Bioconversion of honey bee colony waste by small hive beetle (Coleoptera: Nitidulidae) larvae and the nutritional composition of larvae and frass

Abstract

A global demand for high protein animal feed and crop fertilizer continues to grow, and insects are an increasingly important alternative to conventional sources due to their reduced ecological and economic impacts. The small hive beetle (SHB), Aethina tumida (Murray) (Coleoptera: Nitidulidae), is a considerable cosmopolitan pest of Apis mellifera (Linnaeus) honey bees but may be a useful contributor to circular economies. SHB larvae are omnivorous, consuming pollen, honey, and honey bee brood. When matured, SHB larvae exit the hive to pupate in the soil, leaving their frass and other detritus behind. Here we present a method for rearing SHB larvae on excess stored pollen from honey bee colonies, calculate the bioconversion of the food source to larvae and frass, and report their nutritional content. Larvae showed a nearly 27% feed conversion efficiency, which is comparable or higher than that of other edible insect species. Larvae contained ∼25% of each protein and fatty acids and were low in carbohydrates (∼3%) and sugars (<0.4%). SHB larvae frass contained the highest nitrogen content compared to that of other edible insect taxa but was low in some other elements, such as iron. Given these data, the relatively innocuous larval diet, the "self-harvesting" behavior of the mature larvae, and the easily collected SHB frass, SHB larvae may be a valuable source of animal feed and biomanure. Frames of unused pollen may collect microbial contaminants, which may impose health issues for exposed honey bees. Removal of excess moldy pollen by SHB larvae may ameliorate these issues.

Keywords: biomanure; biorefinery; circular economies; pollen; waste conversion.