Damage to Raisins, Almonds, and Walnuts by Irradiated Indianmeal Moth and Navel Orangeworm Larvae (Lepidoptera: Pyralidae)

Abstract

Damage to raisins, almonds, and walnuts due to feeding by irradiated larvae of the Indianmeal moth, Plodia interpunctella (Hubner), and the navel orangeworm, Amyelois transitella (Walker), was determined. Larvae of both species were reared on bran diet. Age of the larvae when irradiated was 8 d for Indianmeal moth and 13 d for navel orangeworm. Larvae were irradiated with doses ranging from 337 to 497 Gy (gray) before transfer to almonds, walnuts, and raisins. Adult emergence was prevented by all doses. In products containing' irradiated larvae, damage was consistently reduced. The percentage 'of weight losses of almonds infested with untreated India!).meal moth and navel orangeworm larvae and of walnuts infested with untreated navel orangeworm larvae was significantly higher than the percentage of weight loss of those infested with irradiated larvae. Radiation also improved the overall appearance of the product by reducing webbing and frass. These results indicate that although radiation-induced mortality may be delayed, damage to product quality due to infestation by larvae would be significantly reduced. KEY WORDS Insecta, 'gamma radiation, Plodia interpunctella, Amyelois transitella MOST OF THE U.S. DRIED FRUIT and 'nut crop is produced in California (USDA 1985). A major problem in the production and processing of these products is the presence of postharvest insect in-festa~ions. Particularly important are two pyralid moths, the Indianmeal moth, Plodia interpunctella (Hiibner), and the navel orangeworm, Amyelois transitella (Walker). The Indianmeal moth is ca

Using a population growth model to simulate response of Plodia interpunctella Hübner to temperature and diet

“…Management of P. interpunctella in any area containing products that contained an optimal diet like wheat diet would be crucial to avoid generating huge numbers of P. interpunctella moths and product loss. Raisins were chosen for this study as a contrast to wheat diet because dried fruit products can be infested by P. interpunctella and significant damage can occur (Johnson and Vail 1989;Johnson et al 2002). With their high reproductive capacity, populations on raisins were also able to reach high levels in less than 6 months.…”