Benefits of a balanced diet? Mixing prey with pollen is advantageous for the phytoseiid predator Amblydromalus limonicus

Abstract

Plant pollen is an important alternative food for generalist phytoseiid mites ensuring survival and supporting population build-up during periods of prey scarcity. However, in the short term predator efficacy can be negatively affected by pollen provisioning as a consequence of predator satiation or when pollen is preferred over prey. This is counteracted by the fact that, combining pollen with prey in a balanced mixed diet, may benefit the numerical response of the predator and thus, improve the effectiveness of long-term biological control. Here, we assessed the effects of pollen (Typha angustifolia, Zea mays, Pinus brutia) provisioning in a mixed diet with prey (thrips) on the performance and predation efficiency of Amblydromalus limonicus, a predatory mite used against thrips and whiteflies in greenhouse crops. We found that provisioning pollen in mixed diets with high-quality prey resulted in significant decrease in prey consumption. This effect was shown to be stronger for T. angustifolia and weaker for P. brutia when both were combined with thrips larvae. When pollen was provided alongside thrips, this resulted in a significant decrease in juvenile dispersal and oviposition was always higher. The highest value of intrinsic rate of population increase (rm) was recorded for the mix of cattail pollen and thrips, and the strongest increase in rm when thrips were combined with pine pollen followed by corn and cattail pollen. Overall, mixing prey with pollen resulted in higher rm values thus enhancing the medium- to long-term thrips-control potential of A. limonicus.