The European grape berry moth is an important pest in vineyards. Males respond to the female-produced sex pheromone released from a piezo nebulizer in a dosedependent manner in a wind tunnel: <50% arrive at the source at 5-50 pg/min (underdosed), 80% arrive at 100 pg/ min to 10 ng/min (optimal) and <20% arrive at 100 ng/min (overdosed). Males responding to overdosed pheromone show in Xight arrestment at 80 cm from the source. Host plant chemostimuli for Eupoecilia ambiguella increase the responses of males to underdosed and overdosed pheromone. (Z)-3-hexen-1-ol, (+)-terpinen-4-ol, (E)--caryophyllene and methyl salicylate released with the underdosed pheromone cause a signiWcant increase in male E. ambiguella Xying to the source. Time-event analysis indicates a positive correlation between faster activation and probability of source contact by the responding males. The four host plant compounds added to the overdosed pheromone permitted males to take oV faster and with a higher probability of Xying to the source. This suggests that perception of host plant products with the sex pheromone facilitates male E. ambiguella to locate females on host plants, lending credence to the hypothesis that plant products can signal rendezvous sites suitable for mating. Keywords

Plant volatiles play an important role in the lives of phytophagous insects, by guiding them to oviposition, feeding and mating sites. We tested the effects of different host-plant volatiles on attraction of Lobesia botrana males to the female-produced sex pheromone, in a wind tunnel. Addition of volatile emissions from grapevines or individual plant volatiles to pheromone increased the behavioral responses of L. botrana males over those to pheromone alone. At a low release rate (under-dosed) of pheromone, addition of (E)-β-caryophyllene, (Z)-3-hexenyl acetate, 1-hexanol, or 1-octen-3-ol increased all behavioral responses, from activation to pheromone source contact, while addition of (E)-4,8-dimethyl-1,3,7-nonatriene, (E)-β-farnesene, (Z)-3-hexenol, or methyl salicylate affected only the initial behavioral responses. Dose-response experiments suggested an optimal release ratio of 1:1000 (sex pheromone: host plant volatile). Our results highlight the role of plant volatiles in the sensory ecology of L. botrana.

No abstract

Experience modifies behaviour in animals so that they adapt to their environment. In male noctuid moths, Spodoptera littoralis, brief pre-exposure to various behaviourally relevant sensory signals modifies subsequent behaviour towards the same or different sensory modalities. Correlated with a behavioural increase in responses of male moths to the female-emitted sex pheromone after pre-exposure to olfactory, acoustic or gustatory stimuli, an increase in sensitivity of olfactory neurons within the primary olfactory centre, the antennal lobe, is found for olfactory and acoustic stimuli, but not for gustatory stimuli. Here, we investigated whether anatomical changes occurring in the antennal lobes and in the mushroom bodies (the secondary olfactory centres) possibly correlated with the changes observed in behaviour and in olfactory neuron physiology. Our results showed that significant volume changes occurred in glomeruli (olfactory units) responsive to sex pheromone following exposure to both pheromone and predator sounds. The volume of the mushroom body input region (calyx) also increased significantly after pheromone and predator sound treatment. However, we found no changes in the volume of antennal lobe glomeruli or of the mushroom body calyx after pre-exposure to sucrose. These findings show a relationship of antennal lobe sensitivity changes to the pheromone with changes in the volume of the related glomeruli and the output area of antennal lobe projection neurons elicited by sensory cues causing a behavioural change. Behavioural changes observed after sucrose pre-exposure must originate from changes in higher integration centres in the brain.

Abstract. Olfaction is of major importance for survival and reproduction in moths. Males possess highly specific and sensitive olfactory receptor neurones to detect female sex pheromones. However, the capacity of male moths to respond to host-plant volatiles is relatively neglected and the role that such responses could play in the sensory ecology of moths is still not fully understood. The present study aims to identify host-plant stimuli for the European grape berry moth Eupoecilia ambiguella Hb. (Tortricidae, Lepidoptera), a major pest of vine in Europe. Headspace volatiles from Vitis vinifera L. cv. Pinot Noir, Vitis vinifera subsp. sylvestris and five other host-plant species comprising five different families are analyzed by gas chromatography linked to electroantennogram (EAG) recording from male E. ambiguella antennae and by gas chromatography-mass spectrometry. This procedure identifies 32 EAG-active compounds, among them the aliphatic compounds 1-hexanol, (Z )-3-hexenol, (Z )-3-hexenyl acetate and 1-octen-3-ol; the terpenes limonene, β-caryophyllene and (E)-4,8-dimethyl-1,3,7-nonatriene; and the aromatic compounds benzaldehyde and methyl salicylate. Male and female E. ambiguella show similar EAG response amplitudes to individual chemical stimuli and also to mixtures of plant volatiles, as represented by essential oils from ten other plant species. This possibly indicates a common role for plant compounds in the sensory ecology of the two sexes of E. ambiguella.