Direct and prey-mediated vitamin supplementation reshape predator–prey dynamics in Amblyseius swirskii (Acari: Phytoseiidae)

Abstract Micronutrient supplementation has been proposed as a strategy to improve factitious diets for predatory mites, yet the influence of nutrient delivery routes on predator performance remains poorly understood. We evaluated the demographic responses of Amblyseius swirskii (Athias-Henriot) to vitamins B complex, C, and E provided either directly through an artificial dry diet or indirectly via two astigmatid prey mites differing in nutritional suitability, Carpoglyphus lactis L. and Tyrophagus putrescentiae (Schrank). Direct supplementation through a vitamin-enriched dry diet resulted in severe developmental impairment and complete reproductive failure, with fewer than 10% of individuals reaching adulthood and no oviposition observed. In contrast, supplementation of the same diet with mixed pollen restored development and reproduction, supporting stable population performance over 20 generations. Prey-mediated vitamin delivery supported sustained demographic performance in both prey systems, including the nutritionally less suitable T. putrescentiae . Population growth parameters remained stable across generations, with intrinsic rates of increase ( r ) ranging from 0.129 to 0.142 day −1 on the pollen-supplemented dry diet, 0.140 to 0.152 day −1 on T. putrescentiae , and 0.176 to 0.185 day −1 on C. lactis . No evidence of cumulative negative generational effects was detected under indirect supplementation. These findings indicate that predator responses to micronutrient supplementation depend strongly on the mode of nutrient delivery and suggest that trophic mediation may play an important role in stabilising nutrient utilisation in predatory mite rearing systems. The study provides new insight by demonstrating that micronutrient delivery route, rather than vitamin supplementation alone, is a key determinant of predator demographic performance.