Bats have creeped us out since man and bat first met. But not many of us know just how important bats are to mankind’s existence and fewer of us know that at least five species of bats are battling an epidemic that could have devastating consequences for both bat and man.

To quote the U.S. Fish & Wildlife Service, “Worldwide, bats play critical ecological roles in insect control, plant pollination and seed dissemination” (seed dissemination is critical to rain forest regeneration). There are 25 species of North American bat.

Barbara French, a biologist at Bat Conservation International (BCI) in Austin, gave this capsule on the bond between bat and farmer: “A colony of 150 Big Brown bats can protect farmers from up to 33 million rootworms, which are serious crop pests. Many bats feed on moths. The moths lay eggs that develop into caterpillars, like corn earworms and army worms, which feed on a huge variety of crops.” And bats love mosquitoes, too.

That something was terribly wrong in the bat world was first noticed in February, 2006 in Howe’s Cave, 40 miles west of Albany, N.Y. A photograph of hibernating bats showed many had an unusual white dust on their noses, ears and wings; the find was named White-Nose Syndrome (WNS) and in less than 12 months WNS had traveled 450 miles south from Howe’s Cave. The epidemic has now spread to more than 65 caves in nine New England and Mid-Atlantic states and several caves in Canada are suspected of harboring the fungus.

Gray bats and Virginia Big-eared bats are severely threatened: even before WNS they were federally listed as endangered species. Indiana bats are now losing population, nearly to the levels of the endangered Virginia big-eared bats.

Despite the continuing search to find the source of this condition by numerous laboratories and state and federal biologists, the cause of the bat deaths remains unknown.

There really isn’t much to go on; nobody knows what is causing WNS … cavers, pesticides, global warming and more may or may not be the cause. But we do know these three facts:

• Bats hibernate in cool or cold caves and abandoned mines;

• WNS is a cold-loving fungus; and

• During hibernation bats, like all other hibernating mammals, live off their stored fat reserves.

Apparently WNS triggers a desire for food in bats, breaking their hibernation cycle; those that are strong enough to do so struggle to fly out into the cold winter environment in search of non-existent insects. Those bats, too weak to fly, die and fall to the ground. Again, the U.S. Fish & Wildlife Service: “We have found sick, dying and dead bats in unprecedented numbers in and around caves and mines from Vermont to Virginia. In some hibernaculum, 90 to 100 percent of the bats are dying.”

Melia Bayless, another biologist at BCI, says “WNS is a huge scientific mystery … it’s a puzzle. We don’t know yet whether the fungus is the cause (originating on the bat) or whether it’s opportunistic (picked up somewhere else) bu susceptible bats. We don’t know how the fungus is transmitted but we do know other fungus spores (in mammals and animals) can be transmitted and held for a long time.

Discerning diners would probably not find this much of a topic for dinner discussion, but back in the fields where their broccoli is grown, fungus can stop a good crop cold. Most farmers apply fungicides to deal with the problem, but fungicides, a subset of pesticides, can kill beneficial organisms and cause environmental damage in the course of attacking the problem invader.

Fungicides, like other pesticides, also can wind up growing better fungus as the disease adapts to fend off the poison. The fungus becomes resistant to the pesticide, and creeps back ever-more resilient. Which requires more chemical treatments; which can increase resistance; requiring more treatments…

To try to break this cycle, researchers in Canada have been developing new “green” fungicides that are less environmentally damaging because they go in for a targeted kill. This surgical approach plays off the plant’s own defense strategy by attacking the fungal infection as it ramps up to break through the plants defenses. Effectively, the new eco-fungicides, called “paldoxins,” disrupt the fungus’ response to the plant.

It works like this: The plant reacts to the encroachment of the fungus, and puts up a barrier of defenses; the fungus reacts by hitting those defenses with its own chemical reaction.

The paldoxins or anti-fungal agents intervene, rendering the fungus unable to hit back at the plant.  Instead of dropping a bomb – the old way — which can damage the plant and the beneficial organisms that assist its growth, they go in for a guerilla attack, selectively disrupting the fungus’ ability to fight through a plant’s defense mechanisms.   The researchers refer to these agents of targeted destruction as “inhibitors of fungal enzymes” (a term that we non-chemists will thankfully not be tested on).

The benefit is clear — the surrounding landscape is not harmed by paldoxins. Also, in theory, the fungus has been outwitted and should not develop defenses to thwart this type of intervention.

These developments could help save row crops, in addition to produce, according to a press announcement about the findings, released at the 237th meeting of the American Chemical Society over the weekend.

“Conventional fungicides kill constantly,” said study leader Soledade Pedras, a chemistry professor at the University of Saskatchewan. “Our products only attack the fungus when it’s misbehaving or attacking the plant. And for that reason, they’re much safer.”

Not everyone will be convinced. We’ve been down a similar path with other types of pesticides, specifically those that tunnel into a plant’s biology, working from the inside out to thwart pests. But those types of pesticide/plant interventions are different in a key way — they aim to alter the crop plant itself through genetic modifications.

This approach confuses the invading pest, without interfering with the biology of the crop plant, which appears to be a truly safer; plant-preserving, instead of plant-altering approach.

Pedras’ group has developed six synthetic versions of the paldoxins and successfully tested them in the lab on crucifer plants, including rapeseed plants and mustard greens. They plan field tests on other crops, including grasses such as wheat, rye, and oat which are more difficult to protect with fungicides.

The study was funded by the Natural Sciences and Engineering Research Council of Canada and the University of Saskatchewan.

Copyright © 2009 Green Right Now | Distributed by Noofangle Media