This project aims to enhance our understanding of chemical ecology-related adaptations in arthropods and their niche-specific survival strategies. The research focuses on identifying chemosensory genes, including Ionotropic receptors and gustatory receptors, within Ixodes ricinus and Argiope bruennichi. Additionally, the project involves a comprehensive annotation of the Trypodendron lineatum genome. Ixodes ricinus, a critical vector for tick-borne diseases in Europe, is the primary subject of study. Despite its significance in public health, little is known about its chemosensory system, which hinders comprehension of its host-seeking behavior and chemical ecology. The project employs phylogenetic analysis and comparative genomics to investigate chemosensory receptor gene conservation or diversification across seven tick species from five major genera in the hard ticks (Ixodidae). The second objective involves exploring the chemosensory adaptations of Argiope bruennichi, a unique orb-weaving spider species known for its distinctive mating behavior. The research primarily focuses on identifying pheromone receptors, which play a crucial role in A. bruennichi's mating behavior characterized by kin recognition, nepotism, and sexual cannibalism. Finally, the project expands its scope to annotate chemosensory gene families in the ambrosia beetle, Trypodendron lineatum, serving as a secondary biological model. This entails a comprehensive global annotation of the T. lineatum genome and comparative analysis of gene family expansions in relation to other bark beetle genomes, such as Ips typographus and Dendroctonus ponderosa. These comparisons aim to unveil genomic signatures shedding light on the unique lifestyle of ambrosia beetles as fungal farmers and eusocial insects.