Identificazione di semiochimici intra- ed interspecifici di Parahypopta caestrum (Hübner) (Lepidoptera, Cossidae) per lo sviluppo di applicazioni innovative di controllo ecosostenibile

The asparagus sector possesses considerable economic potential worldwide: demand continues to rise, yet production still falls short of fully meeting it. Within Europe, Italy ranks third in overall volume and holds a well-established lead in green-asparagus production, especially in Apulia, where the cultivated area has expanded sharply in recent years. In this context, sustainable plant-health management, crucial for organic crops in particular, moves centre stage. Across the Mediterranean basin the chief asparagus pests are the cossid moth Parahypopta caestrum (Hübner) and the chrysomelid beetle Crioceris duodecimpunctata. P. caestrum poses a growing threat in Apulia, its spread favoured by the larvae’s endophytic development in the roots, limited biological knowledge, ineffective monitoring tools and the scant availability of authorised chemical products. Because obligatory integrated pest management (IPM) cannot be applied and demand for organic asparagus continues to grow, new, sustainable and effective solutions are urgently needed. In this scenario, identifying semiochemicals, sex pheromones and host-plant volatile organic compounds (VOCs), offers promising, low-impact avenues for monitoring and control. Despite the insect’s agronomic importance, the sex pheromone of P. caestrum had never been identified before this Ph.D. project; likewise, no information was available on the ability of C. duodecimpunctata adults to detect and orient toward host-plant odours. The thesis therefore set out to identify the main intra- and interspecific semiochemicals involved in the chemical communication of Parahypopta caestrum and Crioceris duodecimpunctata, two key asparagus pests in southern Italy. The work combined chemical-analytical, electrophysiological and behavioural methods in an integrated approach consistent with IPM principles. Using gas chromatography–mass spectrometry coupled with electroantennographic detection (GC-MS-EAD), the sex pheromone of P. caestrum was identified for the first time. Four EAD-active compounds were isolated: (Z)-9-tetradecenyl acetate, (Z)-7-tetradecenyl acetate, (Z)-5-tetradecenyl acetate and (Z)-9-tetradecenol. Field trials showed that a ternary blend of the three acetates in an 85:5:10 ratio of (Z)-9-, (Z)-7- and (Z)-5-tetradecenyl acetate is significantly more attractive to males than any single component or other binary/ternary mixtures. This blend enabled the monitoring of male flight activity and paved the way for semiochemical-based control strategies. Pheromone-baited traps also allowed large-scale monitoring of P. caestrum distribution and phenology during a three-year survey (2021–2023) in many locations in Apulia and Molise. Interactions between the sex pheromone and plant VOCs were further explored by testing P. caestrum responses to volatiles emitted by Asparagus officinalis. Field trials optimised trap design and pheromone dosage, while a two-season mass-trapping experiment produced a significant reduction in cocoon density in the soil, indicating potential population suppression. The thesis likewise investigated olfactory mechanisms in adult C. duodecimpunctata of both sexes. Electroantennographic and behavioural assays showed that the beetle can perceive numerous asparagus VOCs, but only males exhibited clear attraction to certain plant odours. This behavioural dimorphism suggests an active male role in host-plant location and opens prospects for using kairomones in monitoring. Beyond asparagus and its principal pests, the doctoral work encompassed studies on other insects of agricultural and medical importance, aiming to deepen understanding of olfactory perception and the applied potential of semiochemicals. For the olive fruit fly Bactrocera oleae, electrophysiological and behavioural techniques assessed the effects of biochar-derived smoke waters and essential oils such as that of Carlina acaulis. Interactions between olfactory inhibitors and conventional attractants were explored, demonstrating that short-chain aliphatic aldehydes can markedly reduce catches in traps baited with sex pheromones or food attractants. In the post-harvest arena, the olfactory behaviour of two major stored-product pests was examined: Sitophilus oryzae, in response to volatiles from stored rice, and Stegobium paniceum in relation to VOCs from Chinese plant materials. A simplified GC-MS-EAD system was developed for insects of medical relevance and applied to females of Phlebotomus perniciosus, the principal vector of Leishmania infantum. Finally, in Philaenus spumarius the study demonstrated that males perceive and orient toward volatiles emitted by females, elucidating intraspecific chemical communication in this vector. Taken together, the studies conducted alongside the main project consolidated broad expertise in electrophysiological, chemical-analytical and behavioural techniques applied to insect olfactory ecology, contributing to innovative tools for crop protection and the sustainable management of medically significant vectors.