How do caterpillars recognize the scent of flowers?

The moths only need the essence of the scent of flowers to identify the flower, which is according to a recent study at the University of Arizona, Tucson.

Although the scent of a flower can be made up of hundreds of chemicals, a moth only needs a little bit to recognize the flower. It's almost like recognizing a piece of music, just listening to a few notes played by some of the main instruments, said researcher Jeffrey A. Riffell.

'Most moth species don't care about all chemicals at once. In fact, they usually only pay attention to a few typical substances. ' He continued. This finding opens a deeper look at how the brain can identify specific smells in hundreds of thousands of odors floating in the air.

The UA team recorded in the brains of tobacco-inhabited moths when they smelled only one of the 60 substances that made up the fragrance in the honey that caterpillars liked.

This is the first time researchers have documented the activity of insect brains when they smell all of the odors separately from natural flowers. Previous studies often used only artificial odors. Only nine of them stimulate nerve endings. However, all of these nine must be given at the same time so that these moths fly in and ignite their noses.

Riffell, Hong Lei and John G. Hildebrand of UA's Arizona Research Laboratory and Thomas A. Christensen from UA Language Studies have published their paper on the subject 'Describe and decode important odor compounds 'in today's Biology magazine.

The National Institute of Health and Science Research has funded this research program. How the brain's functioning system can decode odor compounds cannot be understood most clearly.

'Two-thirds of male moths are more environmentally sensitive. As for caterpillars, the ratio is about 90%, ' said Riffell.

The moths of tobacco plants, Manduca sexta, are searching for bile from a paper flower that is scoured by some fancy scent chemicals, from the flowers of sacred Datura. (Photo: Charles Hedgcock RBP)

Tobacco caterpillars, Manduca sexta, are the major moths in the Southwest. Their favorite honey source is the poisonous flower, known as Datura wrightii. Flowers with white trumpet-shaped flowers only bloom in the middle of the night. Female moths lay their eggs in the tree, so that if things are easier, the team only uses male moths for this study.

To search for food, moths must be aware of a flow of poisonous lilac flowers and then trace the scent to the flower.

Riffell showed how to know which chemicals are emitted from flowers and take them to the lab.

He put a flower in a Reynolds® Oven bag and sucked the air out of the bag through a filter to retain the scent. He took the scent that way from 20 different tree species.

Returning to the lab, he gave a solution to the chemicals and injected it into the gas chromatogram. This chromatogram divides the chemicals and sprayes each odor into branched tubes: one branch is taken to a wire caterpillar and the other to a machine to be identified and recorded by individual odors. especially when these smells are released.

The installation has allowed researchers to record activity in the caterpillars' brains as they smell distinct odors. This recording device is hooked to a speaker. If the caterpillar's brain works, the researcher will hear pop-pop sounds, Riffekk said.

'Then you look and see what smell is coming at that time. The caterpillar's brain only reacts to the nine chemicals that come from the daisy flower bouquet, ' he continued.

In order to observe how caterpillars react to these chemicals, he has put artificial substances with such odors on a bouquet of artificial flowers made from white paper. Then he experimented with 420 caterpillars by placing confetti at the end of the wind pipe and a caterpillar on the other end. Other moths are indifferent to this chemical when the same chemicals are given at once. Conversely, if the real lilac is used, these moths immediately fly to and ignite their bile to suck the bile.

When all nine chemicals that affect the brain of caterpillars are placed on confetti, these moths also act in the same way.

'It's amazing - as soon as you combine these substances together, the caterpillars act like drunkards. Rush straight to the flower and spark their flowers into that flower. ' Riffell said.

He suspects that human sense of smell and brain can also work by directing only certain chemical smells into specific smells.