Performance of the microsprayer, with application for pheromone-mediated control of insect pests

An electronically controlled device has been designed to provide reliable, precise, season-long release of insect pheromones without the need for maintenance, refilling, or component replacement. The operational performance of this dispenser technology was evaluated under laboratory and field conditions throughout the summer of 1998 in orchards of Michigan apple (Malus spp.). A simple electronic circuit controlled the opening of an automotive fuel injector connected to a pressurized canister containing pheromone solution. By controlling the duration and frequency of pheromone release anti the concentration of pheromone within the canister, this device, referred to as the Microsprayer, dispensed a desired quantity of pheromone to achieve mating disruption. Containment of multiple: pheromones within the light- and oxygen-free environment provided release of active ingredients throughout the growing season for disruption of mating by >1 pest insect species. The volume released increased linearly with canister pressure, and this increase was positively correlated with ambient temperature. The spatial pattern of primary pheromone deposition was measured, in still air the largest volume deposited was approximate to 80 cm from the point of release. Release from increasing heights above a target surface caused an exponential reduction in the volume of liquid reaching the surface because of solvent evaporation. In orchard trials, microsprayers powered by single 0.5 A Hr 9 V lithium batteries released pheromone every 170 s for 5 mo without appreciable voltage drop. Weight loss from the microsprayers was steady and predictable, and canister pressure remained above 50 psi for the duration of the season. This device shows promise for practical control of insect pests amenable to pheromone mating disruption.