Although most people ignore this, the bats They act as true natural “insect killers”Because they effectively combat agroforestry pests. This has been proven once again by a new scientific study, this time conducted by the University of the Basque Country (UPV/EHU) and the Doñana Biological Station (CSIC), examining the nutrition of a colony of cave bats (Miniopterus schreibersii) is located in a gap in the Sierra de San Cristóbal in Puerto de Santa María (Cádiz).
The hero of this investigation Miniopterus schreibersii, It is Europe’s most gregarious cave bat, forming colonies of several tens of thousands of individuals. It is also a species with a significant flight capacity and its range can extend up to more than 30 kilometers from its shelter.
In the case of the San Cristóbal colony, throughout the study period,Between 3,000 and just over 7,000 copies. And this colony is known to hunt at least with some frequency as far as the southern half of Doñana National Park.
“This great colony can exist and maintain itself in such a humanized space “due to the characteristics of the species, which is an aerial predator of open areas,” says researcher Carlos Ibáñez of the Doñana Biological Station. “This means that it does not depend on the type of plant substrate and also has a large movement capacity,” he adds.
According to Ibáñez, “the environment, although highly humanized, is heterogeneous and offers sufficient alternative resources over time.” Two-thirds of the surface is devoted to a wide variety of agricultural products as well as urbanized areas. The rest consists of patches of natural vegetation, including protected areas such as the Bahía de Cádiz Natural Park and the southern region of Doñana National Park.
They have 39 species of pests in their diet
The study is based on analysis by. metabar coding DNA of prey remains in bat fecal samples. As a result, the scientific team detected something The diet of these bats includes more than 160 species of arthropods, of which 39 are identified as pest species.
The bulk of their food consisted of 24 species; 11 of these were harmful species; There were mostly moth caterpillars. They affect different crops and forest masses (pine and holm oak forests or cork oak forests). These species included the green stink bug, which affects cotton and many types of fruit and vegetables.
In the feeding of these bats two prey that are vectors of pathogens. One of them is the common mosquito. Culex pipesThis virus, which is also the carrier of the Nile fever virus, causes disease cases in people in this region. The second is cigarettes. Neophilaenus campestrisa vector of phytopathogenic bacteria Xylella fastidiosa This is seen as a serious global threat to agriculture in Europe.
Harmful consumption
The composition of the diet changes throughout the year, because there are successive peaks in the availability of different prey. In contrast, the most consumed insects are associated with different habitats and crops. This means that bats use the different habitats available for hunting and change them over time. In this way, when foraging, bats can target successive population explosions of pests affecting different crops or forests.
After determining the species consumed by the bats, the team measured the colony’s harmful consumption, taking into account daily intake, the size of the colony, and the proportion of each prey species in the diet each time.
pine procession case
Total, Between May 11 and October 10, the colony consumed a total of 1,610 kilograms of pests.. More than 90% correspond to 10 species. To get an idea of what these numbers mean, the team focused on the specific case of the procession (Thaumetopoea pityocampa) is a known pest endemic to pine forests.
In the study area, pine forest comprised only less than 3% of the land area used by the colony. Pine forests often form small forests and even cover gardens in urbanized areas. The largest masses are located more than 25 kilometers away, for example in Doñana National Park. For your part, The marsupial has only one reproductive cycle per year, meaning they are only present during a certain period.
The highest number of flights in this region arrive between the second half of August and the first half of September. “They were by far the main catch these weeks. seen in more than 90% of samplesdespite the small surface area of the pine forest,” says Carlos Ibáñez.
“During this time the colony reached its maximum size of 7,200 individuals, partly due to the participation of juveniles that began to fly independently during July, but also to the participation of individuals from more distant refuges.” The population increase was probably associated with the abundance of mock moths.
It was calculated that during these dates the colony consumed up to 6 kg of sacs per day. Since each moth weighs 0.1 gram, this means approximately 60,000 mock moths, or imagos. They would eliminate approximately 173 kg of moths during the season, which is equivalent to 1,730,000 moths). Since there are approximately 10,000 hectares of pine forest, approximately 173 imago are destroyed per hectare.
This colony is legally protected. M.schreibersii It is a sensitive species (CEEA) and the sanctuary is included in the Natura 2000 Network as ZEC (ES120030 Cuevas de la Mujer y de las Colmenas). “But this does not guarantee its long-term preservation,” says researcher Carlos Ibáñez.
“Threats include the possible change of use of the area, the protection of wintering spaces such as the Hundero-Gato and Motillas complexes, the increasing pressure of active tourism activities in the interior and the large number of wind farms. . in your vital area.”
Reference work: https://www.nature.com/articles/s41598-023-46939-7
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