Location: Imported Fire Ant and Household Insects ResearchTitle: Male fire ant neurotransmitter precursors trigger reproductive deveopment in females after mating
|Vander Meer, Robert - Bob|
|CHINTA, SATYA - Foresight Science & Technology|
|JONES, TAPPEY - Virginia Military Institute|
|ADAMS, RACHELLE - The Ohio State University|
Submitted to: Nature Communications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/29/2021
Publication Date: 12/15/2021
Citation: Vander Meer, R.K., Chinta, S.P., Jones, T.H., O'Reilly, E.E., Adams, R.M. 2021. Male fire ant neurotransmitter precursors trigger reproductive deveopment in females after mating. Nature Communications. 4:1-11. https://doi.org/10.1038/s42003-021-02921-5.
Interpretive Summary: Fire ant queens can produce up 5,000 sexual daughters - potential queens - each year (200,000 sterile workers). The queen uses a chemical (primer pheromone) to inhibit the reproductive development of her daughters. If the sexual daughters are removed from the queen's influence they start reproductive development within 7 days. In contrast to this, if the sexual daughters leave the colony during a mating flight and mate, they start reproductive development almost immediately. The time difference suggested that the mechanisms to reproductive development via removal from the queen and via mating are different. This has been a mystery for decades until our discovery that males produce tyramides that are passed on to the sexual daughters during the mating process. Remarkably, the the now newly mated queen (NMQ) has a specific enzyme that hydrolyzes the tyramides to the biogenic amine, tyramine. Analyses of NMQs show high levels of tyramine in the head, thorax, and especially in the gaster. Injection of tyramine into sexual daughters caused them to inappropriately start reproductive development. Tyramides have only been found in the Myrmicinae ant subfamily (over 6,000 species) and we expect additional examples of our discovery within this sub-family. The big question is how have the other ant sub-families evolved to deal with the same queen-daughter problem.
Technical Abstract: Social insects have evolved chemical mechanisms (e.g., primer pheromones) to ensure queens monopolize reproduction, avoiding competition with sexual daughters. When female sexuals are isolated from their queen, their ovaries begin to develop in 2-6 days. In contrast, this physiological shift begins less than 30 minutes after mating, suggesting different mechanisms for the two reproductive development pathways. The mating process triggers rapid female development. Chemical methods were used to determine that tyramides stored in male external genitalia are transferred to female sexuals during mating. Female sexuals rapidly hydrolyze tyramides to tyramine, a biogenic amine, which floods the female hemolymph activating tyramine receptors. Males transfer a biogenic amine precursor to females during mating, activating a mechanism to rapidly overcome the effects of their mother’s primer pheromone.