What is it about?

Invasive fire ants are a serious threat throughout the world. For most countries, once fire ant invasion starts, there's no stopping them. Specific knowledge about the biology of invasive species is invaluable in designing effective strategies against their spread. The failure of the US and China in controlling fire ants clearly illustrate that modern insecticides and technology will not work against fire ants. In spite of a decades-long ever-growing growing literature concerning fire ants biology, little attention has been given to a fundamental step to their invasive success: the founding of new colonies. For a period of several weeks to few months, new queens must defend their egg clutch against local predators and competitors. These include mainly local dominant ant species. In total absence of defending workers, how can the queens succeed? Our study demonstrate lonely fire ant queens are actually heavily armed against invaders. Their venom can be more incapacitating than that of worker's against other ants. Furthermore, we demonstrate that the main incapacitating (by K.O.) effect comes from a single alkaloid molecule which is prevalent among all fire ant venoms.

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Why is it important?

The discovery of a fundamental chemical weapon employed by invasive fire ants during the invasion open a door ajar for new control strategies. For example, key native species may be resistant to fire ant venom incapacitation, and thus used as a natural line of defence. Also, designing strategies to neutralise founding queens is bound to slow down the establishment of new fire ant populations. The implications are countless, awaiting on further studies.

Perspectives

This project took place during a harsh posdoc venture in China. The pressure of limited funds and resources, personal isolation, spurred intense analytical observations of the local fire ants and their competitors. Around southern China, the red imported fire ants are literally *everywhere*. I was very surprised to observe the speed with which a venom droplet from a queen would knockout workers from other common ant species. [Watch Supplementary Videos to share my amazement.] Anyone can do this simple experiment locally. The incapacitating speed is comparable to that of pure nicotine, which is a gold-standard insecticidal alkaloid. I am excited about this new facet about fire ant invasive biology, and would very much like to learn the forthcoming impressions of other colleagues.

Dr Eduardo G P Fox
IBCCF / UFRJ

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This page is a summary of: Queen venom isosolenopsin A delivers rapid incapacitation of fire ant competitors, Toxicon, February 2019, Elsevier, DOI: 10.1016/j.toxicon.2018.11.428.
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