Saturday, October 13, 2012

Bats help with pest control

Tadarida brasiliensis (Credit  Merlin D. Tuttle)
Many bat species are known to be friends to agriculture, their diet helps reduce the need for pesticides, they are important pollinators, and their guano is an effective fertilizer. The Brazilian Free-Tailed Bat (Tadarida brasiliensis) is no exception to this.

But there is more to this - a new study in PLoS ONE shows that the bats are tracking abundance of their prey in space and time. 
By using a qPCR fecal DNA assay (using COII probes and as confirmation of species ID COI Barcodes), scientists were able to show a significant association between the numbers of Tadarida brasiliensis feeding on corn earworm moths (Helicoverpa zea) and seasonal fluctuations in moth populations. The bats actually track local abundance of the moths within the regional landscape.

The larva of Helicoverpa zea is a major agricultural pest that is polyphagous (it can feed on a variety of different plants). It is considered to be one of the costliest pests in the United States, resulting in the loss of millions of dollar. 
Helicoverpa zea (Credit: cyanocorax)

An earlier study assessed the ecosystem services provided by this bat species within the Winter Garden region in Texas. They estimated that the bats provide on average services of 12% ($741,000) of the value of the annual cotton harvest. This accrues from reduced damage to cotton bolls and the prevention of 1-2 pesticide applications per year. 

An impressive value and this is only one agricultural branch researchers have looked at. The value of this bat with an appetite for things that eat crops is certainly much higher. As the authors of the study summarize:
Our results support growing evidence for the role of generalist predators, and bats specifically, as agents for biological control and speak to the value of conserving indigenous generalist predators.


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