Plodia interpunctella (Hübner) (LEPIDOPTERA: PYRALIDAE) LIFE CYCLE ON STORED WALNUTS UNDER CONTROLLED ENVIRONMENTAL CONDITIONS

Resumen

Plodia interpunctella, known as Indian flour moth, is considered one of the most relevant pests of stored products worldwide. Infestation by P. interpunctella is one of the main causes of decrease in the production of walnuts in La Rioja, Argentina. Many investigations have shown that the biological cycle of this species depends on its diet and on environmental conditions. The study of the life cycle of P. interpunctella on stored walnuts was conducted under laboratory conditions at temperature values of 24 ± 1 ºC and average relative humidity of 56 ± 11 %. Eggs were collected daily and separated by batch. The presence of the head capsule exuvia was taken into account to determine the duration of the larval instars. Six larval instars were determined according to the exuvia found. The relationship between the length of larvae and the cephalic width was established by using the correlation coefficient, a key element in the instar characterization and for future tests for pest control. The duration of the complete life cycle of P. interpunctella fed on walnuts was of 71.56 days on average, from egg hatching until the death of the adult. The manipulation of larvae during the study did not affect significantly the duration of the cycle. Data obtained offer valuable information for pest management strategies for stored walnuts.