For half a century, scientists have finally discovered that locusts swarm to become the culprit
Our reporter Lu Chengkuan
Locust plagues, droughts, and floods are also called the three natural disasters in the history of our country, which once caused serious agricultural and economic losses. On the 13th, the Chinese Academy of Sciences held a press conference to introduce a research result published in Nature by the recreational academician of the Institute of Zoology, Chinese Academy of Sciences, revealing the mystery of locust swarms. Researchers have identified the pheromone 4VA (4-vinyl anisole) of migratory locusts, which caused the locusts to swarm.
Migratory locusts are the most widely distributed locusts in the world. Our historical records show that large-scale locust plagues have occurred more than 800 times. From 2019 to June 2020, desert locusts broke out in East Africa and West Asia and spread to more than 20 countries and regions.
Although the locust plague has been accompanied by human development history for a long time, scientists have not been able to figure out the cause of the locust plague. In the past 80 years, there have been many hypotheses about how locust swarms are formed, such as food, breeding grounds, and cluster pheromone hypotheses, but which factor plays the main role and the mystery and mechanism have not been revealed in science.
In the 1970s, scientists gradually realized that clustering pheromones may be the most critical factor that causes locusts to gather. After more than 50 years of hard work, several compounds are considered to be the swarm pheromone of locusts. These pheromones are named locust alcohol, locust phenol, etc. However, none of these compounds can meet all the criteria for clustering pheromone, especially there is no evidence of field population verification.
The Kangle academician team analyzed the body surface and fecal volatiles of the gregarious and scattered migratory locusts, and identified a compound 4VA specifically volatilized by the gregarious locust among 35 compounds. Researchers have determined through a series of behavioral experiments that 4VA is very attractive to different developmental stages and genders of gregarious and scattered migratory locusts.
At the same time, among the four main sensor types on the antennae of migratory locusts, the researchers found that 4VA specifically caused a cone-shaped sensor response. Among the hundreds of olfactory receptors in locusts, they found that the olfactory receptor OR35 located in the cone sensilla is a specific receptor for 4VA. When OR35 was knocked out using gene editing technology CRISPR/Cas9, the neurophysiological response of the antennae and cone sensilla of the migratory locust mutant was significantly reduced, and the mutant also lost its response behavior and attractiveness to 4VA.
Although 4VA can attract and gather locusts in the laboratory, it is important to prove that it has the same effect in the natural environment. The researchers arranged the bait containing 4VA in the field, and through outdoor grass double selection and trapping experiments proved that 4VA has a strong attraction for laboratory populations outdoors. Furthermore, they deployed the lure core directly to Beidagang, Tianjin, an area where locusts occur in the wild. Large-scale block experiments once again proved that 4VA can not only attract wild populations, but also is not affected by the background density of locusts in the natural environment.
"For the first time, the study conducted comprehensive and sufficient identification and verification of migratory locust colony pheromone from multiple levels including chemical analysis, behavior verification, olfactory receptor identification, gene knockout, and field verification, and found and established that 4VA is a migratory locust swarm. Polypheromone, this research paradigm will improve the research of chemical ecology to a new stage." Kang Le said. This research is considered an important breakthrough in entomological research.
In this regard, the transparent reviewer, academician of the American Academy of Sciences, and Professor Leslie Voshall of the Rockefeller University in the United States stated in the review comments that this work has made exciting discoveries and found a long-term search. Locusts gather pheromone molecules. The article contains an astonishing multi-level research. I give unconditional support. This outstanding work should be published in the journal Nature without any delay.
Kangle said that this research not only reveals the mystery of locust colony, but also makes it possible to prevent and control locust green and sustainable. Research will change people’s concepts and methods for controlling locust plagues in many ways. For example, using synthetic pheromone can design trap belts to trap locusts, and use chemical pesticides or biological agents in the trap belts to eliminate them, thereby greatly Reduce the use of chemical pesticides; design antagonists based on the structure of 4VA to prevent the aggregation of locusts; the discovery of the olfactory receptor OR35 makes it possible to use gene editing technology to create mutants with a lack of 4VA response, which can be released into the wild for a long time It is possible to establish a population of locusts that cannot live in groups in the hardest-hit areas, which not only maintains a certain number of locusts in the wild, but also achieves the purpose of sustainable control, and organically combines environmental protection and pest control.
(Science and Technology Daily, Beijing, August 13)