Parasitic fig wasps in India have developed an amazing body appendage over twice as long as their bodies that acts as a zinc-tipped drill to bore into fruit, pierce the larvae of their prey inside, and lay their eggs in the unsuspecting larvae. When the eggs hatch, the offspring of the parasitic wasp eats the larvae from the inside out.
When female parasitoid fig wasps land upon an unripe fig, they tap the rock-hard fruit with their antenna and can sense if it contains larvae of their prey from subtle vibrations and movements inside. If the fig contains the larvae of a suitable host insect inside, the fig wasps drill into the fruit with their long, zinc tipped ovipositors (basically, ovipositors are egg-laying syringes) and into the larvae, where they deposit their clutches of eggs.
The ovipositors of the fig wasps are thin, approximately one-fifth the thickness as a human hair; but, they are strong, with serrated teeth reinforced with zinc, according to a recent study published in the Journal of Experimental Biology by a team of researchers from the Indian Institute of Science in Bangalore.
It’s a delicate process. The fig wasps must be extremely accurate in their appraisal of where the unseen larvae are within the fruit, and they must be quick about it, as insects, birds, or other animals that, in turn, prey on them, could be lurking nearby.
Pits help make the ovipositors of fig wasps more flexible
The researchers noticed tiny pits along the lengths of the shafts. These miniature pits were located near where the structure bends as the female fig wasp drills the tip of her ovipositor into the fruit. The pits are what enables the ovipositors to flex rather than break.
The researchers used an electron microscope to photograph images of the fig wasp at work. When they took measurements of the ovipositors, the researchers discovered that the end of it was very similar to a drill bit, and had along their lengths tooth-like structures. According to Dr Namrata Gundiah of the Indian Institute of Science, the zinc that the researchers found on the ovipositors of the fig wasps “was only at these teeth-like structures.”
Dr Namrata Gundiah and the other researchers theorized that “the zinc is there to harden the tips.” The team of researchers learned that the zinc reinforced tips of the teeth and the tip of the ovipositors of fig wasps were similar in hardness to the acrylic cement used in dental implants.
The researchers involved in the study believe that the ovipositors of fig wasps could lead to the development of refined tools to be used in microsurgery. The creation of micro-syringes could be used to ensure that if surgery was needed, it would be minimally invasive. A tool modeled after the ovipositor of fig wasps would, ideally, mimic them in that they would be flexible, made of relatively cheap, easy-to-find materials, and would never dull.
As far back as 1998, scientists discovered that certain hymenopterous insects like ants, bees, and wasps, had mandibles and ovipositors reinforced with manganese and zinc. Zinc also hardens the jaws of marine worms known as Nereis.
Besides having applications for microsurgery, Dr Namrata Gundiah believes that the same type of technique could be applied to cutting harder materials, like rock. If such a tool was made a part of a vehicle like a Mars rover or robot, rock samples could be perhaps be more easily collected and studied.
The parasitic fig wasps in India with their zinc reinforced built-in drills, their ovipositors, could be helpful in pointing the way to technological advancements which could revolutionize microsurgery. If drills which could double as micro-syringes could be developed that were as thin, but as strong and flexible, as the ovipositors of fig wasps, there would likely be many other applications for them — all thanks to parasitic fig wasps and researchers who attempted to discover some of their techniques.
Written by: Douglas Cobb