Help! They're on Fire!

Help! They’re on Fire!

Among the top ten vicious insects in the U.S. is Solenopsis, also referred to by their common name, “Fire Ant.” Solonopsis is categorized under the order Hymenoptera and under the family Formicidae. Solenopsis invicta (red imported fire ant) can be distinguished from the Solenopsis geminata (tropical fire ant) because S. geminata will have square shaped heads that are of much greater proportion in comparison to the rest of their body whereas S. invicta do not have heads that are characteristically larger than the rest of their bodies. Mounds of fire ants are usually no bigger than 18 inches in diameter and disturbance of the mound leads to an aggressive attack from the fire ants. The queen is capable of laying 1,500 eggs a day and after the eggs hatch, the queen will wait to lay more eggs until the first batch matures. The larval stage of the ant will last 6-12 days followed by the 9 day pupal stage and concluding with the adult worker ant stage. The diet of the fire ant consists of dead insects and dead vertebrates as well as other sources of nutrients from the homes of humans. After a human is bitten by the ant there is typically an initial burning sensation and a fluid filled vesicle at the site of the bite. Lastly, the site of the bite becomes a discolored, puritic, necrotic lesion. Most venoms of fire ants are proteinaceous mixtures, contains alkaloids, and small protein component. The venom of a fire ant is bactericidal, hemolytic, and cytotoxic. Solenopsis invicta is native to South America but was imported into the United States. Today, their colonies are densely dispersed around the gulf coast and intermittently dispersed around the southern U.S. in general. Solenopsis germinata however, is commonly located in tropics. Worker ants are polymorphic, meaning that they consists of many sizes in the range of 2.4-6 mm whereas the queen in a single colony is characteristically larger than the workers. The diet of fire ants typically includes vertebrates, dead animals, insects, and often sweets and fats in human homes.

It has been observed that controlling the Solonopsis invicta species is very tedious and they species has continued to climb toward the northern region of the U.S. from their initial sight of importation in the southern region among the gulf coast. Today, a successful biological control has not been implemented. However, some efficacy has been found to control the spread of Solenopsis geminata, the tropical fire ant invading the tropics, from implementing the use of Pseudacteon bifidus, referred to as the decapitating fly and is a natural predator to the fire ant. The decapitating fly is highly host specific and doesn’t attack other species of ants apart from Solenopsis geminata. In addition, it is self-sustaining and is not also attracted to feces or human food items thus eliminating the potential for the fly to become a pest to humans.

Solonopsis invicta plays a substantial role on the economy in the United States in regards to agriculture, human health concern, and cost associated with controlling the ants. S. invicta continually inhabits and causes harm to soybean crops thus dramatically reducing the production of soybeans. In 1990, it was determined that due to S. invicta, there was a profit loss of $156 million is soybean production alone. S. invicta are also causing damage to other essential U.S. crops, such as potato, okra, and beans, due to their opportunistic feeding tendencies. In addition, stings of fire ants initiates a range of possible symptoms in humans from localized swelling to anaphylactic shock. In regards to the economic cost for the U.S. it has been found that state governments, particularly in the south, have spent over $250 million in order to eradicate the fire and populations.  
Sanford D. Porter, Robert M. Plowes, Charlotte E. Causton, 2018. The fire ant decapitating fly, Pseudacteon bifidus (Diptera: Phoridae): host specificity and attraction to potential food items.
Laura Collins and Rudolf H. Scheffrahn, 2016. Featured Creatures: Red Imported Fire Ants




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