Advancements in Second-stage Apple IPM: 

 Improving the Attractiveness of Baited Red 

 Spheres 



Ronald J. Prokopy, Jian Jun Duan, Patricia Powers, 

 and Max P. Prokopy 



Department of Entomology, University of Massachusetts 



We previously reported [Fruit Notes 54(1): 1-5] on 

 results of the second year of our pilot second-stage 

 apple IPM program in Massachusetts commercial or- 

 chards. One of the major elements in second-stage IPM 

 is the use of red spheres baited with synthetic apple 

 odor for intercepting immigrating apple maggot flies at 

 the orchard perimeter. We concluded that before such 

 an interception system for maggot fly control could be- 

 come broadly successful on a commercial level, some 

 improvements would be needed. One improvement 

 might be enhancing the attractiveness of spheres to 

 apple maggot females, to ensure better capture of a 

 high proportion of females flying from border areas 

 onto apple trees at the orchard perimeter. Here, we 

 describe results of 2 studies conducted in 1989 toward 

 this goal. 



The first study involved evaluating different sizes 

 of unbaited red spheres. More than a decade ago [Fruit 

 Notes 41(6):6-9], we found that spherical shape (mim- 

 icking apple shape) was more attractive to maggot flies 

 than cubical, cylindrical, or rectangular shape. We also 

 discovered that red and 

 black spheres were equally 

 attractive as colors and 

 more attractive than 

 green, orange, yellow, or 

 white spheres. We chose to 

 use red spheres over black 

 ones to permit better vi- 

 sion of a captured maggot 

 fly. Finally, we found that 

 8-cm-diameterred spheres 

 were more attractive than 

 spheres of 4,6,15,23,30, or 

 45 cm in diameter. Here, 

 we wondered if there were 

 any sphere size between 8 

 and 15 cm that might be 

 more attractive than the 8 



We purchased softballs (10 cm), toy balls (14 and 

 18 cm), and volleyballs (23 cm), painted them the same 

 red color as our standard 8 cm croquet balls, coated 

 them v^ath sticky, and hung them in non-sprayed fruit- 

 ing apple trees harboring a low population of apple 

 maggot flies. Foliage and fruit within 10 cm of the 

 sphere surface were removed. Periodically, the 

 spheres were rotated to provide equal time for each size 

 at each position. 



Although the low fly population precluded sub- 

 stantial fly captures, the results (Table 1) do nonethe- 

 less indicate a consistent pattern of greater captures of 

 females on 8 cm spheres than on spheres 10 cm or 

 larger in size. Other recent studies we have carried out 

 indicate that apple maggot female response to fruit of 

 different sizes is partly under genetic control and partly 

 a learned response based on recent experience with 

 fruit of a particular size. From our results here, it 

 appears that if an apple or a red sphere mimicking an 

 apple is larger than 8 cm, neither genetic-based nor 

 learned behavior of females confers strong attraction. 



cm size. 



Table 1. Total apple maggot females captured on unbaited sticky red 

 spheres of different sizes hung in unsp rayed fruiting apple trees (July 27- 

 August 8, 1989). 



•No. replicates per experiment: Expt. 1 = 5; Expt. 2 = 8; Expt. 3=8. Values 

 not followed by the same letter are significantly different at odds of 19 to 

 1. 



18 



FmU Notes, Fall, 1989 



