Pest-controlling bats help save rainforests

Bats that feast on plagues of insects could ease the financial pressure on farmers to turn forest into fields, with the potential to help save rainforests. Several species of bats are already giving rice farmers in Madagascar vital pest control, according to a new study.

Relations between agriculture and conservation are strained in Madagascar, where forests are being converted to agricultural land at a rate of one per cent every year. Much of this destruction is fuelled by the cultivation of rice.

Now however, new research has shown how bats that feast on rice-destroying insect pests could be the answer to helping save the rainforests by easing the financial pressure on farmers.

Co-leading an international team of scientists, Ricardo Rocha from the University of Cambridge found that several species of indigenous bats are taking advantage of habitat modification to hunt insects swarming above the country’s rice fields. Among them are the Malagasy mouse-eared bat, Major’s long-fingered bat, the Malagasy white-bellied free-tailed bat and Peters’ wrinkle-lipped bat.

“These winner species are providing a valuable free service to Madagascar as biological pest suppressors,” commented Rocha in a statement. “We found that six species of bat are preying on rice pests such as the paddy swarming caterpillar and grass webworm. The damage that these insects cause puts the island’s farmers under huge financial pressure and that encourages deforestation.”

The study used ultrasonic recorders and molecular analysis to investigate the feeding activity of insectivorous bats in the farmland bordering the Ranomafana National Park. The researchers found that bat activity was seven times higher over irrigated rice fields and sixteen times higher over hillside fields than in forests.

Meanwhile, DNA barcoding techniques to analyse bat droppings within the rice plantations and nearby forest showed that all six species of bats had fed on economically important insect pests.

Bats comprise roughly a fifth of all Malagasy mammal species and thirty-six recorded bat species are endemic to the island, making Madagascar one of the most important regions for conservation of this animal group anywhere in the world, according to the statement.

Photo credit: Cathrine/ CC BY-NC 2.0

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