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Sex pheromone pest control works great, but it's expensive, in short supply, and hard to import; the reason it can't be made in Taiwan, China, exposed

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Sex pheromone pest control works great, so why is it expensive and out of stock? The reason it's hard to import yet can't be made in Taiwan, China, exposed

A few days ago, Chiayi farmer Guo Mingxian posted a cautionary message on Facebook titled "Insects can't go too far," complaining that the insect army was running rampant, picking only the tender shoots to eat. "I suggest you show some restraint. Wait until the corn grows up and I'll share some with you. Otherwise, I'll report you to the authorities and show no more leniency."

Of the 15 hectares of farmland Guo Mingxian rents, half of the corn seedlings were destroyed by tobacco cutworms and fall armyworms. The seedlings, less than 30 cm tall, were either bitten off at the roots or had their growing points gnawed and left in tatters, leaving him no choice but to plow everything under and replant. The pests cost him several hundred thousand yuan, but that wasn't even the worst of it. "I can no longer supply Leezen and the Homemakers Union, and I don't know how long the shortage will last?" His own corn processed products also came to a halt, and failing his customers left him deeply ashamed.

"I won't cut corners. Killing them off would be easy, but that goes against what I set out to do," Guo Mingxian said. He doesn't use chemical pesticides, and natural disasters and pest outbreaks are risks he expected. The reason he posted his complaint this time was really that he had lost his biological weapon against the insect army: sex pheromones.

Watching the corn in his fields being devoured by the insect army, Guo Mingxian suffered in silence. (Photo / Yang Yuyun)

Usable in both organic and conventional farming, sex pheromones work best when paired with Bacillus thuringiensis

Sex pheromones are a type of attractant. They use the scent released by female insects to lure and kill males. With fewer males in the field, females cannot mate, which naturally achieves pest control. Moreover, this method is not limited to organic growers; conventional farmers can also use it alongside other methods to reduce the dosage of chemical pesticides.

Lin Meifang, a farmer in Fuxing, Changhua, grows winter melons using conventional farming methods. Before using melon fly attractant, she had to spray pesticides about once every three days. After using it, she only needed to spray pesticides twice during the flowering period. "The effect is truly astonishing," she said.

At the same time, sex pheromones can also be used to monitor insect density in the field. Guo Mingxian places pheromone insect traps every 30 m in his fields. About six or seven days after adult numbers increase, they will lay eggs and those eggs will hatch. Applying Bacillus thuringiensis at that point gives the best effect.

An insect trap is placed every 30 m, containing a sex pheromone attractant that lures male insects. (Photo / Yang Yuyun)

Guo Mingxian said his fields are large, but once Bacillus thuringiensis is exposed to sunlight it breaks down easily and its effectiveness drops sharply, so it must be applied accurately, otherwise it is simply wasted. Sex pheromones and Bacillus thuringiensis complement each other, like his traps and ammunition. Without traps, ammunition can only be fired blindly, and the effect is naturally poor.

However, over the past few years, the price of tobacco cutworm pheromone has multiplied several times. In the past, it was put in thin plastic tubes and cost only 10 yuan per dose. Guo Mingxian bought in bulk, and the price could drop to 6 yuan. But now it has been changed to a 2-gram squeeze-tube package, enough for only 20 insect traps, yet it costs as much as 400 yuan, meaning the cost has increased more than threefold.

Lin Meifang has also felt the price increase. She said the plastic-tube melon fly attractant sold on the market costs only 5 yuan, but one squeeze tube costs 280 yuan and contains only the amount of ten plastic tubes, more than a fivefold price increase.

Fall armyworm and sweet potato weevil pheromones out of stock

If pheromones had only gone up in price, farmers could still bear it, but fall armyworm pheromone cannot be bought at all. "I heard the government is controlling it, but who knows where that control has gone?" Guo Mingxian said that last year he found fall armyworms in a small plot of corn. At the time, the Bureau of Animal and Plant Health Inspection and Quarantine came to the field in force and placed a pheromone insect trap, saying it was to monitor control effectiveness. "A year has passed, and not a single person has ever come back to check!" He was both helpless and angry.

