The susceptibility of animal feed containing Dried Distiller's Grains with Solubles to Tribolium castaneum (Herbst) infestation

Understanding the susceptibility of commercially available animal feeds which contain Dried Distiller's Grains with Solubles (DDGS) to insect infestation is the first step in developing a pest management strategy for a stored product. This study is a nascent analysis of animal feed containing DDGS susceptibility to Tribolium castaneum (Herbst) infestation, one of the most important post-harvest insect pests world-wide. Three types of animal feed containing 5-10% DDGS in their formula mixtures were obtained from two feed manufacturers in Indiana, USA including: crumbled poultry feed, pelletized juvenile frog feed, and pelletized adult frog feed. Besides commercially available animal feed, laboratory manufactured feed were simulated by mixing Flour/Yeast (F/Y), T. castaneum normal laboratory diet, with 10, 20, 30, 40, and 80% DDGS (% based on weight). Larval developmental time was used to evaluate feed susceptibility to T. castaneum infestation. The T. castaneum larval period was significantly increased when fed on pelletized adult frog feed, pelletized juvenile frog feed, and crumbled poultry feed (29.8 ± 0.5, 26.0 ± 0.3, and 21.9 ± 0.3 d respectively), compared with F/Y (16.1 ± 0.3 d). The larval period was significantly decreased however, when fed on ground poultry feed (15.5 ± 0.2 d). Insect development on laboratory manufactured feeds was similar to F/Y regardless of DDGS ratios added in this study (15.9-16.9 d). These results suggested that first; particle size (PS) was one of the influential factors on susceptibility of commercially available animal feed to T. castaneum apart from feed chemical composition, and second, adding 10-80% DDGS to the laboratory manufactured feed did not change feed susceptibility to T. castaneum infestation.