Scientists develop insect field monitoring device that preserves high-quality DNA

Have you ever seen a collection device filled with little bugs in the wild? Be careful, you may be missing out on a scientific invention!

Insects are the most prosperous and diverse animal group on Earth. Whether they are annoying mosquitoes, flies, cockroaches, or beneficial bees and beautiful butterflies, insects are everywhere and play a very important role in the Earth's ecology. By studying the spatiotemporal changes of insects in a certain place, changes in distribution patterns, and their evolutionary mechanisms, it can help us understand research issues in many aspects such as environmental protection and climate, and it is also a very important part of global biodiversity research.

Sampling is a critical step in entomological research. In the past, the commonly used sampling device was mainly a window trap, which was usually placed on the path that insects must take. Insects fly in through the window and fall into the collector at the bottom when they hit the back wall. The collector often contains ethanol, propanol and other media to preserve insect samples. This device can achieve efficient and large-scale collection, and is very portable and labor-saving.

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However, the window trap also has a fatal problem - it is not waterproof. When it rains, rainwater will also flow into the collector through the window, diluting the preservative solution at the bottom, causing the DNA of the insect samples to degrade. In addition, condensation water at night and high humidity in the air will affect the preservation of insect samples. Especially in tropical areas with frequent rainfall, DNA degradation caused by water intrusion has a great impact on sample collection.

If complete DNA cannot be collected, subsequent molecular biological testing will not be possible, and DNA sequencing and other related work will not be completed. Research on the systematics, physiology, and ecology of insects will also be limited.

To overcome this problem, previous studies often adopted methods such as increasing the sampling frequency or replacing pure alcohol multiple times. Even so, insect DNA still cannot be preserved in a long-term high-quality manner. In order to better solve this problem and better monitor global insect diversity, the Institute of Zoology of the Chinese Academy of Sciences, Seoul University in South Korea, Imperial College London and the Natural History Museum in the UK jointly developed an insect field detection device called "WET".

The WET device, full name Water-Exclusion Trap, looks very similar to existing traps, but has been improved internally. In conventional collection devices, the storage medium is located below the window. Although insects can fall directly into the medium, external rainwater will also enter the medium. WET changed the original collection bottle design to a double-layer bottle design, with the inner bottle directing rainwater and the outer bottle collecting insects. The design adds a layer of filter above the inner bottle. When insects fall into WET, they will move on the filter until they reach the outer bottle, and then they will fall into it. Rainwater will pass directly through the filter of the inner bottle and cannot enter the outer bottle where the insect sample is stored.

This seemingly simple design greatly improves the integrity of insect samples, and the DNA quality is significantly better than traditional trapping devices. Moreover, the WET device can be 3D printed, and the production cost is also very low, which is conducive to large-scale and rapid promotion. Its advent provides strong support for insect diversity monitoring, molecular biological detection and other research based on DNA technology.

This article is a work of Science Popularization China-Starry Sky Project

Produced by: Science Popularization Department of China Association for Science and Technology

Producer｜China Science and Technology Press Co., Ltd., Beijing Zhongke Xinghe Culture Media Co., Ltd.

Author: Shi Nanping, a popular science writer

Reviewer: Tao Ning, Associate Researcher, Institute of Biophysics, Chinese Academy of Sciences