|EBERT, TIMOTHY - University Of Florida|
|CID, MIGUEL - Consejo Superior De Investigaciones Cientificas (CSIC)|
|FERERES, ALBERTO - Consejo Superior De Investigaciones Cientificas (CSIC)|
|ROGERS, MICHAEL - University Of Florida|
Submitted to: Computers and Electronics in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/15/2015
Publication Date: 8/1/2015
Citation: Ebert, T.A., Backus, E.A., Cid, M., Fereres, A., Rogers, M. 2015. A New SAS program for behavioral analysis of electrical penetration graph data. Computers and Electronics in Agriculture. 116:80-87. doi: 10.1016/j.compag.2015.06.011..
Interpretive Summary: Many hemipteran insects are pests of major crops worldwide because they have piercing-sucking mouthparts that facilitate transmission of plant pathogens such as viruses, bacteria and phytoplasma. Some of the most important hemipteran pests are aphids. Yet piercing-sucking feeding is difficult to research because piercing-sucking mouthparts are inserted into opaque plant tissues. The best means of studying piercing-sucking feeding is via electropenetrography; the insect is made part of an electrical circuit with an electrified plant. Fluctuating voltage signals in the circuit are graphed, and resulting waveforms are interpreted as specific feeding activities. After measurement of waveforms, data consist of a list of different feeding behaviors and associated durations. These data are further processed to yield hundreds of response variables that are compiled and statistically analyzed. The present study first reviews the three major existing programs that perform this function. However, all of these programs present challenges for aphid research, because the programs either do not output the best variables for aphids, or do so but do not test the variables rigorously. The present work introduces a new SAS program that solves this problem by analyzing data more completely and efficiently. The new program calculates variables specifically designed for aphids, and also provides both compilation of data and statistical analysis via powerful Mixed-Model Analysis of Variance. The new program will be especially valuable for large experiments with many insect subjects.
Technical Abstract: Monitoring feeding behaviors of insects whose piercing-sucking mouthparts are inserted into plant tissue is done by making the insect part of an electronic circuit, using electropenetrography (EPG). Fluctuating voltage signals in the circuit are graphed, and resulting waveforms are interpreted as specific stylet activities. After measurement of waveforms, data consist of a list of different behaviors and associated durations. These data are further processed to yield hundreds of response variables that are compiled and statistically analyzed prior to publication. The present study first reviews the three major existing programs that perform this function. Then, a new SAS program is introduced that makes this process more efficient for studies of aphids and related species. The oldest program (Backus 1.0) both compiles data and performs a SAS-based statistical analysis; however it only works with a limited number of variables and is not tailored to aphid studies. The other programs (EPG Calc and the Sarria Excel® workbook) compile a more diverse suite of derived variables more suitable for aphids than does Backus 1.0; however, they do not include statistical analyses. The new program (Ebert 1.0) uses SAS to calculate the same suite of derived variables for aphids as the Sarria workbook, and also provides statistical analysis via powerful Mixed-Model ANOVA using a single software platform. The code is open source, so that this program can be adapted to deal with behavioral idiosyncrasies of a particular study insect. The new program will be especially valuable for large experiments with many insect subjects.