Sublethal Exposure to Cadmium Induces Chemosensory Dysfunction in Fire Ants

Area of Science:

• Environmental toxicology
• Insect chemical ecology
• Molecular biology

Background:

• Ants readily accumulate cadmium (Cd) from their environment.
• Cd contamination can impair olfactory function and social behavior in ants.
• Understanding the molecular basis of Cd's impact on ant chemosensation is crucial.

Purpose of the Study:

• To investigate the molecular mechanisms of Cd exposure on the chemosensory system of the red imported fire ant, *Solenopsis invicta*.
• To analyze Cd-induced changes in chemoreception gene expression, electrophysiology, and behavior.

Main Methods:

• Gene expression profiling of odor binding proteins (OBPs) in *S. invicta*.
• Protein binding assays for selected OBPs with specific semiochemicals.
• Electrophysiological and behavioral assays to assess olfactory sensitivity post-Cd exposure.
• Gene silencing techniques to confirm OBP function.

Main Results:

• Cd exposure increased Cd accumulation and reduced survival rates in *S. invicta*.
• Expression of *S. invicta* OBPs (SiOBPs) was altered, with SiOBP15 upregulated.
• SiOBP7 and SiOBP15 bind to limonene, nonanal, and 2,4,6-trimethylpyridine.
• Cd-exposed ants showed reduced sensitivity to these chemicals but increased sensitivity to undecane.
• Silencing SiOBP7 and SiOBP15 impaired responses to nonanal and undecane, respectively.

Conclusions:

• Cd contamination interferes with olfactory signal transduction in ants by modulating SiOBP expression.
• This leads to chemosensory dysfunction, impacting ant behavior and survival.
• The study identifies specific OBPs involved in mediating responses to semiochemicals affected by Cd exposure.