Recommendations on collecting methods and DNA extraction technique on fire ant (Solenopsis invicta Buren) specimens when screening for microsporidians and social form using PCR

In recent years, the techniques of molecular biology have become more common in the field of entomology. Collection methods and preservation can have adverse effects on the quality of DNA obtained from samples. The common methods used in the field to collect fire ants are pitfall traps, hot dog bait, direct collection from a mound in a talc powder covered vial, and direct collection from a mound. These methods can leave residues on the ants that could inhibit PCR reactions. Ten ant samples were collected using each of the methods mentioned previously. Pitfall traps were left out for 24 hours, 72 hours, 5 days, 7 days, 14 days in order to determine if the amount of time in ethylene glycol effects DNA quality. Each collection method had DNA extracted using two different methods; a phenol:chloroform extraction and a commercially available kit from Qiagen. The protein to DNA ratio recorded was significantly different (<0.05) for the different collection methods but was not significantly different for pitfall traps collected at different time points. Comparing the phenol:chloroform extraction to a Qiagen kit showed a significant difference(<0.05) in the quality of DNA extracted. Our recommendation for field collection of fire ants is to use either direct collection from a mound or hot dog baits. These two collection methods produced the highest quality DNA but were not significantly different from one another.