have been studying since 1 99 1 , we have found substan- 

 tial numbers ofT. pyri and few pest mites during spring. 

 Pest mites usually remain very low until late July, when 

 they begin to increase in numbers but often are con- 

 trolled efficiently by A. fallacis in August. No pesti- 

 cide except prebloom oil has been required. Therefore, 

 we obtained T. pyri from apple trees in Geneva, New 

 York (courtesy of Jan Nyrop) and released them in two 

 second-level IPM orchard blocks in Massachusetts. 

 Here, we report results to date of these releases. 



lease resulted in relatively low numbers in August and 

 September of 1 993, but they increased nearly 5-fold by 

 1 994. Seven of eight trees on which T. pyri were re- 

 leased in 1993 harbored T. pyri in 1994. The harsh 

 winter of 1 993-94 did not seem to have much of a det- 

 rimental impact on T. pyri survival. In addition, the 

 1 994 samples showed that T. pyri had spread in sub- 

 stantial numbers to adjacent trees. In contrast to T. 

 pyri, populations of A. fallacis on sampled leaves were 

 similar in 1993 and (Table 1 



Materials and Methods 



The Geneva population of T. pyri from which we 

 took individuals for release has a long history of high 

 resistance to Guthion^''' and Imidan"^"^', is naturally re- 

 sistant to Sevin^^', and is not affected by benomyl. In 

 1 992, we collected apple tree branches harboring T. pyri 

 from Geneva in July and placed them in eight trees in 

 two orchard blocks where T. pyri had never been found. 

 In 1993, foliage was collected in Geneva in July. Col- 

 lected leaves averaged about one T. pyri nymph or adult 

 each and were kept in a cooler during transport. Using 

 the suggestion of Jan Nyrop, we stapled 40 collected 

 leaves to 40 attached leaves per orchard tree. We did 

 this on four widely spread trees per block in the same 

 two orchard blocks as in 1 992. In August and Septem- 

 ber of 1993 and September of 1994, we examined 100 

 leaves from each tree on which T. pyri were released. 

 No leaves to which Geneva leaves were stapled in 1 993 

 were taken in the samples. In September of 1994, we 

 also examined 100 leaves from trees immediately adja- 

 cent to the release trees. 



Results 



The results (Table 1 ) show that T. pyri became es- 

 tablished in trees on which they were released. In 1992, 

 establishment was poor because of intense rain soon 

 after T. pyri release; however, numbers increased four 

 fold in these trees from 1993 to 1994. The 1993 re- 



Concliisions 



Moving T. pyri from infested leaves of a Geneva 

 apple orchard to previously uncolonized blocks in two 

 Massachusetts apple orchards was effective in estab- 

 lishing and spreading this important mite predator, pro- 

 vided that the transferred infested leaves were stapled 

 to leaves of uncolonized trees. Nyrop (personal com- 

 munication) has suggested an even more effective way 

 of spreading T. pyri: picking flower clusters in bloom 

 and using twist-ties to attach clusters to twigs on 

 uncolonized trees. T. pyri feed avidly on pollen and 

 seem to aggregate there during bloom. Perhaps the 

 ability of T. pyri to survive on alternate food, such as 

 pollen and fungi, in part explains its tendency not to 

 disperse vigorously to previously uncolonized sites. This 

 more sedentary life-style also might explain the tendency 

 of T. pyri to be more resistant to orchard pesticides than 

 A. fallacis. The strong natural resistance of T. pyri to 

 Sevin is an especially positive attribute for growers who 

 desire to use Sevin as a thinning spray. If T. pvri were 

 to become established in most Massachusetts orchards, 

 these predators would almost surely provide a substan- 

 tially, if not fully, effective level of mite biocontrol from 

 early to mid-season and possibly longer. 



Acknowledgments 



We are most grateful to Jan Nyrop for his insights, 

 encouragement, and assistance. 



Fruit Notes, Spring, 1995 



