Assessment of rodenticide resistance, eradication units, and pathogen prevalence in black rat populations from a Mediterranean biodiversity hotspot (Pontine Archipelago)

Abstract

Biological invasions are a growing threat to biodiversity. The black rat, one of the worst pest in the world, is responsible for extensive population decline of many autochthonous and endemic species, particularly in island ecosystems. A number of rat eradication campaigns have been conducted, however, such endeavors do not always result in a complete removal of the pest. This may be due to the occurrence of individuals resistant to common rodenticides and/or a re-invasion of the same environment from interconnected areas when appropriate eradication units are not defined before starting an eradication campaign. Our study is a multidisciplinary approach whereby genetic and epidemiological methods were used to provide background information for successful eradication of black rats. We investigated the occurrence of mutations in the VKORC1 gene known to confer resistance to rodenticides and evaluated the spread of zoonoses across three islands of the Pontine Archipelago, an Italian hotspot of endemic Mediterranean biodiversity and a possible mainland source of invasion. As part of an eradication campaign, we also assessed patterns of genetic diversity at 10 microsatellite loci in order to identify eradication units. We recorded a strong population structure and revealed at least two distinct eradication units. Some degree of admixture was recorded on Ponza, the largest island and likely the main source of rats invading the other two islands. We did not record the occurrence of rats resistant to anticoagulants, but we revealed transmission of vector-borne pathogens in commensal habitats of the Archipelago. Keywords Eradication campaign Á Rattus rattus Á Biological invasions Á Microsatellites Á Zoonoses Á VKORC1 Sara Fratini and Chiara Natali have contributed equally to this work.

A review of mammal eradications on Mediterranean islands

“…In this case, the evaluation of the benefits cannot be carried out only at the level of species and ecosystems but must also include socio‐economic viewpoints (Reaser et al ). For example, researchers should consider the reduction of damage to crops, the absence of pest‐control activities following eradication (resulting in the use of less rodenticides in the long term), and the lowering of risks of humans and other animals contracting zoonoses (Capizzi et al , Fratini et al ). Working on islands that host residents and pets requires a lot of caution in choosing the appropriate eradication techniques and materials that nevertheless allow significant results to be obtained, and also consideration of the consensus regarding these restoration projects, as in the case of black rat eradication at Ventotene in Italy (Capizzi et al ).…”

Genomic Analysis Reveals Subdivision of Black Rats (Rattus rattus) in India, Origin of the Worldwide Species Spread

“…It should be noted that this phylogeography and, in particular, knowledge of the source area is key information when trying to elucidate the invasiveness and other properties of the introduced populations of black rats, e.g., as vectors of human disease [ 40 ]. Taking this more broadly, it is important to emphasize that genetic and genomic studies of the black rat can help our understanding of various aspects of this most destructive, invasive mammal, and its management, as illustrated by recent studies defining eradication units [ 41 , 42 , 43 ].…”

Transformer attention network and unmanned aerial vehicle hyperspectral remote sensing for grassland rodent pest monitoring research

“…The digging activities of rodents also accelerate soil wind erosion and form a large amount of secondary bare ground, resulting in the reduction of grassland area 10 . In addition, grassland rats carry many viruses and are shared hosts for zoonotic pathogens, 11 , 12 such as Leptospira and Escherichia coli 13 , 14 . According to surveys, there are at least 24 epidemics transmitted by rats, 15 the most dreaded of which is the plague.…”