Surveillance tool reveals spectral fingerprints hidden in insect wings – Advanced Science News

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A revolutionary light-based instrument resolves the spectra of hovering fly wings in real time, bridging gaps in insect monitoring and monitoring ongoing biodiversity crises.

Insects are the most diverse group of animals on the planet, maintaining complex relationships with their environment and fulfilling important ecological roles such as decomposition of organic matter and pollination. which is growing Biodiversity The crisis becomes clear when you look at insect numbers, and their decline has a dramatic domino effect on plants and animals.

Monitoring insects and analyzing their distribution over time is important for understanding the factors that influence their abundance and diversity, but appropriate monitoring tools are very limited.

“As a physicist coming into the world of entomology, I was shocked to see how little data we have on insect populations,” said Benjamin Thomas, an associate professor at the New Jersey Institute of Technology. As an expert in optical sensors, he has worked for decades on photonic devices to study insects.

Lack of capacity

The lack of insect repellents is a problem that Mikael Bridegård and his team at Lund University’s Department of Physics have been trying to solve. in Recent paper Published in Advanced scienceThey report an easy-to-use approach that analyzes how an insect’s wings reflect light to determine species and sex, which provides clues about the ecosystem in which the insect lives.

Conventional monitoring techniques are based on captured insects – a small number of observations, labor-intensive and prone to error, especially between similar species – approaches that use light or the analysis of insect wings could change things, allowing researchers to To take special cameras into the field to track free-flying people in real-time.

Thomas, who was not involved in the study, said: “This is a step towards improving the detection accuracy of these sensors, which can make a big difference in the ability to monitor insect populations.” “Combined with new AI tools and machine learning classifiers, this technology is very promising.”

Unique fingerprints of hoverfly wings

Similar to human fingerprints, delicate insect wings can be used for identification. When imaged with a hyperspectral camera capable of capturing a wide spectrum of light beyond the capabilities of our eyes, the architecture of the wings can be reconstructed based on how strongly and uniformly they reflect the light.

“We can see how every subtle shade of color, even those outside the visible spectrum, is affected by the thickness of the wing,” said the Ph.D. student in Bredegaard’s group and first author of the paper. “This detailed color information allows us to accurately study and identify insects based on specific wing patterns.”

To prove their hypothesis, Meng Lee analyzed 600 hoverflies from 30 different species donated by the Lund University Biological Museum. Hoverflies – the number two pollinating insects after wild bees – are a large family of insects with about 6000 species that vary greatly in morphology, larval diet, habitat and behavior. One of their specialties is to imitate other insects such as wasps or bees, and they are often seen “hovering” over their favorite flowers.

When asked whether their findings could be directly translated to free-flying insects (as found in the field), Lee noted that insect wing thickness does not change throughout their lifetime and that “even dried specimens in museums, without moisture, show interference patterns.” [similar to those] Living beings of the same species”.

To demonstrate that their cameras could accurately discriminate between different species of flies, the research team compiled a database of parameters for each species describing the architecture of their wings. They also estimated the species’ wingbeat frequencies, which are now often used to identify insects, based on their body and wing size. By combining all these parameters, the group has 91% identification accuracy; Much higher when using only wing beat frequencies.

They also found that the special characteristics of the wings of hoverflies differ greatly not only between species, but also between sexes. This is also difficult to distinguish with the eye in species where female and male flies are similar, and the additional sex difference is useful when controlling the number and reproduction of insects.

The large size of the hoverfly family, which is reflected in the diversity of behavior among animals, prompted Bridegaard and his team to investigate the correlation of these different traits with the visual behavior of their wings. To do this, they first compared closely related species before relating wing architecture to factors such as behavioral mimicry and habitat type. The team found, for example, that flies with thick wings tend to mimic bees, are active in the summer, and are mainly found in fields and forests.

Interestingly, although closely related species generally have similar wingspans, behavioral traits are more strongly correlated with differences in wing thickness than genetics. This means that the unique characteristics of insect wings are not only identifiers of species and sexes, but also help to further define their ecological niches – especially useful when controlling for the effects of external factors such as agriculture and deforestation on insect diversity.

The future of insect surveillance

This is certainly not the end of the story. Their validation study now paves the way for further studies to improve their method and confirm its applicability to different habitats. The technique needs to be tested and refined for other insect species with very different wing architectures.

According to Thomas,[The analysis] It still needs to be combined with other information to determine the species’ authenticity. It means that we need to create a large database of visual characteristics of each species in order to distinguish different populations of insects.

Bredegaard and his team are hopeful that they will continue to develop their anti-insect device and improve their sensor to further increase, for example, the distance at which the insect can be caught.

Their method can be applied using sensors already used in the field, such as Bridegard and, importantly, on free-flying insects. This could be a promising start to curating the vast database of insects and eventually controlling them in their rapidly changing habitat.

Reference: Meng Lee et al Discrimination of Hoverfly Species and Sexes by Wing Interference Signals, Advanced Science (2023) doi: 10.1002 / advs.202304657



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