Katherine Ingram, a doctoral student at UC-Davis, “is exploring the role bats can play as winged soldiers in the battle against a nonnative pest,” the codling moth, which attacks California’s $2 billion-a-year walnut crop, says Ensia. Some farms lose up to 10 percent of their crop to the codling moth and pesticides are an expensive weapon to use against the moth. Bats are renowned as voracious eaters of crop pests but few studies have parsed their benefit to a particular crop. So Ingram makes the rounds of 15 sites in the Sacramento Valley, writes Susan Moran. She uses recording devices, standing on 10-foot poles in the orchards, to capture feeding calls of bats, and analyzes bat guano to see if it contains moth DNA.
“Preliminary data show that roughly 10 percent of the (guano) samples from beneath Ingram’s bat roosts contain codling moth DNA,” says Ensia, Thanks to DNA analysis, said Ingram, “We know not just that bats eat codling moths, but precisely how much of their diet is this moth.” When all the data are available, Ingram will perform an economic analysis of the financial benefits of bats to determine if they are making an adequate dent in codling moth populations compared to chemical controls. “Ingram notes that the research stands to benefit not only farmers but bats as well by putting an economic price tag on the services they provide, and so boosting their perceived value and, presumably, the desire to conserve them,” says Ensia.