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Vespa velutina is an invasive hornet species that is colonising Europe, generating considerable impacts on honeybees, beekeeping and biodiversity. Control and early warning strategies for this species are mainly based on monitoring plans and procedures of nest detection and destruction. Technological tools (harmonic radar, radio-telemetry) have been developed to increase the probabilities of nest detection in new outbreaks. Since hornets are able to regulate nest temperature, thermography may represent an additional technique that may be used, both alone or in support to other techniques. In this study, the viability of thermal imaging in detecting nests of V. velutina was evaluated in controlled conditions. The influence of different environmental and operative variables (time of the day, presence/absence of leaves covering the nest, distance between the nest and the operator) were tested on three nests detected during August 2018 in Italy. All the nests were detectable by thermal imaging, but environmental and operative variables affect their detectability. The temperature difference between the nests and the surrounding reaches its maximum before sunrise and without a tree canopy covering the nests. Although nests were visible in some cases from 30 m, the detectability was higher at shorter distances, even if this variable may also depend on infrared camera resolution. An increase in the environmental temperature also generates a decrease of nest detectability. Although some limitations could occur, these results show the applicability of thermography in detecting V. velutina nests before the beginning of the reproductive phase, and consequently its potentiality in control strategies.

Invasive alien species could generate a multitude of impacts towards native species. The introduction and spread of Vespa velutina in Europe is raising concern for the conservation of insect’s biodiversity, including wasps due to predation, competition or a combination of these two mechanisms. Nevertheless, most evidence for negative effects on other wasps are based on laboratory experiments, direct observations, and on considerations about the biology and ecology of Vespidae. No field study in Europe explored how the abundance of V. velutina could affect the population of native Vespidae, as expected in case of competition and predation. We analysed how the abundance of V. velutina influenced that of Vespa crabro, 4 years after the arrival and establishment of V. velutina in our study area, in Italy. Moreover, we compared the abundances of three native Vespidae (V. crabro, Vespula vulgaris, Vespula germanica), between our study area and an adjacent uninvaded area with similar environmental conditions. Bayesian Generalized Linear Models revealed that the abundance of V. velutina and V. crabro was positively associated, where V. velutina was scarce. Covariation disappeared only at those trapping sites where V. velutina was extremely abundant. Moreover, abundances of native wasps were similar between the invaded and the uninvaded areas. Implications for insect conservation The wide-scale monitoring activity performed to investigate the effects of V. velutina on native wasps has not detected any negative effects in relation to the presence of the invasive species. More effort is however requested for understanding if V. velutina could really affect native Vespidae at the population-level.

Gravitational hazards, such as rockfall, constitute a major risk in mountainous areas, threatening dwellers, goods, and infrastructures, and ultimately posing a challenge to their development. Ecosystem-based solutions for Disaster Risk Reduction (Eco-DRR), such as protection forests, can play a significant role in mitigating these risks by integrating the protective structures currently adopted, which are often costly and could entail higher environmental impacts. This study develops an economic model called ASFORESEE (Alpine Space FORest Ecosystem Services Economic Evaluation) to assess the protective service forests provide against rockfall within a standardized framework adopting a precautionary approach. The Replacement Cost approach was adopted, measuring the protection effectiveness, the need for protection of the stakeholders and defining a harmonized method for the design of the defensive structures. Applying the model to a case study in the Italian Alps, the results show the forest has a relevant protective effect able to fulfil the stakeholders’ needs, with a value of 30,440 € ha−1, equal to 950 € ha−1 year−1, within the 25-year timespan considered. ASFORESEE could feasibly be adopted in other mountainous contexts, due to its harmonized structure reliant on minimal assumptions. Its adoption would foster the acknowledgment of the forest role and to further support the inclusion of Eco-DRR in local risk management plans.