The astigmatid mite Carpoglyphus lactis as effective supplementary food for generalist predatory mites

Abstract: Generalist predatory mites of the family Phytoseiidae are the backbone of
commercial augmentative biocontrol in protected crops. We here report on the advantages of
using the astigmatid mite Carpoglyphus lactis as factitious food to increase phytoseiid
populations in the crop. A series of semi-field experiments using 13 common crop-phytoseiid
combinations showed an average 4-fold increase of the predator population after 5-7 weeks
when provided with supplementary food weekly, compared to an unfed control. An analysis of 39 semi-field and field experiments including 9 crops and 4 phytoseiid species confirmed that C. lactis consistently increased predator densities compared to the un-supplemented controls. In most of the experiments including pests, the addition of C. lactis also provided better pest control. An experiment with a model crop showed that increasing frequency or dose each lead to enhanced predator population sizes, but improved control requires sufficient supplementary food. We outline the safety of using astigmatid mites as supplementation for crops compared to using pollen.