IM 



SP 



SS 



GC 



IM 



SP 



Figure 1 . Captures of feral AMF on unbailed monitoring traps and 

 percent fruit injured by AMF in 24 plots of apple trees m 6 

 commercial orchards in 2003. Plots with IM=iniidaclopnd-treated 

 PTS, SP=spinosad-treated PTS, and SS=sticky spheres. 

 GC= grower-sprayed plots. 



of sphere exposure, we retrieved two randomly- 

 chosen PTS of each type from each of the six 

 orchards and returned them to the laboratory for 

 testmg. We assessed the fly killing power of each 

 retrieved PTS by exposing 10 walnut husk flies 

 to each sphere (our supply of AMF was depleted, 

 so we substituted adults of this other very closely 

 related species). A single fly (deprived of food 

 for 12-15 hours) was transferred gently to the 

 sphere just below mid-height and allowed to 

 remain up to 10 minutes, after which it was 

 transferred to a small clear-plastic cup supplied 

 with sugar and water. After 72 hours, we 

 recorded whether the fly was dead or alive. 



In our second experiment, we hung one sphere 

 of each of six different types in each of six apple 

 trees that received no insecticide in 2003. Sphere 

 types per tree were as follows: one 2002-version 

 PTS, four 2003-version PTS (topped by discs 

 containing either 0.5%, 1.0%, 2.0%, or 4% 

 spinosad), and one untreated (control) sphere. 

 Spheres were deployed in early July and remained 

 for 12 weeks. At 6, 9, and 12 weeks after 

 deployment, two spheres of each type were 

 brought to the laboratory and assessed for fly 

 killing power using above procedures. 



In our third experiment, we subjected 2003- 

 version PTS to different amounts of artificial 

 rainfall (1, 4, 7, or 10 inches) in a laboratory 

 chamber. The chamber was designed to deliver 



replaced. Each sphere was 

 baited with a vial containing 

 a synthetic 5-component 

 blend of attractive fruit 

 volatiles. The fourth plot 

 received two or three 

 grower-applied sprays of 

 organophosphate insecticide 

 to control AMF. Treatment 

 effectiveness was judged by 

 comparing numbers of feral 

 AMF captured on interior 

 unbailed monitoring traps 

 (four traps on central trees of 

 each plot) and percent injury 

 to fruit in samples taken at 

 harvest (100 fruit per plot). 

 After 6, 9, and 12 weeks 



S 50 



uillL 



6WK 9WK 12WK 6W 9WK 12WK UNTREATED 



IMIDACLOPRID PTS 



SPINOSAD PTS 



Figure 2. Percent mortality of flies 72 hours after exposure for 10 minutes in laboratory cages to PTS 

 retrieved 6, 9, or 12 weeks after deployment in commercial orchards in early July. Each value is based on 

 sphere exposure to 120 flies (10 per sphere x 2 spheres per orchard x 6 orchards) 



22 



Fruit Notes, Volume 69, Spring, 2004 



