Particle manipulation in nature: from honey bees to mammal tails

A horse striking mosquitoes with its tail and a honeybee transporting pollen back to the hive are both examples of animals dealing with the particles that surround them. Understanding these processes can inspire new methods for management of granular materials in industry and insect pest control. This thesis presents experiments elucidating the mechanics of pollen transport in honeybees and tail swinging by mammals. Honey bees carry pollen back to their hive by mixing it with nectar and forming it into a pellet, which they carry in the corbicula, or pollen basket, on their hind legs. We measure the kinematics of the leg movement during the pellet removal process and design and build an apparatus to measure the forces during pellet removal. Faster removal speeds result in larger forces, thus justifying why honey bees remove pollen pellets at a rate much slower than they are capable of. The measured relaxation time of the pellet is far greater than the time scale of removal, so it behaves as an elastic solid during removal and likely during transport. We perform rheological experiments with pollen suspensions showing that the suspension is an attractive yield stress fluid, and that the presence of pollenkitt decreases the viscosity of the suspension. In our work with tail-swinging in mammals, we define two modes of defense: a swish and a swat. Through experiments with a tail mimic we show that the swish creates air flow strong enough to blow mosquitoes off course, preventing them from landing on the animal's body. The swat targets insects that make it through this first line of defense and hits on or near the insect before it has a chance to bite. We report the kinematics of the tail swish and the dynamics of the tail swat. Throughout this thesis, efforts are made to perform testing with physical mimics to understand the strategies employed in nature.

Date

2021-05-14

Resource Type

Text

Resource Subtype

Dissertation

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