BIOLOGY, ECOLOGY, AND ETHOLOGICAL APPROACHES TO THE BIOTECHNOLOGICAL CONTROL OF CLICK BEETLES (COLEOPTERA: ELATERIDAE) IN VEGETABLE CROPS

Wireworms, the soil-dwelling larvae of click beetles (Coleoptera: Elateridae), are among the most harmful pest groups affecting arable and horticultural crops worldwide. Their secretive lifestyle, lengthy and variable life cycle, and limited response to standard control methods present significant challenges for sustainable pest management, especially under current restrictions on chemical insecticide use imposed by European regulations. Therefore, there is a need for species-specific knowledge and the development of environmentally friendly strategies compatible with Integrated Pest Management (IPM). This PhD thesis investigates the biology, ecology, and ethology of click beetles of the genus Agriotes of agricultural importance, with the aim of supporting the development of knowledge-based and biotechnological approaches for their sustainable control in vegetable cropping systems. The research is structured into complementary studies. The first aim focuses on the species composition, population abundance, and adult emergence dynamics of Agriotes spp. in central Italy. Adult monitoring conducted over two consecutive years using sex-pheromone traps revealed the presence of Agriotes litigiosus, A. sordidus, and A. brevis, with A. litigiosus being the most abundant species. Species-specific emergence patterns were identified and related to thermal accumulation, highlighting clear differences in phenology among species. These results provide essential baseline information for improving monitoring tools and optimising the timing of Integrated Pest Management interventions. The second and third aims were designed as complementary components of integrated research framework focused on the development of biologically based alternatives to chemical control. In this context, the second aim explores alternative eco-friendly strategies to chemical control by examining the behavioural responses of A. litigiosus and A. lineatus wireworms to natural substances, synthetic volatile organic compounds (VOCs), and entomopathogenic fungi (EPF). Using dual-choice olfactometer and rhizotron assays under controlled conditions, the study demonstrates that compost teas can act as attractants, whereas synthetic 3-octanone and Metarhizium brunneum (strain KIS/HJS 1868) consistently induced repellence in both species. These findings highlight the potential of semiochemical-based and biological approaches to support push–pull strategies and behavioural manipulation within Integrated Pest Management frameworks. The third aim investigates the taxonomy, phylogeny, and pathogenic potential of previously unknown Ophiocordyceps spp. (Ophiocordycipitaceae, Hypocreales), a fungus associated with the mortality of A. litigiosus. An integrative approach combining morphological characterisation, multigene phylogenetic analyses, functional assays, and pathogenicity tests was applied to A. litigiosus, A. lineatus, and Tenebrio molitor L. (Coleoptera, Tenebrionidae) as a model organism. The results provide new insights into host–pathogen interactions and demonstrate the potential of Ophiocordyceps spp. as biological control agents, while also emphasising the importance of accurate taxonomic and phylogenetic resolution for the effective application of entomopathogenic fungi. Overall, this thesis advances the understanding of Agriotes ecology and behaviour and provides novel contributions to the development of sustainable, biologically based pest management strategies. By integrating population ecology and biology, behavioural ecology, and fungal biocontrol, the work supports the implementation of innovative Integrated Pest Management solutions aimed at reducing crop losses and minimising reliance on chemical insecticides in vegetable production systems.