Identification and evaluation of potential predators of the citrus rust mite, Phyllocoptruta oleivora, in Israel

Abstract

Damage caused by citrus rust mite (CRM), Phyllocoptruta oleivora (Ashmead), is usually negligible in minimally to unsprayed isolated groves located in the central coastal plain of Israel. Assuming that resident natural enemies were responsible for this situation, we monitored the pest’s potential predators in five unsprayed citrus plots, and concurrently determined their feeding habits in the laboratory. In the field Iphiseius degenerans (Berlese) and Amblyseius swirskii Athias-Henriot were the main predators found, the former being dominant during the critical winter and spring months, the period of low pest populations. In the laboratory, when solely CRM was offered, the decline in pest numbers was similar in leaf arenas containing either phytoseiid or the stigmaeid Agistemus cypriusGonzalez. Only I. degenerans, however, seemed to kill fewer CRM in the presence of pollen. While the cessation of pesticide applications during two years was insufficient for reducing CRM populations, observations suggest that a three year break from broad spectrum pesticides would be the turning point for the reestablishment of I. degenerans, the postulated more important predator. Our field and laboratory data suggest that a complex of indigenous, generalist predators could be responsible for the control of CRM in isolated, unsprayed citrus groves on the central coastal plain of Israel.