Managing Colorado Potato Beetle Insecticide Resistance: New Tools and Strategies for the Next Decade of Pest Control in Potato

Abstract

Neonicotinoid insecticides have been the most common management tool for Colorado potato beetle, Leptinotarsa decemlineata (Say), infestations in cultivated potato for nearly 20 yr. The relative ease of applying neonicotinoids at planting coupled with inexpensive, generic neonicotinoid formulations has reduced the incentive for potato growers to transition from these products to other mode of action (MoA) groups for early-season L. decemlineata control. Continuous use of neonicotinoids has resulted in resistant L. decemlineata populations in some production areas of the eastern United States. Continued reliance on neonicotinoids will accelerate L. decemlineata resistance development and result in additional insecticide inputs to manage these populations. Resistance management recommendations for L. decemlineata have focused on rotation of insecticides within the growing season. Growers using at-plant neonicotinoids for early-season L. decemlineata control are encouraged to rotate MoAs for later generations to delay resistance development. Although this short-term insecticide rotation has likely prolonged the utility of neonicotinoid insecticides, reducing reliance on a single MoA soil application at planting will improve the longevity of newer, more reduced-risk alternatives. The objectives of this article are twofold: 1) to provide a review of the current status of L. decemlineata neonicotinoid resistance, and 2) to propose long-term resistance management strategies that arrange reduced-risk MoA groups into several, multiyear sequences that will maximize L. decemlineata control and reduce the probability for resistance development. This recommendation maintains practical and economical approaches for L. decemlineata control, but limits reliance on any single MoA group to minimize selection pressure for resistance development.

Temporal patterns of imidacloprid resistance throughout a growing season in Leptinotarsa decemlineata populations

“…(A) Dynamics of adult population size throughout the growing season, as suggested by Huseth et al , along with collection dates. (B) Median lethal concentration (LC 50 ) estimates representing the four different sampling intervals plotted over the season for the imidacloprid‐susceptible and (C) imidacloprid‐ resistant populations of L. decemlineata .…”

“…The life cycle of L. decemlineata has been previously described in detail, including investigations into which specific developmental stages (e.g., eggs, larvae, adults) are the best targets for insecticide treatments . However, the phenotypic variation in imidacloprid resistance over the growing season in adult L. decemlineata has yet to be examined.…”

“…Previous results by Huseth et al . provide an example of the most common insecticide inputs that are typically applied to potato in this production region, which include both at‐plant, systemic treatments, as well as foliar applications of neonicotinoids throughout the growing season . Huseth et al .…”

A New Tool for Resistance Management: Baseline Toxicity, Ovicidal Activity, and Field Efficacy of the Novel Insecticide Tolfenpyrad on Colorado Potato Beetle, <i>Leptinotarsa decemlineata</i>

“…Leptinotarsa decemlineata has a propensity for resistance development with some level of resistance being documented for 55 different active ingredients in nearly all insecticide groups [10] [12] [13]. While resistance varies between populations and regions, the homogeneity in management of potato increases the risk of resistance [12] [14]- [16].…”

“…Since the 1990s, potato growers have relied on neonicotinoid insecticides as the foundation of pest management [12]. This overreliance on a single class of insecticide has led to a steady decrease in efficacy, and control [10] [18] [19].…”