Rate of Release of Rhynchophorol Pheromone in Relation to Attraction of Rhynchophorus palmarum (L.) (Coleoptera: Dryophthoridae) in Oil Palm Plantations in Colombia

Rhynchophorus palmarum (L.) (Coleoptera: Dryophthoridae) is an important pest in oil palm plantations, and its populations are monitored through rhynchophorol pheromone-baited traps. To optimize the release of rhynchophorol in high-density polyethylene diffusers, five calibers (2, 3, 4, 5, and 6) were evaluated. The experiment was conducted under a completely randomized design with 15 repetitions, recording daily weight loss of pheromones. Release rate of pheromone under laboratory conditions (30.2 ± 0.1°C; 70.8 ± 0.8% relative humidity [RH]) varied between 2.2 and 10.4 mg/day. Three diffusers with 2.4 ± 0.4, 3.6 ± 0.9, and 8.5 ± 1.3 mg/day of release rates, were selected for testing in three palm-growing zones. Adults of R. palmarum captured in traps with different diffusers were counted as well as pheromone weight loss. In two of three plantations, statistical differences were found in the capture of R. palmarum adults among the diffusers that presented different pheromone release rates (Eastern: F = 8.27; df = 2, 9; P = 0.0028; Central: F = 10.79; df = 2, 9; P = 0.0008; Southwestern F= 2.20; df = 2, 9; P= 0.1402). The diffuser with the release rate of 2.4 mg/day was selected because, after remaining 4 mo in the field, the traps with this diffuser registered catches statistically equal to those that had traps with newly installed diffusers. We concluded that the release rate of the pheromone of 2.4 mg/day is optimal for the capture of adults of R. palmarum during a period of 4 mo.

Evaluation of Pheromone Dispensers for Use in Gypsy Moth Detection (Lepidoptera: Lymantriidae)2

Seven controlled-release dispenser formulations containing 500 μg of gypsy moth pheromone (+)-disparlure, were compared in laboratory and field tests. Pheromone release rates, residual pheromone contents, and male moth captures in traps baited with the dispensers were compared following pre-aging of the dispensers in a greenhouse at 35 °C for 0, 4, 12, and 16 wk. The laminate dispenser, now used in USDA detection traps, became less attractive over time as its pheromone release rate and content dropped below the threshold values previously reported as necessary for effective attraction. A polyvinyl chloride coated twine dispenser produced high male moth captures and gave release rates and residual contents above these thresholds (30 ng/h release rate and 100 μg content) at all aging periods. The tube-A dispenser was the most effective of the new commercially prepared formulations, followed by the membrane and tube-B whose male moth captures and release rates tended to increase with aging time. The capsule and film dispensers were the least effective of the formulations tested.