April 28 : A University of Alberta researcher recently carried out a study to find out the reason behind female ixodid tick’s astounding weight gain after a mating session.

In a new research paper published in the Journal of Insect Physiology, Dr. Reuben Kaufman, from the Department of Biological Sciences, has put forward a number of differences between the ixodid tick and her blood-sucking counterparts that help elucidate the weight gain.

After comparing the ixodid tick with mosquitoes, tsetse flies, bed bugs and kissing bugs, Kaufman found that no one matched up to this female African tick when it came to weight gain following mating.

Kaufman suggests that the ixodid tick exhibits a noteworthy difference in lifestyle from the other insects and that it is adaptive for the virgin to remain small before mating.

Kaufman says that first, this species of tick remain on the host for a number of days, rather than minutes.

“In this family of ticks, mating takes place on the host. Most other insects mate before or after their brief blood meal —the two acts are totally separate, but not with these ticks,” Kaufman says.

It takes six to ten days for the female ticks to swell-up fully. First, she attaches herself to the skin, then she feeds to 10 times her unfed weight and finally, after copulation she increases her weight a further tenfold.

In contrast, the virgin tick hardly ever exceeds the essential weight necessary for laying eggs. It hangs on to the host for weeks, waiting for a male to find her, says Kaufman.

If the virgin puts on too much weight and is groomed off the host, it won’t reattach itself to an additional host and will carry on feeding.

“However, if she remains small she still has a chance to reattach itself to another host—hopefully infested with some feeding males– continuing feeding and potentially mate,” says Kaufman. “If a male eventually copulates with her, she will engorge normally and then be able to lay eggs. This is one reason why it might be adaptive for the virgin to remain small until mated.”

On the question of what causes the female to become so bloated, Kaufman says that when a tick does copulate, the male’s seminal fluid contains two enlargement factor proteins that together act as indicators to tell her to complete engorgement. (ANI)