First data on the flight activity and distribution of the ambrosia beetle Xylosandrus compactus (Eichhoff) on carob trees in Sicily

Abstract

The factors influencing the entry and the spread of the black twig borer, Xylosandrus compactus (Eichhoff), in the Mediterranean environment have not yet been characterized. Following its first report in Sicily (southern Italy) in 2016, and due to the high level of damage it causes on one of its host plants (Ceratonia siliqua L.), the flight activity of the pest was studied there. Monitoring was performed from spring 2017 to summer 2018 by exposing red cross‐shaped sticky traps combined with ethanol‐baited bottle traps. The three monitored sites were selected at different altitudes, representing the southern Mediterranean environment where the carob tree is widely present. The results showed that the pest populations are influenced by climatic factors. In particular, the first adults were caught when the maximum daily temperatures were stably higher than 20°C over several continuous days. Xylosandrus compactus occurred widely in the monitored territory and was continuously caught from spring to autumn. Furthermore, the traps used proved to be effective for intercepting the spring flight of the overwintering females. Moreover, the ability of the beetle to spread from a new infested area was also studied. It seems that the pest can spread more than 8 km from the last infested site of the previous flying season. It was not present above altitudes of 400 m in the conditions of the present study. This study represents the first step to better understand the behaviour of X. compactus in a newly colonized environment.