The mass invasion of a new insect, the whitefly, in Bangladesh’s agricultural farms — especially in coconut, banana and guava farms — has put farmers at risk due to its devastating effects on crops.

How the insects are entering the country is yet to be confirmed, but researchers suggest the pest may have spread in the country via the high-yielding coconut imported in 2014 and 2015.

According to a 2022 study, the whiteflies (Aleurodicus rugioperculatus) were first identified in Bangladesh in 2019 on coconut in the southwest. Since then, the insect’s presence has spread across the country with different levels of infestation.

“The insect can damage a plant in many ways, including removing nutrients and water from leaves and disrupting the photosynthesis process,” the study states.

“Initially, we found the pest in coconut trees; however, now the insect has already made 61 types of plants as their hosts,” said Gopal Das, lead author of the study and an entomology professor at Bangladesh Agricultural University (BAU). He added that coconut, banana and guava are the most affected crops by the pest.

Rice, wheat and maize are the primary crops grown in Bangladesh while other crops like jute, tea, banana, guava and coconut are grown as cash crops.

According to media reports, in 2023, Bangladesh was the 12th highest coconut-producing country in the world with a yield of 442,700 tons from 25,335 hectares (62,00 acres) of land, while, in 2021-22, the country produced 430,000 tons of guavas from around 89,000 hectares (219,920 acres) of land. In the case of banana production, in 2020-21, Bangladesh was among the top 20 producers in the world with a production of 826,000 tons.

“We apprehend that the insect somehow entered into the country with the imported coconut plants under a government [nutrition improvement] project launched in 2014,” Das said.

Under the project, Bangladesh introduced three different types of high-yielding coconut varieties. Of them, Siam Blue and Siam Green are from Vietnam and Deejay Sampurna is from India. These short-height trees are believed to produce about three times more than the native varieties.

“We have supplied around 1 million saplings to the farmers through our horticulture centers,” said Abdul Halim, the director of the project under the Department of Agricultural Extension (DAE).

However, many of the farmers across the country have abandoned their plantations because of yields lower than expected and the trees drying up due to the whitefly infestation.

Das said he’s concerned, and that the way the pest attack is spreading, it would very soon be a disaster for the farmers growing popular cash crops.

The origin and invasion of the whitefly

Before the identification of the pest in Bangladesh, whiteflies were observed in farms in southern India’s Tamil Nadu and Kerala states in 2016, in 50 host plants.

A. rugioperculatus was first described in Belize in 2004, while it was first documented as a pest in 2009 in Florida, U.S., where the invasive insect was found on 118 host plants.

Regarding the entry of the insect into Bangladesh, Das said, “Both Vietnam and India could be the source, but we cannot say the exact route as we don’t have any reference or information of the insect in Vietnam. At the same time, just three years before the insect was identified in Bangladesh, it was spotted in India. Considering this, India might be the possible source.”

Meanwhile, conservationists and botanists are blaming the government for not maintaining adequate protection measures, such as bio-safety risk assessment, while introducing foreign plants into the country.

“[It’s not just] in the case of the coconut [plants] — the government did not follow proper procedures while introducing [other] foreign plants like pineapples and others [either]. The invasion of the whitefly would not have reached this stage if the authority had taken proper steps in the beginning,” Farid Uddin Ahmed, a botanist and former executive director of the NGO Arannayk Foundation, told Mongabay.

“Introducing new crops and plant varieties from abroad is nothing new in Bangladesh. But the government should be more careful before the introduction through adequate quarantine, feasibility checks and maintenance of bio-safety rules,” said Jiban Krishna Biswas, former director general of Bangladesh Rice Research Institute (BRRI).

To prevent such hazards, Bangladesh’s government had formulated the Plant Quarantine Act 2011, appointing the DAE as the authority.

“Under [this] law, DAE always tries to follow the instructions in case of importing any plants or crop varieties. However, sometimes it could not be possible to be meticulous due to the weakness of our quarantine facilities,” said Md. Hamidur Rahman, former director general of DAE.

The way out, a possible solution

As whiteflies are new and invasive, the DAE finds the situation difficult to manage and is trying to tackle the infestation with different types of pesticides. Das, however, suggested deploying the parasitoid wasp Encarsia guadeloupae, considered a beneficial insect agriculturally, to tackle the invasion of the whitefly.

Citing the parasitoid as a natural parasite of the whitefly, another study states that using this natural solution has shown success in controlling whitefly populations in other countries.

Das said using the wasps has shown positive results in India, too, and said, “The only possible way to tackle the pest is now to multiply the parasitoid in laboratories and release them in nature, and they will kill the whiteflies.”

Banner image: A. rugioperculatus activity observed on a leaf in Florida. Image by techgrl18 via iNaturalist (CC BY 4.0).

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Citations:

Das, G., Uddin, M. M., Roy, B. K. & Ahemed, M. S. (2022). Identification of Rugose Spiralling whitefly infesting host plants in Bangladesh and assessment of its damage severity. American journal of Entomology, 7(1). doi:10.11648/j.aje.20230701.11

Karthick, K. S., Chinniah, C., Parthiban, P. & Ravikumar, A. (2018). Newer report of Rugose Spiraling Whitefly, Aleurodicus rugioperculatus Martin (Hemiptera: Aleyrodidae) in India. International Journal of Research Studies in Zoology 4(2). doi:10.20431/2454-941X.0402003

Mollot, G., Borowiec, N., Duyck, P.F, Glenac, S., & Quilici, S. (2015). Life-history traits of Encarsia guadeloupae, a natural enemy of the invasive spiralling whitefly Aleurodicus disperses. Journal of Applied Entomology 140(3). doi:10.1111/jen.12236

Naik, I. R., Pavani, T., Upendhar, S. &Neelima, P. (2024). Host Range and Distribution of Invasive Pest, Rugose Spiralling Whitefly Aleurodicus rugioperculatus Martin in Telangana, India. Journal of Advances in Biology & Biotechnology. Volume 27, Issue 12. doi:10.9734/jabb/2024/v27i121839

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