Sharpshooter Insects’ Sexy Vibrations Spell Trouble in the Vineyard – KQED

The complete details arent sorted out, said UC Berkeley plant pathologist Rodrigo Almeida, but it kills the plant sort of by dehydration.

Known as Pierces disease, this infection costs California more than $100 million each year in lost grapevines and efforts to combat it, according to a 2014 report. In Napa and Sonoma valleys and along the coast, the most recent outbreak of Pierces disease which started in 2013 and is just starting to wane caused some vineyards to lose 50% to 60% of their grapevines, said Monica Cooper, a University of California farm adviser based in Napa.

Different types of sharpshooters transmit Pierces disease in different parts of the state. In Napa and Sonoma and on the coast, the native blue-green sharpshooter is the main culprit. In Southern California and the San Joaquin Valley, the invasive glassy-winged sharpshooter a larger red and brown insect spreads the disease.

To keep down sharpshooter populations, growers spray vines with pesticides or with a clay that discourages the insects from feeding and laying eggs. When spraying insecticides isnt possible, such as in residential areas and on organic farms, a tiny insect is released that lays its eggs inside the sharpshooters eggs and kills them. And because blue-green sharpshooters spend the winter feeding on vegetation along rivers and creeks, pulling out invasive plants like the Himalayan blackberry along the Napa River has also helped keep their populations down, Cooper said.

Krugner has been researching a different approach. He has found a way to turn sharpshooters sexual habits against them to dissuade them from reproducing.

Sharpshooters vibrate their abdominal muscles to call out to potential mates on grapevines.

While other insects, such as cicadas, have air sacs that help them communicate, sharpshooters use their entire bodies as noisemakers.

Insects arent one solid piece, Krugner said. The source of the signal is the muscles. Once they vibrate the muscles, the exoskeleton moves. Every tiny bit moves.

The sharpshooters vibrations travel down to the roots and from one vine to another.

Normally, humans cant hear any of these shenanigans. But Krugner can point a laser beam at a grapevine where sharpshooters are calling out and amplify their vibrations using a computer.

When he plays back the vibrations as sound waves, a raucous concert comes alive. Blue-green sharpshooters calls sound like howling monkeys or clucking chickens. Glassy-winged sharpshooters make a sound more like revving engines.

Male and female sharpshooters first call out to identify a potential mate of their same species. Once a related male and female are on the same plant, they play a version of the Marco Polo game to find each other thats how they make up for the fact that they dont see very well. When theyre finally near each other, they perform a courtship call, then join their rear ends and copulate for two to four hours, depending on the species.

Krugner observed that if several female sharpshooters were seeking a mate, one of them would sing longer and stronger and establish herself as the dominant female. All the other females quieted down and only the dominant one mated with the male. He saw the potential to use this information to halt reproduction in the grapevine by confusing insects out searching for action. He played back a recording of a dominant females call throughout vineyard rows by vibrating a metallic electromagnetic shaker he hung from a trellis. This made the grapevines vibrate and broadcast the fake females call to the insects.

I thought Im going to be the dominant female out there. That way I can just shut up all the real ones on the vine, Krugner said. And sure enough, thats what happened.

The males ignored the real female sharpshooters on the grapevine and ended up not mating at all.

Krugners mating-disruption electromagnetic shaker, which he developed using glassy-winged sharpshooters as his model, is still in the prototype phase and hasnt been adopted by growers yet. But he sees a lot of potential. His idea is to make it possible for a grower to play back the calls of several different pests they want to control.

It would be like iTunes, he said.

In addition to studying sharpshooters and a related pest, the variegated leafhopper, Krugner is also investigating the vibrations that black widow spiders make on their spider webs to keep other black widows away. These arachnids can live on table grapes and be mistakenly packed in with the fruit when its harvested into plastic bags.

Theres a number of other pests of grapevines that use vibrational communication, and if Im using my shakers out there, why not hit them all? Krugner said. But to hit them, you need to know what theyre saying to each other.

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Sharpshooter Insects' Sexy Vibrations Spell Trouble in the Vineyard - KQED

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