Scientists Study Behavior of Leading Stored Grain Pest

By Jim Core
May 7, 2003

Safer alternatives to protect stored food products from the Indianmeal moth and its larvae are being sought by Agricultural Research Service scientists at the agency's Center for Medical, Agricultural and Veterinary Entomology (CMAVE) in Gainesville, Fla.

Scientists in CMAVE's Postharvest and Bioregulation Research Unit want to find alternatives that eliminate or reduce conventional pesticides and that also make sense economically. Studies have focused mainly on protecting processed cereal-grain products by using the infesting moths' own behavioral and physiological responses against them.

Cereal products become infested when females lay hundreds of eggs directly on the product or when newly hatched larvae crawl into the product. For a successful infestation, a cereal must have the appropriate nutrients for larval growth. According to research chemist Don Silhacek, the growth rate of Indianmeal moth larvae can vary widely, depending upon the product's nutritive and physical qualities. Scientists are identifying the nutritive factors naturally limiting moth development on some commercial cereal products. Their goal is to design products that appeal to people and animals but aren't susceptible to moth infestation.

A second approach is to limit or eliminate pesticide use by gaining a better understanding of juvenile hormone (JH) regulation of moth development. JH first appears late in embryogenesis and is maintained at high levels during the larval stage, preventing metamorphosis into an adult. Silhacek achieved effective control of moths in cereal products in model warehouses using strategically placed applications of pyriproxyfen, which interrupted embryogenesis and prevented the pests' eggs from hatching.

In another approach, two model warehouses with controlled environments are being used to identify external factors affecting moths' behavioral and physiological responses during cereal product infestation. Researchers are investigating whether moth behavior can be regulated by modifying the warehouse photoperiod (the light/dark cycle) and by substituting different wavelengths of light into it.

Read more about this in the May issue of Agricultural Research magazine.

ARS is the U.S. Department of Agriculture's chief scientific research agency.