Dynamics of Leiodes cinnamomeus (Coleoptera: Leiodidae) Populations in a Black Truffle Orchard From Northeast Spain

Black truffle, Tuber melanosporum Vittad., production is increasing due to an improvement in cultivation management and to the demand for this highly appreciated fungus. However, this intensification of truffle cultivation has led to the appearance of problems related to pest incidence. Specifically, the truffle beetle, Leiodes cinnamomeus (Panzer, 1793) (Coleoptera: Leiodidae), causes significant losses in black truffle marketability. However, its biology is still poorly known, and no effective agro-ecological methods exist to mitigate its damage to the truffles. This study aimed at assessing the population dynamics of L. cinnamomeus over four seasons (2019–2023) in an orchard located in NE Spain and relating these dynamics to weather variables and damage to truffle fruit bodies. Moreover, we described the diversity of arthropods captured in the traps in search of potential natural enemies of this beetle. The maximum population peak was observed in November, except for a single season in which it occurred in December. Moreover, the sex ratio was balanced (0.54 on average), but it varied over the growing season and among years. Significant and positive relationships of the population density of truffle beetles with air temperature and relative humidity were observed. The number of beetles per trap and day was strongly linked to heat accumulation. Finally, the Carabid Percus (Pseudopercus) patruelis (L. Daufour, 1820) was identified as a natural enemy of L. cinnamomeus. These results could be used in the future for monitoring and predicting truffle beetle populations.