Dr Fiorella Esquivel1, Dr Alexandre Casadei-Ferreira2, Associate Professor Ajay Narendra3

1School of Engineering Technology, UNSW Canberra, Canberra, Australia, 2Biodiversity and Biocomplexity Unit, Okinawa Institute of Science and Technology (OIST), Tancha, Japan, 3School of Natural Sciences, Macquarie University, Sydney, Australia

Biography:

I am an early career academic with an interest in sensory ecology, functional anatomy, and biomechanics. I use a range of techniques in my research including SEM, high speed videography, microCT, and 3D printing. I mostly focus on ants and Hymenoptera. My PhD thesis focused on the miniaturisation of antennal sensilla arrays in ants. However, more recently I have been working on disentangling the kinematics of hymenopteran stingers. Initially focusing on honey bees as a case study I am gradually broadening to other Hymenoptera.

Abstract:

Bull ants of the genus Myrmecia are an iconic Australian insect infamous for their painful stings. Their large size, heavy reliance on vision, and huge mandibles make them a striking feature of the Australian bush. Many of us will have been stung while bushwalking or camping and can attest to the ferociousness of a bull ant, actively chasing an organism many times larger than themselves. The potency of their sting is also not something easily forgotten.

Although much is known about the chemistry of their venom, the venom delivery system is less well described. In this study, we set out to describe the anatomy of the bull ant stinging apparatus and record their sting in action. We use light microscopy and SEM to describe the overall anatomy and sensory sensilla. We then build on that information by reconstructing the 3D anatomy using micro-CT imaging. We present our preliminary findings and compare them to previously described hymenopteran stingers.

Myrmecia are visually guided, active predators of other arthropods. Once the prey is firmly clamped in their mandibles, they repeatedly sting the same target. We set out to film their stinging behaviour using high speed videography. We describe some of the stinging choreography comparing a large and small species. Like the case of the honey bee, Myrmecia venom is pumped by the reciprocating action of the valvilli. However, unlike the honey bee, bull ants sting repeatedly and in quick succession by protracting the whole stinger instead of by the action of the lancets. We contrast adaptations in Apis mellifera for deterrence of vertebrate enemies vs the Myrmecia adaptations for active predation of invertebrates.