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Figure 4. For the 2004 study, mean number of male and female PCs captured per trap (only panel traps) according to date. 

 Panel traps were coated with Tangletrap in the woods-facing side (i.e., front) as well as in the orchard-facing side (i.e., 

 back). The area delimited by a dashed line and filled with diagonal lines represents the duration of the petal-fall period in 

 2004. 



Conclusions 



From the 2002 study, we learned that adult PCs 

 are attracted to the odor emitted by traps baited with 

 benzaldehyde and grandisoic acid from at least 24 yards 

 inside the woods. The maxiinum distance considered 

 for this study represents the area more likely to be 

 serving as overwintering sites for PCs (Lafleur and Hill 

 1987). From the 2002 study, we also determined that, 

 once PCs are present on orchard trees, their degree of 

 responsiveness to odor-baited traps decreases 

 substantially, compared to PCs released in the woods 

 that had not been exposed to stimuli provided by a host 

 tree. Similarly, Leskey and Wright (2004) also 

 determined that the responsiveness of southern-race 

 PCs to traps baited with benzaldehyde and grandisoic 

 acid decreased significantly in the presence of apple 

 trees. 



From the 2004 study we determined that, before 

 petal fall, nearly all overwintered PCs trapped were 

 captured in the woods-facing side of panel traps. This 

 supports the notion that, early in the season, 

 overwintered PCs moving into the orchard by means 

 of flight are, most likely, immigrants. We also 



determined that, during and about two weeks after petal 

 fall, there seem to be high rates of movement by PCs 

 from host trees to woods and vice versa. This finding 

 suggests that some PCs may be moving from orchard 

 trees to woods (and vice versa) by the time of petal fall 

 onwards. However, the exact proportion of PCs that 

 may exhibit this behavior has yet to be determined. 



In the preceding Fruit Notes article we reported 

 that nearly all females captured by traps by the end of 

 petal fall were already mated and ready to lay eggs. If 

 PCs captured by traps after petal fall were actually 

 immigrants that had just emerged from overwintering 

 sites and were moving into the orchard block, then we 

 would expect some of those trapped females to be 

 sexually immature or unmated. Results from another 

 study that involved use of pyramidal emergence traps 

 in the same orchard block showed no emergence of 

 PCs beyond two weeks after petal fall. 



Altogether, the evidence presented above, gathered 

 under unsprayed conditions, lead us to the conclusion 

 that some of the PCs potentially found inside orchard 

 blocks immediately after petal fall may be re-colonizers 

 rather than true immigrants, although the exact 

 proportion is still unknown. Under this scenario, some 



12 



Fruit Notes, Volume 69, Fall, 2004 



