Abstract
The almond holds significant economic and nutritional value globally, with California being a major producer. However, due to climate change, diseases and pest infestations are becoming more frequent. Therefore, there is a growing need to establish local almond cultivation methods while minimizing the reliance on pesticides.Eurytoma amygdali, the almond wasp, poses a significant threat to almond orchards in France, causing substantial damage without chemical control. Currently, no effective biological control method can be applied on a large scale. While it is known that female almond wasps are attracted to almond trees by olfactory signals, the volatile organic compounds (VOCs) responsible for this attraction have not been identified in previous studies.The objective of this thesis was to identify the attractive kairomone of E. amygdali females emitted by almond trees, in order to develop attract-and-kill traps in orchards.Our study has identified and quantified 50 VOCs emitted by almond trees, distinguishing between those emitted by vegetative and reproductive organs. Almond emissions primarily consist of widespread compounds, with the majority being sesquiterpenes. Additionally, our study revealed a positive correlation between emissions and temperature, but the composition of the VOC bouquet remained unchanged. Among the 39 VOCs tested using electroantennography (EAG), 29 were significantly detected by females. The ten best-detected VOCs in EAG were selected for behavioural experiments using olfactometry, which allowed us to identify two attractive VOCs and a mixture.These findings will enable us to evaluate the attractiveness of these compounds in a field setting and fine-tune the dosages to enhance the efficiency of the traps.