Open access publications in the SLU publication database

Abstract

The grapevine moth, Lobesia botrana, is a destructive pest of grapevine. Deregulation of many of the insecticides used in the control of this pest along with public demand of residue-free products, have augmented the interest for innovative tools in pest management. Behaviour-modifying semiochemicals can be used for environmentally safe insect management and are a promising alternative to insecticides. The aim of this thesis was (1) to reinvestigate the female sex pheromone and (2) to identify behaviourally active host plant compounds. In the flight tunnel, L. botrana females were attracted to green grapes and shoots of grapevine Vitis vinifera. Females were also attracted to headspace collections from grape, showing that they rely on olfactory cues during host search. Analysis of the volatiles of V. vinifera headspace disclosed high variation in the odour profiles both between varieties of the same species and different phenological stages of the same variety. A synthetic mimic of grape volatiles, consisting of the compounds eliciting the strongest antennal responses, was as attractive as the host-plant to mated L. botrana females in the wind tunnel. The essence of this attractant was boiled down to a blend of three ubiquitous terpenes. The results show that attraction to grape is encoded by a ratio-specific blend of at least three compounds. Grapevine moth is a generalist herbivore. Females were attracted also to its native host, Daphne gnidium. The compounds from D. gnidium which elicited antennal activity attracted more females than the corresponding blend of V. vinifera compounds. In addition, more females were attracted to the compounds co-occurring in Daphne and Vitis, than to the compounds which occurred in Vitis only. Attraction to widely occuring plant volatiles may thus in part account for a generalist feeding habit. Analysis of female sex pheromone glands showed the presence of three previously unidentified compounds. Two of these compounds significantly enhanced the male response to the main pheromone compound. Behavioural studies showed that mating disruption dispensers, applied in the vineyard the previous season emitted pheromone and attracted L. botrana males. This suggests that aged dispensers contribute to the mating disruption effect. An additional study concerned the disorientation technique, a new pheromone-based insect control method. This technique uses a reduced pheromone application rate and its efficacy against grapevine moth was comparable to mating disruption.