Nav: Home

Neonic pesticides threaten wild bees' spring breeding, study finds

May 03, 2017

Neonicotinoid pesticides hinder wild queen bumblebee's reproductive success, according to a new University of Guelph study.

The study is the first to link exposure to thiamethoxam -- one of the most commonly used neonicotinoid pesticides -- to fewer fully developed eggs in queens from four wild bumblebee species that forage in farmland.

"Queen bees will only lay eggs when the eggs are fully developed," said Prof. Nigel Raine, holder of the Rebanks Family Chair in Pollinator Conservation.

If queens need to use energy to clear pesticides from their system instead of investing in eggs, then fewer fully developed eggs will result, he said.

"This will likely translate into slower egg-laying rates, which will then impede colony development and growth."

Published in the journal Proceedings of the Royal Society B, the study was conducted by Raine, along with Mark Brown and Gemma Baron from Royal Holloway University of London.

Neonicotinoids are one of a number of factors contributing to the decline of bees and are currently being phased out or restricted in several countries including Canada.

The researchers examined the impacts of exposing queen bumblebees to thiamethoxam during the spring when they emerge from hibernation and are preparing to lay their first eggs and establish a colony.

"Given the vital role spring queens have in maintaining bumblebee populations, we decided to focus on assessing the impacts at this stage in the life cycle," said Raine, a professor in the School of Environmental Sciences. "These spring queens represent the next generation of bumblebee colonies."

Worker bees from those first eggs are needed to clean and guard the nest, find food and tend to the next batch of eggs. Without those workers, the colony will likely fail, said Raine.

In this study, about 500 queen bees from four species were caught in early spring and for two weeks were fed syrup treated with pesticide doses similar to levels found in pollen and nectar in the wild. They were then observed for another two weeks before they were frozen, dissected and examined.

The researchers found that across all four species the queen bees that were given higher doses of thiamethoxam had smaller, less-developed eggs than the queens not exposed to the pesticide.

Raine suspects the metabolic costs associated with the detoxification required from pesticide exposure results in a reduced amount of nutrients available for other biological processes such as egg development.

The researchers also found queen bees from two of the four species ate less nectar after being exposed to thiamethoxam.

"If their feeding rates drop off, the queens go into a dormant state," said Raine. "They won't have enough energy to fly or to collect pollen to feed their larvae. They may not even have enough resources to lay eggs."

The fact that queen feeding behavior was impacted by exposure to thiamethoxam in only two of the four bee species highlights the reality that sensitivity to pesticides differs among bee species, added Raine.

"Most of the work to determine levels of toxic exposure to pesticide has used honeybees as a model pollinator. But our findings show that bee species vary in their level of sensitivity to pesticides, which is important information that should be factored into regulatory decisions on these chemicals."
-end-


University of Guelph

Related Pesticides Articles:

Two pesticides approved for use in US harmful to bees
A previously banned insecticide, which was approved for agricultural use last year in the United States, is harmful for bees and other beneficial insects that are crucial for agriculture, and a second pesticide in widespread use also harms these insects.
Dingoes have gotten bigger over the last 80 years - and pesticides might be to blame
The average size of a dingo is increasing, but only in areas where poison-baits are used, a collaborative study led by UNSW Sydney shows.
Pesticides can protect crops from hydrophobic pollutants
Researchers have revealed that commercial pesticides can be applied to crops in the Cucurbitaceae family to decrease their accumulation of hydrophobic pollutants, thereby improving crop safety.
Pesticides speed the spread of deadly waterborne pathogens
Widespread use of pesticides can speed the transmission of the debilitating disease schistosomiasis, while also upsetting the ecological balances in aquatic environments that prevent infections, finds a new study led by researchers at the University of California, Berkeley.
Honeybee lives shortened after exposure to two widely used pesticides
The lives of honeybees are shortened -- with evidence of physiological stress -- when they are exposed to the suggested application rates of two commercially available and widely used pesticides.
Pesticides increase the risk of schistosomiasis, a tropical disease
Schistosomiasis is a severe infectious disease caused by parasitic worms.
Wasps' gut microbes help them -- and their offspring -- survive pesticides
Exposure to the widely used pesticide atrazine leads to heritable changes in the gut microbiome of wasps, finds a study publishing Feb.
A proposal to change environmental risk assessment for pesticides
Despite regulatory frameworks designed to prevent environmental damage, pesticide use is still linked to declines in insects, birds and aquatic species, an outcome that raises questions about the efficacy of current regulatory procedures.
SDHI pesticides are toxic for human cells
French scientists led by a CNRS researcher have just revealed that eight succinate dehydrogenase inhibitor pesticide molecules do not just inhibit the SDH activity of fungi, but can also block that of earthworms, bees, and human cells in varying proportions.
Pesticides deliver a one-two punch to honey bees
A new paper in Environmental Toxicology and Chemistry reveals that adjuvants, chemicals commonly added to pesticides, amplify toxicity affecting mortality rates, flight intensity, colony intensity, and pupae development in honey bees.
More Pesticides News and Pesticides Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: The Power Of Spaces
How do spaces shape the human experience? In what ways do our rooms, homes, and buildings give us meaning and purpose? This hour, TED speakers explore the power of the spaces we make and inhabit. Guests include architect Michael Murphy, musician David Byrne, artist Es Devlin, and architect Siamak Hariri.
Now Playing: Science for the People

#576 Science Communication in Creative Places
When you think of science communication, you might think of TED talks or museum talks or video talks, or... people giving lectures. It's a lot of people talking. But there's more to sci comm than that. This week host Bethany Brookshire talks to three people who have looked at science communication in places you might not expect it. We'll speak with Mauna Dasari, a graduate student at Notre Dame, about making mammals into a March Madness match. We'll talk with Sarah Garner, director of the Pathologists Assistant Program at Tulane University School of Medicine, who takes pathology instruction out of...
Now Playing: Radiolab

What If?
There's plenty of speculation about what Donald Trump might do in the wake of the election. Would he dispute the results if he loses? Would he simply refuse to leave office, or even try to use the military to maintain control? Last summer, Rosa Brooks got together a team of experts and political operatives from both sides of the aisle to ask a slightly different question. Rather than arguing about whether he'd do those things, they dug into what exactly would happen if he did. Part war game part choose your own adventure, Rosa's Transition Integrity Project doesn't give us any predictions, and it isn't a referendum on Trump. Instead, it's a deeply illuminating stress test on our laws, our institutions, and on the commitment to democracy written into the constitution. This episode was reported by Bethel Habte, with help from Tracie Hunte, and produced by Bethel Habte. Jeremy Bloom provided original music. Support Radiolab by becoming a member today at Radiolab.org/donate.     You can read The Transition Integrity Project's report here.