DiscoEPG 0.0.4

Open-source package for insects EPG data analysis

DiscoEPG (Discovery EPG) - A library for EPG signal analysis of pierce-sucking insects

Overview

Electrical penetration graph (EPG) is a technique used to study the feeding behavior of sucking insects such as aphids. Specifically, the experimental insect and host plant are made part of an electrical circuit, which is closed when aphid mouthparts penetrate plant tissue. When the aphid stylet is inserted intercellularly, the voltage is positive and when inserted intracellularly, the voltage is negative. Waveforms in EPG have been correlated to specific aphid feeding behaviors by stylectomy followed by microscopy of the plant tissue to determine the approximate location of the stylet as well as observing aphid head movement, posture, and muscle dynamics. EPG is well established and has been widely used to study the mechanisms of plant virus transmission by aphids, the effect of resistant and susceptible lines on aphid feeding behaviors, and to better our understanding of the mechanisms that aphids use to continuously drink from the phloem.

DiscoEPG (abbreviated for Discovery-EPG) package is an open-source Python package, designed to be compatible with the popular Stylet+ EPG System by W. F. Tjallingii [1]. DiscoEPG provides many utilities including data visualization, accurate automatic segmentation, and calculations of various EPG parameters, which facilitate the data analysis stage in the study of EPG signals. The package was used as a helpful support tool for our study in characterizing aphid's behavior based on this data.

The novelty of DiscoEPG lies in the automatic segmentation procedure, which follows a sliding-window technique where the entire signal is broken into non-overlapping segments, then the each of them is labeled independently before concatenating the predictions to form a unified segmentation. Despite being simple, we observe great performance in terms of 1) the segment classification results and 2) the overlap rate between the prediction and the ground-truth aggregated segmentation.

Usage

For DiscoEPG to run properly, you only need to prepare a dataset folder which contains all the dataset containing recordings with the ASCII format obtained from Stylet+ application. Corresponding to each dataset <dataset_name>, there should be one subfolder called <dataset_name> containing the recording data (with .A0x extension) and another one called <dataset_name>_ANA containing the waveform position (with .ANA extension). Each complete recording comprises of multiple recording files. In case the prefix of these data files are different, DiscoEPG will automatically rename them from <file_name>.A0x into <folder_name>_<file_name>.A0x, as well as the analysis file.

Functions

For training a model, predicting segmenation or making visualization, please refer to the example notebooks.

Train ML models for characterizing EPG waveforms

DiscoEPG provides two trainer objects for training Deep Learning (CNN1D, ResNet and CNN2D) and Traditional Machine Learning (XGB, Random Forest, Logistic Regression) for characterizing EPG waveforms. After a model is trained, it can be used for EPG waveform segmentation. The trainer objects also provide post-prediction utilities such as saving checkpoints (for DL models) and plot the segmentation result/ metrics. The syntaxes are closely resemble that of the implementation of ML algorithms by scikit-learn.

Visualization

DiscoEPG allows users to create color plots, in both static and interactive states of EPG recordings. The data visualization functions are based on well-known visualization libraries such as matplotlib and plotly. To help with visualizing a huge numbers of data points, plotly-resampler [2] was incorporated into our package.

EPG parameters calculation

DiscoEPG can calculate various EPG parameters proposed for aphids, adopted from [4].

Acknowledgement

We hugely thanks the authors of the cited work for providing us with necessary tools which were the building blocks for DiscoEPG.

Please cite our paper with

@article {Dinh2024.06.10.598170,
	author = {Dinh, Quang-Dung and Kunk, Daniel and Hy, Truong Son and Nalam, Vamsi J and Dao, Phuong},
	title = {Machine learning for characterizing plant-insect interactions through electrical penetration graphic signal},
	elocation-id = {2024.06.10.598170},
	year = {2024},
	doi = {10.1101/2024.06.10.598170},
	publisher = {Cold Spring Harbor Laboratory},
	abstract = {The electrical penetration graph (EPG) is a well-known technique that provides insights into the feeding behavior of insects with piercing-sucking mouthparts, mostly hemipterans. Since its inception in the 1960s, EPG has become indispensable in studying plant-insect interactions, revealing critical information about host plant selection, plant resistance, virus transmission, and responses to environmental factors. By integrating the plant and insect into an electrical circuit, EPG allows researchers to identify specific feeding behaviors based on distinct waveform patterns associated with activities within plant tissues. However, the traditional manual analysis of EPG waveform data is time-consuming and labor-intensive, limiting research throughput. This study presents a novel machine-learning approach to automate the segmentation and classification of EPG signals. We rigorously evaluated six diverse machine learning models, including neural networks, tree-based models, and logistic regressions, using an extensive dataset from aphid feeding experiments. Our results demonstrate that a Residual Network (ResNet) architecture achieved the highest overall waveform classification accuracy of 96.8\% and highest segmentation overlap rate of 84.4\%, highlighting the potential of machine learning for accurate and efficient EPG analysis. This automated approach promises to accelerate research in this field significantly and has the potential to be generalized to other insect species and experimental settings. Our findings underscore the value of applying advanced computational techniques to complex biological datasets, paving the way for a more comprehensive understanding of insect-plant interactions and their broader ecological implications. The source code for all experiments conducted within this study is publicly available at https://github.com/HySonLab/ML4InsectsCompeting Interest StatementThe authors have declared no competing interest.},
	URL = {https://www.biorxiv.org/content/early/2024/06/11/2024.06.10.598170},
	eprint = {https://www.biorxiv.org/content/early/2024/06/11/2024.06.10.598170.full.pdf},
	journal = {bioRxiv}
}

Contributors

• Quang-Dung DINH, Institut Galilée, Universite Sorbonne Paris Nord, Villetaneuse 93430, Paris, France
• Truong Son HY (PI), Department of Mathematics and Computer Science, Indiana State University, Terre Haute, IN 47809, United States
• Phuong DAO (PI), Department of Agricultural Biology, Colorado State University, Fort Collins, CO 80523, United States

References

1. Tjallingii WF. Electronic Recording of Penetration Behaviour by Aphids Entomologia Experimentalis et Applicata. 1978; 24(3): 721–730.

2. J. Van Der Donckt, J. Van der Donckt, E. Deprost and S. Van Hoecke, "Plotly-Resampler: Effective Visual Analytics for Large Time Series," 2022 IEEE Visualization and Visual Analytics (VIS), Oklahoma City, OK, USA, 2022, pp. 21-25. GitHub

3. Runia, T.F.H., Snoek, C.G.M. & Smeulders, A.W.M. Repetition Estimation. Int J Comput Vis 127, 1361–1383 (2019). GitHub

4. Elisa Garzo, Antonio Jesús Álvarez, Aránzazu Moreno, Gregory P Walker, W Fred Tjallingii, Alberto Fereres, Novel program for automatic calculation of EPG variables, Journal of Insect Science, Volume 24, Issue 3, May 2024, 28.