Advances in bio-pesticides and reduction in chemical pesticide usage
Guizhou white tea farm using conventional pesticides. Image credit: Firsd Tea
China, the world’s leading producer of tea is reducing its dependence on chemical pesticides by adopting the use of safer, greener bio-pesticides. The strategy, which is showing success, has potential for the global tea industry. By Jason Walker
With 1.4 billion people and 128 million hectares of arable land, China faces the daunting task of producing nearly half of the world’s tea while also providing food security for 20 percent of the world’s population. The Peoples Republic of China has been able to attain its current level of success in part due to the application of pesticides and fertilisers. However, over reliance and misapplication of these agrochemicals has raised production costs, contributed to environmental pollution, and created instances of agricultural products with unacceptably high levels of chemical residues. Chinese officials have put a strategy in place that has already begun to curtail the over dependence on conventional agrochemicals by using bio-pesticides that are seen as safer alternatives.
China has become the world’s largest consumer of agrochemicals, at one time using about 30 percent of total fertilisers and pesticides. These pesticides include herbicides, insecticides, and fungicides. In order to combat agricultural production costs while also reducing environmental damage and impacts on human health, China initiated the “Action Plan to Realize Zero Growth in Pesticide Use by 2020” in 2015. Pesticide use in China peaked around 2014 and has been declining since 2016. As a result, goals for curbing growth in pesticide use were achieved ahead of schedule. In fact, some projections estimate that China may be able to completely eliminate its use of chemical pesticides by 2050.
When it comes to China’s tea industry, attaining chemical pesticide-free agriculture may be an especially important goal. About 60 percent of the world’s tea is grown by smallholders. China tea farms do not operate on the plantation models found in places like Sri Lanka and India, so smallholder farms of two hectares or less are very common. In fact, joint research from the Universities of Melbourne, Zhejiang, Fudan, Wuhan, and Stanford have found that smallholder farms in China tend to use agrochemicals less efficiently. This not only results in greater financial costs for the farmer, but also contributes to increased pollution of the soil and water.
China’s tea industry has likewise been shifting away from chemical pesticides towards bio-pesticides. Examples of bio-pesticides that are gaining more widespread use include:
- Beauveria bassiana: B. bassiana is a fungus that naturally occurs in soils and is a parasite in various insects. The spores enter the insect’s body and spread into a fungus, thereby killing the insect. B. bassiana is used against moths and caterpillars that feed on tea leaves. Current studies have not shown any harmful impacts of B. bassiana applications on animals or humans, so there are few regulations or MRL (maximum residue level) guidelines in place when it is properly used.
- Metarhizium anisopliae is another fungus-based insecticide found in soils around the world that is also parasitic in insects. M. anisopliae has been shown to be harmful to reptiles in some conditions. There are also a few regulations or MRL guidelines when M. anisopliae is properly applied.
- Pyrethrins are compounds found in chrysanthemum and have been known to kill or drive off insects since the Chinese began spreading chrysanthemum powders as a bug deterrent as far back as 1000 BC. Pyrethrins are considered safer insecticides when they are applied locally to tea and other crops because UV light and changes in pH break pyrethrins down into harmless chemicals within a relatively short time frame. Studies of variations of pyrethrin, including higher concentrations, exposure to synthetic pyrethroids (like cypermethrin) and pyrethrins combined with piperonyl butoxide (PBO) have shown potential harm to humans and animals. Effects included allergic reactions and potential carcinogenic effects. As such, pyrethrins are regulated and MRLs exist.
- Matrine is an insecticide derived from the Sophora flavescens plant that is native to various countries, including China, India, Japan, and Russia. Sophora flavescens is used in some Traditional Chinese Medicine (TCM) applications. Matrine breaks down relatively quickly in nature. It can be toxic to aquatic animals and should not be used during flowering in order to protect bees. Some MRLs (Maximum Residue Level) are in place for matrine in tea and in some botanicals.
China pesticide
consumption levels from 1991 to 2021. Graph credit: Frontiers in Plant Science (frontiersin.org)
Challenges to bio-pesticides
While bio-pesticides do offer a potentially safer, more sustainable alternative to harmful chemical pesticides, challenges do remain. One of the first of these challenges is cost. Some insecticides, like pyrethrins and matrine can begin to break down within days of application. This may make multiple applications necessary to sufficiently control a pest outbreak.
Successful chemical pesticides often have a track record of remaining active for longer periods of time. Access to, and consistent quality of bio-pesticides has also been a concern for researchers measuring the effectiveness of bio-pesticides on Chinese tea production. In some cases, bio-pesticides need to be combined with chemical pesticides to provide sufficient potency.
Bio-pesticides can also be combined with other green forms of pest control, including:
- Pheromone traps: These traps contain synthesised sex pheromones of targeted insects, thereby attracting and killing tea pests like moths and caterpillars. Pheromone traps have been studied on a small scale of tea production, but results have shown potential for combining pheromone traps with other pest control methods. Pheromone traps provide the benefit of targeting the intended insect without harming beneficial insects.
- Light traps: Seasonal use of light traps has also shown potential as a supporting practice of pest control. Solar-powered lights can be activated after sunset during the growing season to attract moths like the tea looper.
- Sticky traps: The placement of improved sticky traps after spring pruning was shown to capture leafhoppers while trapping fewer beneficial predators, like spiders and wasps.
- Traps and green pest control, along with the proper and timely application of bio-pesticides represent aspects of the pedestals of integrated pest management, namely prevention, monitoring, and intervention.
China’s advance towards reducing its dependence on chemical pesticides and adoption of safer, greener bio-pesticides shows potential for the tea industry at large. Smallholder tea farmers across the globe now have increased options to more efficiently use chemical pesticides while also testing better and safer bio-pesticides that benefit human health, the environment, and economic growth.
- Jason Walker is marketing director of Firsd Tea North America. Prior to his work with Firsd Tea, Walker served in a variety of roles in tea and beverage business capacities. His experience includes business services for small tea companies, a top-ranked online destination for tea consumer education and co-founding a coffee business. His insights draw upon his diverse range of experience in sales, operations and management in the tea world. He may be reached at: [email protected].
