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As Winter turns to Spring

“To arms for the enemy is nigh! Post sentinels, watch diligently, lest by inattention one should allow it to pass unseen and in so doing condemn all to years of struggle and loss.” Anon.

The enemy cometh

A voracious predator of the honey bee stands poised to invade us. In fact, it is highly likely that by the end of the year it will have once again crossed the channel into this country and be in hibernation, ready to emerge when the temperature rises to a consistent 12°C, i.e. at any time from late February 2018 onwards.

The Asian hornet, Vespa velutina, is highly adaptable and resilient. the most agile of hornets, it is capable of catching honey bees on the wing and of taking co-ordinated action against a honey bee colony, wearing it down by constant predation until it finally launches an attack that can destroy the colony completely. Once its presence is confirmed, we either stop V. velutinain its tracks or, as the French have discovered to their cost, we face a prolonged war of attrition.

If all this seems alarmist then consider that a survey of beekeepers in the Perigord (some 420 of them) reported in 2010 that 6% of honey bee colonies were destroyed by V. velutinawith a further 30% seriously weakened. Over-wintering mortality rates in some areas soared to over 40% as a result of colonies being weakened by the Asian hornet. In 2011 alone some 2,000 Asian hornet nests were destroyed in the Aquitaine and Midi-Pyrenees region. In Aquitaine/Gironde beekeepers estimate that they have lost 30–50% of their livelihood. In more recent years the situation has not improved although one beekeeper’s association felt that, at last, they were gaining some control following years of struggle, a period in which “we fed and fed and fed our bees”.

The only sure way of halting V. velutinais to locate and destroy every nest before it produces its founder queens. At this critical point, that is before it has established itself, the 2016 Tetbury incident gives us hope that this may be done but finding nests in September is cutting things too fine. It is essential that we detect V. velutina early if we are to stand any realistic chance of success. We should ask ourselves, would the outcome have been the same if the call had come two weeks later and/or to multiple sightings that would have diluted resources?

Once V. velutinaestablishes a foothold the situation will become very grave indeed. A recent research paper published in France concluded that if one destroyed 60% of nests it would result in less than a 20% reduction in the current rate of spread and only a 30% reduction in density of nests in the following year. Destroying 95% of nests would result in less than 50% reduction in spread and only halve the density of nests. Clearly, once it is established, we cannot rely on nest destruction alone and to achieve the figures quoted the rates of destruction would have to be unrealistically high.

 

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