Tag Archives: fungicides

Perfect poisons for pollinators – available from your local garden centre

We try to make our garden welcoming for bees by growing flowers that provide pollen and nectar throughout the season. We also have some unkempt areas they might want to nest in and we don’t use any pesticides. I enjoy watching the bees foraging on the flowers as they come in to bloom and currently a large cotoneaster bush is full of small bumblebees buzzing loudly as they feed in the sunshine. It’s been very exciting this year to see bumblebees and solitary bees nesting in the dry-stone walls around the garden.

When we need new plants or compost, there is one local garden centre we use. It has a good range of healthy-looking plants and a very nice tearoom! In early spring, it’s also an excellent place to watch one of my favourite bees, the hairy-footed flower bee (Anthophora plumipes), whizzing about in the greenhouses full of flowers. Earlier this year, on a sunny Sunday afternoon in late March, I noticed that these Anthophora had set up nests in the old brick wall of one of the garden centre’s buildings.

Bee 4
A hairy-footed flower bee foraging on plants within the garden centre

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About a year ago, I saw a crowd funding request from the well-known bee-defender and researcher, Dave Goulson from the University of Sussex. He wanted the money to test whether plants sold in garden centres in the UK and labelled as “bee-friendly” actually contained bee-toxic pesticides, applied during production of the plants. I remember being quite shocked to read about this possibility – could I have been buying plants to help the bees that were in fact laced with bee-toxic chemicals?

I wanted to find out more so I got in touch with our favourite garden centre and asked whether they were using neonicotinoid insecticides on their plants. They reassured me that they were not. So far so good. I then asked if their suppliers used neonicotinoids in the compost on the plants they sold. The reply came back “I’m afraid I can’t answer that question without phoning every supplier. Also a few companies we deal with import some of their stock from other European countries. I’m happy to ask my local nurseries when I’m speaking to them.” That’s the last I heard.
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Dave Goulson got his money and went ahead with the analyses. The results of his tests have just been published and they don’t make happy reading;  here is a link to his blog on the topic. He and his colleagues bought 29 pots of flowering plants from well-known garden centres around Brighton (Wyevale, Aldi, B & Q, Homebase). Many were labelled “bee-friendly” and some had the Royal Horticultural Society endorsement “Perfect for Pollinators”.

They analysed a range of pesticides in leaves and pollen from the plants and found that most of the plants contained a cocktail of insecticides and fungicides. In the leaf analysis, only 2 of the 29 plants contained no pesticides. 76% contained one or more insecticide and 38 % contained two or more. 70% of the leaf samples analysed positive for neonicotinoid insecticides, well known for their toxic effects on bees. In the pollen analysis, neonicotinoids were found at levels known to cause harm to bees. So much for “Perfect for Pollinators”.

As a result of his work, B & Q announced that from February 2018 their plants would be neonicotinoid-free. Aldi revealed that they had stopped using neonicotinoids in October 2016, a few months after Goulson’s analyses took place. Neither B & Q nor Aldi  addressed the other chemicals found in the Sussex analysis.

The Horticultural Trades Association issued a statement that I believe is both silly and cynical, basically rubbishing Goulson’s analysis. You can read Dave Goulson’s rebuttal here.
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So, it really is true that when we buy plants to help bees in our gardens from garden centres, we may be unwittingly exposing the bees to harmful chemicals, despite the “bee-friendly” labels. Also, any insect that nips into a garden centre for a feed, especially early in the season when garden centres have an abundance of flowers, may be getting a hit of insecticide at the same time.

So, what do we do if we want to have a bee-friendly garden?

Dave Goulson recommends the following course of action: if you must buy plants, buy from an organic garden centre or, failing that, go to B & Q or Aldi. Better still, grow from seed or swap plants with friends and neighbours.
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One point that has not been discussed so far concerns potential effects on humans of these pesticides found in garden centre plants. Earlier this year, I bought some fruit bushes from the garden centre and these now have a nice crop of plump berries. If these plants have been treated with pesticides, and of course I don’t know if they have, then the fruit will presumably also contain these pesticides. This possibility makes me very angry. I grow fruit in our garden so that we can eat chemical free, fresh, good quality produce. I don’t want to ingest insecticides and fungicides with poorly defined toxic effects on humans.

The featured image shows a hairy-footed fower bee feeding from plants in a lane adjacent to the garden centre

500 dead bumblebees – the chemical blitz of modern farming

In September I wrote about the mysterious death of 500 bumblebees. New information has emerged about this incident so I have rewritten the post:

Earlier this year, Sheila Horne was walking at Hacton Parkway, a public park and conservation area in Havering, East London. April is normally a good time to see insects in their prime so she was very surprised to find many dead and dying bees near the path. She alerted local naturalist, Tony Gunton who identified the insects as bumblebee queens from three species, red-tailed, buff-tailed and common carder. This was not a minor incident, there were as many as 500 bees affected.

Chemical analysis of the dead bees

Natural England was appointed to investigate the insect deaths and samples of dead bees were sent to FERA in York for analysis. The results were released in August and showed that the bees were contaminated with the neonicotinoid insecticide imidacloprid and two fungicides, flusilazole and epoxiconazole. Imidacloprid can be very poisonous to bees and bumblebees are more susceptible to this chemical than honeybees. Imidacloprid is currently subject to a two year partial ban for some agricultural uses in the EU. Neither fungicide on its own is especially toxic to bees although flusilazole was phased out this October because of its high toxicity to fish and because of other potential toxic effects.

A nearby field of oil seed rape as the source of the chemicals?

The chemical analysis raises two questions. Where did the bumblebees pick up these chemicals? Were these chemicals responsible for the bee deaths?

