Commercial-orchard Evaluation of Traps 

 for Monitoring Plum Curculio: 

 2001 Results 



Ronald Prokopy, Brad Chandler, and Jaime Pinero 

 Department of Entomology, University of Massachusetts 



In the 2000 issue oi Fruit Notes, we reported our 

 year 2000 tests in which we compared odor-baited with 

 unbaited traps of three types (pyramid, cyHnder, and 

 Circle) for monitoring plum curculios (PC's) m 

 commercial apple orchards. Results suggested that traps 

 baited with grandisoic acid alone (= synthetic male sex 

 pheromone) captured no more PC's than unbaited traps. 

 However, when grandisoic acid was combined with 

 any one of three different synthetic host fruit volatiles 

 (benzaldehyde, ethyl isovalerate, or limonene), 

 captures by baited traps were about twice as great as 

 captures by unbaited traps. Addition of the synthetic 

 fruit volatiles decanal, hexyl acetate, and trans-2- 

 hexenal to grandisoic acid did not enhance captures. 



Here, we report results of 2001 studies in 

 commercial orchards in which we further evaluated the 

 best odor combinations found in 2000, again in 

 association with pyramid, cylinder, and Circle traps. 



Materials & Methods 



The three types of traps were: (a) black pyramid 

 traps (24 inches wide at base x 48 inches tall) placed 

 on the ground next to apple tree trunks, (b) black 

 cylinder traps (3 inches diameter x 1 2 inches tall) fixed 

 vertically onto horizontal branches within tree 

 canopies, and (c) aluminum-screen "Circle" traps 

 (developed by a grower named Edmund Circle in 

 Alabama for pecan weevil), wrapped tightly around 

 the base of tree trunks so as to completely encircle the 

 trunk and afford maximum chance of intercepting 

 adults walking upward. 



The three synthetic components of host fruit odor 

 were benzaldehyde, ethyl isovalerate, and limonene. 

 Each was purchased from Aldrich Chemical Company 

 and was deployed in small polyethylene vials that fit 

 into the screen-funnel top of a boll weevil trap that 



capped each pyramid, cylinder, or Circle trap. The 

 release rate of each compound was about 10 milligrams 

 per day (achieved by adjusting the type or number of 

 vials per trap according to compound volatility). Each 

 baited trap also contained a plastic dispenser of 

 grandisoic acid (obtained from Great Lakes IPM) 

 designed to release about 1 milligram of pheromone 

 per day. 



Traps were deployed in four plots of apple trees in 

 each of 12 commercial orchards. Each plot consisted 

 of seven perimeter trees. Each tree (save one) contained 

 one baited or one unbaited trap of the above three types. 

 All three baited traps in a plot received the same odor. 

 In each orchard, each of three plots received a synthetic 

 fruit volatile in combination with grandisoic acid. The 

 fourth plot received grandisoic acid alone. 



All traps were deployed at pink (May 2-4). Traps 

 were examined for captured PC's beginning at petal 

 fall (May 14-16) and every 3-4 days thereafter for 7 

 weeks until June 28-30. Vials of benzaldehyde and 

 dispensers of grandisoic acid were renewed on May 

 28-30 (about mid-way through the experiment). At each 

 trap examination, 10 fruit on each of the six trapped 

 trees per plot (= row 1 trees) and five fruit on each of 

 six corresponding but untrapped trees on interior rows 

 3,5, and 7 were examined for PC oviposition scars. In 

 all, 102,800 fruit were examined for PC injury. All plots 

 received two or three sprays of azinphosmethyl or 

 phosmet to control PC. 



Results 



Figure 1 shows that across the entire PC season, 

 Circle traps baited with benzaldehyde plus grandisoic 

 acid (GA) captured numerically more PC's than any 

 other type of baited or unbaited trap, although not 

 significantly more than unbaited Circle traps in the 



Fruit Notes, Volume 67, Winter, 2002 



17 



