Bee's World: Asian hornet, a predator of bees

phage93 (65)in #nature • 6 years ago (edited)

Bee's World: Asian hornet, a predator of bees

_{Proprietary Image}

The bee’s world has been under the spotlight of newspaper and media agencies due to the first international day of the bee, celebrated the last 20th of May. This phenomenon was quite unusual and I hope that it really raised awareness. The bee’s job is really important for the ecosystem and for the survival of the human species as well. It’s always important to remind that a huge share of human crops used to feed us are pollinated from forager bees. Whenever the light of information fades away, a various array of problems shine, such as: - a lack of regulation for pesticides and their usage in intensive agriculture - the fight against nest’s diseases and bee’s predators - the climate changes All these factors are undermining the existence of bees all over the world. The goal with this series is to talk about bee’s killers, insects coming from Asia and Africa that are threatening the italian *“Apis Mellifera Ligustica”*.

Let’s start with the Asian Hornet (Vespa velutina nigrithorax) and proceed with the Beetle Hives (Aethina Tumida), a predator who is seriously putting the bee’s survival at stake, in particular in the Calabria and Sicilia’s regions. The Asian Hornet is a Vespa Velutina that feeds with bees: once it catches bees, it breaks them in half while alive, removes the external surfaces and eats thorax muscles. It’s an extremely aggressive species compared to the European Hornet (Vespa Crabro). The main difference with the European species is that the Asian Hornet is really smaller, about 3 cm long. It’s colour ranges from dark brown to black, with an orange bottom. The head’s area has a yellow to orange color. Its wings are really long, about 5 cm, and its legs are dark with yellow tarsi. His sting injects a venom which is as toxic as the European Hornet.
Avoiding bites it’s always recommended, given that, if allergic, life can be threatened.

_{The Asian Hornet - CC0 Creative Commons}

The Asian Hornet has arrived in Italy too, mostly in the North-East area from the South-West of Asia. Firstly reported in 2004 in France, carried through goods, than it spread in all Europe at a rate of 100 km per year. In Italy it has been circulating since 2013, causing massive damage. In fact the hornet position itself at the entering of the beehive, confronting upcoming bees and limiting their exit when bees have to exit to get nectar and pollen. This state creates a constant stress for bees, bounding their movements and impairing the eggs’ deposition; it ultimately leads to the extinguish of the colony.

_{An attack from the Asian Hornet - CC0 Creative Commons}

Public institutions, universities and bees’ associations have gathered to try to limit the expansion of the Asian Hornet and to eradicate this insect at all, given the damage cause to the honey harvesting. The first aim as a countermeasure is to locate each nest and destroy it before the Queen bee is fecundated. Those nests are really difficult to spot, given their position; they are based not only on the high ground, but also in the lower ground, near bushes and roofs of populated areas. Since the surge of the Asian Hornet, various solutions have been studied. In France researchers have been studying a “parasite hornet” that can neutralize the Asian one; meanwhile the most effective weapon has been a carnivorous plant from North America, the Sarracenia.
This plant has tubular leaves that lead to a funnel structure. Insects are attracted with a nectar secretion and scents that it releases, pushed further down in the tubular structure. Once there, they can’t break free anymore due to a waxy hides and eventually digested from the plant with the use of special enzymes. The european variant of the Sarracena has been proved to be extremely selective. In the botanical garden of Nantes, in the Loire valley, it has been proved that only the Asian Hornet falls in the trap, meaning that european bees and wasps could be safe.

_{Flourish Serracena, property of mine}

Currently there is a study regarding the chemicals produced from the Serracena that attract the Asian Hornet. In Italy, the Council for the research in agriculture CRA API of Bologna has been perfectioning a system that enables to install a small antenna on the hornet, with the aim of spotting the nest and destroying it. A similar project has been worked on by the Liguria Region alongside the Turin’s Polytechnic. This year will be released the first radar that allows to keep track of flying hornets. Last but not least, a “trapping” system has been set up.
This is a 2-step process: a first trap has to be positioned in the end of winter, when the hornet’s queen gets out from nest to search for sugary nutrients to ultimately fly in other areas and create new colonies. The bait is formed of a 4.7% alcohol beer which is not hurting bees and other insects, given that they do not like that mixture.

_{An example of the trap - CC0 Creative Commons}

The trap can be made simply: beer is poured in a plastic bottle and a red or yellow cap, which reminds of mature fruits, is set on trees. It’s an evolution of an old farmer custom, which really works!
The second trap has to be set in summertime, when more hornets fly near the beehive, from sunset to sunrise. In summer the hornet’s habits change: in fact the working hornets are the one in search of nutrients to feed the maggots. This second trap is called “sphere trap”, a glue bait made with fish patè for cats, positioned upon or in between the beehives. Starting from a small sphere, like a little football ball, a small transparent film has to be positioned, covered with mice’s glue. After that, cats’ patè has to be spread on.
The result is that the Asian hornet, attracted from the food, flies on the sphere and get stuck.
What’s incredibile is that all those baits are the result of the mind of beekeepers who are left alone fighting against predators, not only to defend the Apis Mellifera Ligustica, but also to preserve our ecosystem, where we live.

Next time we will talk about the famous hive beetle: Aethina Tumida!

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