The coexistence of humans with small mammals, and especially farmers with rodent species (Rodentia) is an issue for thousands of years as it is related to a variety of problematic parameters, which affect human activities and social structures:
Below are the three most important:
Social aspect and health issues: the recent global pandemic
We are going through an unprecedented global pandemic (SARS-CoV-2) which is most likely due to a zoonotic disease that was transmitted from small mammals (rodents, bats, etc.) to humans. The current pandemic has changed the course of society and the global economy, highlighting the imperative need to regulate and limit the population of harmful small mammals.
According to the World Health Organization and a recent study conducted by 22 experts from IPBES (Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services), pandemics will multiply in the future if we do not manage natural resources wisely. There are still 1.7 million unknown viruses in mammals and birds, of which more than 800,000 can infect humans. It should be noted that 70% of the new catastrophic diseases that have appeared such as Ebola, Zika, Influenza, AIDS, Covid-19, are zoonoses coming from animal pathogens. The solution, according to the research, lies exclusively in reducing the human footprint in nature and changing the model of relationship/exploitation of natural resources, especially in agriculture.
Rodents alone, for example, are carriers of more than 60 human diseases. Some of the most important communicable diseases are plague, typhoid fever, salmonellosis, hemorrhagic jaundice, trichinosis, and especially leptospirosis and tularemia, which cause several deaths annually in Greece and worldwide.
Financial aspect: Destruction of agricultural crops by harmful rodents
Small mammals and especially the large group of rodents are the group with the largest diversity in the world, numbering more than 2000 species and over 300 genera, occupying thus 40% of all mammal species worldwide.
Their large population numbers are related to the high rate of reproduction each year, their rapid adaptation and their extensive geographical spread. The destruction of agricultural crops by rodent outbreaks has been a problem for agricultural management since the beginning of civilization. The first reports of agricultural crops destruction are found in the texts of Aristotle where he recorded that rodent raids could destroy the crop from entire plots of land in one night.
The global rodent damage in forests, and forestry, but mainly in agriculture and in very important crops such as rice, cereals, corn, alfalfa, and other arboreal crops, ranges annually from 15% -20% to 30% of the total world agricultural production. Despite the extensive use of rodenticides and pesticides in agriculture, during the last 40 years, the losses of agriculture from pest disasters have not changed much.
By applying augmenting products and fertilizers, farmers achieve an increase in production in an effort to counterbalance the losses. However, this policy increases all the chemical inputs to the agricultural areas. At the moment, the financial cost of rodents in the world’s agricultural production amounts to several hundreds of millions per year, even billions of euros. A financial cost of such magnitude highlights the need for differentiated solutions, leaving behind the traditional control methods.
Ecological aspect: Application of rodenticides and secondary poisonings in agricultural management
The toxic anticoagulants of 1st and 2nd generation, based on the toxic active substances bromadiolone, warfarin, coumarin and difenacoum, are most usually applied for rodent-control in agricultural ecosystems. The effect of rodenticides application on the agri-food chain for humans is still unknown, as the possible residue in products has not yet been thoroughly investigated. However, it has repeatedly been documented that the application of rodenticides in agricultural areas, often leads to secondary deaths of other higher predators that feed on poisoned rodents (birds of prey, carnivorous mammals, many of which are endangered species).
As a result, intense and ongoing pressure is being exerted on the biodiversity of agricultural ecosystems worldwide, as the practice of toxic rodenticides applications poses an identified risk to higher predators. Barn owl, Common buzzard, various species of falcons and eagle owls such as Falco naumanni and some species of Circus (Circus), as well as the fox (Vulpes vulpes) and other mesopredator mammal species are among the main species of wild fauna that are killed by secondary poisonings.
A global literature review over the last 30 years worldwide, found that more than 34 different species of raptor birds have been exposed to secondary poisoning by toxic rodenticides (residue in 1892 from 3345 cases - 56.6%), 34 other species of birds not raptors (residue found in 207 of 397 cases - 52.1%), 15 species of carnivorous mammals (residue found in 382 of 672 cases - 56.8%), and 10 species of other non-carnivorous mammals (residue found in 212 of 407 subjects - 52.1%).
