Improving biocontrol efficiency by better aligning predator and pest habitats

Abstract: Supplementary foods are widely used in augmentative biocontrol programs to
support the establishment and conservation of natural enemies. Previously, we developed a diet using three astigmatid mite species that enhanced the establishment of phytoseiids, mirids, and anthocorids. This feeding program successfully enhanced the establishment of Orius laevigatus on pollen-deficient crops such as cucumbers and a hairless tomato mutant developed by Rijk Zwaan Breeding BV.
In the current project, we evaluated a new strain of O. laevigatus, specifically selected for
better feeding on astigmatids, in combination with supplemental diets. The primary goal was to control Thrips parvispinus in commercial pepper greenhouses by modifying the predator’s
distribution patterns. Unlike Frankliniella occidentalis, T. parvispinus is more commonly found on the leaves, thus reducing O. laevigatus efficiency. We also tested whether in-crop feeding could improve the performance of other predators on tomatoes. The objectives were to (1) reduce plant-feeding damage caused by Nesidiocoris tenuis and (2) enhance control of Aculops lycopersici on mutant tomato cultivars. A randomized block design was implemented in a greenhouse with three tomato varieties, with and without trichomes. Results showed that the predator feeding system increased O. laevigatus populations on leaves, improving preventative thrips control. Excellent A. lycopersici control was achieved on hairless tomato cultivars, where Transeius montdorensis was established at all plant strata. Additionally, fewer than one-third of N. tenuis populations were found at the tops of plants when the in-crop feeding strategy was used, whereas more than 70 % were there without it. This reduction helps prevent plant damage, even when predator populations are high and pest numbers are low. The discussion explores how distributing food throughout crop plants may improve the spatial overlap of predators with the target pests, thereby enhancing predatory efficiency or reducing the risk of plant damage caused by zoophytophagous predators.