Cold winter temperatures condition the egg-hatching dynamics of a grape disease vector

Area of Science:

• Entomology
• Plant Pathology
• Ecology

Background:

• Scaphoideus titanus leafhoppers transmit Flavescence dorée, a major grapevine phytoplasma disease.
• Vector distribution spans Eastern and Northern Europe, with population dynamics influenced by latitude.
• Previous research suggests winter conditions may regulate leafhopper life cycles.

Purpose of the Study:

• To test the hypothesis that leafhopper egg hatching is triggered by winter cold temperatures.
• To investigate the relationship between cold exposure duration and hatching onset and duration.
• To understand the role of winter diapause in regulating Scaphoideus titanus egg hatching.

Main Methods:

• Eggs from a natural Scaphoideus titanus population were subjected to simulated cold (5°C) and mild winter conditions.
• Cold exposure duration varied from 0 to 63 days.
• Hatching onset, duration, and overall dynamics were monitored and analyzed.

Main Results:

• Temperature cooling significantly affected the onset of egg hatching.
• Hatching onset was negatively correlated with the duration of cold exposure.
• Eggs hatched more rapidly under simulated cold winters compared to mild winters.
• The duration of hatching did not significantly differ based on cold exposure time.

Conclusions:

• Winter cold temperatures are a critical cue for terminating diapause and regulating egg hatching in Scaphoideus titanus.
• The findings support the hypothesis that cold winters are essential for the vector's life cycle, aligning with its North American origin.
• Understanding these thermal cues is vital for managing Flavescence dorée spread in European vineyards.