Quantifying individual fruit fly consumption with Anastrepha suspensa (Diptera: Tephritidae)

Area of Science:

• Entomology
• Pest Management
• Analytical Chemistry

Background:

• Accurate quantification of individual insect feeding is crucial for effective pest control strategies.
• Current methods for assessing bait consumption by fruit flies lack precision, hindering optimization of pesticide efficacy and environmental safety.
• The Caribbean fruit fly (Anastrepha suspensa) is a significant agricultural pest requiring efficient eradication methods.

Purpose of the Study:

• To develop and validate a precise dye-based technique for quantifying individual consumption of baits by adult Anastrepha suspensa.
• To establish the sensitivity, time course, and limitations of the developed quantification method.
• To inform strategies for improving bait/pesticide efficacy and reducing environmental impact in fruit fly eradication programs.

Main Methods:

• Adult Anastrepha suspensa were fed baits containing fluorescein and cresol red dyes.
• Dyes were extracted from individual flies using 0.1 M NaOH.
• Quantification of dye concentration was performed using spectrophotometry at specific wavelengths (491 nm for fluorescein, 573 nm for cresol red).
• Consumption was measured based on extracted dye concentration, with a lower limit of 300 nl at 0.1% dye concentration.

Main Results:

• The spectrophotometric method accurately quantified dye consumption by individual flies, with a lower detection limit of 300 nl.
• Dye ingestion peaked within approximately 1 hour, with movement to the hindgut and potential defecation observed around 4 hours.
• Feeding preference was observed for an upside-down presentation, suggesting potential for enhanced bait efficacy.
• Regurgitation using a J-tube presentation led to a significant overestimation (100%) of actual consumption.

Conclusions:

• The developed dye-based technique provides a precise and sensitive method for measuring individual Anastrepha suspensa consumption.
• This technique is valuable for phagostimulant studies, oral toxicity tests, and resistance studies, leading to improved pest control strategies.
• Findings on feeding position and regurgitation offer practical insights for enhancing the efficacy of bait/pesticide applications in area-wide eradication programs.
• The method has potential applications for other tephritid species, insects, and regurgitation studies.