Distribution Drivers of the Alien Butterfly Geranium Bronze (Cacyreus marshalli) in an Alpine Protected Area and Indications for an Effective Management

Rocchia, Emanuel, Luppi, Massimiliano, Paradiso, Federica, Ghidotti, Silvia, Martelli, Francesca, Cerrato, Cristiana, Viterbi, Ramona and Bonelli, Simona (2022) Distribution Drivers of the Alien Butterfly Geranium Bronze (Cacyreus marshalli) in an Alpine Protected Area and Indications for an Effective Management. Biology, 11 (4). p. 563. ISSN 2079-7737

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Official URL: https://doi.org/10.3390/biology11040563


Cacyreus marshalli is the only alien butterfly in Europe. It has recently spread in the Gran Paradiso National Park (GPNP), where it could potentially compete with native geranium-consuming butterflies. Our study aimed to (1) assess the main drivers of its distribution, (2) evaluate the potential species distribution in GPNP and (3) predict different scenarios to understand the impact of climate warming and the effect of possible mitigations. Considering different sampling designs (opportunistic and standardised) and different statistical approaches (MaxEnt and N-mixture models), we built up models predicting habitat suitability and egg abundance for the alien species, testing covariates as bioclimatic variables, food plant (Pelargonium spp.) distribution and land cover. A standardised approach resulted in more informative data collection due to the survey design adopted. Opportunistic data could be potentially informative but a major investment in citizen science projects would be needed. Both approaches showed that C. marshalli is associated with its host plant distribution and therefore confined in urban areas. Its expansion is controlled by cold temperatures which, even if the host plant is abundant, constrain the number of eggs. Rising temperatures could lead to an increase in the number of eggs laid, but the halving of Pelargonium spp. populations would mostly mitigate the trend, with a slight countertrend at high elevations.

Item Type: Article
Additional Information: Funding information: The project is a collaboration between the Gran Paradiso National Park and the Department of Life Sciences and Systems Biology of Turin University. It was funded by the Gran Paradiso National Park (Italian Ministry for Ecological Transition), founding n. 13/2018 on 08/05/2018.
Uncontrolled Keywords: allochthonous insect, species distribution, Pelargonium, N-mixture models, MaxEnt, mitigation strategy, citizen science, climate change
Subjects: F800 Physical and Terrestrial Geographical and Environmental Sciences
F900 Others in Physical Sciences
Department: Faculties > Engineering and Environment > Geography and Environmental Sciences
Depositing User: Rachel Branson
Date Deposited: 07 Apr 2022 13:00
Last Modified: 07 Apr 2022 13:00
URI: http://nrl.northumbria.ac.uk/id/eprint/48840

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