Variation in Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) progeny adult emergence in different animal feed stored under ventilated and non-ventilated conditions

Abstract

In contrast to the traditional practices of using naturally-available food materials for livestock production, multiplicity types of animal feed are currently available at the market. Prolonged storage of animal feed concurrently with human food items is practiced, and niche users experience the deterioration and possible risk of contamination of animal feed by insects. This study was conducted to determine the infestation of eleven types of animal feed commonly used in Sri Lanka by Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae), a major granivorous insect species. Twenty adults of one-month-old R. dominica were introduced to 20 g of different animal feed: fish feed, rabbit feed, dog feed, cat feed, chick mash, grower mash, layer mash, broiler starter, broiler finisher, bird feed (Bajiri) and rice polish. Each animal feed was maintained either ventilated or non-ventilated. From each animal feed, four replicates were tested. The parent adults were maintained in animal feed for 21 days under ambient environmental conditions (30 °C, 60% relative humidity, continuous darkness), and then sifted out. The progeny adults emerged in each animal feed were determined at monthly intervals for 5 months. In general, fish feed, rabbit feed, layer mash and bird feed (‘bajiri’) were more infested by R. dominica than other animal feed tested. Furthermore, progeny adults emerged in animal feeds differed with the status of ventilation and the duration of storage. The study reveals that the status of ventilation has mixed effects on the infestation of different animal feeds by R. dominica.