Rampant use of agricultural chemical thiamethoxam, a neonicotinoid insecticide present in different doses in nearly 100 agricultural products in Bangladesh, poses serious threats to bees and other pollinators.
20 May is observed as “World Bee Day” with the aim of raising awareness among people, especially the younger generations about the essential role of bees and other pollinators in agriculture.
This year's theme is "Bee Engaged with Youth".
Agricultural chemistry experts have expressed serious concern as farmers have been applying cocktails of insecticides containing thiamethoxam which are much more harmful to the agricultural ecology.
Meanwhile, some entomologists have urged the government and other stakeholders to control the excessive use of thiamethoxam and other harmful insecticides for the conservation of bee colonies and other pollinators.
There is no survey on the bee population in Bangladesh.
However, a couple of years ago, the United Nations Food and Agriculture Organization (FAO) warned that the population of bees and other pollinators was declining in abundance in many parts of the world.
The major causes are excessive use of agricultural chemicals, mono-cropping and intensive farming practices, besides climate change-induced rising temperature, according to FAO.
In Bangladesh, farmers widely use thiamethoxam and cocktails with thiamethoxam in the fields of rice, sugarcane, mango, tomato, mustard, banana, brinjal, marigold, cotton, jute and tea.
The insecticides mainly eliminate brown planthoppers, aphids, jassid leafhoppers, termites, beetles, hispas, helopeltis, thrips, and yellow stem borers, among other bad insects.
However, the chemicals kill beneficial insects too.
“Direct contact with thiamethoxam will kill bees instantly. Those who are intoxicated somehow will lose their hives and they will die,” said Professor Mohammad Sakhawat Hossain from Sher-e-Bangladesh Agricultural University’s Department of Entomology.
Exposure to neonicotinoid insecticides like thiamethoxam causes bees’ behavioural alteration and physiological disruption, sometimes leading to lethal effects on them, according to a study titled, “Evaluating the Impact of Commonly Used Pesticides on Honeybees (Apis mellifera) in North Gonder of Amhara Region, Ethiopia.”
After being sprayed, neonicotinoids are either coated on seeds or soil, allowing them to spread through plant tissues and ultimately appear in pollen and nectar.
Another study titled, “Past insecticide exposure reduces bee reproduction and population growth rate” reveals that neonicotinoids disrupt learning and memory in honey bees, and solitary bees also suffer similar damage.
These chemicals impair bee reproduction when used in higher concentrations - leading to fewer offspring, according to the study.
Another study titled “Effect of insecticides on foraging behaviour of honeybee (Apis mellifera L.) on mustard (Brassica napus)” found a drastic reduction, on an average of 75%, in the number of visitor bees after application of insecticides including thimethoxam at the mustard field during full bloom.
Why bees are important?
About two-thirds of the world's crop plants depend on pollination by insects or animals.
This process enhances human nutrition by fostering abundant, diverse, and high-quality production of fruits, nuts, and seeds.
For food production, human livelihoods and biodiversity, bees provide the important ecosystem service of ensuring pollination and reproduction of many cultivated and wild plants.
According to FAO, bees and other pollinators influence 35% of the world’s crop production.
“Insecticides, though harmful to all kinds of insects, have become an integral part of ensuring food security in Bangladesh, protecting the cash crops from damage,” said Professor Zakir Hossain, a faculty at the Bangladesh Agricultural University’s Department of Agricultural Chemistry.
“Even so, I would recommend strict control over the rampant use of insecticides. I am seriously concerned about the application of chemical cocktails that are supposed to be more lethal to beneficial insects. Misguided by insecticide sellers, unaware farmers are using these cocktails," he added.
Department of Agricultural Extension (DAE) approves 11 products containing thiamethoxam. Among them, some are the mixtures of chemicals like ethion, chlorantraniliprole, fipronil, imidacloprid and emamectin benzoate.
SM Shorab Uddin, additional director (pesticide administration and quality control) at DAE, said his department approves pesticides, insecticides and miticides upon clearance from the Department of Environment and related crop research institutes.
“We have not yet analysed the impacts of thiamethoxam on bees and other pollinators,” Shorab said.
Working for a future free of poison
Among thousands of farmers chasing the increasing domestic food demand with agricultural chemical-depended high-yielding crops, a few young people have been dreaming of a non-toxic safe food supply.
Delowar Jahan and his peers are those who have established a biodiversity farm Pran Boichitra Khamar on a two-decimal land in Kautia village of Manikganj.
Apparently, the young farmers grow indigenous crop varieties while avoiding synthetic fertilisers and insecticides.
They believe in the importance of pollinators like bees. They claim that for the last six years in Kautia village, they have been doing integrated farming which primarily supports all kinds of organisms but reduces pest attacks naturally.
“When aphids attack the crops, ladybugs appear to prey on them. Apparently, tailorbirds also flock to the field to feed on ladybugs. There are small lizards on the field which also feed on the insects,” Delowar explained the natural pest control.
He believes that 80-90% of pest control can be done if farmers design an integrated farming of diversified crops, following well-maintained soil nutrition management.
Nutrient-rick soil helps the growth of healthy and insect-resistant plants while integrated farming ensures the natural elimination of bad insects, he added.
