I appreciate there is a lot of confusion but that's because we have individuals posting from different territories without regard to the topographical and ecological differences between the territories and without regard to the prevailing conditions of infestation.
The issue of competition is competition between indigenous vespines (UK) / vespids (Med) and the invasive velutina. Any spring trapping which results in destruction of even small numbers of indigenous vespines/vespids will enhance the chances of velutina queen survival and nest maturation. It is all to do with population level numbers rather than individual experience.
Think of it this way. Spring trapping in the UK will create pockets of opportunity for velutina to exploit resulting in 'ink blots' of infestation. The more ink blots the more likelihood of sexuals encountering sexuals from other nests and successfully mating.
The UK is not naturally ecologically conducive to velutina. It's important that beekeepers don't unwittingly make it more conducive by unnecessarily removing vespine competition which will simply have the effect of increasing resources for velutina to establish itself.
The situation in the UK is very very different from that in continental Europe.
My comments to Richard were not at a personal level. They were at a territorial population level. Velutina has exploded in France because the wrong strategies were adopted concentrating on trapping and hive protection instead of species specific eradication.
Species specific eradication has the benefit of tipping conditions in favour of indigenous vespines both in terms of resource and in terms of direct interaction. Velutina will kill indigenous vespines at a favourable but not absolute rate meaning that indigenous populations have to be numerically superior to stand any chance of survival. Spring trapping of bycatch, however small that bycatch, will always favour velutina because it is a top line predator.
To respond to Richard's question. Perpignan is vespid territory, i.e. has a native mix of vespines and polistes wasps. Polistes wasps are simply not a problem for hives as they specialise in hunting smaller flying insects such as mosquitos. Polistes wasps which have open multiqueen colonies are easy prey for velutina and will be the first mass casualties to velutina but because they tend only to be noticed around recreational water activities, they aren't missed by the local populus. Polistes wasps are an integral line of defence against the spread of mosquito borne diseases.
Velutina will appear in February in Perpignan because it is a warmer Med climate. However, such unqualified comments are unhelpful to beekeepers in the UK who may take that as a cue to taking early spring trapping action. Perpignan has the disadvantage of being ecologically conducive to velutina so the issue of competition is of a different order and not so finely balanced as in the UK. The balance between vespines and polistes in Perpgnan is such that one would not expect much in the way of vespine bycatch anyway. So any bycatch that you have will have vastly greater impact. Why? Because polistes wasps can't resist velutina in the same way they resist smaller vespines. They can't withstand velutina attacking their open nests. Moreover vespine populations are naturally less abundant which accentuates the impact of even the smallest bycatch.
So Richard, you are suffering from the collective approach adopted in France which has not worked. That is the point I am making. My recommendation is to focus on species specific eradication and encourage local vespid populations to recover. Until such time as that strategy is adopted universally you will be slated to continue with local eradication which needs to be maintained even when numbers of velutina crash otherwise they will rebound.