Evaluation of Formulations and Release 

 Rates of Benzaldehyde, an Attractive 

 Fruit Odor for Plum Curculios 



Jaime Pinero, Sara Hoffmann, and Ronald Prokopy 

 Department of Entomology, University of Massachusetts 



In the 2000 Issue of Fruit Notes, we reported on a 

 2000 study showing that benzaldehyde in association 

 with plum curculio (PC) pheromone (grandisoic acid) 

 was the most attractive odor bait combination for PCs 

 when compared with other odor baits affixed to panel 

 and pyramid traps. In that study, we also found that 

 although traps baited with benzaldehyde plus 

 pheromone were very effective at determining the 

 beginning, peak, and end of PC immigration into apple 

 orchards from overwintering sites, benzaldehyde 

 seemed to be less attractive to PCs after -10 days of 

 exposure to sunlight. Subsequently, we found that the 

 clear high-density polyethylene vials used in that study 

 allowed UV-polymerization of about 10% of the 

 benzaldehyde contained in the vials, which may have 

 diminished or masked some of the attractiveness of 

 benzaldehyde. We concluded from that study that 

 research should be aimed at improving the formulation 

 and longevity of benzaldehyde and optimizing the 

 amount of benzaldehyde used as odor bait. 



Here, in an attempt to improve trap ability to 

 capture PCs, we compared different formulations, 

 release rates, and positions of benzaldehyde-releasing 

 dispensers in tops of branch-mimicking cylinder traps 

 placed on apple tree limbs. We also evaluated different 

 amounts of benzaldehyde in association with PC 

 pheromone in Circle traps, which are wrapped 

 completely and tightly around apple tree trunks and 

 are designed to intercept adults crawling up tree trunks. 



Materials & Methods 



We performed four different experiments. The first 

 three were conducted in 200 1 and involved use of black 

 cylinder traps. The fourth was carried out in 2002 and 

 involved use of Circle traps. All evaluations were 

 performed in unsprayed sections of apple orchards or 



in backyards containing unsprayed apple trees. 



Experiment 1. In this test, conducted from June 6 

 to July 3 (200 1 ) in Atkins orchard (Belchertown, MA), 

 we evaluated (using cylinder traps) four different 

 formulations of benzaldehyde alone (without 

 pheromone) released from dispensers placed either 

 inside or outside of the frap tops. Formulations tested 

 were: (1) Great Lakes IPM (Vestaburg, MI), (2) IPM 

 Technologies (Portland, OR), (3) four 400-'/4l high- 

 density clear polyethylene vials (VWR Scientific 

 Products; Boston, MA), each filled with 4OOV4I of 

 benzaldehyde (as in 2000), and (4) one 1-ml low- 

 density white polyethylene vial (Wheaton; Millville, 

 NJ) filled with 1 ml of benzaldehyde. Unbaited traps 

 served as a control treatment. For each formulation, 

 the estimated release rate of benzaldehyde was about 

 1 mg per day except for the white vials, which released 

 about 2.5 mg of benzaldehyde per day. Each treatment 

 was replicated 4-5 times. 



Traps were deployed in perimeter-row apple frees 

 and on apple frees located in rows 2, 3, and 4. Traps 

 were inspected for PC captures 2 to 3 times per week. 

 At each inspection session, trap tops were rotated 

 (within a replicate) one position (clockwise). 



Experiment 2. This test, conducted from May 29 

 to July 3, 2001 in Atkins orchard, was aimed at 

 evaluating different amounts of benzaldehyde released 

 from 1-ml low-density white polyethylene vials in 

 association with cylinder traps. Each white vial released 

 about 2.5 mg of benzaldehyde per day. 



Treatments evaluated were: (1) one white vial 

 (placed inside a frap top), (2) one white vial (placed 

 outside a frap top), (3), five white vials (inside), (4) 

 five white vials (outside), (5) 15 white vials (outside), 

 and (6) unbaited traps as a confrol freatment. For 

 treatments 2 and 4, vials were hung vertically from the 

 periphery of the frap top using copper wire, about 2 



Fruit Notes, Volume 67, Fall, 2002 



