Tabic I. Laboratory response indices (RIs) ol plum curculio ailulls lo individual odor compounds al three 

 concentrations in solvent 



Compound 



1% 



0. 1 % 



0.01% 



live was the stimulus. 



Ifi the field, green boll weevil traps were placed on 

 the ground beneath the canopy of unsprayed apple trees 

 approximately one yard from the trunk at each cardi- 

 nal point. Compounds being tested were diluted in min- 

 eral oil to a 5% concentration and applied to a 3-inch 

 piece of cylindrical cotton wick that was wrapped in 

 aluminum foil and attached by a wire to a boll weevil 

 cone-shaped trap top. One end of the wrapped foil 

 cylinder was clipped to permit dissemination of odor. 

 For each tree, two traps were baited with an individual 

 compound and placed at north and south positions, and 

 two traps baited with mineral oil only (the control) were 

 placed at east and west positions. After 48 hours, the 

 number of PCs captured in each of the traps was 

 counted, traps were baited with fresh wicks, and posi- 

 tions of traps were rotated around the tree so that com- 

 pound-baited traps were in east-west positions and 

 control-baited traps were in north-south positions. This 

 procedure was repeated 12 times. A .second experi- 



ment was conducted using only the most and least at- 

 tractive compounds at two concentrations: 5 and 0.5%. 

 In this experiment, procedures were nearly the same 

 as in the first experiment except this procedure lasted 

 only 24 rather than 48 hours, and was repeated only 10 

 times. To measure the attractiveness of a particular 

 compound, a Field Response Index was created by 

 subtracting the number of PCs responding to the con- 

 trol (C) from the number responding to the treatment 

 (T), dividing by the total number of PCs captured in the 

 treatment and control traps, and then multiplying by 100. 

 Thus, RI = 1(T - C )/ (T + O] X 100. The greater the 

 RI, the more attractive the compound. 



Results 



Laboratory Results. For compounds at 1 %, none 

 of the RI values were significantly (Table I). AtO. I'^f, 

 ethyl isovalerate jiiovided a positive and significant RI. 

 Other compounds did not result in significant RIs at 



16 



Fruit Notes, Volume 6.^ (Number 3), Summer, 1998 



