Solenopsis invicta – also called red imported fire ants (RIFA) to distinguish them from other Solenopsis species and species called “fire ant” – is an extremely aggressive ant species native to central South America and now introduced in the southern United States, southern China and some locales in Australia. They are called “fire ants” due to their painful sting, which includes the toxin solenopsin (C17H35N). Fire ant attacks can be very painful to humans and large livestock, and fatal to smaller livestock and wild animals. Further, RIFA have had harmful ecological effects by out-competing native ant species as well as unsustainable predation levels of plant seeds, other invertabrates, and even small animals. However, there have been some attempts to use these qualities to control the spread of ticks and agricultural pests.
Control Methods[edit | edit source]
Several factors make it difficult to eradicate fire ants. One major challenge is that queens can be located 2-3 feet below ground. Also, many colonies have multiple queens.
Large scale[edit | edit source]
- Phorid fly (Pseudacteon tricuspis, P. curvatus) – Various regional and local authorities in the US have released these natural parasites of the RIFA. So far reports indicate an overall reduction in infestation rates. Some success has also been achieved using phorid flies as a vector for the pathogen Kneallhazia solenopsae.
- Quarantine – Local authorities in the US and Australia have enacted quarantines on materials that may harbor fire ants.
Home and farm[edit | edit source]
- Pesticides – Compounds like pyrethrins are commonly used. While these chemicals may have little to no direct effect on human health, they can have long-lasting effects on soil organisms.
- D-limonene – This hydrocarbon derived from the rinds of citrus fruit appears to be the most effective known natural method of controlling fire ants. Works by destroying ant's exoskeleton. Small portions of orange oil can be added to water and then applied to mounds. Commercial organic products featuring d-limonene are also available.
- Boiling water – A very common and easy method. Studies show around 60% effectiveness in eradicating colonies. Typically repeated applications are necessary. Best times to apply are when many ants are near the top of the colony: warm and sunny days, and immediately after rain showers. Caution is needed to prevent burns to self, others and important plants.
- Diatomaceous earth – As with other arthropods, DE can be very effective. However, it is also harmful to beneficial species. DE is also not effective when wet. For best results it should be mixed into the mound itself.
- Corn meal – A common remedy which has shown little effectiveness in scientific studies. It is supposed to work by expanding in the ant's gut after being consumed.
- Soda water (seltzer) – Another home remedy. Carbon is believed to accumulate lower in the hive, thus asphyxiating the ants present at those levels, such as the queen. Field trials have shown it to be ineffective.
- Physical removal – Potentially hazardous as the ants may attack whomever is removing them.