Imported Fire Ant Species and Their Hybrid in Tennessee: Interrelationships with Biological Control Agents, Ant Morphology, and Geographic Locations

Manoj Pandey, Tennessee State University


Interrelationships of red (Solenopsis invicta Buren) (RIFA) and black (Solenopsis richteri Forel) (BIFA) imported fire ant (IFA) species and their hybrid (HIFA) with worker size, integument coloration, and biological control agents were studied. The IFA species and hybrid were identified using cuticular hybdrocarbon and venom alkaloid indices obtained from gas chromatography and mass spectrometry. Worker size of the IFA species and their hybrid was compared. The average worker size of RIFA was significantly smaller than BIFA or HIFA. No statistical differences were detected in the average worker size of BIFA and HIFA. Likewise, no relationship was found between size of the IFA workers and geographic location or elevation in Tennessee. These findings may impact the establishment of size-dependent biological control agents like Pseudacteon phorid fly. The HIFA dominated the IFA distribution in Tennessee. With the exception of a few isolated RIFA samples, HIFA was the only IFA found in east Tennessee and also predominated in middle Tennessee, while mixed populations of BIFA and HIFA occurred in west Tennessee. The HIFA population appears to be increasing in prevalence in west Tennessee compared to previous studies. The integument coloration of IFA samples was measured using a portable spectrophotometer and compared to cuticular hydrocarbon and venom alkaloid indices used to determine IFA species and hybrid status. Significant differences were found between RIFA and BIFA in integument coloration, while HIFA coloration generally fell somewhere in-between RIFA and BIFA depending on cuticular hydrocarbon and venom alkaloid index value. Some color attributes exhibited a polynomial relationship with cuticular hydrocarbon and venom alkaloid indices. Because color attributes were not linear between BIFA and RIFA, it may be difficult to relate color change to a particular HIFA hydrocarbon or venom alkaloid value. Pseudacteon genetic material was detected molecularly at equivalent rates among colonies with or without Solenopsis invicta virus and Kneallhazia solenopsae Knell Allen Hazard infections. The method used for Pseudacteon detection may be useful for surveying the establishment and distribution of Pseudacteon phorid flies in large areas.

Subject Area

Ecology|Entomology|Plant sciences

Recommended Citation

Manoj Pandey, "Imported Fire Ant Species and Their Hybrid in Tennessee: Interrelationships with Biological Control Agents, Ant Morphology, and Geographic Locations" (2017). ETD Collection for Tennessee State University. Paper AAI10615002.