End of an Era of Easy Pest Solutions

Colorado potato beetle, Leptinotarsa decemlineata. Source: D. Cappaert, Michigan State University, Bugwood.org

The Colorado potato beetle is a beautiful creature, but probably only if you’re an entomologist, an artist of the environment, or a ten-year-old who refers to it as “cool” and puts the word “dude” at the end.

Andrei Alyokhin, professor of entomology at the University of Maine, is interested in the Colorado potato beetle (CPB) because it attacks one of Maine’s most reliable and stable crops: the potato. CPB is native to Mexico and the southwestern United States, but its range has expanded over the last two centuries to cover about 10 million square miles across North America, including Maine.

Growers have traditionally managed CPB with insecticides. However, CPB resistance to insecticides is now prevalent. Alyokhin and his colleagues say that the degree of CPB resistance varies across geographies. So, what is causing this variation and how can this information be used to help improve IPM? 

Alyokhin’s team has narrowed the set of possible causes to the number of generations, crop rotation, volunteer potatoes, frequency of resistant alleles, insecticide intensity, and trap rows. It turns out that no single factor could be identified as universally responsible for CPB developing resistance in all of the regions and this is very important in more ways than one.

“We know diversification of techniques is important in managing CPB, but it involves more than just throwing a bunch of practices at it and hoping a few stick,” says Alyokhin. Since the 1970’s, it has been argued that susceptible gene pools of pest organisms, like  CPB, should be treated as non-renewable resources. Like preserving the oil and gas deposits buried deep within the earth through conservation, so too can CPB be managed with insecticides, if the chemicals are used in a judicious manner.

Alyokhin and his colleagues write, “The [IPM] approach requires substantial extra effort to understand the system and to determine the best ways of dealing with CPB.” The extra effort is the reason why IPM is not just another input that can be bought and sold. It must be learned and applied.