New pests infest highland farmer’s crops and vegetables

New pests infesting greenhouse vegetables in Laya

With vegetable and crops infested by pests, the communities of Laya are concerned of food security

Sangay Rabten from Thimphu

Introduction of greenhouse vegetable plantation had once instilled hope to the farmers of Laya.

Foreseeing a bright future, the farmers of the community dreamt of better yields of vegetables which would add variety and spice to their culinary habits.

Tshoki, 31, from Nyelu was excited to take up greenhouse vegetable farming. Initially, she could harvest a good quantity of organic vegetables for the first time in the history of Laya.

However, Tshoki and other farmers are beginning to feel the effects of climate change and its impact on their vegetable yields.

Climate change has affected millions of farmers across the globe and Bhutan is no exception. The dynamics of crop diseases and pest influx are changing rapidly due to changing climate.

The common pests that once infested the lowland areas have today started to infect plants of the highlands. Agriculture scientists claim that managing them has, therefore, become a huge challenge in the country.

Laya is located in the northwestern part of the country at an altitude of 3,800 meters above sea level in Gasa dzongkhag. Inhabited by about 1,108 ethnic people known as Layaps, this pocket of the region is indeed a treasure trove of culture and ethnicity.

Though the primary source of food and income of these nomads are from the yaks, wheat is also the main staple food of them. Few years back, these highlanders started to plant vegetables in greenhouses which helped them procure food from their own farm, easing the hurdle they faced going to Punakha to buy essential items.

The rising temperatures are having a direct effect on pests and diseases on crops even in higher altitudes. Studies claim that there has been a rise of temperature by 3°C in Gasa in the past two years.

The farmers of all seven villages of Laya Gewog have witnessed the common pests of the hot region infecting their vegetables grown in the green house and even wheat and barley. The farmers said the insecticides have started harming their only cereal-wheat and chilies and cabbages grown in greenhouses. 
Sonam Dorji, 42, from Lungo village said that the farmers of Laya are experiencing new pest challenges infesting their plants.

Radish and turnip are age-old grown vegetables while barley, mustard and wheat are also grown. Spinach, chili, broccoli, beans, cucumber and cabbages are new vegetables grown by the highlanders in greenhouses. 

To ensure sustainable social and economic well-being of the Bhutanese people through adequate access to food and natural resources, the Department of Agriculture (DoA) had introduced the greenhouse vegetable plantation in the highland.

Of late, Sonam Dorji said the community has witnessed pest infestation both for age-old grown crops and vegetables and newly introduced vegetables. He said that mostly cabbage is being infested by the pests.

Pema Choki, 31, from Nyelo said with the introduction of new vegetable plantations have added varieties to their menu. She said it has helped to reduce investment for the vegetables and hopes it sustains.

However, she said that their worst fears seem to come true as crops and vegetables are damaged by the insects.

Dorji from the same village also claims that new plant diseases are impacts of climate change. He blames influence on plant pathogens that are often inconsistent triggered by climate change. “Unlike before, our barley cannot ripe on time,” he said.

Even a young class VIII dropped farmer, Tshering Yangden, 15, from Lungo is concerned of her crops and vegetables getting damaged by pests. She says the population in their communities are increasing and definitely food requirements would surge.

“I am concerned about future food security if our plants are infested,” she laments, adding that she plans to expand her greenhouse plantation. However, she is discouraged by the unfavorable happenings in her garden.

Similar challenges are faced by the farmers of Laya Khatoed. Sangya Zam, 30, from Khatoed said that the framers of her village have been witnessing infestation of new pests to their crops and vegetables since 2018.

Sangay Zam said, “Our crops and vegetables are invaded by insects. The vegetables are damaged at night, mostly onions and garlic.”

For the last two years, armyworms have started to damage paddy and buckwheat, according to the farmers of Khatoed.

The farmers of Laya noticed that their crop and vegetable production has also declined over the years. They shared that if the farmers encounter such affects every year, not only their community but the whole nation will face a food crisis.

The gewog agriculture extension officer, Tshelthrim, shared that with the introduction of greenhouse plantation, pests like cabbage white butterfly, mites and aphids have started to infest. He said that cabbage white butterflies infest cabbage, cauliflower and broccoli while aphids infest tender vegetables and chili plants.

The agriculture extension officer admits that the impacts are due to climate change. He said that the scale would accelerate with the evolution and changing geographic distribution.

The agriculture extension officer of Lunana, Yonten Phunthso, also reported similar problems faced by the farmers. Under his extension, greenhouse vegetables are affected by aphids and white butterfly.

The extension officer said infestation by common pests even in higher altitude is a concern. Though it is not a concern at economic threshold, he said food security impacted by climate issues is a concern.

The Senior Economist and Food Systems Specialist, Livelihoods of International Centre for Integrated Mountain Development (ICIMOD), Dr Abid Hussain, said that the rise in temperature is resulting in changes in agro-ecological conditions in mountain cropping zones and pastures.

He said, “Climate change is one of the factors resulting in the increased pest infestation in agriculture in hilly and mountain areas (highlands).”

The senior specialist said that in the Hindu-Kush Himalaya which includes Bhutan, it has been observed in the last couple of decades that due to temperature rise, high-altitude pastures and single cropping zones are getting favorable for cultivation of multiple crops.

Valleys and relatively low altitude hilly areas are also facing increased pest infestation.

In high altitude mountains, the elevation of snowline is also gradually increasing, which favors the shift of crop cultivation to high altitudes (single cropping zones and pastures) where cultivation was either limited or was not possible in the past due to persistent snow cover.

