Purging a pepper plague: WorldVeg fights black thrips in India’s chili fields 

– 29 April 2026 –

K. O. Swaroop investigates black thrips resistance in chili at WorldVeg headquarters. Pic by Neil Palmer (WorldVeg).

In early 2021, chili farmers in Bengaluru, in India’s southern Karnataka state, noticed something strange.

The flowers and leaves of their plants were covered in tiny dark insects with thin, elongated bodies.

They were used to dealing with attacks by whiteflies, leafhoppers, broad mites, and several different kinds of thrips.

But these insects looked different.

They were, in fact, black thrips (Thrips parvispinus). Native to southeast Asia, they routinely attack chili fields in Thailand and Indonesia and emerged in India as pests of papaya in 2015. Soon they had found a taste for chili – a crop central to Indian cuisine and livelihoods, grown on around 700,000 hectares in the country.

The sap-sucking pests stunt plant growth, cause flowers to drop off – inhibiting fruit development – and generally weaken plants. They also feed on the fruits, causing direct damage and reduced marketability.

In India, a country with an annual chili output of around 2 million tonnes – the highest in the world – black thrips was very bad news.

Soon enough, chili farmers in the states of Tamil Nadu and Andhra Pradesh also reported outbreaks. Then, farmers in Telangana, Gujarat and Kerala too. Losses were as high as 70-100% in some places. Simply put, it was devastation – and in many areas, the pest continues to pose a serious and costly challenge for farmers today.

(Left) A chili plant susceptible to black thrips. Pic by Neil Palmer (WorldVeg). (Right) A chili flower infested with black thrips, in Hyderabad, India. Pic by Derek Barchenger (WorldVeg).

Small insect, big rethink

The rapid spread of black thrips was the result of a perfect storm of conditions. The pest has a very short life cycle and rapid reproductive potential, the latter exacerbated by warmer temperatures and higher humidity linked to climate change. In India, large-scale monocrops of chili and overuse of pesticides had removed many natural enemies.

Almost as quickly as black thrips took hold, WorldVeg chili breeders were on the case. The idea was simple: Developing thrips-resistant chili varieties would increase the effectiveness of thrips control and may delay and also reduce the transmission of tospoviruses.

The Center was already an expert in pepper breeding, with a decades-long track record of developing hundreds of chili pepper varieties equipped with heat tolerance and disease resistance – often multiple forms of resistance combined in each variety. But breeding for insect resistance was new, and responding to an active, fast-spreading pest added urgency to the challenge.

Breeders quickly screened two pepper species, Capsicum annuum (chili) and Capsicum chinense (habanero), conserved at the organization’s international genebank at its headquarters in Tainan, Taiwan. This quickly identified nine resistant and tolerant lines – mostly fiery habaneros.

All nine were evaluated in open-field conditions at the WorldVeg South and Central Asia regional office in Hyderabad, India. This culminated in a demonstration field day in late 2023, where around 50 seed companies associated with the Asia and Pacific Seed Association (APSA)-WorldVeg Vegetable Breeding Consortium had the opportunity to evaluate them. The results were strong: Not only were the lines resistant to black thrips, they were also resistant to the other kinds of thrips routinely found in chili fields in India and elsewhere.

Fast-tracking resistance

These early successes laid the foundations for the next round of work. Using recurrent selection – a powerful technique in plant breeding that involves choosing the most resistant plants, crossing them, and testing their offspring over multiple cycles –Recognizing the need to learn more about black thrips, and to extend breeding for resistance in chili beyond India, a special APSA project – funded entirely by seed companies – was launched in 2024.

This took the work to another level, and where the team is currently focusing. It involves sequencing and analyzing the plant’s DNA to understand which regions are linked to thrips resistance. Once those useful genetic regions are identified, scientists can develop simple DNA markers to quickly find the most thrips resistant plants. This helps speed up breeding by allowing researchers to select stronger, more resilient chili lines much earlier, making it faster to develop improved varieties for farmers – even though releasing a new variety still takes several years.

In addition, teams in Taiwan – and more recently in India – are exploring the natural chemical signals chili plants produce and how these influence insects, an area known as metabolomics. This work has identified a series of volatile organic compounds in the pepper lines, believed to either repel or attract black thrips and as well as the related melon thrips (Thrips palmi). The breeders are most interested in repellents to develop host resistance, but understanding attractant compounds provide a basis to characterize susceptibility factors in the host, something that can be bred against instead of for.

“Breeding doesn’t deliver overnight solutions – but what matters is how quickly you can respond, mobilize the right tools, and start moving in the right direction,” said Derek Barchenger, leader of the Center’s pepper breeding program.

“WorldVeg was able to respond rapidly to the emergence of black thrips and other new pest outbreaks because of our close partnerships with private seed companies through the APSA–WorldVeg Vegetable Breeding Consortium, which provides critical field intelligence across the region,” he continued.

“Combined with our continuous breeding efforts, direct access to the diversity conserved in our genebank, and the ability to rapidly mobilize and introgress useful traits into adapted breeding backgrounds, this allows us to act far faster than would be possible if breeding had to start from scratch each time a new threat emerged.”

In the meantime, India’s chili farmers continue to rely on a combination of chemical control and integrated pest management strategies, to try to keep black thrips in check, underscoring the need for pest-resistant chili varieties.

But a solution is on its way – and the black thrips outbreak has already sharpened WorldVeg’s focus on host plant resistance.

What began as a crisis has already proven to be a catalyst.

This work falls under the Climate Resilience action area of the WorldVeg Global Strategy (2026–2033).

Read about how the WorldVeg pepper breeding program just had a record year for new varieties and distributions, reaching a quarter of the world.