Chemical Screams and Faulty Intelligence

When plants are bitten, they emit a “chemical scream”, writes Ed Yong. That means they emit chemicals in the air that do one or more of the following:

1. Confuse or repel the pests;
2. Attract wasps or other insects that would attack the predator!
3. Signal other parts of the same plant to ramp up defenses.

Sometimes, these signals can spread across entire fields warning other plants in the vicinity. Neat, right?

But wait, it gets even more fascinating. The silverleaf whitefly can “hack this communication system”! Somehow, in ways not yet understood:

1. They change the warning signal of the plant to convey the wrong type of threat (microbial v insect).
2. Even better (or worse, depending on whether you are pest or plant), this “faulty intelligence” can then make the plant “more susceptible to the whiteflies”.
3. And since, as mentioned at the top, the signal percolates to the entire field of plants, the entire field is now ripe for the picking. The field in this misinformed state allows whitefly to grow “faster than they would have on plants that had received no warnings at all”.

All this would explain why the silverleaf whitefly is so devastating in its invasions.

So what’s next in this war? Who can say, but humans as farmers are on the side of the plants. Ergo, humans are building machines that “eavesdrop on the chemical alarms of plants, warning farmers of infestations in real time”.

And then there are particular wasps that feed on these whiteflies. They home in on the chemicals released by the infected plants to attack the whiteflies:

“The whiteflies can fool their hosts, and the neighbors of their hosts, but they can’t fool the wasp.”

And so round and round we go in these evolutionary battles.