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DAILY ACTIVITY OF APPLE BLOTCH LEAFMINER ADULTS^ 



T.A. Green and R.J. Prokopy 

 Department of Entomology 



Over the past 8 years, the Apple Blotch Leafminer (ABLM), Phyllonorycter 

 crataegella, has become a serious pest in commercial apple orchards east of the Hudson 

 River, High populations of this organophosphate resistant insect have been associated 

 with reduced fruit size, premature fruit ripening, and reduced fruit set the following 

 year in some cultivars. 



In a previous issue of FRUIT NOTES (Spring, 1983) we reported on the development 

 of a visual monitoring trap for ABLM adults. Concurrent with that work, we conducted 

 a study of the behavior of ABLM moths in and around commercial apple orchards. Our 

 study has thus far been restricted to the second and third adult flights, occurring in 

 early July and late August, respectively. 



To determine the location and activity of ABLM adults, we performed 1 minute 

 observations of various tree structures including the upper leaf surface, lower leaf 

 surface, fruit, trunk, and ground cover, at 1 hour intervals. We recorded the numbers 

 of ABLM observed at each location. In like fashion, we observed the tree canopy for 

 flight activity. 



Our results are presented in Figure 1. We found the primary location of stationary 

 ABLM throughout the day to be the lower leaf surface. We observed a number of mating 

 pairs, again predominantly on the lower leaf surface, and exclusively before 11:00 AM. 

 We also observed several ovipositing females, all on the lower leaf surface, and all in 

 the late afternoon and evening. 



We found flight activity to be concentrated during two periods of the day, from 

 sunrise to 3-4 hours after sunrise, and from 3-4 hours before sunset to sunset. The number 

 of flights observed per minute during the AM flight period was approximately 2.5 times 

 that of the PM flight period. During the AM flight, landings on the upper leaf surface 

 outnumbered lower leaf surface landings by a 2 to 1 margin. This ratio was reversed 

 in the evening. 



To further investigate the differences observed between the two flight periods, 

 we captured flying ABLM and determined their sex. We employed three capture methods: 



^ We wish to express our appreciation to research assistants Geoffrey Hubell and Martin 

 Rose, and to the following families for use of their orchards: Jack DeLuca, Ed Roberts, 

 Dave Shearer, Harvey and Marvin Peck, Ray Davis, and Cameron Sewell (in New 

 Hampshire). 



