How pollution is thwarting pollination: Researchers reveal fumes from car exhausts are confusing insects
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Pollution can confuse insects and stop them pollinating plants, researchers have warned.
They say rising levels of new odours in the air can confuse the delicate noses of moths and other insects.
They say the effect could be causing major problem for pollinators such as bees.
A pollinating moth Manduca sexta, this one with a wing span of about 4 inches, feeds from a Sacred Dutura, or Datura wrightii, flower: Researchers found truck fumes confused the insects
TOBACCO HORNWORM MOTH
Researchers studied the tobacco hornworn moth.
The tobacco hornworm moth - a large, nocturnal insect with a wingspan of about 4 inches (10 cm) - ranges from Canada to Central America, including across the United States.
These moths, whose olfactory abilities are as good as a bloodhound's and vastly better than a human's, can fly up to 80 miles (130 km) a night searching for their favorite flowers such as the Sacred Datura.
The nectar of these fragrant white, trumpet-shaped flowers that bloom only once at night is an important food source for the moths, which pollinate the flowers.
Females also go to the flowers to lay eggs.
After hatching, the larvae eat the plant's leaves.
Scientists have wondered how pollinating insects such as these moths track down the flowers they need and whether competing odors - natural and manmade - can mess things up.
In a study published in the journal Science, University of Washington researchers placed the tobacco hornworn moths in a laboratory wind tunnel and exposed them to an array of odors such as car and truck exhaust fumes and fragrances of other plants.
Human sources of pollution fouled up their ability to find flowers and changed how the flower's scent was processed by olfactory neurons in the moth's brain.
'Pollinators like bees, butterflies and moths use their sense of smell to locate flowers from long distances, but we found that scent from neighboring vegetation, and even pollutants given off from vehicle exhaust, can disrupt the moth's behavior,' University of Washington biology professor Jeffrey Riffell said.
'Now for the moths that are flying long distances, they can't adequately smell the flowers and at times won't even know the flowers are there,' Riffell added.
'We really need to conduct more experiments to find out if these pollutants, or even certain plants, might similarly disrupt other pollinators, like honeybees, that are agriculturally important.'
The tobacco hornworm moth - a large, nocturnal insect with a wingspan of about 4 inches (10 cm) - ranges from Canada to Central America, including across the United States.
In the U.S. Southwest, their favored flower is the Sacred Datura, also known as angel's trumpets.
In a wind tunnel and a computer-controlled odor-stimulus system, the moths were tested to see how well they could distinguish different intensities of Sacred Datura fragrance, as well as mixes of background odors from other plants such as the creosote bushes that often grow nearby.
Researchers fear a similar effect could be happening with other key pollinators, such as the honeybee
The researchers also piped in chemicals such as those emitted in vehicle exhaust.
The researchers tracked the neuron pathways activated by placing an electrode into the moth's antennal lobe. The antennae serve as an insect's nose. The antennal lobe is the part of the brain that processes odors from the antennae.
The moths can zero in on flowers hundreds of yards (meters) away if there are not too many competing odors. Such odors mess with the balance of excitation and inhibition in the olfactory system, keeping the moths from recognizing the flowers.
'The total combination of dynamic odors, including floral signature odors as well as anthropogenic pollutants, can affect the success of olfactory-based resource finding,' University of Arizona researcher Leif Abrell added.
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