Feeding bioassay for stored-product insect pests using an encapsulated food source

• Published in: Journal of stored products research Vol. 38; no. 4; pp. 319 - 327
• Main Author: Epsky, Nancy D.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.01.2002; Elsevier Science
• Subjects: Biological and medical sciences; Encapsulated food; Feeding behavior; Fundamental and applied biological sciences. Psychology; Invertebrates; Medically important nuisances and vectors, pests of stored products and materials: population survey and control; Oryzaephilus surinamensis; Pests of stored products; Sitophilus oryzae; Tribolium castaneum; Tribolium castaneum; Feeding behavior; Encapsulated food; Sitophilus oryzae; Oryzaephilus surinamensis; Encapsulation; Pellet; Thermoplastics; Coleoptera; Insecta; Silvanidae; Stored food product; Tenebrionidae; Plastic film; Pest; Pest behavior; Diet; Arthropoda; Liquid product; Curculionidae; Invertebrata; Feed
• ISSN: 0022-474X; 1879-1212
• DOI: 10.1016/S0022-474X(01)00025-X

A procedure that was developed to encapsulate liquid and semiliquid diets was used to encapsulate dry diet for use in a feeding bioassay for beetles that are pests of stored products. Vacuum was used to form Parafilm ® into numerous 6 mm diameter wells. The wells were filled with clean sand (control) or ground dry dog food (test), and the Parafilm ® sealed to produce individual pellets. A single pellet was then placed in the center of a 9 cm diameter Petri dish and feeding activity of groups of ten adults of Sitophilus oryzae (L.), the rice weevil; Oryzaephilus surinamensis (L.), the sawtoothed grain beetle; and Tribolium castaneum (Herbst), the red flour beetle, was tested. The number of insects on the encapsulated pellet and the amount of food or sand scattered were checked hourly for the first 8 h of the study and after 24 h. Few insects were observed on pellets containing sand and little or no sand was observed scattered outside of the pellet, so the presence of dog food in the pellet was needed for insects to feed on the pellet. In tests with encapsulated dog food, the amount of food scattered provided a better quantitative measure of feeding than the number of insects on the pellet. Insects that were starved for 48 h caused greater amounts of food scatter than insects starved for 24 h prior to the test. In direct comparisons among all three species, T. castaneum responded the most slowly and the bioassay may be improved by increasing the amount of time starved. Sitophilus oryzae responded very quickly and the entire pellet was essentially consumed within the first 4–5 h of the study. The encapsulated diets provide a promising method to evaluate feeding behavior of stored-product insect pests.