Although many overlook it, bats play a vital role as natural insect controllers, effectively reducing pests that threaten agroforestry systems. A recent study conducted by the University of the Basque Country UPV EHU and the Doñana Biological Station CSIC focused on a colony of cave bats Miniopterus schreibersii in a gap of the Sierra de San Cristóbal near Puerto de Santa María in Cádiz. The findings highlight how these bats contribute to pest regulation in agricultural landscapes, even within highly humanized spaces.
The star of the study is Miniopterus schreibersii, Europe’s most gregarious cave bat. It forms colonies that can number in the tens of thousands and has impressive flight capabilities with a range extending well over 30 kilometers from its roost. Throughout the study period the San Cristóbal colony consisted of between 3,000 and just over 7,000 individuals, and it is known to forage as far as the southern portion of Doñana National Park on occasion.
Researchers note that this large colony can persist in humanized environments due to the species characteristics. It is an aerial predator of open spaces and does not depend on a specific plant substrate, plus it has substantial mobility that enables broad foraging. This adaptability allows it to navigate fragmented landscapes and utilize a mosaic of resources across the region.
Two thirds of the study area comprises a mix of agricultural lands and urban development, while the remaining areas include natural vegetation and protected zones such as Bahía de Cádiz Natural Park and the southern Doñana region. This heterogeneity provides alternative resources over time, supporting the bats even in altered habitats.
They target 39 pest species in their diet
The research team identified bat prey using DNA metabarcoding of fecal samples. The diet of these bats includes more than 160 arthropod species, among which 39 are pest species. The majority of food consisted of 24 prey species, with 11 confirmed as pests. The diet is rich in moth caterpillars that threaten various crops and forest stands, including plantations of pine and oak and cork oak habitats. Among the pest species detected is the green stink bug, a known threat to cotton and several fruits and vegetables.
These bats also consume insects that act as vectors for pathogens. For example, Culex mosquitoes carry diseases in the region, and certain planthoppers can spread bacteria harmful to crops. This natural pest control reduces disease pressure and supports agricultural health in shared landscapes.
Seasonal diet shifts and pest suppression
The composition of prey changes through the year as prey availability shifts. The most consumed insects are linked to different habitats and crops, so bats move between habitats to exploit successive pest outbreaks. By tracking the intake and the colony size, researchers estimated how much harm is avoided through adaptive foraging as pests peak in different crops and forests over time.
By analyzing species consumption patterns, the team calculated daily intake and the proportion of each prey type within the diet across the season. This approach helps quantify the pest suppression provided by the colony and its contribution to ecosystem services in the area.
Pine procession case and pest dynamics
From May 11 to October 10 the colony consumed roughly 1 610 kilograms of pests, with more than 90 percent belonging to ten key species. The study highlights Thaumetopoea pityocampa, a well-known pest of pine forests. Pine habitats occupy a small portion of the landscape, yet large colonies frequently feed near distant pine masses that lie beyond urban areas. The colony’s reproductive cycle means individuals are present in a defined seasonal window, with peak foraging occurring late summer into early autumn.
During these peak weeks the colony was observed to catch the majority of their prey in a relatively small pine area. The researchers note that this period coincided with a rapid expansion in both movement and foraging activity, driven by abundant mock moths that provided a food pulse for the colony.
Estimates suggest a dramatic impact on moth populations. It is calculated that during the peak period the colony could consume up to six kilograms of moths daily. With each moth weighing about 0.1 gram, that implies around 60 000 moth individuals or imagos. The broader implication is the elimination of roughly 173 kilograms of moths over the season, equivalent to about 1.73 million individual moths. Considering pine forests cover sizeable areas, the per-hectare impact is substantial and highlights the bioeconomic value of the bats in forested and mixed landscapes.
The Miniopterus schreibersii colony is legally protected, recognized as a sensitive species in conservation frameworks and part of Natura 2000. Although protections exist, long-term preservation is not guaranteed. Threats include shifts in land use, changes in wintering sites, increasing tourism pressure in inland areas, and the proliferation of wind farms. These pressures can impact the bats’ feeding and roosting patterns, underscoring the importance of balanced landscape planning for sustained ecosystem services.
For further context, the study aligns with broader evidence of bats contributing to pest control in agricultural regions and natural ecosystems. Insights from this work reinforce the practical value of conserving bat populations as part of integrated pest management strategies across Europe. The findings are supported by peer-reviewed research and field observations from the San Cristóbal site and surrounding natural areas.
Note: This summary reflects the study focus on prey diversity, seasonal diet shifts, and the pest suppression realized by bat predation in mixed landscapes. The research demonstrates a tangible link between bat activity and reductions in pest damage across crops and forested habitats, illustrating a natural ally in sustainable agriculture and biodiversity preservation.