Neither question can be answered definitively but as so many dying bees were found together in one place, it seems likely that the source of the poisoning was close by. Hacton Parkway lies alongside arable farmland and at the time of the poisoning some of the land was planted with flowering oil seed rape, so it is a reasonable conclusion that the bees had been feeding there. Because of the chemical analysis, it was initially assumed that the crop had been planted using seed treated with imidacloprid ahead of the ban and that the imidacloprid had killed the bees. Natural England have recently concluded their investigation and found that in fact the seed used to plant the crop had been treated with another neonicotinoid, thiamethoxam. Neither imidacloprid nor epoxiconazole had been used on the crop and the last spraying with flusilazole was in November 2013. Analysis of the dead bees for thiamethoxam failed to detect any of the chemical but this could have been due to losses before the analysis.

What killed the bees?

So, why did these bees die? Because there are so many unanswered questions we cannot be sure. The dead bees were contaminated with imidacloprid but the oil seed rape crop was not the source. We can only assume that the bees fed elsewhere on imidacloprid-treated crops and were flying with this chemical in their systems. It is known that at typical field concentrations, imidacloprid does not kill bumblebees.

There is also the question of how the bees were exposed to the two fungicides if the oil seed rape had not been sprayed with these chemicals during the flowering season. As with the imidacloprid, we have to assume that the bees were exposed elsewhere. It is possible that the fungicides weakened the bees or made them more susceptible to the neonicotinoids. There is some evidence for such interactions for other insecticide/fungicide pairings.

Because the bees died close to the treated crop, the focus of lethality has to be on the thiamethoxam, now known to have been used on the oil seed rape. Although thiamethoxam is indeed an insecticide, there is evidence from one lab-based study and another field study (albeit lacking controls) that, at field-realistic concentrations, thiamethoxam is not lethal to bumblebees. I find it unlikely, therefore, that thiamethoxam alone killed the bees, providing the farmer followed safety guidelines.

We shall never know what actually happened at Hacton Parkway but my best guess is that these bees were flying with the three chemicals in their system and encountered the thiamethoxam-treated oil seed rape. When they fed from it, they picked up the additional neonicotinoid. Two neonicotinoids, with perhaps synergistic effects of the fungicides, were too much and they died.

The investigation is now closed!

The investigation is now closed and it will be impossible to resolve the many questions raised by this incident, which is a pity. Despite this uncertainty, the results of the chemical analysis stand. These bees died with three chemicals in their bodies: one neonicotinoid and two fungicides. They were also exposed to a second neonicotinoid. This was no laboratory experiment; this reflects what is happening around us when these chemicals are used. Have a look at this report to see more evidence of the widespread use of chemicals in UK farming. Our agricultural practices have led to this chemical blitz and the result is the deaths of important pollinators. How often is this occurring on a lower level but not being noticed or reported?

I should like to thank Tony Gunton (local naturalist) and Helen Duggan (Press Officer, Health and Safety Executive) for sharing information about this incident.

500 dead bumblebees – pesticides leave their deadly trace

Earlier this year, Sheila Horne was walking at Hacton Parkway, a public park and conservation area in Havering, East London. April is normally a good time to see insects in their prime so she was very surprised to find many dead and dying bees near the path. She alerted local naturalist, Tony Gunton who identified the insects as bumblebee queens from three species, red-tailed, buff-tailed and common carder. This was not a minor incident, there were as many as 500 bees affected.

Natural England was appointed to investigate the insect deaths and samples of dead bees were sent to FERA in York for analysis. The results were released a few weeks ago and showed that the bees were contaminated with the neonicotinoid insecticide imidacloprid and two fungicides, flusilazole and epoxiconazole. Imidacloprid is very poisonous to bees with bumblebees being more susceptible to this chemical than honeybees. Imidacloprid is now subject to a two year partial ban for some agricultural uses. Neither fungicide on its own is especially toxic to bees although flusilazole is due to be phased out this October because of its high toxicity to fish and because of other potential toxic effects.

But where did the bumblebees pick up these chemicals? We cannot be sure but as so many dying bees were found together in one place, it seems likely that the source of the poisoning was close by. Hacton Parkway lies alongside arable farmland and at the time of the poisoning some of the land was planted with flowering oil seed rape, so it is a reasonable conclusion that the bees had been feeding there. It is thought that the crop had been sown in autumn 2013 using seed treated with imidacloprid, just ahead of the ban. According to John Rennie of Natural England there had been no spray applications of insecticides or fungicides since the beginning of 2014.

So, why did these bees die? Because there are so many unanswered questions we cannot be sure. The imidacloprid used on the oil seed rape has been blamed by some but I can’t see how this could be a problem if the farmer followed safety guidelines. There is good evidence that exposure to typical agricultural levels of imidacloprid does not kill bumblebees although there is also good evidence for sub-lethal effects on behaviour and reproduction. It is, however, becoming apparent that neonicotinoids such as imidacloprid accumulate in soil so perhaps exposure levels of the dead bees were higher than expected. Soil testing would be informative here.

There is also the question of how the bees were exposed to the two fungicides if no spraying was performed during the flowering season? Does this mean that these chemicals persist for long periods or has there been spraying elsewhere? Perhaps the fungicides weakened the bees or made them more susceptible to the imidacloprid. There is some evidence for such interactions for other insecticide/fungicide pairings.

Although the investigation continues, it may be quite difficult to resolve some of these questions. Despite this uncertainty, the results of the chemical analysis stand. These bees died with three chemicals in their bodies: one insecticide and two fungicides. This was no laboratory experiment; this reflects what is happening around us when these chemicals are used. Our agricultural practices have led to this and the result is the deaths of important pollinators. How often is this occurring on a lower level but not being noticed or reported?

With thanks to Tony Gunton for talking to me about this incident