Pheromone and Pest Control
In 1960, Morton Beroza, a chemist from the USDA, suggested using sex pheromones to paralyze long-range mating communication systems for pests. He discussed in detail that if agricultural areas set up many information sources that emit insect pheromones, some and even most male pests will only gather at those fake information sources. If this is the case, then these male pests will not be able to mate with female pests and produce offspring of such pests.
In 1967, Harry Shorey, an entomologist from the University of California, followed Porozza’s research direction and first demonstrated that pheromones can be used to interrupt the mating of an insect. At that time, the experiment subject of pheromone was cabbage butterfly. But it is not clear how these pheromones work. Researchers speculate that in practice, large doses of pheromones can not only confuse male insects, but also camouflage them as female pheromone divergent sources and cause some male insects to ignore all pheromone divergent sources.
The method of mating disruption has now become a technology that benefits farmers. These farmers have suffered heavy losses due to pests, because those pests are already immune to many types of pesticides. In Mexico, where about half of the tomatoes consumed in the United States are grown there, tomato pinworms have destroyed nearly half of the harvest in a year. Growers began to set tomato pinworm sex pheromones in tomato fields. These pheromones were spread through plastic pipes tied to tree stumps, tomato stems and plants. According to research statistics, only about 4% of female tomato pinworm were able to mate with male tomato pinworm in this situation. In contrast, about 50% of female tomato pinworm successfully mated in fields where no pheromone distribution source was set nearby. It can be seen that the effect of pheromone on mating interruption is very obvious.
Pheromones can also be used as bait for pest traps. In 1980, large-scale capture of bark beetles in the devastating beetle disaster saved large areas of forests in Norway and Sweden. Researchers use pheromones as bait to spread disease to target pests, which can cause them to become infertile. After being temporarily captured, these pests are released to infect other pests.
Farmers also use pheromones to help detect when pesticides should be spread on crops. For example, in order to effectively defend against small apple moths, farmers must spread pesticides at critical times after the caterpillar stage of the pest. Researchers have developed a sticky trap for cydia pomonella whose bait is the pheromone of the moth. Farmers check those traps in orchards every day and detect peaks in moth populations. If this number reaches a certain standard, it means that the moth’s eggs have reached the peak of hatching, and farmers will spread pesticides in the orchard, so that the pesticide will kill the largest number of newly hatched pest caterpillars. Some farmers also use pheromone to monitor traps, and only spread pesticides when the number of pests is close to the level of harm to the crop, thereby reducing the environmental harm of pesticides.
Future research will make pheromones more widely used in pest control. Researchers have also discovered the neurological principles of pheromone-stimulating insect responses and the secrets of the enzymes that insects use to stop pheromone to cut off certain biological signals. Researchers are still studying how insects produce pheromones, how they respond, and exactly what affects them to do so. For example, researchers are now beginning to unravel the secrets of hormone-induced pheromone production and the complex proteins that bind pheromone to its receptor. These fascinating basic studies will lead to a new design of molecules that affect insects’ response to pheromones, as well as better ways to use pheromone or other compounds to control pests.