Predatory mites are the most important natural enemies used for biological pest control in greenhouse horticulture.

Many of these predatory mites are mass-reared on prey mites that feed on fungi growing on bran. In collaboration with companies in the Netherlands and Spain, we investigated whether predatory mites could also be reared directly with artificial diets based on insect proteins. High-quality proteins from sources such as black soldier flies and mealworms were found to be suitable food sources.

However, formulating these semi-liquid diets wasn’t easy as the predatory mites were unable to consume diets offered in microcapsules. The next step, therefore, was to focus on diets for prey mites. Several species of prey mites were reared on diets with different nutritional values. When administered on plants, the prey mites reared on high-protein diets produced predatory mite populations five times the size of those feeding on bran-reared prey.

These nutritious prey mites can therefore enhance pest control by quickly boosting populations of predatory mites.