Windborne pollen provisioning cover crops (WPPCC) for enhancing thepopulation levels of Euseius scutalis and improving citrus rust mite control

Abstract: The citrus rust mite (CRM) Phyllocoptruta oleivora (Eriophyidae) is acosmopolitan pest of citrus. Even though Euseius spp. have been categorized as specializedpollen feeders, they can effectively control pests, especially when pollen is abundant. In thepresent study our objectives were to determine whether pollen provisioning could: 1)enhance populations of the indigenous predator Euseius scutalis and 2) improve CRMcontrol. To test these hypotheses we conducted experiments on seedlings in a climatechamber and in an orchard. In the climate chamber, the effects of pollen and predator releaseon CRM and predator levels were very significant. CRM populations reached almost 8500on the negative control with no predators, zero CRM and 130 predators on plantsprovisioned with E. scutalis + pollen, and an intermediate level of 100 CRM and nopredators when E. scutalis was released without pollen. Similarly in the seedling field trial,windborne pollen released from patches of Rhodes grass successfully enhanced natural E.scutalis populations, which resulted in a significant reduction in CRM levels. In contrast, onseedlings distant from the grass patches, no predators were detected and CRM populationsincreased substantially. Taken together, the results of these two experimental setupsdemonstrate the potential of E. scutalis for CRM control and the importance of pollenprovisioning for control efficacy.