Bees: How Important Are They and What Would Happen If They Were Extinct?

The Conversation - I Need to Know August 19, 2019

How important are bees and what will happen when they go extinct? Is there research into what is killing them? I’ve been told it’s weed killers… – Tink, aged 18, Cornwall, UK.

Bees – including honey bees, bumble bees and solitary bees – are very important because they pollinate food crops. Pollination is where insects move pollen from one plant to another, fertilising the plants so that they can produce fruit, vegetables, seeds and so on. If all the bees went extinct, it would destroy the delicate balance of the Earth’s ecosystem and affect global food supplies.

There are more than 800 wild bee species within Europe, seven of which are classified by the International Union for Conservation of Nature (IUCN) as critically endangered. A further 46 are endangered, 24 are vulnerable and 101 are near threatened. While it’s unlikely that all bee species will be wiped out anytime soon, losing these threatened species would still have a big impact on pollination around the world, wiping out plant species, some of which we rely on for our food.


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But the problem goes far beyond bees. In fact, honeybees are responsible for only one third of crop pollination and a very small proportion of the wild plant pollination. There are a diverse range of other insects including butterflies, bumblebees and small flies that do the rest of the work – and it looks like these insects are in trouble too.

A bumblebee, pulling it’s weight. Emily L Brown, Author provided

A bumblebee, pulling it’s weight. Emily L Brown, Author provided

A recent study suggests that as many as 40% of the world’s insect species are in decline. Insects are facing extinction rates that are eight times higher than vertebrates. In Germany, scientists have recorded losses of up to 75% of the total mass of insects in protected areas.

These trends lead scientists to believe that about a third of all insect species – that’s nearly 2m – may be threatened with extinction. And that figure is growing by over 100,000 species every year. Yet hard data on threatened insect species is lacking, with only 8,000 records actually assessed by the IUCN.

Here’s a rundown of what scientists believe to be the top causes of declines in insect diversity and abundance.

Invasive species

Invasive predators, parasites and disease-causing bacteria called “pathogens” have been blamed for the collapse of honeybee colonies around the world.

Recently, the spread of the Asian Hornet in Europe has caused great concern. This species preys on honey bees, and a single hornet is capable of killing an entire hive.

There is some evidence that wild bees in North America have declined in the face of fungal and bacterial diseases.



Of course, in the past bees have coexisted with these pathogens. The fact that scientists have seen more bees lost to these diseases in recent times is probably linked with the bees’ increased exposure to pesticides, which can damage their immune systems.

Pesticides

Pollution – particularly from exposure to pesticides – is a key cause of pollinator decline. There are three types of chemical pesticide widely used in the UK: insecticides targeting insect pests, fungicides targeting fungal pathogens of crops and herbicides targeting weeds.

Insecticides contain chemicals that can kill pollinators, so they’re clearly a threat. But they may not be the greatest problem pollinators experience. Herbicides are actually used five times as much in farming as insecticides. These weed killers target a huge variety of the wild plants that bees need to forage.

Environmentally-friendly farming schemes recommend planting wildflower strips on the edge of crops, to provide safe refuge and food sources for pollinators. Yet drifting clouds of herbicide from growing fields can contaminate these wildflower strips.

Wildflowers border farmland in Sussex, UK.  Shutterstock.

Wildflowers border farmland in Sussex, UK. Shutterstock.

The most cutting-edge research suggests glyphosate (the most commonly used weed killer) can impact the gut microbes of bees, which can have devastating implications for their health.

Although exposure to herbicides and pesticides used by farmers is likely to be one of the main causes of pollinator decline, the chemicals used by city authorities and civilian gardeners might also be harming bees and other insects. So, for the bees’ sake, it’s best to avoid using them where possible.

Climate change

Global warming is believed to be a major driver of wild bee declines. Some wild bees can only survive in a narrow range of temperatures. As their habitats get warmer, the places where they can live grow smaller. For example, some might be forced to live at higher altitudes, where it’s cooler, reducing the space they have to live in.

Habitat destruction

The way land is farmed has been associated with declines in biodiversity and pollination. Farming destroys the kinds of spaces that bees use to nest, it takes away the diversity of food that bees use to forage on and it even has wider impacts on other animals like wild birds, mammals and amphibians.

While countless insect species are currently going extinct, those that remain are taking their place, so it’s unlikely that crops will stop being pollinated any time soon. Generalist species such as the buff-tailed bumblebee, the European honey bee and common small black flies, which can survive in a huge range of temperatures and conditions, will become the main species pollinating our food sources, while rarer, more specialist species will decline.

