Pseudomonas aeruginosa, a facultative pathogen of red palm weevil, Rhynchophorus ferrugineus

Area of Science:

• Entomology
• Microbiology
• Pest Management

Background:

• The red palm weevil is a significant agricultural pest.
• Understanding its pathogens is crucial for developing control strategies.

Purpose of the Study:

• To identify and evaluate the pathogenicity of Pseudomonas aeruginosa against the red palm weevil.
• To compare the efficacy of different inoculation methods for P. aeruginosa.

Main Methods:

• Red palm weevil larvae and pre-pupae were subjected to intra-haemocoelic injection, force feeding, or wading in P. aeruginosa suspensions.
• Median lethal dose (LD50) and median time to death were determined for each method and insect stage.
• The effect of a secondary invader, Serratia marcescens, on P. aeruginosa pathogenicity was assessed.

Main Results:

• Intra-haemocoelic injection was the most effective method, with lower LD50 values compared to force feeding or wading.
• Small larvae were more susceptible to P. aeruginosa infection than larger larvae or pre-pupae.
• Serratia marcescens did not enhance P. aeruginosa pathogenicity but accelerated larval death.

Conclusions:

• Intra-haemocoelic injection of Pseudomonas aeruginosa is a highly effective method for controlling red palm weevil.
• Larval susceptibility to P. aeruginosa varies by developmental stage, with smaller larvae being more vulnerable.
• Co-infection with Serratia marcescens can hasten mortality but does not increase the primary pathogen's virulence.