How Can Ants Be Attracted to Sperm?
WouterSeveral species of ants produce chemoattractants, such as the odorant progesterone in cumulus oophorus and the sea stars’ “resact”. Sperm chemoattractants are released from the female reproductive structures, such as the egg jelly of sea stars and the egg accessory organs of hydrozoans.
Sperm chemoattractants can be proteins, peptides, or other substances, and have been identified in several species. Sperm chemoattractants have been found in sea stars, cuttlefish, abalone, and sea urchins.
Sperm attractants can induce chemotaxis, or the movement of spermatozoa towards an egg. This is a well-known behavior in vertebrates, marine invertebrates, and nematodes. Sperm chemoattractants vary from species to species, but are often proteins.
A recent study examined the effects of rival seminal fluid on sperm motility. Among other things, rival seminal fluid induces motility and may also induce ROS damage, leading to sperm mortality.
In addition to its ability to induce motility, rival seminal fluid may also induce metabolic exhaustion of genetically different sperm. This may lead to sperm mortality, but the molecular mechanisms behind this are unclear.
One of the possible explanations is that sperm use molecular cues from rival seminal fluid. However, the mechanisms of sperm incapacitation in Acromyrmex leaf-cutting ants are unlikely to have evolved in the same direction as those of queens.
Sperm incapacitation has been predicted in ant queens, but it is not yet known how they achieve this. In many species, such as the leaf-cutting ants, the queen has an enlarged bursa copulatrix, which encloses her spermatheca and contains little or no fluid.
