Badger Beat Patterns of Resistance in Wisconsin Colorado Potato Beetle Populations

Is it time for proactive pest management programs that integrate non-neonicotinoid insecticides?

By Russell L. Groves, University of Wisconsin-Madison Department of Entomology

For almost three decades neonicotinoid insecticides containing clothianidin, imidacloprid and thiamethoxam have been the cornerstone of at-plant insect pest management in cultivated potatoes.

The U.S. Environmental Protection Agency (EPA) granted the first imidacloprid registration to Miles Laboratories (now Bayer Crop Science), in 1994, for use on turfgrass and ornamentals. One year later, the initial registration of imidacloprid

(Admire 2F) posted for potato growers.

Producers had access to a new group of water-soluble, systemic insecticides that provided excellent control of leaf-feeding pests like the

Adult Colorado potato beetles colonize on early emerging potatoes. Photo courtesy of D. Cappaert (www.insectimages.org)

Colorado potato beetle (CPB), or Leptinotarsa decemlineata, as well as piercing-sucking insect pests (e.g., green peach aphid [Myzus persicae], potato aphid [Macrosiphum], and potato leafhopper [Empoasca fabae]), and below-ground insect pests, including immature stages (grubs) of wireworms, white grubs, and flea beetles.

Since the initial registration of imidacloprid, other neonicotinoid insecticide registrations like clothianidin and thiamethoxam soon followed for at-plant or below-ground uses.

Over the past 27 years, the benefits afforded to producers by this mode of action (MoA) group (Insecticide Resistance Action Committee MoA Group 4A, http://www.irac-online. org/) have included versatility in application method (e.g., at-plant in-furrow, seed-treatment, foliar, chemigation, irrigation drip, and side-dress), longer periods of residual control when applied at planting, and a broad spectrum of pest control.

When initially registered, the U.S. EPA had designated several neonicotinoids as either “reduced risk” (RR) or as “organophosphate alternatives” during these initial registration processes.

The RR designation resulted in an expedited review and regulatory decision-making process given what was understood about these compounds and that they met one or more of the following criteria: i) limits impacts on nontarget organisms; ii) reduces acute and chronic exposure to farm workers; and iii) decreases additional pesticide use (U.S. EPA 2013).

Insecticide Resistance

Although the adoption of these soilapplied neonicotinoid insecticide uses could be regarded as largely beneficial to the potato industry given that far fewer broad-spectrum foliar insecticides (e.g., carbamates, pyrethroids, and organophosphates) have been used, the emergence of insecticide resistance and other nontarget and environmental impacts