EPG-12 amplifier for electrical penetration graph

Key Features:

• 12 independent recording channels
• AC and DC recordings
• Gain 50 … 550
• Lowpass filter for AC and DC
• Notch filter (50 Hz or 60 Hz)

Electrical Penetration Graph (EPG) Recording: Operational Principles

Electrical Penetration Graph (EPG) recordings are utilized to quantify the penetration and feeding mechanisms of insects possessing piercing mouthparts, including aphids and leaf bugs.

A voltage source (alternating or direct current) is connected to a soil electrode positioned adjacent to the plant's root system. A thin gold wire is affixed to the insect and linked to a preamplifying headstage. During insect feeding on plant tissue, a minute electrical circuit is established. Electrical signal variations originating from the plant and insect can be measured:

• EMF – electromotive force: predominantly resulting from fluid movement within the insect's stylet, generating "streaming potentials".
• R-components: resistance variations, primarily influenced by valve position changes in the insect's feeding canal.

Direct Current Recording – Biological Voltage Measurements

• Employs an adjustable constant voltage
• Quantifies EMF and R-components
• Identifies physiological occurrences (cellular penetration, consumption, salivation)
• Optimal for comprehensive feeding examination

Alternating Current Recording – Resistance Fluctuations

• Employs an adjustable alternating voltage
• Quantifies R-components exclusively
• Emphasizes mechanical feeding behavior
• Dependable and consistent for extended recording periods

npi's EPG-12 instrument is capable of recording in both alternating current and direct current modes.