Factors influencing sterile codling moth (cydia pomonella l.) recapture, dispersion, and effectiveness as a control tactic in apple orchard systems / Robert T Curtiss, III.

The sterile insect technique is a proven technology used in the control and eradication of a number of pest insects over large areas. However, using this technology on a farm scale is a new and unproven application that until now has not been explored. This dissertation examines the impact of integrating the sterile insect technique for codling moth (Cydia pomonella) into existing farm-scale commercial apple pest management programs, methods of release, the sterile insect's interactions with the orchard, how existing management schemes are compatible with releases of sterile C. pomonella, the role of sterile female moths and dispersive distances. The main objectives were to 1) determine the impact of release methods on moth dispersal; 2) measure moth dispersal in contemporary trellised or netted orchards, and in orchards planted on steep terrain; 3) determine male and female dispersal in orchards treated with pheromone mating disruption; 4) establish release densities and timings to manage C. pomonella; 5) integrate sterile codling moths into existing commercial apple pest management programs; 6) elucidate the role of sterile females in controlling C. pomonella males; 7) determine the probability of male and female codling moth catches from specified distances using traps baited with a pheromone/kairomone combination lure in a single-trap, multiple-release experimental design; and 8) apply this information for estimating trap plume reach, maximum moth dispersive distance and absolute pest density based on moth catch in traps. Comparison of releases by hand at a single central location versus evenly released throughout the orchard showed higher overall recapture of sterile moths in all traps placed within the orchard when they were released at the center, suggesting that higher numbers of moths were retained in targeted areas with this method. For releases by hand or by unmanned aerial systems (UAS), recapture of sterile moths was higher when released by UAS. Orchard characteristics were found to impact sterile moth dispersal from single central locations; moths moved away from release points more in trellised orchards than in those with large old single trees. Male and female dispersal in orchards with mating disruption was similar, but shorter than in orchards without mating disruption. Sterile codling moths released on commercial farms controlled wild populations when released at densities ranging from 500 to 2000/ha and increasing numbers of sterile females were shown to increase the disruption of wild populations. Deploying sterile males and females at lower densities than the standard 2000/ha or targeting the peak flight of one or both generations showed promise as a means of making SIT a more cost-effective tactic for managing C. pomonella at a farm scale. In orchards with mating disruption, the plume reach of a single codling moth trap baited with a PHEROCON® CM-DA COMBOTM Lure + AA Lure (Trece, Inc.) was found to be very small, maximum dispersal distance was ca. 100-130m, corresponding to a trapping radius of ca 3-5ha. Pest density estimates, based on capture of a single moth in traps, were shown to correspond to 113-180 moths/ha.

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