Multispecies interactions affect cytoplasmic incompatibility in Tribolium flour beetles

Area of Science:

• Microbiology
• Entomology
• Genetics

Background:

• Cytoplasmic incompatibility in *Tribolium confusum* is caused by a maternally inherited rickettsia-like bacteria.
• Infection leads to sterility in crosses between infected males and uninfected females.
• Tetracycline treatment can cure beetles of this bacterial infection.

Purpose of the Study:

• To investigate if other microbial species, specifically actinomycetes or fungi, can cure *Tribolium confusum* of the rickettsia-like bacteria.
• To identify specific microbial strains capable of curing the infection.

Main Methods:

• Infected *Tribolium confusum* progeny were raised on wheat grain molded with various strains of *Streptomyces* (actinomycete) and *Penicillium* (fungi).
• Microbial strains included known tetracycline producers and related species commonly found in grain.
• Curing rates were assessed by observing the reproductive success of treated beetles.

Main Results:

• *Streptomyces aureofaciens* (NRRL 2209) demonstrated high curing rates (8/10 males, 9/10 females).
• Other tested strains, including *Streptomyces griseus*, *Penicillium verrucosum*, and *Penicillium aurantiogriseum var. polonicum*, showed low or no curing rates.
• No curing was observed in control groups (autoclaved grain, brewer's yeast).

Conclusions:

• Specific actinomycete and fungal strains can effectively cure *Tribolium confusum* of rickettsia-like bacterial infections.
• The findings suggest that localized antibiotic contamination in grain, from microbes like *S. aureofaciens*, can create pockets of cured insects.
• This phenomenon may contribute to the observed polymorphism of infection within natural *Tribolium* populations.