Released Typhlodromus pyri Show 

 Success in Colonization and Dispersion 

 in Massachusetts Apple Orchards 



Xingping Hu, Ronald Prokopy, Starker Wright, and Jennifer Mason 

 Department of Entomology, University of Massachusetts 



Phytoseiid mite predators frequently are efficient 

 biocontrol agents against pest mites in apple orchards 

 throughout the world. The phytoseiid predator most 

 prevalent in Massachusetts apple orchards is 

 Amblyseius fallacis, found in more than 80% of or- 

 chards sampled in a recent survey, but the next most 

 prevalent phytoseiid predator is Typhlodromus pyri, 

 which was found in fewer than 1 0% of orchards sampled 

 [Fruit Notes 59(2):10-11]. Our experience with A. 

 fallacis over the past two decades is that although it 

 may become highly effective in suppressing pest mites 

 during August and September, it generally is not effec- 

 tive in suppressing pest mites in May, June, or July. 

 There appear to be two principal reasons for this short- 

 coming of A. fallacis. First, according to Jan Nyrop 

 (personal communication) of the Geneva Agricultural 

 Experiment Station in New York, A. fallacis is unable 

 to survive winter temperatures lower than about -8_ F. 

 Second, A. fallacis are susceptible to several orchard 



insecticides and fungicides. Even mass-releases of A. 

 fallacis in Massachusetts orchards in late June, after 

 most spraying has ceased, have failed to yield effective 

 biocontrol of pest mites. 



The experience of Jan Nyrop with T. pyri in west- 

 em New York apple orchards over the past several years 

 indicates that it can survive very cold winter tempera- 

 tures much better than A. fallacis and that it can toler- 

 ate several orchard pesticides better than A. fallacis. 

 Shortcomings of T. pyri are its inability to respond to 

 increasing populations of pest mites as fast as A. fallacis 

 can and its inability to spread from tree to tree, block to 

 block, and orchard to orchard as well as A. fallacis. 

 Even so, T. pyri consistently has proven to be more 

 reliable than A. fallacis in providing season-long pest 

 mite control in many parts of the world, including New 

 York, so long as it is sufficiently abundant in early spring 

 and pest mites are not overly abundant at that time. 



In one of the 12 second-level IPM blocks that we 



Fruit Notes, Spring, 1995 



