Tag Archives: Acari

Friday Fellow: Cuban-Laurel-Thrips Mite

by Piter Kehoma Boll

Last week I introduced the Cuban Laurel Thrips, which feeds on several fig trees, such as the Chinese Banyan and the Cuban Laurel. Today, we will continue up the food chain and talk about a mite that is a parasite of the cuban laurel thrips. Named Adactylidium gynaikothripsi, I decided to give it the common name “Cuban-Laurel-Thrips Mite”.

The Cuban-laurel-thrips mite was described only in 2011 from Cuban laurel thrips populations in Greece. This is the fourth mite of the genus Adactylidium known to parasitize the Cuban laurel thrips, the other four being Adactylidium ficorum (“fig-thrips mite”), A. brasiliensis (“Brazilian thrips mite”) and A. fletchmani (“Fletchman’s thrips mite”). As you can imagine, in order to parasitize an insect as small as the Cuban laurel thrips, these mites are even smaller, measuring about 0.1 mm in length.

An adult female of the Cuban-laurel-thrips mite. Extracted from Antonatos et al. (2011).

The life cycle of the Cuban-laurel-thrips mite, which is basically the same for all species of Adactylidium, is very bizarre. Adult females feed on the eggs of the Cuban Laurel Thrips. They start their adult life wandering over fig leaves looking for a suitable thrips egg to attack. Once finding one, they pierce the egg’s shell with their chelicerae and attach to it like ticks and start to eat. They feed on a single egg across their entire life. If they are unable to find an egg, they may also attach to an adult thrips as a last resource, or else they die of starvation in a few hours.

Once a female starts to eat, a small group of eggs, usually between 5 to 10, begins to develop inside her. The eggs grow during the first 48 hours after the female attached to the egg, making her double in size and becoming something like a spherical egg sac. The eggs hatch around this time and the mite larvae remain inside their mother. These larvae lack mouth parts, so it is believed that they absorb nutrients from her mother directly through the body surface. About 24 hours later, the larvae turn into nymphs, which remain inactive inside the shed skin of the larva. They also lack any mouth parts.

Female Cuban-laurel-thrips mites attached to eggs of the Cuban laurel thrips. Extracted from Antonatos et al. (2011).

Another 24 hours pass and the nymphs turn into adult mites. They are still inside their mother when this happens. The adults consist always of a single male and several females. This male then starts to copulate with his own sisters, still inside their mother’s abdomen, and, when copulation is finished, they start to tear their mother’s body apart to get free, killing her in the process. Once outside the body, the male dies in a few minutes, never eating anything other than his own mother. The females, on the other hand, start to look for thrips eggs on which to feed, only to be killed by her own children less than 4 days laters.

This entire life cycle may look very insane from our human perspective, but nature was never interested in following our moral rules.

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References:

Antonatos SA, Kapaxidi EV, Papadoulis, GT (2011) Adactylidium gynaikothripsi n. sp. (Acari: Acarophenacidae) associated with Gynaikothrips ficorum (Marshal) (Thysanoptera: Phlaeothripidae) from Greece. International Journal of Acarology, 37(sup1), 18–26. doi: 10.1080/01647954.2010.531763

Elbadry, EA, Tawfik, MSF (1966) Life Cycle of the Mite Adactylidium sp. (Acarina: Pyemotidae), a Predator of Thrips Eggs in the United Arab Republic. Annals of the Entomological Society of America, 59(3), 458–461. doi: 10.1093/aesa/59.3.458

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Filed under Arachnids, Friday Fellow

Friday Fellow: Giant red velvet mite

by Piter Kehoma Boll

While walking through an Indian market, you may end up finding something like this being sold as food:

Hmm, it looks like some sort of chips or dried seeds. Photo by Pankaj Oudhia.*

Hmm, it looks like some sort of chips or dried seeds. Photo by Pankaj Oudhia.*

It may look as some sort of crispy seed or dried fruit, some local chips, maybe? But they are actually giant mites… edible mites! They are used in India as a medicine, especially to treat paralysis and allegedly to increase sexual drive, a reason for the popular expression “Indian Viagra”.

But this edible arachnids are actually quite cute when alive. Known cientifically as Trombidium grandissimum and popularly as giant red velvet mite, they are fluffy like a piece of velvet, have a strong red color and reach up to 2 cm in length, a record for mites, which usually measure way less than a milimeter.

I would love to raise them as a pet. Wouldn't you? Photo by Brian Gratwicke.**

I would love to raise them as a pet. Wouldn’t you? Photo by Brian Gratwicke.**

As adults, the giant red velvet mites live freely and prey on small animals, mainly insects, and their eggs. The larvae, on the other hand, start their life as a parasite, attaching themselves to another invertebrate, usually an insect, but sometimes an arachnid, and suck their hemolymph (“blood”). Later, this parasitic larva develops into a free-living nymph that abandons the host and begins to live more like an adult.

The genus Trombidium has many species in the Palearctic Ecozone, so if you are wandering in a forest in Europe or Asia, you may find the giant red velvet mite or one of its cousins.

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References:

Southcott, R. V.  1986. Studies on the taxonomy and biology of the subfamily Trombidiinae (Acarina: Trombidiidae) with a critical revision of the genera. Australian Journal of Zoology, 123: 1-116.

Wikipedia. Trombidium. Available at: <https://en.wikipedia.org/wiki/Trombidium&gt;. Access on July 21, 2016.

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Filed under Friday Fellow, Zoology