Orientational disruption of codling moth, Cydia pomonella (L.) (Lep., Tortricidae), by concentrated formulations of microencapsulated pheromone in flight tunnel assays

The effects of two formulations of microencapsulated pheromone (CheckMate CM-F), containing 14.3% (E,E)-8,10-dodecadien-1-ol (codlemone), on the behaviour of the male codling moth, Cydia pomonella (L.), were evaluated in a flight tunnel after several periods of formulation ageing. The two treatments of CheckMate CM-F evaluated consisted of the label-recommended field rate of 50 g active ingredient (a.i.)/ha diluted in: (1) a standard 1000 l of water (low concentration 0.05 g/l), and (2) a low volume of 100 l of water (high concentration 0.5 g/l). The low-concentration treatment was formulated by diluting 0.071 ml of CheckMate CM-F in 500 ml of water and the high-concentration treatment contained 0.71 ml of CheckMate CM-F in 500 ml of water. Wax-paper strips (2.1 x 20 cm) were treated at 0.06 ml of solution/cm². The mean (±SE) number of CheckMate CM-F microcapsules adhering to treated wax-paper strips in the high-concentration treatment (398 ± 38) was sevenfold greater than that (57 ± 5) counted on wax-paper strips treated with the low concentration. Both low- and high-concentration treatments prevented anemotactic orientation of male codling to an adjacent 0.1 mg codlemone lure for up to 24 h after application. These moths flew out of the release cages, but exhibited erratic and short flights not restricted to any plume and ending at the tunnel walls or the floor. This occurred with approximately 60 and 400 microcapsules per wax-paper strip in the low- and high-concentration treatments, releasing codlemone at approximately 0.15 and 1.5 μg/h respectively. After 2 days of ageing, the low-concentration treatment no longer interfered with the ability of males to find the codlemone lure. However, the number of males contacting the lure was significantly reduced for up to 6 days with the high-concentration treatment relative to the control and low-concentration treatments. The high-concentration treatment no longer impeded normal orientational flight after 2-6 days of ageing; but, it diverted males from the codlemone lure by causing them to land on the adjacent treated wax-paper strips. This occurred at a release rate of approximately 0.7 μg codlemone/h from approximately 400 microcapsules per wax-paper strip distributed as clumps of approximately 30 microcapsules per 14 mm². We suggest that an initial but short-lived disruption mechanism like camouflage is followed by a longer period of false-plume following to clumps of microcapsules. The low-volume, concentrated application method for disseminating pheromone microcapsules warrants further investigation for moth codling, as well as other pests because this approach may improve the efficacy without the need for increasing the field application rate.