Parasitoid wasps

[PinkButterflies]

Many of us 'breed' butterflies & moths in controlled conditions to increase local numbers only to find some of our charges have be parasitised by the tiny wasps who are out there and predating on every stage of the lifecycle.
So, two items for discussion here;
The fruit industry buys in large numbers of these 'natural' defenses to keep caterpillar numbers down and increase fruit production. All fine if these parasitoid wasps stuck to codling moth larvae and stayed in the orchard. Trouble is of course is that they don't do either and will range anywhere they want and pick on any appropriate target. I don't know what kind of numbers occur naturally but the industrialisation of such wasp number will definitely impact on our threatened butterflies. What, if anything, can organisations such as UKB do about this?
Second, what can we do in our own back gardens and flight-houses to combat these wasps? What I do is keep the enclosures closed as much as possible, watch for and kill any I find inside and put up sticky fly-traps which seems to be quite a successful combination. I also put down garlic puree as the wasps are attracted to the cat dropping and it may just disguise the smell a bit.
Anyway, open to thoughts and info from others.

[Padfield]

To kick off the discussion, I have two questions. They are not intended provocatively, except in the sense of provoking comment!

Firstly, is there any evidence imported parasitic wasps are having a detrimental effect on British butterfly populations?

Secondly, is there any point in breeding butterflies 'to increase local numbers'? Surely, the only local numbers that count are those that belong to the self-sustaining local population. If the population is not self-sustaining, I would think the way to rectify this is by addressing environmental issues, not masking the failure with released butterflies ...

Guy

[Pete Eeles]

Also - the association between a butterfly species and parasitic wasps can be quite specific, with certain parasites targeting individual butterfly species. Species that come to mind are the parasites of Large White, Holly Blue and Marsh Fritillary.

Cheers,

- Pete

[Neil Hulme]

Indeed, there isn't a shred of scientific evidence to suggest that "industrialisation of such wasp number will definitely impact on our threatened butterflies" and we should strive to avoid such scare-mongering.

The parasites and parasitoids which are involved in a constant seesaw battle with their host species are 'part and parcel' of that species' autecology. We should not attempt to upset the balance of nature, and it's not going to work anyway. If you protect a generation of captive-bred individuals from wasps and tachinids, and then release them, their progeny will be subject to the same natural, cyclical % rate of attrition as the next generation of 'wild' butterflies.

It is highly commendable to try and assist our highly pressured butterfly fauna, but the best way to do this really is to help improve their natural habitat, and let Mother Nature do the rest.

BWs, Neil

[PinkButterflies]

My discussion was not intended to be 'scientific' just to ask what this forum thought about the subject. I have a friend who works for a large company that produces these wasps for industrial purposes and millions of them are put into the environment, as I say, not in any targeted way but to try and protect crops. No doubt there is also significant sales to individuals for garden or allotment use. My point was that this is unregulated and upsets the 'natural' balance. You can take or leave that simple factor.
Having lost considerable numbers to wasp larvae I will continue to watch for and protect against them.

The second point which contests the value of releasing is odd. Numbers are generally declining across all species so adding to the numbers will impact positively to counter this. Of course the underlying factors are environmental and guess what, I'm not just optimistically hoping my releases will change much alone, no of course I'm also active in environmental issues. I work with the local council to improve habitat in parks and we do a lot of beneficial planting as well as removal of alien species which are dominating local woodland.

I find it odd that the usual British response is to criticise but there you go.

[Susie]

I find it odd that the usual British response is to criticise but there you go.

.....said PinkButterflies criticising the perfectly reasonable responses received from the other forum members

[Pete Eeles]

I find it odd that the usual British response is to criticise but there you go.

I think you'll find that the responses are facts or opinions, rather than criticisms.

Cheers,

- Pete

[Padfield]

Yes - no criticism intended or implied. On my first point, I am unaware of any threat to UK butterflies from imported biological control species and simply wondered what the evidence was. If there really is a threat, of course, we should be aware of it and acting on it. But evidence is needed. On the second point, I do politely disagree with you, though to what extent depends on the species involved. I can see no reason at all why releasing butterflies should increase their wild numbers or benefit the species. Clearly, there is no harm in releasing common species, like small tortoiseshells, or highly mobile species, like painted ladies. But I would have thought releasing any species that was actually threatened would be counterproductive, except as part of a documented and preferably authorised (re)introduction to an area that could sustain the species but where it doesn't currently fly. I live in a country where there are a lot of extremely rare butterflies and numerous threats to them but I have never heard of any attempt to support any of them by breeding and release.

I'd prefer to characterise the British as pragmatic, rather than critical!

Guy

[Willrow]

What specific species of parasitoid wasp is being used? This is highly relevant as most (if not all) British butterfly species that are infected are to the best of my knowledge infected by specific wasp species ie. Cotesia sp in the case of Marsh Fritillary. It would prove interesting to know a little more about these 'industrially produced wasps' before we consider any possible conflicting conservation issues. Would it be unreasonable not to expect any British company producing/breeding these insects for control of other (British) insects to be both licensed and tightly regulated by the appropriate body. There are EU laws vigourously applied to prevent or (at least) try to prevent wherever possible any serious environmental problems or damage.

As regards any evidence to support any possible 'suggestion' that our British butterfly species are being infected by 'industrially produced wasps' I will leave to my sage fellow UK Butterflyers.

Research on insect parasitology is costly, complex and sophisticated, yet absolutely essential for human food resources, and we butterfly enthusiasts and ecologists have received a 'side-benefit' from these research findings and used these findings to assist in our attempts to help protect and conserve our British butterfly species.

It is better to have no information than misinformation, but I still believe in good interesting (respectful non personal) debate and input on all subjects relating to our butterflies and the Great British environment, so let us not worry about provocation or any scare-mongering, this is after all UK Butterflies

Bill

"When in doubt...venture out"

[PinkButterflies]

There are mainly Ichneumon, Braconid & Chalcid wasps available and these are not particularly species dependent.

As for local release, of course it will make a difference and we only release where the local environment can support that species. As I said, we also do a lot to enhance the ecosystems around us too.

I'll now go back below the firing line and get on with what I was doing.

[David M]

Shame if you do that, PB. All contributions to this forum are welcome, especially those that elicit debate, which yours undoubtedly have.

Personally, I never knew that these wasps were bred for such purposes so thanks for highlighting it.

[Paul Wetton]

I hope the companies that produce these wasps and release them perform some work looking at the impact of their work on the natural environment. If they don't, they should or they should be prevented from releasing these wasps - in my opinion.

I've mentioned this before with regard to releasing non local butterflies into a population. The genetic make up of the released butterflies may give them an advantage over the local butterflies and the entire population could then take on the genetic make up of the released individuals. The problem lies when a virus or other disease comes around that the locals were immune to but not the released stock. Then where there was a small population there could be none. This may not happen but is it worth the risk. Not so - again in my opinion.