Defra: An assessment of key evidence about Neonicotinoids and bees

Well, you wait awhile for an interesting report on neonicotinoids, and three come along at the same time. Buses must be like neonic reports. This one should set the conspiracy theorists into melt-down. Defra are showing their hand. I wonder what pose the Scottish Government is going to strike?

An assessment of key evidence about Neonicotinoids and bees

March 2013

Executive summary

Three recent studies in which bees were dosed with neonicotinoids showed sub-lethal
effects on bees [1-3]. The results from these studies contrast with a growing body of
evidence from field studies that has failed to show an effect of neonicotinoids when
bees are allowed to forage naturally in the presence of crops treated with
neonicotinoids [4-8]. The evidence suggests the reason for this difference is over-
dosing of bees in the dosing studies; in all cases there is evidence that the doses of
neonicotinoids presented to bees under laboratory or semi-field conditions were
unrealistically high. The dosing studies therefore represented the extreme case in a
field situation. In the only study in which dose was measured [1] the dose was much
greater than would have ever been experienced in a field situation.

A concentration of 1-5 μg/l of neonicotinoid in nectar appears to be the threshold below
which an effect tends not to be observed [9] and most residue measurements in the
nectar and pollen of treated crops are normally at or below this level [4,6,7,10,11]. In
addition, examination of bee foraging shows that they tend not to feed exclusively on
treated crops [7], thus diluting any effects of neonicotinoids. Consequently, the
evidence of effects of neonicotinoids on bees come from studies [1-3] in which doses
were likely to have been at least 2-10 times above this threshold.

There is a possibility that field studies did not have the statistical power to show effects
but the accumulated evidence across several independent studies suggests that this is
unlikely and, any effects that are present are likely to be small and not biologically
significant. Moreover, oilseed rape (OSR) requires insect pollinators to support its
productivity [12-18]. The fact that OSR treated with neonicotinoids has been a
productive crop for over a decade in the UK is itself evidence that pollinator
populations, including bees, are not being reduced by the presence of neonicotinoids.
Conclusion: While this assessment cannot exclude rare effects of neonicotinoids on
bees in the field, it suggests that effects on bees do not occur under normal
circumstances. This assessment also suggests that laboratory based studies
demonstrating sub-lethal effects on bees from neonicotinoids did not replicate realistic
conditions, but extreme scenarios. Consequently, it supports the view that the risk to
bee populations from neonicotinoids, as they are currently used, is low.

Interesting review and to my knowledge the first which has cast serious doubts about the methodology of the Whitehorn et al study.

One thing that bothered me in the Defra report is the comment that OSR still yields well so the pollinators must be OK. Seems far too casual to be using for this kind of thing, especially when it is known that bees are not that important for the pollination of rape.

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Putting bee colonies on oil seed rape is supposed to increase the yield by up to 15%. reference escapes me for the moment but it is from Australia or NZ

Yes, but it is a weak argument to use that to say that the rape still yields well, so the pollinators must be OK. If it really was pollinator armageddon out there, we'd have spotted it by now. They are responding to the more alarmist calls from conservationists. The more sane and rational ones (me for example!) would say that there are still bumble bees in arable areas, but are the populations and is the species diversity lower than it should be simply because of neonics? You wouldn't deny that by simply saying the rape yields well, so all is fine in the countryside.

It should be blindingly obvious to all that habitat loss is the big one, and those pressing for a ban on neonics - if neonics are more or less harmless in the way they are being used - are doing nature conservation a disservice. A disservice because they are taking the focus away from the real issues, and in the long run the loss of farm pesticides may cause more land to be used for food production than is necessary. That is why it is wrong, wrong, wrong to press for extreme action unless you are sure it is right.

There's me having a pop at Defra, SWT, Buglife, Soil Association, Friends of the Earth and the more excitable wing of the SBA all in one forum post.

the soil dwellers might be the best place to look for probs with Neonics
Or the nibblers like beetles etc.
They form the basis of a food chain
Creatures which munch them might be at risk
Bees could be affected but they have a short life at the time of year when Rape flowers
Back at the hive there seems to be no observable effect on brood etc.
The production tons/hectare rape has gone up considerably so there is room for maneuver