Threats to Bees - Studies

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There is always someone ready to take advantage of a crisis situation for personal gain, no matter how much harm this will cause

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POLLINATORS UNDER PRESSURE

Bees threatened by booming macadamia nut industry


From left: Unsplash / Miguel Zalazar | Municipality workers spray pesticide in Pakistan, 04 September 2019. (Photo: EPA-EFE / Shshzaib Akber) | Unsplash / Ankith Choudhary

By Onke Ngcuka | 31 Jul 2022

Rapid growth in macadamia nut cultivation in South Africa has been good for farmers, but not for beekeepers, who are losing bee colonies to intense insecticide use.
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Bees are among the major pollinators of a large number of the plants we eat and, as the demand for food grows, these key insects are under pressure. Farmers are growing crops at a rate that requires more pesticides, which have negative effects on insects, particularly bee colony populations.

Macadamia cultivation in South Africa has grown so rapidly that the country is now Australia’s main competitor for the title of the world’s number one nut producer – with more than 700 growers in the country. The boom in demand for macadamias, boosted by global health trends, has made South Africa the largest commercial planter in the world.

While pesticides to protect the value of the nuts have benefitted farmers and the economy, they have damaged the crop pollinators.

Inge Austin, Mpumalanga Beekeeping Interest Group coordinator, told Daily Maverick “macadamia bee value” was high, with a recent study showing an increase of up to 62% in nut set and quality where nut trees are pollinated by honey bees.

“Yes, bees are required for adequate pollination. The problem is when they apply pesticides when the bees are there, during flowering season,” Austin explained.

Schalk Schoeman, research and extension manager at Macadamia South Africa (SAMAC), told Daily Maverick that while solitary bees were found in large numbers as pollinators, about 90% of macadamia pollination was done by honey bees.

Austin explained that both pesticides and fungicides negatively affected bees when applied in flowering season. Unseasonal rains, which have come a month earlier than usual in the Lowveld region in the past two years, have caused fungal infections in flowers and this has prompted farmers to use fungicides while the bees are still pollinating.

Dr Adriaan du Toit, chairman of the board of directors at the South African Bee Industry Organisation (SABIO), told Daily Maverick pests have always been a problem in agriculture but training and awareness initiatives aim to ensure the use of the right chemicals at the right time.

“We are working very closely with the macadamia association (Macadamias South Africa); we are trying to persuade farmers to spray chemicals at night when the bees are not active,” said Du Toit. “We have had huge successes with that and many farmers are changing their practices at their own cost. We are making them realise we need to have healthy bees.”

But it’s not just the time of spraying that affects bees, the type of pesticide is also an issue.

The pesticide neonicotinoid has been banned in Europe for its neurotoxic effect but is still available and widely used in South Africa. The pesticide, which travels through a plant from its root, becomes a neurotoxin to bees within 10 days of use.

Schoeman said neonicotinoid was still legal in South Africa but he suspected this may change in the future. Alternatives were being developed, but farmers with rough terrain, difficult for tractors to reach for alternative pesticide use, are left with few options.

“There are a bunch of new pesticides available in South Africa but the regulating authorities make it difficult for these products to go through the registration process. It really can take a couple of years for a chemical product to be registered,” said Schoeman.

“The other thing is, even if you release natural products, it also has to be registered. Act 36 (Fertilisers, Farm Feeds, Seeds and Remedies Act 36 of 1947) mandates that anything used in agriculture has to go through a rigorous process of scrutiny.

“I do not see a problem with that, the only problem I see is the time it can take. It can take five to seven years and I wish it was a bit shorter. In agriculture, when things change, you have to be there and go with the change. You can’t react too slowly as that’s going to pull the competitive rug from under us,” Schoeman said.

Austin said beekeepers understood that farmers had to use pesticides on crops but it had to be done in an environmentally friendly way that did not kill bees and other pollinators.

She added; “Macadamias are not the only crops that are detrimental to the health of honey bees; there are several of them. But, because there is such a huge growth of the macadamia industry in the country, it is something we are really concerned about because they need bees so desperately yet our colonies often dwindle after they have been on the macadamias. They don’t always die outright then, but in the months that follow you have a slow collapse; it’s like they never really recover.”

Du Toit said: “From both industries (beekeeping and macadamias), we try to educate farmers on the choice of pesticide because there are alternatives. But that will take time and is a continuous effort.”

About a third of crops depend on pollinator insects in their flowers. Without them, crop production would decline by about 5% in high-income countries and 8% in low- to middle-income ones, Our World in Data has found.

Crops that heavily rely on bees for pollination include fruits such as apples, apricots, blueberries, cherries, mangoes, peaches, plums, pears and raspberries. Nuts such as almonds, cashews and kolas, along with avocados, are also highly dependent on pollinators. Kiwi fruit, melons, pumpkins, watermelons, as well as cocoa beans and brazil nuts, would lose about 90% of their yields without pollinators.

While spraying Doom on insects has become instinctual, the 40% decline in insects could spell disaster for humanity as the Earth’s ecology relies on insects to maintain processes that keep everything alive. The “windshield phenomenon” has proven that the decline in the number of insects on your windshield is an indicator of the decline in insect populations globally, has shown the decline of insects due to a number of factors.

