SA physics student a Top 100 Falling Walls Lab finalist

Physics students Alem Gebru at the instrument he developed for his PhD research at Stellenbosch University. The telescope uses laser radar and sunlight to remotely classify and observe the interactions of vast numbers of insects on landscape scale. Photo: Stellenbosch University

He recently competed against 21 entries in the South African leg of the competition that took place in Johannesburg and will have three minutes to present his idea to a select jury of scientists and business people at the conference.

The Falling Walls initiative was started 20 years after the fall of the Berlin Wall. It aims to foster discussion on research and innovation and promote the latest scientific findings among a broad audience.

"I have always wanted to do research that will be relevant to society and especially Africa," the Ethiopian-born student says. He came to Stellenbosch University (SU) on a TRECCAfrica fellowship, after obtaining an MSc in physics at Lund University in Sweden.

As part of his doctoral research in the Department of Physics at SU, he developed a technique to classify insects remotely, based on the frequency of their wing beats and iridescence features. The instrument, using laser radar and sunlight, can also determine their sex and the direction of flight. Insects are the largest and most diverse animal group on earth. Yet it remains exceedingly difficult to study their movements and interactions in their natural habitat.

Radical transformation in information gathering

The new method promises a radical transformation of the way entomologists collect data about large numbers of insects and their interactions. It is especially relevant in the study of pests such as mosquitoes, or the wellbeing of important pollinators such as bees.

Gebru says his technique involves the use of both a laser radar system and natural sunlight. "If one wants to use light to detect something, you need to choose a specific light source with a smaller wavelength than the size of the thing you want to detect, which, in this case, are insects. We implement an optical technique called Light Detection and Ranging (LIDAR). That is because LIDAR has a wavelength which is much smaller than the tiniest insect."

The instrument can also switch to using sunlight. "The moment an insect flies into the telescope's field of view, the scattered light is reflected back onto the telescope and goes to the beam splitter where the light is broken into both visible and infrared light."

Critical for environmental monitoring

Prof Erich Rohwer, head of the Department of Physics at SU and his supervisor, says more efficient and accurate insect-monitoring techniques could give us a detailed understanding of insect activity and help to get a better picture of the environment.

Alem's co-supervisor is Dr Mikkel Brydegaard, from Lund University in Sweden, who specialises in laser radar and optical remote sensing of insects. He is also involved with the development of realistic instrumentation and optical sciences in Africa and South America.

According to Dr Brydegaard modern electro-optic methods now allow for the assessment of the abundance and fluxes of pests like mosquitoes and beneficial insects like bees on a landscape scale. "The method has the potential to significantly increase our understanding of, and ability to quantify and manage, the ecological environment.

In conjunction with his supervisors and other scientists, Gebru has already co-published two articles in international peer-reviewed journals and presented his work at two international conferences.