New Study Reveals Fungicide Reduces Insect Fertility by 37pc

Motaher Hossain :

The use of pesticides has increased alarmingly across the globe in pursuit of higher crop yields and crop protection. This trend is visible not only in Bangladesh but in almost every country. Such indiscriminate use of pesticides poses a severe threat to public health, depletes soil nutrients, and is pushing many species of insects toward extinction.

Ironically, the very food we depend on for survival—fruits, vegetables, and crops—is produced using pesticides. Humans survive, while countless insects perish—often indiscriminately. Among them are not only harmful pests but also beneficial insects that play vital roles in maintaining ecological balance. Due to excessive pesticide use, many insect species are now on the verge of global extinction.

A recent study highlights this alarming trend. Researchers found that spraying fungicides on fruits and vegetables does greater harm to insects than expected. Even pesticides used at so-called “safe” levels cause major damage.

A new study from Macquarie University in Sydney, Australia, reveals that chlorothalonil, a fungicide commonly used to prevent fungal infections in crops, disrupts insect reproduction and even kills them. Researchers tested its impact on fruit flies (Drosophila melanogaster), a widely used insect model in laboratory studies.

Fruit flies represent countless similar insects in the wild. Unlike crop-damaging pests, these flies consume decayed fruit and play an important role in breaking down organic waste and recycling nutrients in farms and orchards. They are also a crucial part of the food chain, serving as prey for many species.

Lead researcher Darsika Disawa, a PhD candidate, explained that even very low concentrations of chlorothalonil had significant effects on the reproduction of fruit flies. The study found that exposure reduced egg production by 37% compared to unexposed flies.

Chlorothalonil is already banned in European Union countries but is still widely sprayed in Australia to control fungal diseases. Its residues are found in soil and water near farms, with concentrations ranging from near zero to 460 mg per kilogram of food. Alarmingly, it is often used preventively—even when no disease is present—under the misconception that it only affects fungi. In reality, it devastates other species as well.

The ecological damage is not limited to insects. Growing up in the 1990s in rural Bangladesh, I witnessed rivers, canals, and wetlands teeming with native fish species—climbing perch, catfish, snakeheads, barbs, prawns, and many others. During the monsoon, local people could even catch fish by hand. Fish were so abundant that surplus harvests were dried into shutki (dried fish).

Today, that abundance has almost disappeared. Excessive pesticide use in agriculture is one of the main culprits. Many native fish species are now facing extinction.

Admittedly, thanks to the relentless efforts of fisheries scientists, Bangladesh has made remarkable progress in fish production. Artificial breeding and aquaculture have significantly increased supply, with some once-endangered small species now being farmed again. The government proudly claims that Bangladesh has achieved self-sufficiency in fish production.

According to the UN Food and Agriculture Organization’s State of World Fisheries and Aquaculture 2024 report, Bangladesh has overtaken China to become the second-largest producer of freshwater fish in the world, and it remains fifth in aquaculture production.

Yet the reality is different at the grassroots level. In village markets, native fish are now rare. Instead, stalls are dominated by farmed carp, tilapia, pangas, and other hybrid species. The few native fish available—such as puti, tengra, bain, or native catfish—are priced so high that they are out of reach for lower- and middle-income families.

Alongside pesticides, destructive fishing methods are accelerating the crisis. The widespread use of banned nets—such as current jal and China duari—and even electric shock devices has devastated fish populations.
The breeding season of most native freshwater fish runs from late May to mid-August. After the first monsoon rains, rivers, wetlands, and floodplains fill up, allowing fish to disperse and spawn. But during this crucial period, many professional and seasonal fishers indiscriminately catch broodfish (egg-bearing mothers) despite laws prohibiting it. Due to weak enforcement, the laws remain ineffective, pushing native fish closer to collapse.

To protect native fish, sanctuaries (abhoyashrams) have been created in several districts, aiming to provide safe breeding grounds. But greed and poor monitoring undermine these efforts. Stronger enforcement is essential. Technologies like drones and river police patrols could help curb illegal fishing.

Equally important is reducing dependence on chemical pesticides. Farmers need training, incentives, and government support to adopt organic or biological pest control methods. Such measures would not only help protect native fish but also preserve soil fertility, water quality, and public health.

The unchecked use of pesticides is silently eroding biodiversity—from beneficial insects to native fish species—while creating an illusion of agricultural success. Bangladesh may be climbing the global ranks in fish production, but if native species vanish, the ecological and cultural loss will be irreparable. Protecting biodiversity requires urgent, coordinated efforts—balancing food security with the health of ecosystems.

(The writer is a journalist and General Secretary of the Bangladesh Climate Change Journalist Forum).