The small hive beetle (Aethina tumida) is a pest of honey bees, but it can also be deployed in beneficial ways. New research shows that small hive beetles can be reared on excess honey bee pollen in controlled settings, and their pupae and frass can then be converted into animal feed and biomanure. (Photo by Jeffrey W. Lotz, Florida Department of Agriculture and Consumer Services, Bugwood.org)

By Andrew Porterfield

Andrew Porterfield

Several species of insects, including yellow mealworms (Tenebrio molitor) and house crickets (Acheta domestica) are raised as sources of animal and even human food. This can be done in a so-called “circular economic” process—in addition to producing usable products such as feed and biomanurethe insects also reduce biowastes from other agricultural or commercial processes.

Meanwhile, the European honey bee (Apis mellifera) is no stranger to insect pests. One significant pest of bees is the small hive beetle (Aethina tumida), a sub-Saharan native that now lives all over the globe. It is known for damaging honeybee colonies when its larvae consume bee pollen, honey, and brood, leaving the remaining honey fermented and unusable by both bee and human.

However, the way that the small hive beetle consumes honey could be key to not only providing nutrition and fertilizer but also to maintaining the health of honey bee hives. Steven Cook, Ph.D., research entomologist at the U.S. Department of Agriculture’s Bee Research Laboratory in Beltsville, Maryland, and his colleagues found that small hive beetle larvae could be reared on excess stored pollen from honey bee colonies, converting the food source to feed and fertilizer while keeping the excess fermented pollen from harming the beehive. Their research was published in September in the Journal of Economic Entomology.

Small hive beetle females have high reproductive rates with lifetime fertility, leaving large numbers of larvae in infested honey bee colonies. These larvae can crawl long distances to find suitable places for pupation, and adults fly long distances, attracted by the smell of bees and hive products. At the same time, honey bees collect pollen as a protein source to produce more bees. The bees turn pollen into “beebread,” which young honey bees feed upon. In many hives, bees collect excess pollen and store it. The pollen may go unused if disease or parasites have already harmed the colonies. Such stored pollen can ferment, become moldy, or just take up valuable space in a hive.

Using honey bee colonies at the USDA facility in Maryland, Cook’s team fed A. tumida larvae excess pollen stored in beeswax comb frames. The team collected A. tumida adults from the colonies and grouped them according to their sex. The team first examined bioconversion of excess pollen by the beetles, placing three male and three female adults in mating chambers. The team weighed first instar larvae, and 10 days later they weighed larvae in their wandering instar phase and collected accumulated frass. The researchers also analyzed larvae and frass for chemical and nutritional content.

In the second study, the researchers placed seven pollen-bound honeycomb frames into plastic bags, perforated to let the beetles breathe but not escape. They then placed eight female and eight male beetles into each bag containing a frame.

The researchers found that larvae showed 27 percent feed conversion efficiency, which is equal or higher than conversion efficiency of other edible insect species. The larvae themselves contained 25 percent protein, 25 percent fatty acid, and low carbohydrate and sugar content. The beetle larvae’s frass had the highest known nitrogen content of any edible insect. The larvae had higher caloric content than many other edible insects and even more than conventional meat sources such as chicken or pork.

“(The) small hive beetle appears to be a good candidate for inclusion to the repertoire of insects used as animal feed, and … valorize agricultural waste (in the form of honey bee-collected pollen) into nutrient-rich biomanure,” the researchers write. “Frames of unused pollen may collect microbial contaminants, which may impose health issues for exposed honey bees. Removal of excess moldy pollen by beetle larvae may ameliorate these issues.”

The researchers warn, however, that beekeepers and managers should be careful about deploying the small hive beetle in a circular economy. It remains a pest to bee colonies, after all. “They should be kept in completely enclosed conditions to prevent them from escaping and potentially causing harm to local honey bee populations,” they write.

Andrew Porterfield is a writer, editor, and communications consultant for academic institutions, companies, and nonprofits in the life sciences. He is based in Camarillo, California. Connect with him via LinkedIn or via email at [email protected].