Determining Optimal Rearing Substrates for Growth and Survival of the Lesser Mealworm, Alphitobius diaperinus

• Jessica Tarpley, , University of Delaware

• Michael Crossley, Entomology and Wildlife Ecology, University of Delaware

The world’s growing human population demands more efficient and sustainable food
production. Insects could help meet this challenge by converting food waste into
nutritious biomass. The lesser mealworm (Alphitobius diaperinus) is a significant
nuisance insect impacting the poultry industry, but was approved in January 2023 for
human consumption in the European Union, creating an opportunity to turn a pest into a
valuable waste upcycler. Here, we examined the growth and survival of lesser
mealworm larvae over four weeks reared on different feeds varying in their ratio of
wheat bran to chicken feed (3:1, 2:1, and 1:1) and with the addition of yeast. The
experiment was replicated ten times with 20 larvae per petri dish kept at 30 degrees
Celsius in darkness, using 7-day-old larvae obtained from beetles originating in
commercial broiler farms in DE. Every seven days, the number and mass of surviving
larvae, and mass of remaining feed was measured. We found that larvae reared on the
3:1 ratios of wheat bran and chicken feed consumed more, gained more weight, and
were more efficient at converting feed into larval biomass. Though larvae performed the
worst on the 1:1 ratio of wheat bran to chicken feed, performance improved with the
addition of yeast; an effect that was not apparent in the 2:1 and 3:1 ratios. Our results
suggest that manipulation of the lesser mealworm diet can greatly enhance their
performance, thus increasing conversion efficiency and yield of edible insect biomass to
feed a growing human population. While these findings offer exciting clues in
determining optimal rearing substrates for lesser mealworm larvae, further investigation
is recommended to determine whether and how higher wheat bran ratios might further
enhance their growth and performance.