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Hi Everyone,

We have a mold issue and want to work out how to prevent this in the future. if someone is able to help we would be really grateful! Also, does someone know if there are health precautions that should be taken when handling these specimens? I don't know what kind of mold it is.

Students collected Diptera across several field sites. They were stored in separate Eppindorf tubes for max. 1.5 hours until the tubes were transferred to an ice box. They were then kept in the freezer in the tubes since then - for max. 2 weeks in a home freezer (so I would estimate about 0 or -1 degrees C) and around 3 months in a -20 degrees C freezer.

Now the students are opening the tubes for pinning, and noticing a strong smell. Under the microscope I can see lots of them are covered in whitish-yellow mold, and I can see condensation in the tubes.

I would have thought, being stored at -20 degrees C, this would have prevented mold growth? When I notice mold on a fly, I put it in the -20 freezer to kill the spores. Could it be that the spores had time to grow and spread while being stored at 0 degrees C? That is the only explanation I can think of so far. I would have also recommend to the students to pin as soon as possible after collecting to allow them to air dry, I think leaving them stored so long opens us up to such issues.

I also noticed a couple of them have a black, kind of oily appearance, where the outer surface seems to be coated or stripped off. Is this freezer damage or something else?

I will add some photos. If anyone has any ideas or suggestions that would be great, thank you so much

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image - mold

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image - oily black appearance