PHEROMONE TRIALS FOR THE MONITORING OF CYDIA SPLENDANA IN CHESTNUT PLANTATIONS OF FRANCE

The attractiveness of five different pheromone blends was compared during the 2003 flight period of the chestnut moth, Cydia splendana. The trials were carried out over a 6-week period in two regions of France, Dordogne and Gard, approximately 400 km apart. The blends tested were 10 µg of E8,E10-12:Ac (EE) alone or combined with 0.5, 2 or 10 µg of Z8,E10-12:Ac (ZE) as well as 2 µg of EE combined with 10 µg of ZE. The results from both regions clearly showed that while EE was the major pheromone component, the addition of 0.5, 2 or 10 µg of ZE improved the attractiveness of the lure to C. splendana males in a dose-dependent manner. However, the 2:10 ratio of EE/ZE resulted in a significantly lower number of C. splendana males being captured when compared with the 10:2 ratio of the same lure. While the majority of C. splendana was captured during the first two weeks of the flight period in the Gard region, numbers increased continuously in Dordogne. This difference may be due to the immigration of moths from other hosts (e.g. oak) in the Dordogne region. Two other species, C. ulicetana (Dordogne) and C. fagiglandana (Gard), were also caught but their numbers only represent 4% of the total catch in both regions. While C. ulicetana responded equally to all blends, most C. fagiglandana were attracted to the EE isomer alone, with blends containing the ZE isomer being inhibitory to this species. The three Cydia species not only differed in their pheromonal responses but they also showed some degree of temporal separation over the C. splendana flight period.