The sweet potato weevil pheromone is also out of stock. Cai Youcai, who grows sweet potatoes in Xiangshan, Hsinchu, said biological control cannot achieve a 100 percent effect, but pheromones solved 90 percent of the problem and do not leave harm behind in the field. However, about a year ago, Chaoyang University of Technology, which supplied him with sweet potato weevil pheromone, could no longer continue supplying it for free because its field research had ended, and it could not sell it either. "I don't know what regulations it's stuck on. It's clearly a good thing. Shouldn't the government overcome the difficulties and help farmers and schools?" Cai Youcai's tone was full of incomprehension.

Caught in the act while chewing corn leaves: fall armyworm (Photo / Yang Yuyun)

Academia has the ability to manufacture, but regulations restrict commercialization

Cai Youcai's doubts indeed point to the bottleneck currently facing academia. Zeng Ruichang, director of the Pheromone Center at Chaoyang University of Technology, said that under the Pesticide Management Act, sex pheromones are classified as biological pesticides. Leaving aside that educational institutions cannot engage in business activities, even if a university wanted to sell sex pheromones, it would need to register for a pesticide factory license and obtain a sales permit. Various administrative regulations have constrained the channels through which academic institutions can assist farmers.

Domestic academic institutions have a long history of research on biological control. Taking Chaoyang University of Technology as an example, the school established its Pheromone Center as early as 12 years ago. It has now developed more than 20 sex pheromone formulations, respectively targeting common lepidopteran pests in the field, such as various diamondback moths, or coleopteran pests, such as the sweet potato weevil, for trapping and killing, while also making it possible to confirm insect density in the field and apply organic pesticides accurately.

Zeng Ruichang said pheromones target flying adults, while microbial preparations target larvae crawling in the field, "like a two-pronged attack from the air force and the army." But this land-and-air battle only keeps insect numbers under control; it does not wipe them out completely. Therefore it can maintain ecological balance and does not burden the environment. It is a very friendly pest management technique.

However, according to Zeng Ruichang's observations, in recent years the government's pace of commercializing pheromone technology seems to have slowed. By contrast, microbial control has become the main force, which may also be seen in government policies subsidizing materials such as Bacillus thuringiensis. Although Chaoyang University of Technology has developed 20 pheromone formulations, due to regulatory restrictions most of these formulations remain in "research reports." Only after technology transfer and a lengthy pesticide registration process can they barely become commercial products in the future.

Zeng Ruichang, director of the Pheromone Center at Chaoyang University of Technology (Photo / Yang Yuyun)

The new microcapsule paste formulation is long-lasting and not more expensive, but importing the technical material really is difficult

In fact, Taiwan, China's pheromone manufacturing technology is very mature. In the past, pheromones were injected into plastic tubes with a syringe, and both ends were sealed. When farmers used them, they only needed to cut open the seal and place it in an insect trap. After the pheromone was released, it could lure insects. But because the tubing easily causes pollution, the Chaoyang University of Technology team used "microcapsule" chemical technology to coat the pheromone inside capsules. By adjusting the thickness of the capsules, they control the efficiency and timing of pheromone release, the so-called "slow-release" effect.

In 2014, Chaoyang University of Technology had already transferred the tobacco cutworm pheromone microcapsule paste formulation technology to Chung Hsi Chemical. It only passed pesticide sales registration in 2018. In the past, plastic tubes lasted only one month, but the slow-release microcapsule paste formulation lasts as long as two months.

Hua Guoxun, a specialist at Chung Hsi Chemical, said that although a 2-gram squeeze-tube paste of tobacco cutworm pheromone can only treat 20 insect traps, it can last two months, equivalent to 40 plastic tubes. The cost is also 10 yuan per trap per month. If calculated at 600 yuan for a 4-gram paste, it is only 7.5 yuan per trap per month, so it is not more expensive, and it can also reduce the generation of plastic tube waste.

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