Tracking the early spatio-temporal dynamics of phytoplasma multiplication within its leafhopper vector

Area of Science:

• Plant pathology
• Insect vector biology
• Bacteriology

Background:

• Phytoplasmas are bacteria transmitted by insect vectors, crucial for plant disease epidemiology.
• Understanding phytoplasma multiplication dynamics within vectors after acquisition is key to disease management.
• The impact of acquisition duration on early phytoplasma colonization in vectors is not well-defined.

Purpose of the Study:

• To investigate the spatio-temporal patterns of *Flavescence dorée* phytoplasma multiplication in *Euscelidius variegatus* after short acquisition access periods (AAP).
• To model phytoplasma dynamics and estimate multiplication rates based on varying acquisition durations.

Main Methods:

• Insects were exposed to short (4-h) and medium (2-day) acquisition access periods.
• Phytoplasma load was quantified in insect tissues over time.
• Data were integrated with existing studies and analyzed using a Bayesian hurdle-lognormal model.

Main Results:

• Short AAPs (4-h, 2-day) resulted in significantly lower phytoplasma loads compared to longer durations, post-latent period.
• Model predictions showed gradual phytoplasma load increase following similar trends to longer AAPs but consistently lower.
• Even brief feeding (2-day AAP) could lead to loads near the transmission threshold in some vectors.

Conclusions:

• Acquisition duration critically influences early phytoplasma colonization and multiplication dynamics in insect vectors.
• Brief feeding events can be sufficient for phytoplasma infection and potential transmission, affecting disease risk.
• Findings provide insights into phytoplasma transmission under natural conditions with incidental vector feeding.