Suppression of mating in Ephestia cautella (Walker) (Lepidoptera: Phycitidae) using microencapsulated formulations of synthetic sex pheromone

Abstract

The suppression of mating in Ephestia cautella caused by permeation of the atmosphere with the synthetic sex pheromone component (Z, E)-9,12-tetradecadienyl acetate (ZETA), dispensed from thin- and thick-walled microcapsules or polyethylene vials, was investigated in small simulated cocoa stores. The concentration of airborne pheromone was measured and the emergence of the F 1 generation was used to assess the degree of reproductive control. In one trial, F 1 emergences were reduced by over 97% when a population density of 0.25 moths/m 2 surface area was exposed to a nominal pheromone rate of 10 mg/m 3 dispensed from vials giving an airborne pheromone concentration of 1–3 μg/m 3. The exposure of similar population densities of moths to a pheromone rate of 20 mg/m 3 dispensed from thin-walled microcapsules sprayed onto woven polypropylene sheeting resulted in airborne concentrations of 0.3–2.9 μg/m 3 and between 70 to 88% reduction of F 1 emergence. The low air concentration of pheromone achieved with thick-walled microcapsules appeared to result in enhanced mating compared with the controls. The overall performance of microencapsulated pheromone was no better than pheromone dispensed from polyethylene vials and the more extravagant use of synthetic pheromone was a positive disadvantage. The development of an easily applied “point-source” pheromone formulation is recommended.