Dietary enrichment of Tyrophagus putrescentiae improves Amblyseius swirskii rearing efficiency: linking prey biochemistry to predator demography.

Abstract

Optimizing nutrient transfer across trophic levels has become an important approach to enhance the biological efficiency and sustainability of predator-prey rearing systems supporting augmentative biological control. This study examined how dietary enrichment of the factitious prey Tyrophagus putrescentiae (Schrank) influences its biochemical composition and subsequent effects on the demographic performance of the predatory mite Amblyseius swirskii Athias-Henriot; one of the most widely used biocontrol agents in protected crops. Eight dry diets were tested, including a basal mixture (Diet 1: wheat bran + baker's yeast) and seven enriched formulations varying in animal- and plant-derived components. After three generations of prey rearing, we quantified the biochemical composition (protein, triacylglycerol, glycogen) of T. putrescentiae and the corresponding life table parameters of A. swirskii. Diets containing both animal and plant supplements; particularly Diet 6 (basal diet + cat food + mixed pollen), Diet 7 (basal diet + starch + dog food + cat food + mixed pollen), and Diet 8 (basal diet + dog food + cat food + mixed pollen + vitamin mix); significantly enhanced predator fecundity, shortened developmental time, and increased the intrinsic rate of increase (r), with Diet 7 achieving the most balanced performance. Glycogen reserves in the prey were positively correlated with predator reproduction, underscoring the importance of carbohydrate-based energy allocation in trophic transfer. These results establish a mechanistic nutritional framework to improve the quality and productivity of mass-reared predatory mites, directly supporting the efficiency and scalability of biological control programs.