Dwindling wind may alter predator-prey balance

Diminishing wind speeds caused by climate change may affect the ability of some insects to capture their prey, according to a new study.
The study by a University of Wisconsin Madison zoologist is among the first to demonstrate the way "global stilling" may alter predator-prey relationships.
"There are all sorts of other things that are changing in the environment that affect animals and plants and their interactions," said Brandon Barton, a UW-Madison postdoctoral researcher.
Earth's poles are warming faster than the equator, robbing the atmosphere of some of the temperature differential that creates wind, researchers said.
Lady beetles eat a major soybean pest, the soybean aphid. Barton grew plots of soybeans in alfalfa fields, protecting some with wind blocks and leaving others in the open.

He found two-thirds more lady beetles in the plots hidden from the wind, and twice as many soybean aphids on the plants growing in the open.

Wind has no direct effect on the aphids, tiny insects that hug the plants and anchor themselves while feeding with a needle-like mouthpart called a stylet.
"The aphids appear on the plants whether it's windy or not, and we showed that in lab experiments," Barton said.
"But when you add the predators, with the wind block, the beetles eat something like twice as many aphids," said Barton.
In his lab trials - simulating wind with fans and windless movement with a machine that tugged on tethered plants to shake and bend them - a stilled soybean plant represented a smorgasbord for the lady beetle.

"How do you do your duty as a predator if you're entire world is moving around?" said Barton.
"If the plant is moving, it takes four times as long for the predator to start eating, and it eats less than half as many aphids in an hour," Barton said.
Slower natural wind speeds could reduce the amount of pesticide required to keep soybean aphids from wrecking harvests. And the wind research may present other opportunities for pest control.
"By growing trees or not harvesting them around a field, you may be able to have an indirect effect on the number of aphids on your soybean plants," said Barton, who wondered what other close animal relationships may be disrupted by shifting winds.

"The mechanism may be different for other predators, but it's not hard to start thinking about effects," he said.
The study was published in the journal Ecology.