August 29, 2013
Controlling Pests By Controlling Their Libido
Getting rid of pests is a farmer’s nightmare. You could spray and spray those chemical pesticides and those little buggers just keep coming. One of the reasons why common pest control methods aren’t always effective in keeping pests at bay is that insects can breed fast, and breed a lot. A single pair of mosquitoes having sex, for example, can breed thousands of young mosquitoes within weeks.
But, what if you could stop them from breeding too much? And what better way to stop them from having sex than to cut down their libido?
In a finding that could pave the way for an environmentally-friendly way to get rid of pests, scientists have identified a key protein that regulates sexual activity in insects.
The joint study by scientists in the US, South Korea and Slovakia observed the growth and life cycle of fruit flies, red flour beetles and silk moths.
The protein they discovered, called natalisin, is found in the brain of these insects and is part of a system of proteins that carry chemical signals in the body.
The researchers found that at least three pairs of neurons in the brain carry these proteins, particularly those in regions where the signals from different senses “converge.” This led them to think that perhaps natalisin could be involved with mating behavior, because flies need to rally all their senses and perform multiple actions in order to attract and seduce their mate.
To find out what role natalisin plays, they used a genetic technique called mRNA interference to knock out the gene that controls making of the protein. They found that the insects that didn’t have natalisin had reduced sex drive and were unable to reproduce.
The “copulation” rate for the male flies (i.e. the number of males that had sex with females) that didn’t have natalisin was only 10 percent compared to the 40-50 percent of those flies that had the protein.
“The male doesn’t send a strong enough signal to the female to get her attention. We’re not sure if that’s because the male can’t really smell her or because he is not developed enough to signal her,” Yoonseong Park, one of the authors of the paper is quoted as saying in the press release.
Females without natalisin also appeared to spend more time grooming themselves than letting the males get close enough to mate with them, and therefore producing less number of eggs.
The researchers believe that the newly-identified protein is similar to another brain protein called tachykinin found in a wide range of animals from frogs to humans (they call the two proteins “ancestral siblings” in the paper). Tachykinin is involved in expanding blood vessels and relaxing muscles as well as evoking behavioral responses.
The best part about natalisin is that the protein is found only in insects. Therefore, coming up with pest control methods that target the protein specifically (such as drugs that inhibit protein production), will not harm plants or animals, the researchers believe.
The finding also “sheds new light on how the brain functions” and “provides more information about the basic biology of the fruit fly, which is the model insect for research,” Park said in the release.
The study was published in the journal Proceedings of the National Academy of Sciences.
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