Ectoparasitic mites on ants


Hello AntBlog team,

I have a few questions and I was wondering if you could help me?

I recently acquired a small colony of Camponotus morosus, I housed the colony inside an aerated autoclaved concrete nest, however just after the colony had moved in I was taking photos and noticed what appear to be very large (In ant terms) mites, I have only noticed 2 of the mites in the colony so far, the thing is I cannot manually remove the mites unless the workers come out to forage with them on as the nest is affixed to the inside of a glass tank.

Strangely the mites only seem to attach to the very small minor workers who do not leave the nest to forage, they are mobile and I have seen them moving from one ant to another and they always latch on the underside of the ant, they do seem to bother the worker they latch on to.

I was wondering if you could give me any information on these mites as they are unlike any ant associated mites I have come across before.

How can I get rid of them? Are they parasitic or phoretic? Will they hurt my colony?

And finally if you have any information on C. morosus you could give me I would really appreciate it, I'm afraid I have not been able to find a lot of information out on the internet as of yet!

Regards,
~Daniel
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Dear Daniel,

Wow! Those mites are really amazing! We contacted a colleague, Kaitlin U. Campbell, who is an expert in mites found on ants to see what she had to say:

"Dear Daniel,

Thanks for sending the great pictures of these exciting mites you found! As you might imagine mites are pretty difficult to identify from images, and the specimens typically must be mounted on microscope slides to get accurate identifications. You are correct about these being very large mites (in terms of ants on mites). There are very few people working on mites associated with South American ants that aren't army ants, and to my knowledge none of them have looked at Camponotus. If this mite is truly associated with Camponotus morosus and not just there by accident, it is likely a new species. The best identification I can give you from these pictures is that it is in the Mesostigmata. Unfortunately this doesn't provide much information in terms of what they are doing. Here is a summary we do know about ant associated mites:

The majority of ant associated mites typically fall into 3 subgroups of mites: Mesostigmata, Heterostigmata, and Astigmata. All of these groups have members that ride on the ants (phoresy). Astigmata and Heterostigmata are typically smaller in size than the Mesostigmata. The Astigmata and Heterostigmata that I have encountered are generally believed to be fungivores or bacterivores taking advantage of the resources inside the ant nests, and possibly cleaning up when they are not riding on the ants. There are only a few genera of Heterostigmata that are known parasites. Because of their mouth parts and what little we know of their ecology, we believe these two groups are the least likely to cause any harm to the ants. In fact the phoretic Astigmata (their Deutonymph stage) do not even have mouths and only get mouths when they develop to the next stage after the disembark from the host!

The Mesostigmata, however, are a different story. Many of these have large enough mouth parts that they could actually cause damage to the hosts. The majority of the "mesostigs" are still thought to just use the host to get around (they are probably predators of other mites, Collembola, and nematodes or scavenging in the nests), but a few are known to pierce the hosts' cuticles or feed on brood. As you can image, mite behavior is difficult to study, so few have actually looked into this in detail. The most well studied Mesostigs are either associates of Army ants (many of which have really unusual body shapes), Macrodinychus species parasitizing developing brood, or Antennophorus species a cleptoparasite (steals food) on Lasius ants. What you have is not any of these! Yours looks most similar to the Antennophorus species, and may be in the same Suborder, but without having the specimen on a slide it's not going to be possible to tell.

Concerning whether they are bad for your colony- As I mentioned before, very few mites are known to actually cause damage to their ant hosts. I am suspicious of your mites, however, because of their orientation on the ants. They seem to be positioned in areas with their heads near soft tissue, and you said they do seem to bother the ants. The ants could just be bothered because the mites are large and cumbersome to be carrying around, though. They could potentially be harming the ants, and you should monitor the mites behavior and the health of your ants. It's very difficult to get rid of mites on the ants without harming the ants with any chemicals. Since you only have a couple it would be best to just remove them individually from the ants if you can ever get the small ants to exit the nest area. If they are seriously harming the colony, your only option may be to open the nest and remove the ants carrying the mites. I would just watch them closely and resort to active removal if they seem to cause a lot of damage.

If you are able to remove the mites and interested in knowing what they are (I sure am!), please preserve them in ethanol and send them to me and/or take individual pictures of the dorsal and ventral sides of the mites.

This is a cool find, and I'll be interested to hear more! I hope this helped!"

Best regards,
Kaitlin U. Campbell (guest expert), Corrie Moreau & the AntAsk Team

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