A new strategy of environmentally safe control of chestnut tortricid moths

Insect pest damage represents the mean restricting factor for the chestnut (Castanea sativa Mill.) fruit production in Italy and in Europe. Especially tortricid moth species are constantly very noxious because their larvae feed on developing nuts, thus causing important harvest losses. Although the early chestnut moth (Pammene fasciana L.) attack results only in an early drop of fruits at the beginning of the development, more serious damages are produced by the intermediate and the late chestnut moths, Cydia fagiglandana (Zell.) and C. splendana (Hb.), respectively. Larvae penetrate the nuts and develop into them, digging a tunnel and eating the endosperm. Usually damaged fruits fall during the summer, but in some cases they may complete the ripening and can be harvested as part of the crop. The chemical control of C. fagiglandana and C. splendana is not advisable to preserve the naturalness of the final product and the safety of the chestnut grove. Moreover, the endophytic development of the larvae, the large size of the trees and the characteristics of the Italian chestnut orchards make difficult and not economically advantageous the use of pesticides. Previous studies conducted on the use of tortricid sex attractants showed a potential control ability on both species. On this basis a novel, low impact control method can be achieved by combining the classical mating disruption approach to the use of a new kind of dispenser. A canister housed in a plastic cabinet, called “puffer”, repeatedly sprays proper pheromone doses on a 12- or 24- hour schedule. Puffers, produced by Suterra®, are strategically located in the chestnut orchards, hung on tree branches at heights of 6-8m, in number of 2.5 per ha. Besides the low impact for the environment, this approach shows many advantages since it is very easy to apply and, when optimised, also cheap. Therefore, a large scale trial was initiated to test the efficacy of this approach in three Italian regions: Trentino (north-eastern Italy), Tuscany (central Italy) and Campania (southern Italy). In each region, 19 puffers were located in chestnut orchard areas of about 8ha. Traps (pagoda type), baited with specific pheromones, were installed at heights of 2-4m inside and outside the treated area to verify the effectiveness of the puffers. For each species, 3 traps were placed in the central part of the treated area and 3 traps in the untreated plot and used as control. The traps were checked weekly, removing and counting adults. At the harvest time, fruit damage was also evaluated in treated and untreated areas. First data suggest that the “puffer approach” is quite easy to apply and feasible. Even if such methods need pluriannual trials to be evaluated, preliminary results are encouraging and suggest good perspectives to obtain a complete biotechnical control of Cydia spp.