Maximizing Information Yield From Pheromone-Baited Monitoring Traps: Estimating Plume Reach, Trapping Radius, and Absolute Density ofCydia pomonella(Lepidoptera: Tortricidae) in Michigan Apple

Abstract

Novel methods of data analysis were used to interpret codling moth (Cydia pomonella) catch data from central-trap, multiple-release experiments using a standard codlemone-baited monitoring trap in commercial apple orchards not under mating disruption. The main objectives were to determine consistency and reliability for measures of: 1) the trapping radius, composed of the trap’s behaviorally effective plume reach and the maximum dispersive distance of a responder population; and 2) the proportion of the population present in the trapping area that is caught. Two moth release designs were used: 1) moth releases at regular intervals in the four cardinal directions, and 2) evenly distributed moth releases across entire approximately 18-ha orchard blocks using both high and low codling moth populations. For both release designs, at high populations, the mean proportion catch was 0.01, and for the even release of low populations, that value was approximately 0.02. Mean maximum dispersive distance for released codling moth males was approximately 260 m. Behaviorally effective plume reach for the standard codling moth trap was < 5 m, and total trapping area for a single trap was approximately 21 ha. These estimates were consistent across three growing seasons and are supported by extraordinarily high replication for this type of field experiment. Knowing the trapping area and mean proportion caught, catch number per single monitoring trap can be translated into absolute pest density using the equation: males per trapping area = catch per trapping area/proportion caught. Thus, catches of 1, 3, 10, and 30 codling moth males per trap translate to approximately 5, 14, 48, and 143 males/ha, respectively, and reflect equal densities of females, because the codling moth sex ratio is 1:1. Combined with life-table data on codling moth fecundity and mortality, along with data on crop yield per trapping area, this fundamental knowledge of how to interpret catch numbers will enable pest managers to make considerably more precise projections of damage and therefore more precise and reliable decisions on whether insecticide applications are justified. The principles and methods established here for estimating absolute codling moth density may be broadly applicable to pests generally and thereby could set a new standard for integrated pest management decisions based on trapping.

Improving monitoring tools for spotted wing drosophila, Drosophila suzukii

“…The data on proportion of D. suzukii recaptured in the field cages are highly unique to date because virtually nothing is known about how to relate captures in a monitoring trap to absolute density of these flies; no precise action thresholds for D. suzukii have been developed to date. Our finding that a single baited trap in a 4‐m‐diameter field cage captured 30% of D. suzukii released therein is an important first step in the process of translating capture number for this pest into an estimate of absolute density, as has recently been accomplished for codling moth, Cydia pomonella L. (Miller et al., ; Adams et al., ). Given that a D. suzukii trap in a substantially smaller cage than that used for C. pomonella captured only 30% of released flies, we predict its sampling power in the field may be remarkably weak and that any level of capture in such a trap may signal an already very high D. suzukii population.…”

Interrelation of mating, flight, and fecundity in navel orangeworm females

“…The robust dispersal capacity of adults may help explain the challenges encountered with this species when developing treatment thresholds based on pheromone trap data (Burks et al., ; Burks & Higbee, ). The number of males captured in a pheromone trap is dependent on the distance over which the plume is attractive, and the distance travelled within the sampling period before encountering the plume (i.e., trapping radius) (Wall & Perry, ; Miller et al., ; Adams et al., ). Our flight mill data indicate that the trapping radius for a 1‐week monitoring interval (frequently used by pest management consultants) is potentially very large, which reduces the local specificity of information obtained from navel orangeworm pheromone traps.…”

Will Peri-Urban Cydia pomonella (Lepidoptera: Tortricidae) Challenge Local Eradication?

“…The peri-urban pheromone traps had twice as high a catch rate as those in export orchards. While the behaviorally effective plume reach is thought to be <5 m for codling moth, the total trapping area for a single trap is estimated at approximately 21 ha in contiguous apple orchards [42]. Trap competition would have been much higher in export orchards than in peri-urban areas, as the traps were much closer.…”