In Bangladesh, honeybee populations are dwindling as unaware farmers use insecticides, particularly neonicotinoids, which disrupt their foraging and survival.
Experts are seriously concerned about the use of chemical cocktails comprising neonicotinoids without extensive research.
Despite worldwide concerns over neonicotiniods, Bangladesh authorities are yet to address the issue due to lack of awareness.
See All Key Ideas
In February, during the flowering time of black cumin (Nigella sativa), beekeeper Pavel Hossen set up an apiary on leased barren land adjacent to farmer Abdul Hakim’s crop field in Kazirhat of Shariatpur, a district under Dhaka division and an emerging hub of spices, including the black cumin seeds.
Pavel deployed Apis mellifera honeybees to collect nectar from the blooming cumin flowers. However, the hive boxes didn’t yield as much honey as expected.
“Bees cannot forage freely across insecticide-treated crop fields. Their population growth is also slowing down,” Pavel recently told Mongabay.
During a visit to Kazirhat in late February, the village’s agricultural landscape appeared fragmented by plots of different crops, including rice, wheat, coriander, black cumin, garlic, mustard and other vegetables.
The use of agricultural chemicals like neonicotinoids as insecticides is popular with the cultivation of most of the mentioned crops. However, very few farmers know the permissible doses or potential effects of excessive use of insect killers on bees.
Most of the farmers, like Abdul Hakim, said, “I spray the amount of chemicals that the sellers advise.” In a village market, agricultural chemical sellers with expertise in conservation of biodiversity is a rare thing.
Entomologists and apiculturists have observed that rampant use of agricultural chemicals like neonicotinoids, present in different doses in nearly 600 brand products in Bangladesh, poses serious threats to bee colonies and other pollinators.
“Because of food shortages, limited foraging grounds and frequent poisoning from insecticides, the population of honeybees is decreasing alarmingly,” said Bangladesh Institute of Apiculture’s executive director, Nurul Islam.
There is no survey on the bee population in Bangladesh.
However, in 2019, the Food and Agricultural Organization of the United Nations warned that the population abundance of bees and other pollinators was declining in many parts of the world.
The major causes were identified as excessive use of agricultural chemicals, monocropping, intensive farming practices and climate change-induced rising temperatures.
Honeybees hovering around hive boxes.
Honeybees hovering around hive boxes. Image by Sadiqur Rahman.
Full-time farmer Abdul Hakim, unaware of the side effects, applies insecticides as per advice from the sellers.
Full-time farmer Abdul Hakim, unaware of the side effects, applies insecticides as per advice from the sellers. Image by Sadiqur Rahman.
Neonicotinoids: Threats to bees
In Bangladesh, farmers widely use neonicotinoids and their cocktails with other chemicals in the fields of rice, chiles, beans, sugarcane, mangoes, tomatoes, mustard, banana, brinjals, marigold, cotton, jute and tea.
Bangladesh’s Department of Agricultural Extension (DAE) permits the use of acetamiprid, clothianidin, dinotefuran, imidacloprid, nitenpyram, thiacloprid and thiamethoxam, all neonicotinoid insecticides, for the protection of crops.
The insecticides mainly eliminate brown planthoppers, aphids, jassid leafhoppers, termites, hispas, helopeltis, thrips, hairy caterpillars, mealybugs, hoppers, semiloopers, and yellow stem borers, among other insects harmful to agriculture, according to the list of permitted pesticides.
However, these agricultural chemicals can cause behavioral alterations and physiological disruptions among beneficial insects like bees, sometimes killing them.
A study published in 2024 finds the use of imidacloprid, clothianidin and thiamethoxam as highly toxic to bees.
Mamunur Rahman, a corresponding author of the study and professor in the Department of Entomology at Gazipur Agricultural University, said chronic neonicotinoid exposure results in a significant decline in adult bee populations through reduced brood surface (the eggs, larvae and pupae of honeybees) and diminished pollen collection capacity.
“These neurotoxic compounds of neonicotinoids selectively target nicotinic acetylcholine receptors (nAChRs) in insects, leading to disrupted neural signaling, impaired foraging efficiency and colony-level dysfunction,” Mamunur said.
