Froghoppers Can Generate Extremely Negative Pressures, Making Them the Animal World's Super-Suckers

A new study recently showed that Philaenus spumarius froghoppers are piercing plants using their mouthparts to feed exclusively on xylem sap, a fluid made mostly of water that moves through the internal plumbing of plants.

A ScienceNews report specified that insects tiny enough to sit on an eraser of a pencil have to suck harder than any known creature to tap an unlikely nutrition source.

Not only is the substance greatly bereft of nutrients, but it's under negative pressures as well, akin to a vacuum. Sucking the sap needs suction power equivalent to human drinking water for 100-meter-long straw.

Such a feat, as indicated in this report, appeared so unlikely for the small insects that some scientists questioned whether xylem sap truly "could be under such negative pressures."

However, both biomedical and metabolic evidence suggest that froghoppers can produce negative pressures greater than one megapascal, the study authors said.

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Generating Extreme Negative Pressures

According to biochemist Jake Socha, at Virginia Tech in Blacksburg, who was not part of the work, it is incredibly impressive. The researchers used an array of methods to tackle a long-standing problem. He added these insects are well-update for producing extreme negative pressures.

The problem, this research indicated, is long-standing since the measurement of negative pressure is tricky. Within xylem, sap pulled like a string, caught in a tug-of-war between airy leaves and spongy oil.

Piercing the plant with pressure probes can break that international tension, and thus, scientists usually use a more indirect approach.

A similar Dawson County Journal report said, cutting off part of a plant and having the leafy end stuck in a pressure chamber with the steam sticking out, the study authors can turn up the pressure put on the outside of the plant until it just exceeds the internal pressure of the plant and xylem sap can exceed one megapascal.

Froghoppers' Suction Power

Those small froghoppers and other insects feed on xylem sap has strengthened skepticism about these measurements, explained comparative psychologist Philip Matthews at the University of British Columbia in Vancouver.

For instance, elephants only produced 0.02 megapascals of negative pressure when they suck huge quantities of water through their trunks, paltry compared with froghoppers.

Some researchers think it is just too energetically costly to extract this stuff, that [xylem pressures cannot be that adverse. It has to be easy to extract, explained Matthews if froghoppers will survive on something quite dilute.

Matthews and colleagues, doubtful of skeptics, sought to measure the sucking abilities of froghoppers through two methods, including the biomechanical and metabolic approaches.

Essentially, froghoppers produce suction power with a structure similar to a pump in their heads, where muscles pull on a membrane to produce negative pressures similar to a piston.

Through the use of micro-CT scans of four insects, the scientists measured the length and strength capacity of such structures and then calculated the sucking potential of the insects through the use of the simple physical formula of pressure equals force divided by area.

Clearly, based on the calculations, the froghoppers can generate the tensions, so they must be feeding at xylem tensions around this level, explained Matthews. He added one would not evolve such a massive capacity unless he were using it.

Spike in Metabolic Rate by Up to 85%

The team validated this more abstract approximation by calculating the amount of energy froghoppers are expending while sucking on pea, bean, or alfalfa plants.

That particular energy needs to be proportional to the pressures that the insects need to overcome in plants. By placing feeding froghoppers in chambers measuring expelled carbon dioxide, scientists could compute the metabolic rate of the insects. The research team used cameras as well to track the amount of liquid the bugs excreted.

Once froghoppers begin to suck, their metabolic rate spiked by up to 85 percent from resting rates, and the insects excreted more than when they were at rest.

The study, The cibarial pump of the xylem-feeding froghopper Philaenus spumarius, produces negative pressures exceeding 1 MPa, published in the Proceedings of the Royal Society B.

Related information about froghoppers is shown on Cuckoo54's YouTube video below: