New study may help develop ways of killing harmful pests

Discovery that mammal breath causes aphids to flee plants could lead to natural pesticide.

The University of Haifa discovery that leaf-eating bugs, such as aphids, identify mammals that come to eat the plant on which they are sitting by sensing their breath, may be the first step in the development of an environmentally friendly form of insecticide.
Researchers in the lab of Prof. Moshe Inbar, Ph.D. student Moshe Gish and Prof. Amotz Dafni, published an article on their work in the journal Current Biology.
Insects that eat plants are often in danger of being swallowed by mistake when a mammal comes along for dinner and eats them along with the leaf or branch.
In a first-of-its kind study, the researchers wanted to know if the bugs have a specific mechanism that protects them from this.
They examined a type of tiny aphid that lives in colonies, sucks the liquid from plants and is regarded as a significant pest that preys on agricultural produce.
They studied a number of signs by which the aphids could reliably identify in real time the approach of a sheep, goat or other mammal.
Among them was movement of the branch, a sudden shadow or the mammal’s breath. They found that identifying the breath causes the whole colony of insects to fall immediately to the ground.
Using a system that simulates mammal breathing, they examined the specific elements in the breath that are used by the aphids to identify danger.
It turned out that the aphids did not identify specific volatile chemicals in the mammal’s breath. Instead, the combination of sudden air flow at a temperature and humidity level of the animal’s breath cause the aphid colony to abandon ship.
This falling is significant, because the insects then lose their exclusive source of food and have to walk to a new plant while facing the danger of dehydration, starving to death or being exposed to a predator on the ground. Thus quickly identifying the mammal with a high degree of accuracy is important to its survival.
Even though they are very small, aphids developed clever and efficient survival methods when they meet up with animals that are much larger than them, the University of Haifa researchers wrote.
Apparently, other insects use similar mechanisms that show that there is a complex interaction between mammals and plant-eating insects. The findings from the new study may help develop ways of killing off harmful pests, they concluded.