Pathogen-induced release of plant allomone manipulates vector insect behavior

Area of Science:

• Plant-insect interactions
• Chemical ecology
• Agricultural entomology

Background:

• Infochemicals are crucial for mediating communication in ecosystems.
• Cacopsylla picta is a key vector for Candidatus Phytoplasma mali, the causal agent of apple proliferation disease.
• Previous research indicated phytoplasma-infected apple plants emit beta-caryophyllene, attracting C. picta.

Purpose of the Study:

• To confirm the attractiveness of beta-caryophyllene to C. picta.
• To investigate if the insect's response to beta-caryophyllene is influenced by its experience or infection status.
• To evaluate the potential of beta-caryophyllene as a tool for managing C. picta populations.

Main Methods:

• Olfactometer bioassays were used to test the attractiveness of beta-caryophyllene.
• Field studies were conducted to assess the efficacy of beta-caryophyllene in natural settings.
• Sticky traps baited with synthetic beta-caryophyllene were deployed in apple orchards.

Main Results:

• Synthetic beta-caryophyllene demonstrated high attractiveness to newly emerged adult C. picta, irrespective of healthy apple odor presence.
• The psyllid's attraction to beta-caryophyllene was independent of its prior odor exposure or infection status.
• Traps baited with beta-caryophyllene successfully captured both male and female C. picta in apple orchards.

Conclusions:

• Phytoplasma infection manipulates host plant odor by inducing beta-caryophyllene, influencing vector behavior.
• Beta-caryophyllene acts as a phytopathogen-induced plant allomone, attracting its vector.
• This finding presents a promising avenue for developing novel monitoring and mass-trapping strategies for C. picta.