Improved Pesticide-treated Wooden 

 Splieres for Controlling Apple 

 Maggot Files 



Xing Ping Hu, Andrew Kaknes, and Ronald Prokopy 

 Department of Entomology, University of Massachusetts 



In recent years, we have been working 

 toward development of pesticide-treated spheres 

 as a substitute for sticky spheres in controUing 

 apple maggot flies. In the Spring 1996 issue of 

 Fruit Notes, we reported on progress made 

 through 1995 on development of pesticide- 

 treated wooden spheres. Here, we assessed 

 residual effectiveness against apple maggot 

 flies of the best-performing version of pesticide- 

 treated wooden spheres developed through 

 1995 versus a new tjrpe developed in 1996. We 

 also evaluated the performance of each of these 

 sphere types in controlling apple maggot flies in 

 a small commercial orchard. 



Materials and Methods 



The 1995-version spheres consisted of three 

 layers of materials: first layer = 76% sugar, 4% 

 wheat flour, and 20% Glidden gloss red paint; 

 second layer = 1% Digon 4E (=0.5% dimethoate), 

 and 99% Glidden gloss red paint, third layer = 

 shellac. The layer of shellac was intended to 

 reduce the loss of fly feeding stimulant (sucrose) 

 from the sphere surface during rainfall. To a 

 significant degree, this loss was prevented. 

 However, following rainfall or a series of heavy 

 dews, spheres coated with shellac sometimes 

 turned whitish in color, rendering them less 

 visually attractive to apple maggot flies than 

 completely red spheres. 



The 1996-version spheres featured a new 

 approach to extending the residual activity of 

 sucrose. Rather than rely on application of 

 shellac (or several other applied substances 

 that we evaluated prior to 1995) to extend the 

 residual activity of sucrose, we instead drilled 



14 evenly spaced holes (1/4 inch diameter x V2 

 inch deep) into each sphere and filled each hole 

 with a mixture of 94% sucrose, 6% flour. This 

 was followed by application of 2 layers of paint 

 (same composition as first 2 layers of paint 

 applied to 1995 - version spheres). 



To assess toxicity of spheres to apple 

 maggot flies, in early July of 1995, twelve 1995- 

 version spheres were hung fi-om branches of 

 apple trees near Prokopy's small commercial 

 orchard in Conway. Every other week 

 thereafter until apple harvest, two spheres 

 were brought to the laboratory for assays. In 

 early July of 1996, the same procedure was 

 followed for 1996-version spheres. For assays, 

 thirty flies were allowed to stay and feed on 

 each sphere for up to five minutes, follovdng 

 which, flies were placed in cages and examined 

 for mortality 24 hours later. Rainfall was 

 measured by a rain gauge placed near trees. 



Comparison of pesticide-treated spheres 

 with sticky spheres for providing direct control 

 of apple maggot flies was made in the Prokopy 

 orchard, which consisted of 50 trees (10 rows x 

 5 trees per row, primarily Liberty/M.26). In 

 1995, each tree in the five eastern rows received 

 two 1995-version pesticide-treated spheres, 

 whereas each tree in the five western rows 

 received two sticky (Tangletrap-coated) spheres. 

 In 1996, the arrangement was reversed, with 

 each tree in the five eastern rows receiving two 

 sticky spheres and each tree in the five western 

 rows receiving two 1996-version pesticide- 

 treated spheres. Spheres were deployed in July 

 each year, were unbaited, and were positioned 

 optimally for attracting apple maggot flies. At 

 harvest, every tenth picked apple was 



Fruit Notes, Volume 62 (Number 2), Spring, 1997 



