Severe pesticide resistance making spraying more and more ineffective? Experts teach you to use pesticides smartly

Farmers often feel that a certain pesticide was once very effective, so why does it become less and less effective the more they spray? The answer may be that "resistance" has developed. In fields across the country, severe resistance has already been found in pests such as red spider mites (spider mites) and diamondback moths. In recent years, the Bureau of Animal and Plant Health Inspection and Quarantine of the Council of Agriculture, the competent authority, has begun to focus on "resistance management," promoting the idea that farmers should use pesticides smartly to avoid resistance while also reducing costs.

The Department of Entomology of National Taiwan University held the "Resistance Management Strategy Workshop" on May 3 and 4 at the university's Yunlin Branch, inviting experts to share research results and attracting participation and exchange from industry, government, and academia. In his introduction, Feng Haidong, Director-General of the Bureau of Animal and Plant Health Inspection and Quarantine, stated clearly at the outset that the Council of Agriculture Chairman had called for a slogan of halving pesticide use in ten years. "As long as pesticides are used smartly, the amount used can be reduced, but the same effect can still be achieved," while also allowing these pesticides to maintain good control efficacy.

Otherwise, excessive or incorrect use of pesticides will instead lead to resistance, making pests impossible to control. "This not only causes production losses, but also brings many other risks, including health risks to consumers, harm to other members of the environment such as bees and earthworms, and finally risks for traders." For example, last year mangoes could not be exported to South Korea, which was a trade barrier caused by pesticide use.

Resistance causes pesticide companies to lose credibility and profits, but management is difficult to carry out

Since there are already many real cases of resistance in the field, should this information be made public so farmers know about it, so they do not continue buying ineffective pesticides, wasting money while also damaging the ecology and affecting their own health?

Lin Guanhua, a researcher at the Pingtung Agricultural Experiment Station of Daoli Company, pointed out, "This area of information is extremely lacking." He believes a basic framework should be established to collect field resistance conditions through various information sources and channels. For example, pesticide companies receiving farmer complaints that a certain pesticide is ineffective could also be a source; it need not necessarily be information published in formal academic journals. He hopes industry, government, and academia can integrate this.

Resistance easily leads farmers to increase pesticide dosage. What is the attitude of pesticide companies toward this? Several pesticide industry representatives at the scene acknowledged that currently only a limited number of pesticide companies conduct their own resistance monitoring. However, Zhang Xianyi, manager of Sumitomo Chemical Taiwan, said, "Resistance surveys are beneficial to us." The manufacturers' position is also that they hope to give this information to farmers. Otherwise, if farmers spend money unnecessarily on pesticides that are ineffective when used, "they will think your company's pesticides are no good, and then farmers will stop using them in the future," which also damages the company's credibility and reputation.

Lin Wenyi, product development manager at Bayer Taiwan, also added that for multinational manufacturers, their position is consistent with that of farmers: neither wants resistance to occur. This is because developing a new pesticide costs 10 billion, and registration in Taiwan takes as long as five years, so of course they do not want a new pesticide to quickly become ineffective after it comes out. Pesticide companies all have internal usage guidelines. "The problem is how to convey correct knowledge to grassroots farmers, and related demonstrations still need to be strengthened."

"Keanbo" is a vivid example of a pesticide that failed because of resistance. Xu Rujun said that in 2010 Keanbo was a very effective pesticide, but by 2013 it had failed, after being used for less than three years.

Experts said that resistance management is crucial to how long a pesticide product's sales period can be extended and will affect pesticide companies' interests. Therefore, large multinational companies or original compound development companies place great importance on resistance management. However, after the eight-year patent period ends, the market enters a red ocean, and many companies can produce it, but not every company is necessarily willing to do resistance management. If A does not sell it and B continues to sell it, then it is actually the one who does not sell it that suffers.

Lin Wenyi gave an example: a few years ago the company wanted to carry out resistance management and recalled all goods from pesticide stores once the farmers' period of use had passed. "But later we were scolded terribly by farmer friends, and small retailers also scolded us, and there were also a huge number of smuggled products outside."

Bureau of Animal and Plant Health Inspection and Quarantine: Mode of action will soon be labeled; pesticides are the last option for control

The Bureau of Animal and Plant Health Inspection and Quarantine also plans to put classification numbers for mode of action on pesticide labels to strengthen resistance management. Feng Haidong said the regulations will be announced this year. He also emphasized again, "Pesticides are not the only option; they should rank third." There should be at least two approaches ahead of them: first, reduce the occurrence of pests from the management side; second, first look for whether non-chemical pesticide control techniques can be used. Finally, when there is no choice but to use pesticides, low-risk and safe products should be chosen and used correctly, so as to reduce the occurrence of resistance and lower risks to products, human health, and the environment.

Note: For "Search for Classification and Mode of Action of Agricultural Pesticides," please click here

References:
"Guidelines for Pesticide Resistance Management": https://www.baphiq.gov.tw/files/web_articles_files/baphiq/16344/15763.pdf
Bureau of Animal and Plant Health Inspection and Quarantine "Crop Pest Resistance Section": https://www.baphiq.gov.tw/view.php?catid=16343
Insecticide Resistance Action Committee: http://www.irac-online.org/
Fungicide Resistance Action Committee http://www.frac.info/
Herbicide Resistance Action Committee http://www.hracglobal.com/
Rodenticide Resistance Action Committee http://www.rrac.info/