He added that the cascading ecological consequences extend beyond bee mortality, contributing to suboptimal pollination efficiency and potential honey contamination.
Currently, importers of crop protection chemicals in Bangladesh are searching for alternatives as they have found a high level of resistance to neonicotinoid thiamethoxam among brown planthoppers and stem borers in rice fields.
Mahadee Hasan Pathan, secretary-general of the importers’ platform Bangladesh Crop Protection Association, said, “Combinations of neonicotinoid with carbamate, cartap, acetamiprid, nitenpyram and pymetrozine are being popularized among farmers for better outcome [pest control].”
Bangladesh Agricultural University’s Department of Agricultural Chemistry professor Zakir Hossen understands that pesticides, though harmful to all kinds of insects, have become an integral part of ensuring food security in Bangladesh.
“Despite this, I am seriously concerned about the application of chemical cocktails without extensive research,” he said, adding that these cocktails could be more lethal to beneficial insects.
Chronic neonicotinoid exposure results in a significant decline in adult bee populations, reduced brood surface, and elevated queen supersedure (replacement) rates with low colony stability.
Chronic neonicotinoid exposure results in a significant decline in adult bee populations, reduced brood surface, and elevated queen supersedure (replacement) rates with low colony stability. Image by Sadiqur Rahman.
Beekeepers monitoring hive boxes at Kazirhat, Shariatpur.
Beekeepers monitoring hive boxes at Kazirhat, Shariatpur. Image by Sadiqur Rahman.
Why do restricting neonicotinoids matter?
Bangladesh imports crop protection chemicals mostly from China, India and some Western countries.
Researchers have found that bees in China are at high risk from exposure to neonicotinoids.
Indian researchers, studying the impacts of imidacloprid, acetamiprid, thiacloprid, thiamethoxam, clothianidin and dinotefuran, have found thiamethoxam and imidacloprid as “least safe to bees.”
In 2013, the European Commission restricted the use of plant protection products and treated seeds containing clothianidin, imidacloprid and thiamethoxam to protect honeybees.
Biodiversity conservationists in Bangladesh often demand banning pollinator-killing agrochemicals, especially neonicotinoids. But the DAE that licenses agrochemical imports hardly responds to the call.
The department’s pesticide administration and quality control wing approve pesticides, insecticides and miticides upon clearance from the Department of Environment and related crop research institutes.
Surprisingly, in a recent visit to the DAE’s headquarters in Dhaka, none of the particular wing officials entertained questions about the neonicotinoids and their impacts on pollinators.
“We are unaware of the side effects of neonicotinoids,” said Nur E Alam Siddique, deputy director at the pesticide administration and quality control wing.
Dead bees lay on the ground beside hive boxes.
Dead bees lay on the ground beside hive boxes. Image by Sadiqur Rahman.
To mitigate the threats of neonicotinoids and ensure the resilience of pollinator-dependent agroecosystems, entomologists suggest the enforcement of stronger laws on the application of neonicotinoids.
“The integration of biorational approaches and biopesticides presents a scientifically robust and ecologically adaptive alternative,” Mamunur said.
Banner image: Beekeepers monitoring hive boxes at Kazirhat, Shariatpur. Image by Sadiqur Rahman.
Decline of Cambodia’s native bees spells trouble for country’s farming future
Citations:
Sadia, H., Karki, P. R., Afroz, M.,Khan, H., Hossain, M. M. & Rahman, M. M. (2024). The Exposure of Pesticides to Honeybees: A Global Threat to Food Security. Online Journal of Biological Sciences. 24. 232-243. doi:10.3844/ojbsci.2024.232.243
Shi, M., Guo, Y., Wu, Y. Y., Dai, P. L., Dai, S. J., Diao, Q. Y. & Gao, J. (2023). Acute and chronic effects of sublethal neonicotinoid thiacloprid to Asian honey bee (Apis cerana cerana), Pesticide Biochemistry and Physiology, Volume 194. doi:10.1016/j.pestbp.2023.105483
See Topics