Cross-Resistance: A Consequence of Bi-partite Host-Parasite Coevolution

Area of Science:

• Evolutionary Biology
• Insect Pathology
• Host-Parasite Interactions

Background:

• Host-parasite coevolution can alter host interactions with other community members.
• Cross-resistance, where resistance to one parasite confers resistance to another, is a known phenomenon in host-parasite evolution.
• The red flour beetle (Tribolium castaneum) serves as a model organism for studying insect-pathogen interactions.

Purpose of the Study:

• To investigate cross-resistance to Bacillus thuringiensis and Pseudomonas entomophila in Tribolium castaneum after coevolution with Beauveria bassiana.
• To explore the underlying gene expression mechanisms associated with observed cross-resistance.
• To determine if coevolution with B. bassiana confers resistance to oral toxicity from other pathogens.

Main Methods:

• Tribolium castaneum larvae were subjected to coevolutionary experiments with Beauveria bassiana.
• Survival assays were conducted to test for cross-resistance to Bacillus thuringiensis and Pseudomonas entomophila.
• Gene expression analysis was performed to identify molecular mechanisms of resistance upon B. bassiana exposure.

Main Results:

• Larvae evolved with B. bassiana exhibited positive cross-resistance to B. thuringiensis but not to P. entomophila.
• Gene expression analysis showed upregulation of markers associated with oral infection routes following B. bassiana exposure.
• The observed cross-resistance to B. thuringiensis was linked to enhanced resistance against oral toxicity.

Conclusions:

• Coevolution with the entomopathogenic fungus Beauveria bassiana confers significant cross-resistance to the bacterium Bacillus thuringiensis in Tribolium castaneum.
• This cross-resistance is likely due to evolved resistance to oral toxicity, suggesting shared infection or toxicity mechanisms between B. bassiana and B. thuringiensis.
• The lack of cross-resistance to P. entomophila indicates distinct infection pathways or toxins employed by this pathogen compared to B. bassiana and B. thuringiensis.