Neonicotinoids and bees: A summary of studies done

You have probably heard the long name neonicotinoids when the topic of struggling bee populations has come up.

But what exactly are these chemicals, and what do they have to do with bees?

This is a topic that is long, in-depth and still being studied, but we will do our best to break it down a little bit.

First, a neonicotinoid is an insecticide that affects the central nervous system of insects, causing paralysis and death.

Neonicotinoids include imidacloprid, acetamiprid, clothianidin, dinotefuran, nithiazine, thiacloprid and thiamethoxam. Check the labels of any of your gardening products for these chemicals.

The issue of neonicotinoids comes in when they reach beyond their intended targets. The insecticides can spread as dust, spray drift and can get into waterways where the chemicals are taken up by plants through their roots and spread into all plant tissues, including pollen and nectar.

The chemicals are very hardy, persisting in soil for years after application, in woody plants up to six years and some untreated plants will absorb residue from a previous year.

These residues are then consumed by pollinators, including honeybees and native bees.

This graphic, by the Xerxes Society, is very helpful in showing ways that neonicotinoids can affect foraging bees.Graphic about neonictonoids and bees

Neonicotinoids affect bees in a variety of ways. Clothianidin, dinotefuran, imidacloprid and thiamethoxam have been found to be highly toxic through contact and ingestion, while other varieties are considered moderately toxic.

Even when the neonicotinoids are not lethal, according to a Xerxes Society report, they cause “problems with flight and navigation, reduced taste sensitivity, and slower learning of new tasks, all of which impact foraging ability and hive productivity.”

It goes on to say “Larvae exposed to sublethal doses of imidacloprid in brood food had reduced survival and pupation, altered metabolism and reduced olfactory response as adults.”

A Canadian study found that pesticides also impaired bee defenses. Normally, a bee colony will clean out its dead and sick brood to protect the healthy, but affected colonies stop taking these protective measures and sick bees stay in and infect the hive more often.

The same study also found that affected hives also tended to lose their queen and struggled to find a new one. And we all know, no queen equals no hive.

Neonicotinoids have also been found to impair native bumblebee and solitary bees such as the blue orchard bee and red mason bee, both of which are important pollinators.

(Read why mason bees might be better pollinators than honeybees.)

The issue with dwindling pollinator populations, from monarch butterflies to native bees to honeybees, goes beyond just one source though.

Our pollinators need more native habitat and food sources and less pesticides and fertilizers. The focus should be on restoring our environment to its natural state wherever we can, including adding native areas to our yards and gardens.

(Learn about five decorative milkweeds to beautify your yard.)

From contacting your legislators to encourage them to protect pollinators to taking measures to care for pollinators in your own yard to advocating for people to plant natives and use less chemicals in your area, you can make a difference in this issue.

(Read how honeybees survive the winter.)

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