In a new paper published in the BMC Plant Methods journal, VIRTIGATION partner Stichting Wageningen Research (WR) showcases a new innovative software tool – the Eggsplorer – to facilitate whitefly counting and determination of plant-insect resistance.
Whitefly counting: currently a tedious & lengthy process
A well-known method for evaluating plant resistance to insects like whiteflies, is by measuring insect reproduction or oviposition. Whiteflies are vectors of economically important viral diseases, such as the viral diseases caused by the plant viruses ToLCNDV or TYLCV. Commonly, scientists place whiteflies in their experiments on plants using clip-on-cages, where they can lay hundreds of eggs on susceptible plants in a few days. When quantifying whitefly eggs, most researchers perform manual eye measurements using a stereomicroscope. Compared to other insect eggs, whitefly eggs are many and very tiny, usually 0.2 mm in length and 0.08 mm in width; therefore, this process takes a lot of time and effort with and without prior expert knowledge. As plant insect resistance experiments require multiple replicates from different plant accessions, an automated and rapid method for quantifying insect eggs can save time and human resources, according to the WR authors, which included their VIRTIGATION lead scientists Micha Gracianna Devi and Lotte Caarls.
The methodology of WR's new Eggsplorer software tool
In their methodology paper, the WR researchers present thus a novel automated software tool for fast counting of whitefly eggs, to accelerate the determination of plant insect resistance and susceptibility. First, they collected leaf images with whitefly eggs from a commercial microscope and a custom-built imaging system. Then, the WR scientists used the collected images in the training of a deep learning-based object detection model. After that, the WR authors incorporated this model into an automated whitefly egg quantification algorithm, deployed in a web-based software tool called Eggsplorer. Upon evaluation on a testing dataset, the algorithm developed by the WR researchers was able to achieve a counting accuracy as high as 0.94, r2 of 0.99, and a counting error of ± 3 eggs relative to the actual number of eggs counted by eye. The WR scientists then used the automatically collected counting results to determine the resistance and susceptibility of several plant accessions. The WR authors found that their novel software tool Eggsplorer delivered significantly comparable results in counting whiteflies, as when using the manually collected counts for analysis.
Paving the way for fast determination of plant insect resistance and susceptibility with the Eggsplorer
WR’s novel Eggsplorer software tool is the first work that presents a comprehensive step-by-step method for fast determination of plant insect resistance and susceptibility, by using an automated whitefly counting tool. Their results show that the Eggsplorer tool could count whitefly eggs obtained from two different imaging setups. The algorithm testing results also showed that the Eggsplorer can be used on images generated from various microscopes. The WR authors thus state that even users of other microscopes can simply upload their own images in the web application and quantify the whitefly eggs found in their leaf samples. Alternatively, the WR researchers suggest that a custom-built imaging setup, such as the AutoEnto, can also be used for faster image acquisition and sampling.
In the outlook of their publication, the WR scientists propose that their methodology can be a reference to other researchers for determining plant–insect resistance and susceptibility in a quantitative and practical manner. In the future, the WR team hopes that images from other leaves may also be obtained to train new models and make the web-based application even more versatile. This could be done by incorporating images of other insect eggs such as mites, thrips, and other harmful insect pests, in order to transform the novel Eggsplorer software tool into a universal platform for determining plant–insect resistance.
More info about WR's new Eggsplorer software tool
The full version of WR’s methodology paper in the BMC Plant Methods journal titled “Eggsplorer: a rapid plant–insect resistance determination tool using an automated whitefly egg quantification algorithm” is available online here since 20 May 2023. It has been authored by two of WR’s principal investigators in VIRTIGATION, Micha Gracianna Devi and Lotte Caarls. The dataset underlying WR’s peer-reviewed, open access scientific publication is available in the VIRTIGATION Zenodo community. Find out more about VIRTIGATION’s scientific publications on our website here.