Dr Arbid Hussian said an increase in temperature in highlands favors the conditions for pests to migrate from lowlands to highlands and to survive and grow in highlands.

Under temperature rise, crop plants have also become more susceptible to attack by insect-pests because of weakening of their own defensive system resulting in pest outbreaks and more crop damage. 

The National Program Development Specialist of FAO Bhutan, Sherab Wangchuk, said that the rising temperatures will make insect pests to spread and expand into new geographical areas, especially to high altitude areas.

He said that rising temperatures and precipitation would also lead to longer survival of pests as they migrate to more favorable environments and climate to find food sources.

An associate professor from the College of Natural Resources (CNR), Sonam Tashi, said that pests migrate to more suitable climatic conditions and infestation could be because of poor management practices, including lack of nutrient management.

He said that the pests migrate for food, resources, and suitable weather conditions.  In coming years, perhaps, climate change could further speed up pest migration as all animals, including pests would want to survive and thrive.  

The associate professor said that pest infestation means food loss through crop damage and impact on quality and the associated cost in managing new pests.

He added that climate change could impact all regions, and those regions which are dependent more on agriculture could be impacted even more if business as usual continues because food production, to a large extent, is dependent on weather conditions.

The National Program Development Specialist said that loss of crops to pests is a concern for Bhutan, especially the arrival of new pests every year.

Recently, the country also recorded about 17 new wasp species which consist of Eumeninae (Potter wasp), Polistinae (Paper wasp) and Vespinae (hornets).

The minister for agriculture and livestock, Yeshey Penjor, earlier said that the change in weather patterns would cause natural disasters and will destroy communication infrastructure which will disrupt food distribution.

The director general of the International Technology Bureau of Rural Development Administration, Korea, Dr Taek-Ryon said that Bhutan is not exempted from the food security problem during the sixth General Assembly of the Asian Food and Agriculture Cooperation Initiative (AFACI) last year.

He said that lower-income people are most vulnerable to face the food shortage.


Farmers in Bhutan are advised to use natural pesticides as it is the most common pest control method. The farmers of highland communities are also advised to use natural pest control methods by the DoA.

Understanding the effects of chemical fertilizers, the farmers of Laya use locally made pesticides to control the pests. They use chili ferment, garlic leaves and cow urine to control the pests.

Dechen Wangmo, 26, from Pazhi village said that the villagers are not allowed to use chemical fertilizers. However, farmers of Khatoed admit they had to use even chemical fertilizers.

The gewog agriculture extension officer, Tshelthrim, said that they advise farmers to use bio-pests.

The agriculture extension officer of Lunana, Yonten Phunthso, said that besides farmers being mandated to use bio-pesticides, the local agriculture office had taught farmers to use nets to stop the pest and apply the ash. The farmers are also instructed to close the greenhouse at night and open only during the day.

The Senior Economist and Food Systems Specialist, Livelihoods of ICIMOD, Dr Abid Hussain said that the measures need to start from national level with a periodic review and revisions in the agroecological zonation.

He said, “According to changing agroecological conditions, native resistant crops species need to be promoted in highlands. The introduction of insect susceptible cultivars or crops will increase the risk of rapid pest infestations.”

He also said that the governments also need to launch an awareness program of farmers on pest-management in the changing climate.

At the local level, Dr Abid Hussain said that farmers can focus more on climate resilient and native varieties. He said farmers can also adapt the integrated pest management (IPM) practices with proper training on IPM through government programs.

The Senior Economist and Food Systems Specialist said that internationally, there is a needl to acknowledge the loss of crop productivity caused by climate change induced pest infestations.

Governments including Bhutan can pay attention to improve the evidence on attribution of pest infestations to climate change and consider the pest-infestations under the slow onset impacts of climate change in their national loss and damage assessment frameworks.

He said it will help the governments to get adequate funds in future from the global ‘loss and damage fund’. Established in COP 27 in Egypt, this fund aims to provide financial assistance to nations most vulnerable and impacted by the effects of climate change.

Dr Arbid Hussain said that the developing countries should support in terms of finance and technology for better adaptation and improving resilience in food production systems.

If not, he said that it will impact the sustainability of food systems not only in highlands but also at national levels in the developing world through negatively impacting the crop productivity, increasing production costs, affecting food safety (shift from organic to inorganic production), and resulting in high food prices (inadequate economic access to food).

The National Program Development Specialist of FAO Bhutan, Sherab Wangchuk, said that integrated pest management is required at the national level and surveillance of pests at the local level.

He said research on pest management plays an important role at the global level and also sharing of research findings and innovative solutions.

The organization recommends sustainable management of forests and focuses on the use of marginal lands and implementation of pest resistant biotech crops through research and innovation. 

The National Program Development Specialist said that the carbon emitting countries should commit to support climate finance for loss and damage by climate induced disasters, and finance mitigation and adaptation programs, supporting transfer of technologies, including digital.

Associate Professor Sonam Tashi said that there is a need to study and make farming more robust and resilient through adaptation of technologies and practices that conserve the ecosystem.

Without a healthy ecosystem, he said food production will not be possible or sustainable. Simple practices such as diversified crop rotation, crop covering, use of organic mulch and manure and systematic integrated farming system could contribute to building resilience.

Sonam Tashi said that the carbon emitting countries should switch to more green technologies by investing in research and technologies and commit to support less privileged countries for the common good.  

  The writer is a reporter of Business Bhutan. This story is funded by Bhutan Media Foundation, supported by Canada Fund for Local Initiatives.