A room full of insect wings stuck to pages but now being digitised is helping scientists understand how climate change affects insects and humans.
Clues embedded in more than 200,000 pairs of tsetse fly wings kept at Stellenbosch University (SU) could reveal how climate affects the tsetse fly population — and therefore livestock and humans — according to a scientific team using artificial intelligence to process their information.
The unusual insect database, which also includes a treasure trove of field information such as temperature and rainfall, is the biggest of its kind worldwide.
The wings date to the 1960s and were collected in the Zambezi Valley in Zimbabwe during an 11-year study at the Rekomitjie Research Station, which attracted the attention of SU mathematics professor John Hargrove. The wings and associated records were relocated to SU's South African Centre for Epidemiological Modelling and Analysis, (Sacema), which is leading the digital project with help from the university’s department of information technology.
If temperatures continue to increase there is a danger that tstese friel may re-emerge
— SU mathematics professor John Hargrove
“This invaluable data set may hold the answers to what caused the dramatic collapse of tsetse fly (Glossina pallidipes) populations in the valley over the past 30 years and whether we’ll be faced with their possible re-emergence in areas such as the Kruger National Park in a warmer climate,” the university’s science writer Wiida Fourie-Basson wrote in a recent research update.
What makes the database particularly relevant to climate change is tsetse flies are hugely susceptible to changes in temperature because, unlike mammals and birds, they cannot regulate their own body temperature. It means the state of their wings could be a proxy for their wellbeing. By “decoding” the wings, matching shape, size and other defining features, scientists can predict how changing temperatures could prompt an increase or decrease in tsetse fly numbers.
The research would have particular relevance to Africa, which has long been plagued by sleeping sickness disease borne by the tsetse fly.
Mitigating disease impacts of the tsetse fly was one of the key aspects of work at the Rekomitjie Research station where Hargrove worked for 30 years with another world leader in entomology, Dr Glyn Vale.
“Through his groundbreaking work on tsetse flies, Vale paved the way for the design of a prodigious number of innovative field experiments that sparked a revolution in researchers’ understanding of tsetse fly biology. While still working in Zimbabwe today, Vale is a Sacema research associate. Together, the pair (Vale and Hargrove) analyse and publish papers based on the tsetse fly data set,” Fourie-Basson said.
However, researching wafer thin wings is sensitive work, hence the need to digitise each set — or as many as possible. “Initially, the wings were stuck onto the pages with cellotape, which is not the best way to preserve them,” Fourie-Basson said this week. “When John [Hargrove] realised the wings are getting damaged in the process he laminated each of those pages. Some of the wings were already damaged to such an extent that they cannot be digitised, but there is still sufficient data left to extract.”
In addition to the wings the database includes ovarian dissection data from more than 180,000 female tsetse flies, nutritional data from 40,000 tsetse flies and catches from more than 10 sampling systems used since 1960. “There are also valuable temperature, humidity and rainfall records, as well as other meteorological data collected from the same area since 1959,” said Fourie-Basson.
“So far, the team has barely scratched the surface. Only two of the 27 boxes [14,000 of 205,000 pairs of wings] have been digitised.”
Understanding climate change effects on the tsetse fly would help scientists predict the future species distribution. A dramatic decrease in tsetse fly numbers in Zimbabwe’s Mana Pools National Park since 1990 coincides with a significant increase in the area’s main daily temperature. Conversely, an increase in temperature in areas of South Africa considered too cool for the tsetse fly may see the species establish itself, bringing with it the threat of tsetse fly-borne diseases.
Hargrove believes Zimbabwe’s Hwange National Park and the Kruger National Park have suitable hosts and habitats for tsetse flies.
Hargrove warns: “Tsetse did occur in these areas in the 19th century, but their numbers were always marginal because the winters were too cold. With the huge rinderpest outbreak of the middle 1890s, when the vast majority of ungulates [hoofed animals] died, tsetse disappeared from these areas and have never re-established again. If temperatures continue to increase there is a danger they may re-emerge,” he said.
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