A neuropeptide named natalisin regulates the sexual activity and reproductive ability of insects, according to a new study in which the neuropeptide is observed and named Natalisin is composed of short chains of amino acids in the brain of insects and arthropods and the finding may open new possibilities for environmentally friendly pest management.
The study looked at natalisin in Drosophila melanogaster, Bombyx mori and Tribolium castaneum - fruit flies, red flour beetles and silk moths - to understand the patterns of natalisin expression and to assess the phenotype of natalisin RNAi. These insects have four life stages of development - egg, larva, pupa and adult - allowing scientists to observe the insects throughout the entirety of their life cycle to find what natalisin controls.
Natalisin is part of insects' and arthropods' peptidergic system -- a genetic network that uses small peptides as neurotransmitters to chemically relay messages throughout the body.
The researchers saw that in all three insects, natalisin was expressed in three to four pairs of neurons in the brain.
"Natalisin is unique to insects and arthropods and has evolved with them," said co-author Yoonseong Park, professor of entomology at Kansas State University. . "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."
Using RNA interference, or RNAi, the researchers looked at what happened when natalisin was silenced or knocked out from the insects' brains.
They found that the absence of natalisin in the brain led to the insects' physical inability to reproduce as well as reduced their interest in mating.
"For example, we saw that knocking out the natalisin in the fruit fly makes them unable to mate," Park said. "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."
Park said he anticipates this neuron knockdown will help scientists develop targeted control methods for pest insects that would be environmentally safe. Because natalisin is only found in insects, a future insecticide would not affect plants, animals or humans.
Additionally, Park said the finding is likely to benefit the scientific community. It sheds new light on how the brain functions with the neurosystem, and provides more information about the basic biology of the fruit fly, which is the model insect for research.
Citation: Hongbo Jiang, Ankhbayar Lkhagva, Ivana Daubnerová, Hyo-Seok Chae, Ladislav Šimo, Sung-Hwan Jung, Yeu-Kyung Yoon, Na-Rae Lee, Jae Young Seong, Dušan Žitňan, Yoonseong Park, and Young-Joon Kim, 'Natalisin, a tachykinin-like signaling system, regulates sexual activity and fecundity in insects', PNAS August 26, 2013, doi:10.1073/pnas.1310676110