“A rethinking of current agricultural practices, in particular a serious reduction in pesticide usage and its substitution with more sustainable, ecologically based practices, is urgently needed to slow or reverse current trends, allow the recovery of declining insect populations and safeguard the vital ecosystem services they provide. In addition, effective remediation technologies should be applied to clean polluted waters in both agricultural and urban environments,” says a study conducted by scholars from Australia, Vietnam and China.

With macadamia pollen being sticky and not being able to be pollinated by wind, the crop requires dispersal agents such as bees.

Austin said: “We as beekeepers are not saying to farmers, ‘Don’t spray’. We are saying, ‘Spray at the right time with the right stuff’. I would normally encourage them to check labels before spraying, avoid mixing chemicals unless indicated, spray at night when bees and other pollinators aren’t active, scout to spray areas where you need to and not to blanket spray. When farmers blanket spray it’s costly to the environment, because you are killing everything. You walk in some orchards and you don’t see the beneficial predators; the only things alive are the pests they are trying to kill!” DM/OBP

[Lisbeth]

Honeybee lifespan could be half what it was 50 years ago – new study

Published: November 14, 2022


Honeybees are vital pollinators. BigBlueStudio/Shutterstock

A new paper shows how the lifespan of the adult honeybee appears to have shrunk by nearly 50% in the past 50 years. The European Red List for Bees suggests nearly one in ten species of wild bees are facing extinction. Imagine how we would react if human lifespans halved. The equivalent would be if the average woman in the UK was living to 41 instead of 82 years old.

Our future is intertwined with bees. Without bees and other pollinators, we cannot grow the majority of crops we depend on for food.

This research could help explain the high levels of bee colony deaths around the world over the past few decades. Bee deaths were particularly severe in the USA in the winter of 2006-7, when some commercial beekeepers lost 90% of their colonies.

Unexplained high rates of bee colony deaths have also been reported in Canada, Australia, Belgium, France, the Netherlands, Greece, Italy, Portugal, Spain, Switzerland, Germany, Finland and Poland. In the cold winter of 2012-13, 29% of honeybee colonies in the UK died.

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50 years of data
The authors, Anthony Nearman and Dennis van Engelsdorp from University of Maryland, used mathematical modelling to show lower bee life expectancy could lead to mass colony death. According to their study, since 1969, honeybee life span in the US has dropped from a median of 34 days to just 18 days.

The authors studied worker bees removed from hives and kept in cages, not wild bees, which may have affected their results. But if not, something really worrying is going on.


Beekeeper checking honey on the beehive frame in the field full of flowers. We couldn’t do without bees. Juice Flair/Shutterstock

The authors believe modern honeybees may be suffering from higher prevalence of disease such as deformed wing virus, which has become more common since its discovery 40 years ago, due to the global spread of its vector, the varroa mite. Modern bees may be weakened by new generations of pesticides that did not exist 50 years ago.

Often the pollen that bees feed to their larvae is contaminated with pesticides. This could be making matters worse because bees exposed to low doses of a highly toxic group of pesticides called neonicotinoids have reduced resistance to disease.

Another explanation the authors offer is that bee genes may have changed. Honeybee lifespan is linked to their genes. Artificial (by beekeepers) or natural selection may favour bees with shorter lifespans. Scientists are seeing this happen in other species. For example cod now mature earlier and when they are smaller in size because overfishing means fish rarely survive long enough to grow large.

Perhaps stressors in the modern world, such as pesticides and disease, mean honeybees rarely survive for a long time. So their evolution might favour a live-fast-die-young lifestyle.

Everyone’s problem

Bees are already facing many pressures on their survival. A separate study by the University of Bristol, released in November 2022, found that fertilisers are altering plants’ electric field which is changing the way bees sense flowers. It is putting them off from visiting flowers. And bee habitat is disappearing. Since the 1930s, 97% of wildflower meadows have been lost in the UK as farming has intensified.

Fascinating though it is, this new study raises more questions than it answers (as good science usually does). The data is based on groups of worker bees kept in cages. This method is often used to study the effects of stressors (such as pesticides) on bees.

In these sorts of experiments, researchers would normally set up control groups at the same time and under identical conditions. Nearman and van Engelsdorp used the historical data from control groups in many such studies carried out around the USA since 1969. As the authors acknowledge, this is a weakness in their report.

They can’t guarantee that lab conditions have stayed the same since 1969. Perhaps older studies tended to use wooden cages and modern ones use plastic. Cage sizes may become smaller or larger. The ariflow in modern incubators may now be faster – or slower. Such details are rarely noted. Anything that changed over the past 50 years could explain the reduction in longevity.

It won’t be easy for scientists to unravel the study’s findings. But if we could find historical data on wild honeybee longevity from previous decades, we could compare them with measurements from today’s world. This would help scientists rule out the possibility that the study’s results were affected by lab conditions.

Reduced bee life expectancy means reduced pollination. Bees and other pollinating insects are essential to a good harvest for 75% of the crops we grow worldwide. They also pollinate about 80% of all wild plants. All species of bees face similar challenges to honeybees, but we do not know if their life expectancy has changed. If bees are really living for less time in the wild, we need to know why.