This examination provides the advantage table 5 of a direct measurement of the impact of pheromone dispensing on mating and not just an indirect effect on mate finding by males as measured by exposing pheromone-baited traps within larger field cages. In a second step, we withdrew pheromone dispensers from the inside of the field cage to test if the method would also be suited to measure the effect of prevailing sex pheromones in the vineyard. Unfortunately, mating was less disrupted, indicating that the technique of using a cage without a dispenser placed inside may have limitations. Additional analyses showed that the tissue of 800��m mesh covering the prototype reduced air flow into cages by almost 90%, whereas a mosquito net of 1500��m mesh size had 75% air permeability [19].

The tissue was therefore replaced by the more air permeable mosquito net. Thereafter, the proportion of females mated was significantly lower within cages surrounded by pheromone dispensers compared to females similarly exposed in the reference vineyard. Thus, the refined cages with the more permeable mosquito net appeared suitable for measuring the effect of the prevailing sex pheromone regime on mating disruption.Finally, we refined the duration of insect exposure and the number of insects exposed. Our trials revealed that mating did not significantly increase with the length of exposure of insects within the cages. The exposure of insects of the right age for one night is sufficient to evaluate the effectiveness of different mating disruption schemes in grape moths.

However, the proportion of females mated increased with the number of exposed couples. Whereas high densities (>12 couples/cage) demand a considerably greater amount of work in order to rear, expose, and dissect insects, differences between the two pheromone Anacetrapib treatments used here were unverifiable at low moth densities (<5 couples/cage). This is in accordance with Vick et al. [32] and Palaniswamy et al. [24] who also observed only small differences between mating disruption schemes at low pest densities. The exposure of about eight couples in the field cages seems therefore to be optimal. This corresponds to a grape moth density of 840��000 couples per hectare (B. Bloesch, personal communication), a pest pressure that is extremely high and that has rarely been observed in commercial vineyards. To conclude, the exposure of eight couples within our field cages during a warm and rainless night allows to compare different pheromone mating disruption schemes targeting grape moths under standardised semifield conditions.4.2.