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Mites on fruit flies - Pics, Video
#1
A few days back, I was having a discussion with several other frog nerds about mites in fly cultures. Everyone seemed to have a differing opinion on how they get into the cultures.
One thought that the mites are pretty much ever present in the cultures due to the materials used.
Another thought that the mites migrated from the environment into the cultures, so preventative measures were the only way.
Yet another mentioned that they may get introduced at some point and then get carried between cultures by the flies - even prior to the 30 day mark that is their generally accepted life cycle time.

Being the guy I am, I tend not to just take peoples word for it. I like to see things with my own eyeballs and confirm, at least in my own (and albeit highly unscientific) way.
My cultures have always been very clean, I rarely see mites due to very strict culturing practices, keeping cultures on fresh mite paper, not keeping mites past 30 days, using boiling water in media, etc. I am mite-free I thought.. not so fast.

In my experiment, I took two cultures from approx. 10, 15, and 25 days after culture. I usually make batches from two separate brands of media(why I do this .. I have no explanation for that, but I digress), represented by Repashy Superfly, and NEHerp's Media.
I swabbed every culture, and also took about 6-8 flies from each and smashed their heads with fine tweezers(to keep them from running away, and to preserve anything that may be attached to them Big Grin).

I busted out my 2000x stereoscopic microscope, and went to town.

First off, I took some samples of the medias that I am using - All came back clean in every sample. No mites present that I could see at any magnification.
Culture cups/lids were clean, nothing present.
I flip flop back and forth between excelsior and coffee filters - neither of which did I find any mites on after about an hour panning the stage around.

At this point it seems unlikely that mites that would take interest in FF cultures would be present on these materials, unless they were migrating across them to get to the fly cultures.

On with the flies / swabs.

10 days after culture:
No visible mites present on any swabs, or any of the flies from either media

15 days after culture:
Few VERY tiny mites on swabs. Also found what appear to be baby mites clinging to flies

25 days after culture:
Nearly adult mites on swabs. Few larger baby mites clinging to flies. Nothing on cup visible to the naked eye.

[Image: DSC00481.JPG]

This was interesting to me, as I had always assumed that my cultures were clean, when in fact they were just as mite riddled as any other. Not only that, but the mites were hitching a free ride over to fresh cultures, even if I make new cultures in about the middle of the current cultures life. I suppose I was just out culturing the mites - getting rid of the old cultures before the babies had a chance to become visible, and the adults were too few to be readily noticeable.

While I am sure that given a situation when cultures are set out unprotected, mites will migrate into a culture and make the infestation worse - this is unlikely to occur in cultures kept with some method of prevention (sprays, paper, powder).

From what I am seeing, even protected cultures that "look" mite free, with 100% clean culturing materials, may have them in some capacity and they are just transferring between cultures on the flies.

Any thoughts/experiences/comments on this?

P.S. if you really want to be creeped out, here is a video I took of the mite climbing around on the fly(ignore daughters jibber jabber in the audio - she was being my lab helper):

[youtube]1Tiwrp0w6x4[/youtube]

watch it in 720, and keep an eye to the right. You'll see it climb up on the body and then on the flies leg.
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#2
Nice post! Very cool photo. Nice to see documentation of flies transporting mites!

I too have struggled with mites despite using mite paper and in-culture mite control chemicals. Like you I suspected the flies themselves were the main vehicle for contamination based on my reading, so I started using extra supplements to dust my seed flies and mechanically sift them with two kitchen strainers of difference screen sizes. The theory I had read on the forums was the dusting dislodges the flies. The sifting should separate them, though finding a strainer with a screen size that allows mites through but holds melanogaster is more difficult than hydei.

Dusting/sifting seemed to help the hydei, but I continued to have problems with melanogaster. I added allowing the melanogaster to crawl out of my sifter to the prep regiment, and a daily wipe down of the cups' exterior to dislodge any mites to the maintenance regiment and my melano cultures have improved.

Though these are un-scientific observations, it visually looks like my mite populations have dropped substantially and more importantly my yields are more consistent. I think it's unrealistic to expect an elimination of mites, but I'm OK with that as long as they don't interfere with predictable culturing. So yeah, I'd agree that the flies themselves were most likely the source of my cross contamination issues.
Jim from Austin --- Lorenzo keepers PM me about a US breeding program
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#3
EXCELLENT mite-on-fly thread. Great start and best,most concise and applicable info I've seen yet. Pics are key here as well.

My thoughts.

the Grain mite and the FF are almost a certain co-existence. One with the other. They are only a big deal if the hobbyist is lazy, sloppy with his culturing or has an allergy to the mites, otherwise Mites = no big deal.

Biggest method of transfer:

90% - Using already contaminated cx's

10% - Mites 'walking from cx to cx (unless you stack your cx cups, in which case you are asking for trouble).

Again, great thread and thanks !
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#4
joneill809 Wrote:...so I started using extra supplements to dust my seed flies and mechanically sift them with two kitchen strainers of difference screen sizes. The theory I had read on the forums was the dusting dislodges the flies. The sifting should separate them, though finding a strainer with a screen size that allows mites through but holds melanogaster is more difficult than hydei.

It's funny you mention dusting flies, as this is exactly what I've been doing as well. I have a large jar of old Rep-cal(before I switched to calcium plus), that I have been using to dust them, and a flour sieve to separate all the residual dust from the flies before going into the culture. My wife wasn't happy about me stealing her sieve.. but it's for the good of the many(flies) Big Grin
I've been doing it for about a month now, and cultures are space out enough that I will be able to take another look to see if it is indeed having any effect.


Philsuma Wrote:EXCELLENT mite on fly thread. Great start and best,most concise and applicable info I've seen yet. Pics are key here as well.

My thoughts.

the Grain mite and the FF are almost a certain co-existence. One with the other. The are only a big deal if the hobbyists is lazy, sloppy with his culturing or has an allergy to the mites, otherwise Mites = no big deal.

Biggest method of transfer:

90% - Using already contaminated cx's

10% - Mites 'walking from cx to cx (unless you stack your cx cups, in which case you are asking for trouble).

Again, great thread and thanks !

Thanks!
I am in total agreement with the co-existence statement. In watching the baby mites that I found on the flies, they remained on the fly and would not venture away from it until it completely stopped moving. I have a sneaking suspicion that there may be some level of reliance on the flies for mobility of the young(they are quite slow movers when they are babies). While this may seem totally obvious to some, it hadn't occurred to me that since they are generally considered a nuisance by hobbyists.

Another thought- Because of them being consistently found together in cultures by hobbyists everywhere, I wonder if we were to completely remove the mite from the flies environment, if it may have a negative impact on the flies life cycle. Similar to how other animals such as fish, and even humans suffer if we are put in too sterile of an environment. SImply put - Perhaps there is something the flies gain from the existence of the mite, if kept in balance, that we haven't considered?
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#5
Excellent theory. I concur.

Take a look at some FF in a CX sometime. Watch for them to shake or do a little dance. It's the mites that are riding on them...itching them. Funny.
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#6
Very cool thread. Im going to share it on our Entomology FB page.
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#7
Timely Bump
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