Neonics: the common pesticides wreaking havoc on the sleep of insects

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By Ellesse Jun Huan Low, Second Year Chemistry

Neonicotinoids (shortened to neonics) are a common type of pesticide which is widely used in crop protections. Two new studies led by scientists at the University of Bristol recently discovered the harmful effect of neonics on disrupting the sleep of bumblebees and fruit flies.

Just like humans, insects require a good night’s sleep. It’s needed for them to carry out essential activities, such as hunting and foraging. However, modern agricultural practices might be interfering with this important process more than previously thought. Researchers at the University of Bristol have found that certain types of pesticides (known as neonics) have been hugely interrupting the sleep cycle of insects like bumblebees and fruit flies.

The use of neonics has been found to be detrimental to the sleep cycle of many insects | Unsplash/ Amy Lynn Grover

Bumblebees, one of the primary pollinators, are known for pollinating plants and flowers during the dark. They actively forage throughout the night and get sleep during the day. However, it has been found that neonicotinoid-contaminated honey and flowers can disturb the sleep of insects. This problem appears to be concerning as a large percentage of plants, including fruits and vegetables, rely on pollinators to reproduce. Bumblebees play an essential role in this field.

The research indicated a significant reduction in their foraging activity when the toxins enter the bee’s body whilst collecting pollen. This leads to the dramatic decrease of pollination opportunities as well as the bee population too.

The study showed that neonics have a substantial effect on the amount of sleep taken by both flies and bees. Dr Kiah Tasman (lead author) explained: ‘If an insect was exposed to a similar amount as it might experience on a farm where the pesticide had been applied, it slept less, and its daily behavioural rhythms were knocked out of sync with the normal 24-hour cycle of day and night.’

Neonicotinoid-contaminated honey and flowers can disturb the sleep of insects

Meanwhile the fruit fly study, published in Scientific Reports, mentioned how pesticides interfere with the function of the insect’s brain as well. It was identified that the fly’s central nervous system is especially sensitive to neonics. They found a threshold value, above which severe damage would be caused to the fly’s brain cells. Concerningly, most modern farms use this amount of the pesticide.

Other effects include memory loss for bees, causing significant changes to their biological clock which confuses their sleep-wake cycle. He also added it impairs their navigation and learning, for example, they may be unable to scavenge for food in their natural habitat.

Dr James Hodge, senior author for the study, stated that being able to sense what time of day it is is important for knowing when to be awake and forage but it seems like the insects are unable to sleep- which has subsequently affected their health and memories. Dr Sean Rands, the study’s co-author, acknowledged that bees and flies have similar structures in their brain. Neonics therefore have similar effects on bees too.

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The extensive usage of neonics may have benefited farmers and helped them achieve bountiful harvests. Nonetheless, it is clear that insects have been suffering the consequences. If these pesticides affect the sleep-cycle of bees and their ability to pollinate, this may lead to food shortages.

The hazardous insecticide was banned by the European Union, and the UK government promised to keep this in place post-Brexit. Despite this, last month the UK signed emergency authorisations for its use. The studies have encouraged calls for the use of neonics to be prohibited globally, to avoid potentially decimating the populations of foraging insects and risking food shortages.

Featured image: Unsplash / Filipe Resmini


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