transgenic potato fields than in nontransgenic potato fields. In contrast, adults of Coleomegilla maculata (De Geer) were not affected by the treatments. We predict that L. grandis will rapidly disperse from seed-mixed and 100% transgenic potato fields because of the low densities of L. decemlineata in these fields. However, C. maculata will thrive and flourish in fields containing transgenic potato, especially when alternative prey or plant pollen are available.