Insect Larvae Fed Mycotoxin-Contaminated Wheat – a Possible Safe, Sustainable Protein Source for Animal Feed?

Demand for increased food production, particularly protein, is increasing with the world’s growing population. Alternative and sustainable sources of animal protein will be required to reduce environmental impacts of conventional livestock production. Historically, insects have been typical dietary components within eastern countries, and their nutritional value is proportionally comparable to conventional meat. The yellow mealworm (Tenebrio molitor) is an edible insect, rich in crude protein and crude fat. Moreover, there is evidence that mealworms are able to utilize mycotoxin-contaminated wheat as a food source without accumulating the mycotoxins, thus providing a value for low-grade wheat along with a more sustainable and cheaper source of crude protein for animal feed. The aim of this study was to measure production traits, survivability, and determine whether mealworms can detoxify mycotoxins (specifically deoxynivalenol, DON) when fed Fusarium-damaged, high mycotoxin wheat. To achieve these objectives, naturally-contaminated grain was sorted to obtain four levels of DON: control (0.2 ppm), low (2 ppm), medium (10 ppm) and high (12 ppm). These levels were fed to larvae (7-9^th instar) per replicate for feeding (n= 300) and breeding (n=200) trials. Each treatment was replicated 5 times and the endpoint for both experiments was when 2 pupae where observed (mean = 32.8±3.2 days). Larvae were fasted for 24 hours and frozen prior to mycotoxin analysis by HPLC/MS. Fusarium graminearum was culture-isolated from highly chalky damaged kernels. Survival rate tended to be higher in the high diet treatment than the other treatments (P=0.0534) when using GLIMMIX procedure in SAS. Average daily gain (ADG) mean was estimated as 604.9542 mg/day per replicate (300 larvae), and there was no significant difference between treatments (P=0.1489). Nevertheless, the feed conversion ratio was significantly higher for low mycotoxin diet (mean=84.6141, P=0.0001) when compared to other treatments. Conversely, DON, was measurable within the mealworms across all replicates with a mean of 0.1291 ppm and a range of 0.0977–0.1902 ppm with 6.3%, 1.2% and 1.1% of ingested DON were detected in dry bodies from low, medium and high mycotoxin diets, respectively. Notably, DON concentrations were not significantly different between diets (P=0.8828) and are far below the regulatory limits for food or feed. From our research, Tenebrio molitor does not appear to accumulate harmful mycotoxins when fed highly contaminated grain, and with further research, could conceivably be used as a sustainable, safe protein source in animal feed.