Some French beekeepers post themselves on guard outside their hives armed with a badminton racket and spend the day swatting hornets! Others use the ‘insect zapper bats’ sold on-line. One beekeeper in France killed eighty hornets in a single day by this method, but with no noticeable effect on the number of hawking hornets, this is not surprising given the daily rate of reproduction of hornet workers. The beekeeper would have had to maintain his rate of swatting every day to make any impact on the hornet nest’s numbers.
Management
Management of one’s bees will become even more important especially as the seasonal cycle progresses. Making sure colonies are strong and ready to go in the spring will help get reserves built up early, but it is hive management in August and September that is going to be the challenge. Not exposing honey-filled frames is a particular point made by French beekeeping organisations, but that is also good beekeeping practice. Timing of inspections is going to be even more important; the Asian hornet has a habit of returning to its nest at dusk, so that time may present a hive inspection opportunity. Uniting colonies will be necessary because weak ones will not make it through the period of peak predation and winter. Be ready to commence feeding when flight activity is curtailed by hawking; and not just syrup. I have not come across evidence of the practice, but it may be necessary to ensure that water is available at the hive, perhaps within ‘la museliere’.
More traps and chemical warfare
There are two other trapping methods that I should mention. The sticky trap is simply a sheet, usually yellow, an attractant in itself, with a glue covering that is revealed by peeling off a protective film. In tests by the INRA it did not perform well. Yet such a trap is commonly used against the Asian hornet’s close relation, the giant Asian hornet. Attracted to the sheet by a piece of bait, the hornet becomes trapped by the glue, and once that happens it is quickly joined by other hornets attracted by the pheromones given off by those trapped. The Asian hornet is similarly attracted to other hornets caught in a trap and that is all too evident with the ‘piege artisanal’. Furthermore, if, as in Japan, the trap is placed on top of the hive or on the ground just below the hive entrance, I see no reason why it should not work and so I have added sticky traps to my armoury.
Chemical warfare is something we wage on insects on a regular basis and it was therefore not surprising that some beekeepers in France have tried to wage chemical warfare on the Asian hornet. Catching hawking hornets in a net and spraying them with fibronil flea spray before releasing them to return to their nest seems to work. After a dozen or so hornets had been treated a beekeeper reported that the nest was killed and predation ceased; until another hornet nest filled the vacuum and so the relief was temporary. This is a potential weapon in the armoury and, coupled with the fact that the Asian hornet always returns to its nest at dusk, we might suppose that there is an element of control in the process. However, the risk of collateral damage is far too great. Furthermore, where is the nest that has been poisoned? Many insecticides degrade far too slowly in the environment and are dangerous to other wildlife, including birds and bats. It is not a practice that I can recommend nor one I would use.
Research in France is concentrating on the production of an artificial Vespa velutina pheromone that can be used in spring trapping and some researchers are looking into poisons that have a less harmful effect on the environment and non-target species.