Residual Activity of Insecticide 

 on Wooden and Plastic 

 Pesticide-treated Spheres 



Bradley Chandler and Ronald Prokopy 



Department of Entomology, University of Massachusetts 



To date, all tests of pesticide-treated spheres (PTS) 

 for control of apple maggot flies (AMF) in commercial 

 apple orchards in Massachusetts have been conducted 

 using spheres made of solid wood. As of spring 2001, 

 wooden spheres in the form in which they have been 

 purchased and sold by commercial pest management 

 supply companies for the past three decades (rejected 

 croquet balls) no longer are manufactured. Hence, if 

 PTS capped by discs of sugar and wax are to remain 

 viable as a potential means of controlling AMF (see 

 preceding article) then an alternative to wooden PTS 

 must be found. For several years, Great Lakes IPM of 

 Vestaburg, Michigan has been producing and marketing 

 durable hollow plastic spheres for coating with 

 Tangletrap and use in monitoring populations of AMF. 

 Such plastic spheres (or a similar type) are the most 

 likely spheres to be used for future control of AMF by 

 sugar-capped PTS. 



Here, we report on studies conducted in 2001 

 evaluating the residual activity of insecticide in paint 

 applied to wooden and plastic spheres. 



Materials & Methods 



Wooden spheres were the same 3.25-inch diameter 

 spheres that we have had on hand and have been using 

 for several years in our studies on sugar-capped PTS. 

 Plastic spheres were 3.5 inches in diameter and 

 purchased from Great Lakes IPM (marketed as 

 "reusable red ball traps"). Before painting, plastic 

 spheres were shaken in a container of sand to roughen 

 the surface. Preliminary testing showed that paint 

 containing insecticide tended to chip off of non- 

 roughened plastic spheres. In addition to clean-surface 

 wooden spheres and roughened-surface plastic spheres, 

 we also evaluated wooden spheres that had been treated 



in 2000 with a coating of latex paint containing 2% 

 (a.i.) imidaclopnd (Provado) and exposed for 12 weeks 

 in commercial orchards in 2000. These spheres were 

 not cleaned before application of paint and insecticide 

 in 200 1 . Rather, they were partially covered with sooty 

 mold that grew on sugar on the sphere surface during 

 field exposure in 2000. 



All spheres received a single coating of black latex 

 paint containing 4% (a.i.) imidacloprid (Provado) 

 before deployment. The only exception was control 

 spheres, which received paint but no insecticide. Half 

 of the pesticide-treated wooden and plastic spheres 

 received 20% sugar (sucrose) in the mixture applied 

 to the sphere surface. The remaining half received no 

 sugar in the paint. Addition of sugar to the paint 

 mixture assures presence of sugar on the sphere surface 

 at the time of sphere deployment, but could result in a 

 tendency of paint to deteriorate or chip off during field 

 exposure. 



In early July, all spheres were hung from branches 

 of apple trees in an unsprayed section of the 

 Horticultural Research Center in Belchertown. Spheres 

 remained in place for 12 weeks, when they were 

 returned to the lab for evaluation of residual toxicity 

 of insecticide. For this, we applied a 20% sucrose 

 solution to the surface of each sphere to stimulate fly 

 feeding and then exposed 10 AMF individually to two 

 spheres of each type. Flies were allowed to remain on 

 a sphere for up to 10 minutes, after which they were 

 transferred to clean cups with food and water. Mortality 

 was measured at 72 hours. 



Results 



Data presented in Table 1 show that 90-100% of 

 AMF exposed to each type of wooden or plastic PTS 



Fruit Notes, Volume 66, 2001 



35 