But as generalist species move in to take the place space left by the losses of specialists, and complex ecosystems become dominated by a couple of generalists, the whole system becomes far more susceptible to a single sudden change. Insects form the base of many intricate food webs, their decline will result in a complex cascade of impacts on vertebrates, threatening ecological stability.

https://theconversation.com/bees-how-important-are-they-and-what-would-happen-if-they-went-extinct-121272

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Herbicides, Not Insecticides, Biggest Threat to Bees

AGFAX   By Bonnie Coblentz    December 17, 2015 

People who care about honeybees know that insecticides and pollinators are usually a bad mix, but it turns out that herbicides used to control weeds can spell even bigger trouble for bees.

Jeff Harris, bee specialist with the MSU Extension Service and Mississippi Agricultural and Forestry Experiment Station researcher, said herbicides destroy bee food sources.

“When farmers burn down weeds before spring planting, or people spray for goldenrod, asters and spring flowers, or when power companies spray their rights-of-way, they’re killing a lot of potential food sources for bees and wild pollinators,” he said.

Harris said the direct effect of these chemicals on bees is so much less of an issue than their loss of food supply.

“Disappearing food is on the mind of beekeepers in the state,” he said. “That is even more important to them than losses of bees to insecticides.”

Johnny Thompson, vice president of the Mississippi Beekeeping Association, is a cattle and poultry farmer in Neshoba County who has been in the bee business for the last 10 years.

“Before we got back into bees, I sprayed pastures by the barrel to kill weeds. As a cattle farmer, weeds are a nuisance,” Thompson said. “I’m trying to grow grass for the cows to eat and not weeds, but as a beekeeper, those weeds are not weeds. That’s forage for the bees.”

Today, Thompson said he uses the bush hog more than he sprays herbicides to keep the food supply for bees intact on his land.

“If you kill everything the bee has for food, you may as well go in and spray the hive directly. The bees are going to die,” he said. “All the emphasis is being put on insecticide, but the greater risk to bees are the herbicides.”

He has made management changes for the sake of his bees’ food supply, but he recognizes the tension between current agricultural management practices and pollinators’ best interests.

“When you travel through the Delta or the prairie part of the state in February, the row crop land is purple with henbit blooming. By the end of March, it’s all gone because farmers burned it down with chemicals to try to kill everything in the field before they plant,” he said.

“They burn it down early because weeds in March or early April are a reservoir for insect pests to the crops that will soon be planted,” Thompson said.

Crops in the field, especially soybeans, are great sources of bee forage, and farmers and beekeepers can coordinate to protect both of their interests. 

“We moved bees to the Delta this summer to make soybean honey,” Thompson said. “We’re working with the growers to try to put the bees in areas that are fairly protected and won’t get directly sprayed.”

But farmland is not the only place bees find food. Yards, roadsides, golf courses and power line rights-of-way are other places bees forage when plants are allowed to bloom naturally.

“We need to stop looking at them as weeds and instead look at these plants as forage,” Thompson said. “I can manage around the insecticides, but if herbicide use means there’s nothing for a bee to eat, there’s no reason to put a hive in an area.”

http://agfax.com/2015/12/17/pollinators-herbicides-not-insecticides-biggest-threat-to-bees/

Effects of Sub-lethal Doses of Glyphosate On Honeybee Navigation

The Journal of Experimental Biology   Accepted July 2, 2015

Research Article/Abstract

Glyphosate (GLY) is a herbicide that is widely used in agriculture for weed control. Although reports about the impact of GLY in snails, crustaceans and amphibians exist, few studies have investigated its sub-lethal effects in non-target organisms such as the honeybeeApis mellifera, the main pollen vector in commercial crops. Here, we tested whether exposure to three sub-lethal concentrations of GLY (2.5, 5 and 10 mg/L corresponding to 0.125, 0.250 and 0.500 µg/animal) affects the homeward flight path of honeybees in an open field. We performed an experiment in which forager honeybees were trained to an artificial feeder, and then captured, fed with sugar solution containing GLY traces and released from a novel site (the release site, RS) either once or twice. Their homeward trajectories were tracked using harmonic radar technology. We found that honeybees that had been fed with solution containing 10 mg/L GLY spent more time performing homeward flights than control bees or bees treated with lower GLY concentrations. They also performed more indirect homing flights. Moreover, the proportion of direct homeward flights performed after a second release at the RS increased in control bees but not in treated bees. These results suggest that, in honeybees, exposure to GLY doses commonly found in agricultural settings impairs the cognitive capacities needed to retrieve and integrate spatial information for a successful return to the hive. Therefore, honeybee navigation is affected by ingesting traces of the most widely used herbicide worldwide, with potential long-term negative consequences for colony foraging success.

Read at: http://jeb.biologists.org/content/early/2015/07/09/dev.117291.abstract