Sometimes, small things in life can even be taken literally, like my interest in small organisms and ecology. Close to the swimming pool I noticed humming-bird hawk moths (Macroglossum stellatarum), a death’s-head hawk moth (Acherontia atropos) and oriental hornets (Vespo orientalis) visiting the flower garden. They caught my eye, like cats catch a mouse in the dark. Especially the oriental hornets were abundant.
And again I am amazed... I never knew that oriental hornets are so clever in design! They use a breathing apparatus by lifting the yellow plates* of their exoskeleton on their abdomen, to let the airflow in. Just like slightly opened window shutters.
"The hornets’ entire abdomen is the equivalent of a human lung and they breathe by actively pumping air through small holes located there, called spiracles. They exhale by contracting muscles that pull the abdominal segments together, forcing air out through the spiracles. When these muscles relax, the segments spread out, the abdomen expands and air is sucked in." Yong 2009
*Plates at the end of the body are often referred to as ‘tergites’: in this case the yellow stripes on the body of the hornet, acting like window shutters.
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| Oriental hornet (Vespo orientalis); notice the yellow tergites on the abdomen (the yellow stripes). Photograph taken in Lindos area, Greece. |
The oriental hornet is a real carnivore and it will attack and eat other insects. Cyprian honeybees use a very interesting tactic to try to protect their colony from raiding oriental hornets. During an attack they form a protective ball around the hornet and they suffocate it by blocking the tergites on the abdomen, so the hornet can’t lift them to breathe (Yong 2009; Papachristoforou et. al 2007). To put it in other words: the window shutters of the oriental hornet are blocked, at least if it can't escape the firm grip of the protective ball!
There is even more magic to the oriental hornet... The yellow colours of its body are used to trap and absorb sunlight, just as solar energy panels do. The yellow colour sustains Xanthopterin. Xanthopterin works as a light harvesting molecule transforming light into electrical energy (Walker 2010). The oriental hornet is therefore capable of producing electricity!
The use of solar energy converted to electricity gives an exclusive insight in the metabolism and behaviour of this insect. Most hornets and wasps are more active in the morning than during the day, so they won't heat up too much. Not for the oriental hornet! They are more active in the middle of the day when the intensity of sunlight is highest, to absorb as much sunlight as possible. The solar energy contrived this way is especially useful for energy draining activities, like digging activities.
Electric currents also play a major role in the development of the pupae with an intricate system of thermoregulation* within the pupae’s silk. It makes the oriental hornet an extraordinary photovoltaic creature: using solar energy converted to electricity as energetic nutrient (Ishay & Litinetsky 2011).
*Thermoregulation: maintenance of a constant internal body temperature independent from the environmental temperature.
The more I learn, the more I am inspired by these interesting capabilities of the oriental hornet and the remarkable defence of the Cyprian honeybees. These are thrilling examples about the oriental hornet, a small predator, in relation to their environment and their prey.
Literature
Ishay JS and Litinetsky L (2011) Oriental Hornet, Tel Aviv University, last update August. 15, 2011.
Papachristoforou, Rortais, Zafeiridou, Theophilidis, Garnery, Thrasyvoulou & Arnold (2007) Smothered to death: Hornets asphyxiated by honeybees, Curr Biol 17: R795-796
Walker M (2010) Oriental hornets powered by 'solar energy', published in BBC News Dec. 6, 2010.
Yong E (2009) Mobs of honeybees suffocate hornets to death, Discover Magazine Blogs, July 5th 2009.
