Biological mite control in Hudson and Champlain Valley Apple Orchards Through the Distribution and Conservation of Typhlodromus pyri 2002
Project leader: J. Nyrop, Department of Entomology, NYSAES Cornell University, Geneva, NY 14456
Cooperators: K. Iungerman, P. Jentsch and D. Straub
Type of grant: Biological control and pest biology
Project location: throughout the northeast
Abstract: Biological mite control is a feasible alternative to pesticide-based control that is sustainable, possibly of lower cost, and void of the concerns that use of chemical pesticides raise. The mite predator Typhlodromus pyri has been shown to provide complete and sustained control of European red mite in apples in a variety of locations throughout the northeast. While previous research has indicated that T. pyri can be an effective biological control agent in eastern New York, there has been no large-scale demonstration of this technology. Beginning in 2001, we undertook such a demonstration effort. Typhlodromus pyri were introduced into 11 orchards in the Hudson valley region and into 8 orchards in the Champlain valley region. We also surveyed for T. pyri in other orchard blocks and conducted trials to evaluate chemical pesticides that might be used to control tarnished plant bug and were not highly toxic to T. pyri. We found that T. pyri could provide control of European red mite in eastern New York and that the predator persisted in orchards in these regions. We also learned that T. pyri is indigenous to these regions and introduction of the predator into orchards is therefore unnecessary. Use of T. pyri will only require careful selection and use of pesticides that are not highly toxic to this natural enemy. The insecticides Avaunt and Actara are alternatives to pyrethroids for tarnished plant bug control and are not toxic to T. pyri.
Although efficacious miticides continue to be developed and made available, the costs of control using these materials are escalating during a period when many orchardists are attempting to remain viable by minimizing expenses. Furthermore, chemically-based mite control programs may be environmentally harmful and the potential for resistance to miticides by the pest mites is a concern. Biological control of mites is an economically and technologically feasible alternative to pesticides. Two species of predaceous mites predominate in commercial orchards in New York, Amblyseuis fallacis and Typhlodromus pyri. While these two phytoseiid mites look very similar, they have very different biologies and it is T. pyri that is the most effective biological control agent (Nyrop et al. 1998). In fact, when T. pyri is conserved in commercial apple orchards, it can eliminate the need for miticides (Walde et al. 1992, Hardman et al. 1991, Blommers 1994). Primary among the differences that lead to T. pyri being a more effective biological control agent are that it survives in apple trees year round and can achieve quite high densities on a variety of alternative food sources including pollen and fungal spores (Breadth et al. 1998, Nyrop et al. 1998). Typhlodromus pyri is common in western New York apple orchards, and was thought to be relegated to this geographic area. However, research has demonstrated that T. pyri can provide effective biological control in both the Champlain and Hudson valley apple growing regions. This research also suggested that T. pyri was indigenous to at least a few orchards in these areas. These results indicate that a mite biological control program based on conserving T. pyri could be very effective in these apple growing regions.