Provision of pollen allows Tetranychus urticae control in clementines with Euseius stipulatus

Abstract: The phytoseiid mite Euseius stipulatus commonly occurs in citrus orchards inSpain and other Mediterranean countries. This predator is able to feed and reproduce onpollen, though it is also known as a predator of the spider mites Panonychus citri andTetranychus urticae in citrus. The capability of phytoseiid mites to develop and reproduce onpollen has been utilized to control mite pests by increasing predator numbers in the crop withartificial supply of pollen. We investigated if the addition of pollen would have the sameeffects on E. stipulatus, ultimately allowing effective T. urticae control in clementines. Wefirst evaluated under semi-field conditions whether the addition of pollen would increasepredator numbers in the crop and thereafter tested if pollen supply would allow effectivecontrol of T. urticae, and if supplemental releases of Phytoseiulus persimilis would increasethe effectiveness against T. urticae, under spring and summer conditions in southern Spain.The results revealed that E. stipulatus numbers were much higher when pollen was added. Inthe spring trial, when pollen was added, pest levels remained under the action threshold andthus no P. persimilis releases were necessary. In the summer experiment, T. urticae levelswere again significantly suppressed when pollen was supplied, though the pest slightlyexceeded the action threshold, thus requiring P. persimilis releases. Nevertheless, theadditional P. persimilis releases did not provide better control than E. stipulatus together withpollen.