While Calvin’s research focuses on resident pests, another entomology research project deals with migratory pests, which come with their own challenges. Entomologist Shelby Fleischer has developed Pestwatch, a coordinated system of monitoring migratory pests of vegetable crops, particularly sweet corn. “Pennsylvania ranks in the top five states for producing fresh market sweet corn,” he says, “so we’re interested in optimizing production through integrated pest management. To do that, you need to monitor insect population density, insect life stage, and crop stage.

Entomologist Shelby Fleischer checks a pheromone trap for corn earworm moths. Data from the traps are combined with other information in the Pestwatch database to map insect activity.

“So if we knew more about when and where these immigrants arrive each season, we could dramatically reduce insecticide use,” he continues. “Unfortunately, because of farm and crop diversity, spatial segregation of farms, the long distances that these migratory pests travel, and the smaller size of many farms in the Northeast, traditional IPM monitoring programs, such as field scouting, can be a logistic and economic challenge.”

Fleischer monitors two migratory species of lepidopterans—moths and their caterpillar larvae— that eat sweet corn: corn earworm and fall armyworm. “Fall armyworm is a true migrant that has no physical mechanism that allows it to get through harsh times,” he explains. “It doesn’t hibernate or suspend development. The corn earworm is more of a mix—we might have some overwintering here, but just how much is hard to measure.”

The female corn earworm moth, Fleischer explains, deposits a single egg on the silk of an ear of corn, then another egg on another ear of corn, and so on. “So one female doing a good job can spread out 500 eggs in a few nights. When we do the math, we can conclude that 30 to 50 females can blanket a crop-acre and cause 80 to 100 percent infestation.” Within three days after the eggs are laid, they hatch into larvae, and within another four days they manage to crawl into the ear, hidden from any pesticide application. While one management option is to blanket-spray insecticide so that it’s already on the silk when the eggs are laid, more accurate monitoring could help growers avoid possibly unnecessary blanket spraying.

One measuring method that’s had some success is pheromone trapping, which traps male insects. Presuming that females are laying eggs at the same time the males are flying, researchers can monitor egg laying indirectly by counting male insects caught the night before. Data from the pheromone traps, combined with field scouting, can provide some sense of the migratory process and how to manage crops accordingly.

“We monitor insect activity, and we want to use information technology to map this activity in real time,” Fleischer says. “For that we need people—what we call the human infrastructure of Pestwatch.” Extension educators throughout Pennsylvania play an important role by establishing and monitoring field sites, then entering data from those sites online. The data is processed in the form of maps that allow users to see a time series graphic for each site, as well as a point map of all sites.

If we knew more about when and where these insects arrive each season, we could dramatically reduce insecticide use.

“We worked with Doug Miller and his group at Penn State’s Center for Environmental Informatics to create this interactive cartography,” says Fleischer. “Doug saw the potential for using Macromedia Flash as an application for pulling data in and rapidly mapping it back out. He and his group created this system, which links time series graphics with a map interface so users can get up-to-date pheromone trapping data from any site. In extension, we’re seeing a shift toward dynamic information, and that’s what Pestwatch gives us.”