Spiroplasmas from coleopterous insects: New ecological dimensions

Area of Science:

• Microbiology
• Entomology
• Biological Control

Background:

• Spiroplasma are helical, wall-less prokaryotes causing diseases in plants, arthropods, and vertebrates.
• The search for microbial agents for biological control of coleopterous insects led to the discovery of two novel spiroplasmas in beetles.

Purpose of the Study:

• To identify and characterize spiroplasmas from beetles for potential biological control applications.
• To investigate the cultivability, serological distinctiveness, and potential pathogenicity of newly discovered spiroplasma strains.

Main Methods:

• Isolation and identification of spiroplasmas from infected Colorado potato beetles (CPB) and green June beetles (Cotinus nitida).
• Cultivation attempts using conventional spiroplasma media and SM-1 formulation.
• Serological testing to determine the relationship of the CN-5 spiroplasma to existing serogroups.
• Observation of motility in natural fluids and culture media.

Main Results:

• A spiroplasma was found in CPB, prevalent in gut fluids and sputum, but unculturable in standard media.
• A second spiroplasma (CN-5) associated with green June beetles was readily cultured and serologically distinct, representing a new serogroup (IX).
• Both spiroplasmas exhibited active motility; CN-5 motility was observed in culture media.
• Neither spiroplasma showed evidence of pathogenicity to its natural host, but spiroplasma pathogenicity to other insects suggests biological control potential.

Conclusions:

• Two distinct spiroplasma strains were identified in beetles, one of which represents a new serogroup.
• The cultivability and distinct serological profile of the CN-5 spiroplasma highlight its novelty.
• The motility and known pathogenicity of spiroplasmas suggest potential for developing biological control agents against economically important insects.