How to Stop Insects from Having Sex: Lower Neuropeptide Levels in Their Brains

Want to stop insects from breeding? There may be a new way to do so. Scientists have identified a neuropeptide named natalisin that decreases the desire for sexual activity in pest insects. 

The neuropeptide itself is composed of short chains of amino acids in the brains of insects and arthropods. Natalisin is actually part of these creatures' peptidergic system, a genetic network that uses small peptides as neurotransmitters to chemically relay messages throughout the body.

In order to better understand natalisin, the researchers looked at the neuropeptide in fruit flies, red flour beetles and silk moths. These insects all have four life stages of development--egg, larva, pup and adult. This allowed the researchers to examine the insects throughout the entirety of their life cycle to find out what natalisin might control.

"Natalisin is unique to insects and arthropods and has evolved with them," said Yoonseong Park, one of the researchers, in a news release. "It appears to be related to a neuropeptide called tachykinin that is in mammals and invertebrates. While tachykinin is involved with various biological processes, including the control of blood flow in mammals, natalisin is linked to reproductive function and mating behavior in insects and arthropods."

In the end, the researchers discovered that in all three insects, natalisin was expressed in three to four pairs of neurons in the brain. They then used a tool called RNA interference (RNAi) in order to see what would happen when natalisin was silenced or knocked out from the insects' brains. They found out that the absence of natalisin actually led to the insects' physical inability to reproduce as well.

"For example, we saw that knocking out the natalisin in the fruit fly makes them unable to mate," said Park. "The female is too busy grooming her body for the male to approach her. 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."

The findings could help researchers develop better methods to control pest insects in the future. In addition, it could lead to more environmentally safe methods to do so. Since natalisin is only found in insects, future control applications would not affect plants, animals or humans.

The findings are published in the journal Proceedings of the National Academy of Sciences.