Decoding bat droppings

Macadamia farmers could benefit from collaborative work between South African and Danish scientists, who aim to identify the insect prey contained in bat guano.

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Analysis of the droppings is expected to prove that bats are feeding on stinkbugs, a serious pest in the macadamia industry.
The collaboration between the University of Venda (Univen) and the Centre of GeoGenetics in Copenhagen, will see three Danish researchers visit Univen in August to collect guano samples.

“Once we have proof that bats are eating stinkbugs, they will become more important to farmers who will hopefully take steps to conserve them,” said Prof Peter Taylor, of Univen’s Department of Ecology and Resource Management. Taylor said that refraining from spraying insecticides an hour after dusk when bats feed was a simple, effective conservation measure. “Building or erecting bat houses also encourages bats to roost and breed.”

Taylor was working towards finding the correct set of conditions and bat house designs for macadamia orchards. Subtropical technical advisor Tshifhiwa Radzilani estimated that the macadamia industry lost R34 million per year to stinkbug damage. “Farmers can lose up to 80% of their crop to stinkbugs,” he said.Radzilani is running a trial to determine the efficacy of stinkbug trap crops planted in close proximity to macadamia orchards.

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A 2011 study of bat droppings near sugar cane farms in Swaziland, conducted by Prof Ara Monadjem of the University of Swaziland, estimated that about 2 500 bats were feeding on between 5t and 10t of insects a year. Insect prey included moths, flies and stinkbugs, including the moths of two sugar cane pests: Eldana (sugar cane borer) and Mythimna (army worm).