Estimating plume reach and trapping radii for male and female Cydia pomonella (Lepidoptera: Tortricidae) captured in pheromone-kairomone baited traps in Washington State apple orchards under mating disruption.

Male Cydia pomonella (L.) (Lepidoptera: Tortricidae) dispersion has largely been studied in nonmating disrupted orchards due to synthetic pheromone interference with capture in monitoring traps. Little is known about female dispersion. This study aimed to characterize male and female dispersion in mating disrupted commercial apple orchards. Sterile C. pomonella recapture data from single-trap multiple-release experiments using PHEROCON CM-DA COMBO + AA Lure-baited orange Pherocon VI delta traps was interpreted to determine pheromone-kairomone lure-baited trap effective area, trap deployment density for effective monitoring, and absolute male and female C. pomonella density in mating disrupted Washington commercial apple orchards. The maximum plume reach of the pheromone-kairomone lure in mating disrupted orchards was <5 m from the baited trap for both sexes. Maximum dispersive distances for 95% of the released C. pomonella in mating disrupted orchards were 106 and 135 m for males and females, yielding trapping areas of 3.87 and 6.16 ha, respectively. Estimates were consistent across 3 growing seasons and represent the first records of male and female dispersal distance and monitoring trap efficacy from commercial C. pomonella mating disrupted apple orchards. With relevance to commercial monitoring programs and economic thresholds in mating disrupted orchards, traps should be deployed at a density of 1 per 3-6 ha. Capture of a single male or female C. pomonella corresponds to at least 82-104 C. pomonella within the 3-6 ha trapping area. This refined C. pomonella capture interpretation in pheromone-kairomone baited traps in mating disrupted commercial apple orchards yields more precise damage estimates and assists in insecticide-use decision making.

Sharpening the Precision of Pest Management Decisions: Assessing Variability Inherent in Catch Number and Absolute Density Estimates Derived from Pheromone-Baited Traps Monitoring Insects Moving Randomly.

During a trapping study interval, each target insect is either caught or not caught. Therefore, the current analysis treats trapping as a binomial process. Data from a binomial calculator, along with computer simulations of random walkers, documented that the inherent variance associated with estimates of absolute population density generated by a single catch number in a pheromone-baited monitoring trap becomes very high when catch probability averaged across the trap's sampling area falls below 0.02, as is the case for most insect trapping systems operating in the open field. The imprecision associated with interpretations of single catch numbers renders many current pest management decisions risky and unsatisfactory. Here we reinforce how single-trap, multiple-release experiments can and should be used to measure catch probability, plume reach, and trap sampling area. When catch probability lies in the danger zone below 0.02, steps are suggested for how multiple traps might be deployed to raise composite catch probability to a level where estimates of absolute pest density become reliable. Heat transfer is offered as an appropriate conceptual model for the mechanics of trapping. A call is made for a radical rethinking in the designs of insect monitoring traps in light of their significant current deficits highlighted by this study.

Line-Trapping of Codling Moth (Lepidoptera: Tortricidae): A Novel Approach to Improving the Precision of Capture Numbers in Traps Monitoring Pest Density.

This field study of codling moth, Cydia pomonella (L.), response to single versus multiple monitoring traps baited with codlemone demonstrates that precision of a given capture number is alarmingly poor when the population is held constant by releasing moths. Captures as low as zero and as high as 12 males per single trap are to be expected where the catch mode is three. Here, we demonstrate that the frequency of false negatives and overestimated positives for codling moth trapping can be substantially reduced by employing the tactic of line-trapping, where five traps were deployed 4 m apart along a row of apple trees. Codling moth traps spaced closely competed only slightly. Therefore, deploying five traps closely in a line is a sampling technique nearly as good as deploying five traps spaced widely. But line trapping offers a substantial savings in time and therefore cost when servicing aggregated versus distributed traps. As the science of pest management matures by mastering the ability to translate capture numbers into estimates of absolute pest density, it will be important to employ a tactic like line-trapping so as to shrink the troublesome variability associated with capture numbers in single traps that thwarts accurate decisions about if and when to spray. Line-trapping might similarly increase the reliability and utility of density estimates derived from capture numbers in monitoring traps for various pest and beneficial insects.