were cleaned. Captured AMF were soaked in 

 paint thinner to dissolve the "sticky," and later 

 dissected to determine the proportion of females 

 that contained mature eggs. 



Results 



The results (Table 1) show that in each year, 

 more AMF were captured on spheres baited 

 either with one vial each of ammonia and butyl 

 hexanoate, two vials of ammonia, or two vials of 

 butyl hexanoate, than on unbaited spheres. 

 Captures of females in both 1990 and 1991, and 

 of males in 1990, were significantly greater for 

 1 vial each of ammonia and butyl hexanoate 

 than for 2 vials of ammonia or 2 vials of butyl 

 hexanoate, between which there was no signifi- 

 cant difference. 



This finding surprised us. Although both 

 ammonia and butyl hexanoate were known to be 



attractive to AMF, as we mentioned, each is 

 associated with a different type of response. 

 Ammonia emanates from proteinaceous food in 

 a condition favorable to fly feeding. Butyl 

 hexanoate is emitted by host fruit in a condition 

 favorable as a site for fly mating and oviposition. 

 Because we previously found that sources of 

 AMF food in nature occur almost exclusively on 

 foliage rather than on fruit [Fruit Notes 55(3):1- 

 5], we did not expect that the odor of ammonia 

 would attract so many AMF to red spheres. We 

 do not yet understand the basis of AMF attrac- 

 tion to ammonia-baited red spheres. 



We also found that compared with the per- 

 centage of mature females (63 to 65%), as op- 

 posed to immature females, captured on spheres 

 baited only with butyl hexanoate or on unbaited 

 spheres, the percentage of mature females (48 to 

 55%) captured on spheres baited only with am- 

 monia was slightly lower. This difference likely 



Table 1. Mean numbers of apple maggot females and males captured on sticky red spheres 

 hung in fruiting trees in a commercial apple orchard and baited with different attractive 

 odors over the trial periods (12 days in 1990 and 37 days in 1991). 



Year 



Baits* 



1990 None 

 Butyl hexanoate 

 Ammonium carbonate 

 Ammonium carbonate 

 and butyl hexanoate 



1991 None 



Butyl hexanoate 



Ammonium carbonate 

 Ammonium carbonate 

 and butyl hexanoate 



27.7 a 



45.2 a 



170 



58.3 a 



75.8 a 



163 



*Six replicates per treatment type in 1990; four replicates in 1991. Values within 

 year not followed by same letter are significantly different at odds of 20:1. 



Fruit Notes, Fall, 1991 



