Measuring Behavior 2005: Tjallingii

Electrical monitoring of penetration activities of insect mouthpoarts with concurrent video recording: What is invisible?

F. Tjallingii

Laboratory of Entomology, Wageningen University, Wageningen, The Netherlands

The electrical penetration graph (EPG) is a recording technique to monitor plant penetration of piercing moutparts (stylets) of insects, such as phloem feeding aphids, whiteflies, leaf- planthoppers, etc. The electrical signals form a sort of ‘encoded’ information in the EPG signal (fluctuating voltage) on the activities related to mechanical stylet penetration, saliva excretion, .uid ingestion, as well as on the position of the stylet tip in the plant tissue. Although many aspects of the relations between the electrical signals and the biological phenomena have been esteblished so far, there still are a number of unknown waveforms on one side and a number of potential insect actvities that have not been related to a waveform. Combining EPG recording with a number of other techniques has been used in the past 25 years to establish the present waveform correlations. Concurrent EPG and video recording was one the combinations used but the main advantage of EPG recording is the fact that information is given on insect activities and tissue positions of stylet tip are not visible. So, we need to focus on visible aspects of mainly invisible events. Using .uid diets covered by a Parafilm membrane is one of the additional tools to observe stylet propagation and saliva secretion although in the diet the stylet penetration behavior is not identical to plant tissues. On the other hand in some (semi) transparant species we may be able to focus on muscles contractions related to stylet penetration, salivation, or sucking. Such information is rather fast and therefore to analyse the video/EPG relations, any played back video recordings should in synchrony with played back EPG signals. We will report on our recent experiences with the newest soft-/hardware combinations introduced on the market and compare this with older methods.

Paper presented at Measuring Behavior 2005 , 5^th International Conference on Methods and Techniques in Behavioral Research, 30 August - 2 September 2005, Wageningen, The Netherlands.