Do systemic insecticides harm bees?

I've just finished harvesting my pathetic crop of broad beans - the annual battle with blackfly. Two years ago I tried not spraying at all, as although the plants were infested with blackfly, I had more ladybirds than you could shake a stick at. But they weren't man enough for the job, and the blackfly infestation actually killed all my plants.

Last season and this, I've used a contact spray, late evening when the bees have finished pollinating. But the plants still suffer badly.

I avoid using systemics as I have always assumed that the insecticide would get into the nectar and kill the bees. Does anyone know if this is actually the case?

I think the jury is out on that one, it's all probably connected with the neonicotinoid argument.  The problem is that like wind farms & TB in badgers  opinions are so deeply entrenched on one side or the other that it is impossible for there ever to be any rational debate.  Add into the mix big, rich chemical companies that can make the science say whatever they want, probably nothing will ever be proven.  That doesn't help your broad beans.  Have you looked into whether there are any varieties more resistant to blackfly, or any companion planting that you can sacrifice?  What do organic growers recommend for blackfly control?  Where do blackfly appear from?  Can you cover the plants with a fine mesh before the blackfly get on them but after the bees have had a chance to get at them?  
Sorry, more questions than answers.

Ploshkin wrote: Have you looked into whether there are any varieties more resistant to blackfly, or any companion planting that you can sacrifice?  What do organic growers recommend for blackfly control?  Where do blackfly appear from?  Can you cover the plants with a fine mesh before the blackfly get on them but after the bees have had a chance to get at them?  

Actually, no, I hadn't thought about changing variety. It is a particularly nice one with green skinned beans. And no, I hadn't thought about companion planting/organic blackfly control - will look at that.

The mesh will be a non-starter as the blackfly infestation starts well before the flowers open. I know the recommendation is to pinch out the tips of the plants, but they never seem to start there. They cover the entire length of the stem, on all sides, the underside of the leaves, the green parts of the flowers and the beans themselves.

Actually, I think I've started this in the wrong place, as it's more about blackfly than bees.

I think it's a fine place to discuss this FB - after all, everything is connected in one way or other...
I've had the same annual battle with blackfly (except this year my broadies were so pathetic that not even the blackfly were interested!) I have used a soap based insecticide to keep them down a bit, but as it's a contact insecticide you have to spray a lot. I don't think it affects bees though.

I think the answer regarding neonicotinoids and bees is "strongly implicated". The EU seem to think so, at least.

With regards to the organic solution - a strong blast with the hose dislodges a lot of them. Dandelion's idea of soft soap is also an organically acceptable option, pyrethrin (contact insecticide) has in the past at least been regarded as an organically acceptable treatment on the basis of the (IMHO, bogus) argument that it is a naturally occuring compound.

But the true organic way of thinking is to wonder why you have such a severe problem to begin with. It is unusual for blackfly to actually kill the plants - I usually only get it in the tops, and on the pods later on. Are they growing happily and vigorously ? What's your soil like ? Are they overwintered, or spring planted ? I have always grown autumn planted ones, which perhaps get off to an earlier start in spring before the blackfly find them ?

Chilli-head wrote:But the true organic way of thinking is to wonder why you have such a severe problem to begin with.  It is unusual for blackfly to actually kill the plants - I usually only get it in the tops, and on the pods later on.  Are they growing happily and vigorously ? What's your soil like ?  Are they overwintered, or spring planted ?  I have always grown autumn planted ones, which perhaps get off to an earlier start in spring before the blackfly find them ?

This year, unusually, I had both overwintered, and spring planted, broad beans. They were all as badly hit as each other. I start my plants in rootrainers, planting them out once they are a good size. My garden is London clay, but I always try to incorporate organic matter for peas and beans.

I've always had bad blackfly problems, but before I understood the potential harm I used to use systemics prior to the plants coming into flower.

Have you ever tried sowing them direct ?

Some reckon that soft growth attracts aphids, and if grown 'tougher' they might be less appealing to them. Now, I have one plot (the garden) on sand and the other (the allotment) on Bedfordshire clay, despite them being quite close - crazy variability we have around the Greensand ridge. I can get broad beans to grow on both, though I have to admit that the losses are heavy in a wet winter on the clay. The yeild is higher on a good year though, which is why I struggle on.

Chilli-head wrote:

With regards to the organic solution - a strong blast with the hose dislodges a lot of them.  Dandelion's idea of soft soap is also an organically acceptable option, pyrethrin (contact insecticide) has in the past at least been regarded as an organically acceptable treatment on the basis of the (IMHO, bogus) argument that it is a naturally occuring compound.

Ha - yes! My family are pretty fed up with my stock reply to the argument 'It's completely natural' which is 'yes - and so is hemlock!'

Chilli-head wrote:Have you ever tried sowing them direct ?  

No, I haven't, but that may be worth a try. The constant overgrowness of my garden does tend to harbour slugs and snails. Most of what I sow direct I never even see emerge as the little buggers get there first. That's why I start everything in pots. Also rats and mice have taken seed before now, and foxes like to dig too. But I will think about how I can protect them without encouraging soft growth.

I looked into biological controls, and there doesn't seem to be anything really. Interesting to see that blackfly overwinter on spindle and guelder rose - I'm not aware of any around here, although 2 gardens away is very overgrown and unkempt.

I appreciate all the suggestions - it's certainly given me food for thought.