Nutritional management of Carpoglyphus lactis diets enhances Amblyseius swirskii performance for biological control

Mass-rearing of biocontrol agents requires nutritionally optimized factitious prey. This study evaluates how dry diets shape Carpoglyphus lactis quality as prey and impact Amblyseius swirskii performance. To this end, the base diet (Diet 1) consisted of wheat bran and baker's yeast. Seven enriched diets were prepared by adding specific ingredients: Diet 2 (dog food), Diet 3 (starch), Diet 4 (vitamins), Diet 5 (dog and cat food), Diet 6 (dog food, cat food, pollen), Diet 7 (starch, dog and cat food, vitamins), and Diet 8 (dog and cat food, pollen, vitamins). Life table parameters of A. swirskii were recorded, and macronutrient content (crude protein, ether extract, water-soluble carbohydrates) in diets and biochemical composition (protein, triacylglycerol, glycogen) in two C. lactis colonies analyzed. Results indicated significant differences in development time, total lifespan, and fecundity. Diet 8 led to highest fecundity (39.26 eggs/female); Diet 3 yielded longest total lifespan (38.50 days); Diets 4 and 8 had shortest generation times. Intrinsic rate of increase (r) ranged from 0.149 day⁻¹ (Diet 2) to 0.183 day⁻¹ (Diets 4 and 6), with most diets showing similar r-estimates. Prey protein was positively correlated with fecundity and energy-rich diets promoted adult longevity and faster development. Together, these results suggested that protein and glycogen levels in C. lactis may contribute mechanistically to reproductive output, developmental timing and adult longevity in A. swirskii, although direct causal links remain to be confirmed.