Chinese scientists have deciphered the smell code of insects, opening a new chapter in the prevention and control of agricultural pests

How do insects sense smell in the eyes of biologists? And how does it behave? It has become an important topic in the study of insect chemical ecology. Wang Guirong and his team have been working on the functional identification of insect olfactory receptors, which is simply to find odor molecules that regulate insect behavior. However, there are thousands of odor molecules, and finding a key receptor for a specific behavioral response is undoubtedly a needle in a haystack. After more than ten years of research, Wang Guirong and his team have found a high-throughput method. A green and efficient regulator of insect olfactory behavior was successfully screened.

Recently, Wang Guirong's team from the Shenzhen Institute of Agricultural Genomics of the Chinese Academy of Agricultural Sciences, together with Huazhong Agricultural University and the Institute of Plant Protection of the Chinese Academy of Agricultural Sciences, successfully revealed the fine structure of insect odor receptor complex and analyzed the interaction mechanism between odor receptor and ligand. The deciphering of the olfactory "code" of insects has laid the foundation for the research and development of new insect green pesticides. The paper was published on June 14 in the international journal Science.

For insects, smell is the way they live. Insects rely on a sensitive sense of smell to sense chemical signals in the environment. Insects have a very sensitive sense of smell, which can directly provide "navigation" for their foraging, courtship, spawning and other behaviors. In the process of olfactory recognition, odor receptors (OR) play a central role, which can be activated to convert external chemical signals into bioelectrical signals, thereby mediating the corresponding behavioral responses of insects.

The alarm pheromone receptor is one of them, and studies have found that most aphids release small droplets containing the alarm pheromone ((E)-β-farnesene (EBF) from their abdominal tubes when they are attacked by natural enemies or other dangers, "warning" neighboring aphids to quickly escape or fall. In the previous work, Wang Guirong's team successfully revealed a new mechanism of aphid's alarm pheromone recognition, and further clarified the internal mechanism of how the alarm pheromone cleverly regulates the accurate location of aphids by natural enemies, providing a new perspective for understanding the interaction between insects. These findings demonstrate the great potential of EBF and its analogues as regulators of insect behavior.

Wang Guirong said various crop diseases and pests that occur every year pose a serious threat to food security. The application of insect olfactory behavior regulators is a globally recognized green control technology, which has the advantages of high biological sensitivity, strong selectivity and environmental friendliness, and can achieve long-term pest control. Therefore, the development of green biopesticides based on the characteristics of insect olfactory regulation has become an important research direction at present, and clarifying the molecular regulatory mechanism of insect olfactory is an important basis for this research.

In this study, with the help of cutting-edge cryo-electron microscopy technology, the structural characteristics of ApOR5-Orco complex of alarm pheromone receptor of pea aphid were deeply investigated, and its high-resolution cryo-electron microscopy structure was analyzed in ligand-bound and unbound states. At the same time, the molecular mechanism of insect odor recognition channel gating is revealed. Wang Guirong pointed out that this discovery provides a valuable molecular basis for the screening of lead compounds based on the target structure, and opens up a new way for the creation of efficient and specific green insect behavior regulators.

Kangle, an academician of the Chinese Academy of Sciences, believes that this study has laid a theoretical foundation for the high-throughput screening of pesticides and repellents based on structural biology, which will strongly promote the development of new products for green pest control and provide support for achieving a safe, green and sustainable agricultural production model.

Song Baoan, academician of the Chinese Academy of Engineering, said that this is a major breakthrough in the research field of insect olfactory coding mechanism, which significantly enhances China's core competitiveness in the research field of insect behavior regulators. The creation of targeted small molecule green pesticides is an international frontier research topic and a major national strategic demand. This research has laid a theoretical foundation for the development of insect behavior regulators, and is expected to give rise to a number of green and efficient new products for insect behavior regulation.