While farmers are always wary of insect pests threatening their crops, the early part of a growing season is a time of particular concern, as seedlings can be highly vulnerable should an infestation occur.
In corn, for instance, billbugs, imported fire ants, corn leaf aphids, and stink bugs are just a few examples of “sporadic” early-season pests that rarely turn out in force but, when they do, have the potential to destroy a field of seedlings.
Over time, for many growers, it has become common practice to plant seeds treated with neonicotinoid insecticides essentially as “insurance” against the possibility of such pests’ arrival—whatever that chance might be. But this approach doesn’t always align with the goals of integrated pest management (IPM), which seeks to avoid the unnecessary use of chemical controls. It’s a dilemma that Thomas W. Sappington, Ph.D., research entomologist at the Corn Insects & Crop Genetics Research Unit at the U.S. Department of Agriculture’s Agricultural Research Service (USDA-ARS), hopes might one day be solved.
“The nagging question we are trying to address is to what extent, and with what frequency, are these many pests actually to be expected in farmers’ fields in economic numbers,” he says.
Sappington and a team of USDA-ARS colleagues have just published a new collection of reports in the open-access Journal of Integrated Pest Management that tackle this complex question of predicting the potential impacts of sporadic early-season pests. In the series of papers, they examine such pests for corn, cotton, soybean, and wheat, focusing on how often infestations happen without preventative measures and the factors that influence the risk of infestations in any given field.
In the profile on early-season pests of seedling corn, for instance, 16 pests are examined.. For each the authors note its prevalence by region, historical data on past losses incurred by the pest, and numerous risk factors.
“Most of these pests will exert little or no pressure in most fields most of the time. They are considered ‘sporadic’ and ‘minor’ for a reason,” says Sappington. “But, the interactions of factors affecting risk across multiple pests are complex. Limiting risk from one pest may increase risk for another. For example, in corn, reduced tillage decreases risk from seedcorn beetles but increases risk from corn flea beetle.”
As Sappington and colleagues compiled these reviews of research on early-season pests, they gained a deep understanding of the complexity of predicting the potential impacts of multiple potential pests in any given field in any given year. In short, there are no easy answers.
“Every person has a different tolerance level for risk. Having these reviews at hand will help farmers and those who advise them cut through the fog of anecdote, marketing, and uncertainty to better assess the actual risk of getting hit by any or all of these pests on his or her particular farm in a particular year, and thus make more informed decisions, whatever their personal tolerance of risk may be,” Sappington says.
The reports in the collection may also give others a greater appreciation for the task that IPM professionals face in finding the optimum combination of management methods for any number of potential insect pests.
“I think it is important not only for farmers, ag professionals, and entomologists but also for regulatory agencies and the general public to understand how complicated this issue is, and reading through these reviews will make it obvious that this is so,” Sappington says. “Like everything else involving ecology and biology of organisms in an ecosystem—even in the relatively ‘simplified’ worlds of agro-ecosystems—it’s complicated. And moving forward productively with new ideas or large-scale plans will require a deep appreciation of nuance.”