The red imported fire ant, Solenopsis invicta (Hymenoptera, Formicidae), is an invasive ant species from South America to the United States and is responsible for approximately six billion dollars (U.S.) every year. In 2004, as part of an effort to find a self-sustained, long term biological control agent against S. invicta, researchers discovered the first ever known virus to infect Solenopsis sp., the Solenopsis invicta virus-1 (SINV-1). RNA interference (RNAi) is a known regulator of biological systems in insects and was used in this study to manipulate viral titers of SINV-1 in individual S. invicta workers and whole S. invicta colonies. By exposing S. invicta workers and whole colonies to a whole isolated SINV-1 virions and double stranded RNA (dsRNA) complementary to SINV-1, viral titers of SINV-1 were shown to significantly increase and decrease respectively. Increases and decreases in SINV-1 viral titers were shown to correlate with S. invicta worker mortality in infected S. invicta colonies. Differences in gene expression across SINV-1 and dsRNA treated S. invicta workers was measured by predicting the existence of 110 micro RNAs (miRNAs) in S. invicta, and measuring the relative abundance of each. The expression of five screened miRNAs was measured in SINV-1 infected S. invicta workers exposed to SINV-1 viral isolate, water, and dsRNA, with miRNAs Bantam and miR-8 determined to be significant components of the innate immunity of S. invicta against SINV-1.

Date of publication

Spring 5-27-2015

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