Intra-and interspecific variations in flight performance of oak-associated Agrilinae (Coleoptera: Buprestidae) using computerised flight mills

Several Agrilinae species (Coleoptera: Buprestidae) are thermophilous forest borers, and some are also major invasive pests. They are expected to be favoured by climate change and the global deterioration of forest health, and expand their range and damage. Flight behaviour and performance of these insects are poorly known despite their critical role in dispersal and their relevance to management. This study aimed to assess intra-and inter-specific variability in active flight of several Agrilinae species and effects of sex and mass on this variability. We assessed the flight performance of eleven oak-associated species (nine Agrilus, one Coraebus, one Meliboeus) plus one herb-associated Agrilus. Computer-monitored flight mills were used to measure flight parameters of 250 beetles. Overall, flight capacities were rather homogeneous among species, with a dominance of poor flyers and only Coraebus undatus showed outstanding performance. Beetles generally performed several short flight bouts within one trial, and only a few individuals sustained long flight. The maximal total distance covered across multiple assays until death ranged from 170 to 16 097 m, with a median between 35 and 966 m (excluding individuals that never flew). Add to this interspecific variability, flight distances varied greatly among individuals, but were not influenced by sex. Preflight body mass had mixed effects depending on the species, presumably related to dispersal patterns. In our experimental conditions, most species had limited average dispersal capacities over multiple flight trials. Overall, long-distance dispersal and colonisation events probably depend on a small proportion of individuals which largely exceeded the median performance.