with four ro six gcncr.UKnis per year. These 

 phytoseiids may also overwinter .is adults in trees 

 if prey are available to feed on m late siiinmer and 

 early fall; otherwise, they disperse from the trees 

 and overwinter in the ground cover. Occasionally, 

 they can be found in trees when HRM eggs start to 

 hatch just before bloom, but are usually scarce 

 until mid-July because of high winter mortality or 

 lack of ERM as a food source before bloom. Adult 

 A. fallacis lay twice as many eggs as T. pyri, 

 immatures and adults consume nearly a third more 

 ERM per day than T. pyrt, and immatures develop 

 into adults in a third of the time required by T. 

 pyri. A. fallacts feed mainly on spider mites. 

 Therefore, when prey mite numbers are low in the 

 trees, A. fallacis will disperse out of the trees to 

 locate another food source, possibly in the ground 

 cover. A. fallacis are more effective at reducing 

 high red mite populations than T. pyri, but this is 

 often after ERM have done considerable damage 

 to the leaves. 



Based on generation time, oviposition rate, 

 and prey consumption, it would appear that T. 

 pyri is a less effective biological control agent than 

 A. fallacis. But the advantages T. pyri has over A. 

 fallacis are its greater winter hardiness, its use of 

 alternative food sources when ERM are not 

 present, and its tendency to remain in trees when 

 ERM are scarce. When ERM numbers are low, T. 

 pyri will stay in the tree canopy feeding on pollen 

 and rust mites, and will continue to be a presence 

 as ERM numbers start to rise. 



Because A. fallacis are often absent from trees 

 or are in very low numbers in trees in early spring. 



ERM often build to damaging levels bclorc A. 

 fallacis exercise control. I . pxri will consistently 

 maintain ERM populations at low levels provided 

 these predators are conserved. T. pyri usually 

 cannot control ERM populations in excess of five 

 to seven per leaf, and it can take 2-3 years for 

 sufficient numbers of 7. pyri to build in an orchard 

 to realize biological control. Once predators are 

 established, the benefits are great as the need for 

 miticides can be eliminated. 



Data from an orchard at the New York State 

 Agricultural Experiment Station into which T. pyri 

 were released into two blocks of Delicious trees 

 will serve to illustrate the effectiveness of this 

 predator. In this orchard, no miticides were used 

 since 1991, fungicides have consisted of captan 

 and Nova, and pesticides have been restricted to 

 Imidan, Sevin, Bt, and Provado. Dynamics 

 between T. pyri and ERM were measured between 

 1992 and 1997. Results are summarized in Table 

 1. Since 1992 ERM numbers have been kept well 

 below threshold levels (500 mite days) and 

 predator numbers have steadily increased. 

 Averages shown here are the average of temporal 

 counts from June 1 to September 1. 



Is Typhlodromus pyri an effective predator 

 throughout the northeast? Yes! Until recently, T. 

 pyri was thought to be common in eastern north 

 America only in central and western New York 

 and Nova Scotia. Therefore, in 1996 we 



embarked on a project with cooperators in all the 

 New England states to introduce and establish T. 

 pyri throughout this region. There is no apparent 

 reason why T. pyri should not survive and thrive 



Fruit Notes, Volume 64 (Number 1), Winter, 1999 



