Small insect enclosure field cages: A simple method to assess mating disruption

Abstract: Mating disruption is an effective and sustainable integrated pest management techniquethat is now established in a broad range of cropping systems. For example, it is a popular alternativeto insecticides for controlling the grape berry moth Eupoecilia ambiguella Hb. (Lepidoptera,Tortricidae), a main pest of European vineyards. A downside of this environmental friendly pestcontrol technique is the challenging assessment of its efficiency in the field. In order to obtainreliable results, newly processed pheromone dispensers have to be tested at a large spatial scalewhere pest densities, crop variety, cultural practices, microclimate etc. can vary considerablyamong trial sites. The realisation of statistically sound results therefore asks for numerousindependent replicates, which are time-consuming, space-demanding and expensive. The aim ofthis work was to facilitate the evaluation of the efficiency of mating disruption. We tested thesuitability of small insect enclosure field cages for a pre-evaluation of the impact of sexpheromones on insect mating. Our enclosure field cages consisted of a cubic metal frame of 35cmside length that was covered with gauze tissue. Cages were installed in the centre of pheromonetreated and untreated vineyards. Thereafter, various numbers of grape berry moth couples wereexposed for 1, 2 or 3 days. The impact of pheromones was assessed by counting the number ofmated females, e.g. the number of dissected spermatophores. Our data showed that mating wassignificant lower in pheromone treated compared to untreated vineyards. Moreover, there weresignificant differences among pheromone dispensers tested and mating disruption generallyincreased with the amount of pheromone diffused. Overall, the exposure of eight couples for onenight seemed to be optimal for comparing different control schemes. Our study showed that smallinsect enclosure field cages offer a fast, simple, cheap and reliable method to measure the impact ofpheromones on insect mating. Data obtained in such trials may therefore help predicting thevalue/use of setting-up large-scale field trials. In conclusion, small insect enclosure field cages mayfacilitate the development and assessment of semiochemical lures.