As the saying goes, a mother knows her child best, and that applies to insects as well. The female adult is very picky about her choice of spawning place and always lays her eggs in a safe and favorable place for the development of her offspring. Because of the limited activity of many insects in the larval stage, the oviposition selection of adults is more important for the reproduction of their offspring. It is well known that there is a pair of “noses” – antennae on the head of insects. Insects use it to find hosts, identify mates, and avoid natural enemies. But surprisingly, scientists from the Institute of zoology, Chinese Academy of Sciences, recently discovered that the tail of a moth actually has the function of “nose”. This moth, tobacco budworm, is an important agricultural pest in China. In order to ensure that their offspring can grow up in a suitable environment, the female moths have double insurance. In addition to having a pair of antennae to feel the smell, they also use the ovipositor at the end of the abdomen to smell the plant smell, and accurately locate the eggs in the right place. For a long time, the research focus of insect olfactory experts has focused on the antennae of insect olfactory organs. The olfactory hairs on the antennae are used to sense the smell of insects. There are two olfactory sensory neurons (OSNs) in each hair. Olfactory receptors (ORS) and costimulatory receptors (orco) are co expressed in the dendrites of these neurons, which play an important role in olfactory perception. It is generally believed that insects find their hosts under the guidance of antennae input signals, and then lay their eggs on or near the host by means of ovipositors at the ventral end. The team led by Wang chenzhu, a researcher at the Institute of zoology, has been studying the olfactory and gustatory mechanisms of important agricultural pests in China for a long time. Helicoverpa armigera and Helicoverpa assulta are closely related species, but the host range is very different. The Helicoverpa armigera can feed on more than 300 plants of 68 families, while the Helicoverpa assulta only feeds on a few plants of Solanaceae, such as tobacco and pepper. How to find the host plant accurately and lay eggs? This is the question they’ve been trying to answer recently. Previously, their work mainly focused on the study of antennae. < / P > < p > in transcriptome studies on two species of insects, scientists unexpectedly found that an odor receptor or31 was highly expressed in the ovipositor of Helicoverpa assulta, which was much higher than that in the antennae of Helicoverpa armigera, but not in Helicoverpa armigera. They began to wonder what the odorant receptor was doing, wondering if the ovipositor could also “smell” odors. Therefore, they first confirmed whether or not or31 was co expressed with orco in ovipositors. Using two-color in situ hybridization, they found that or31 and orco were co expressed in ovipositor cells, which had the molecular structure of olfactory function. < / P > < p > then, what are the odorants tuned by or31? They then co expressed or31 and orco in Xenopus laevis oocytes. Combined with double electrode voltage clamp technique, they screened out 12 ligand compounds that could cause cell current changes, among which z-3-hexenyl butyrate was the most effective. < p > < p > by scanning electron microscopy, they found that the ovipositors of moths had structures similar to hair like sensilla on the antennae. In addition to a apical pore, there were many micropores on the wall of the ovipositors, which confirmed that these sensilla not only provided taste sense, but also had olfactory function. Furthermore, the single sensilla recording technique was used to confirm that these ligands could induce electrophysiological responses of some trichosensilla on ovipositor. < p > < p > to verify that the olfactory function of antennae is not only used in the oviposition process of female moths, the researchers treated the oviposition medium with the smell of pepper, and compared the oviposition selection response of female moths with antenna excision and normal female moths. The results showed that the female moths with antennae removed still preferred to oviposit on the medium with pepper smell, although the preference index was significantly lower than that of normal female moths. In the other oviposition selection experiment, cis-3-hexene butyrate was directly used to treat the oviposition medium. It was found that both female moths with antennae removed and normal females preferred to lay eggs on it, and there was no difference in preference index between the two. This indicated that the antennae and ovipositor were used simultaneously when the female moths felt the odor mixture of the host plants, but it seemed that the ovipositor controlled the sensation of cis-3-hexene-butyrate. Based on the above results, the researchers believe that or31 expressed in ovipositor has olfactory function, which can help tobacco budworm to accurately locate its oviposition on a few host plants. It is very important to understand the olfactory system of animals in both basic biology and practical application. This work breaks through the limitations of people’s traditional understanding of smell, and will also inspire neurobiologists to explore olfactory pathways beyond the head organs of animals. Tobacco budworm is a kind of oligophagous insect that only damages tobacco and pepper. The research findings not only help us understand the evolution of host range of herbivorous insects, but also provide new ideas for agricultural entomologists to control pests.