Noy, Michael; Izhar, Yahonatan; Abrahams, Jonathan; Coll, Moshe

Since its entry in 2001, the persea mite, Oligonychus perseae, has become a primary pest of avocado in Israel. Field trials over three consecutive growing seasons were conducted to develop an action threshold for the pest. To identify its indigenous predators and to evaluate methods for their conservation, we monitored populations in orchards and performed trials in three spatial scales: in Petri dishes, on seedlings and in the field. We found that mite populations caused significant foliar damage. Mean tri-annual yield was reduced by 20% when mite populations were high (≥250 mites/leaf) in comparison to yields attained when plots were sprayed at a threshold of 50-100 mites per leaf. Euseius scutalis was by far the most abundant predatory mite species in Israeli avocado orchards. Laboratory experiments in Petri dishes and on seedlings showed that it significantly reduced adult persea mite populations. In the seedling experiment and in the field we also found that conservation of this predator through the provisioning of supplemental food (i.e. maize pollen) substantially increased E. scutalis populations and enhanced persea mite control. In addition to E. scutalis, we found four generalist insect predators that fed upon and ripped open the nests of persea mite. The high proportion of torn nests found in the field suggests that these predators are important contributors to the control of the persea mite.