Backswimmer Fungal Disease?

[Malcolm Banks]

I have noticed several backswimmers (Notonecta glauca) in my pond with what appears to be a fungal infection (see pic). This also occurred last year at the same time, ie March, when the overwintering backswimmers are towards the end of their lives. I have dome a search on WAB, Google and PubMed but cannot find a reference much less a description of this, but I feel sure it is not uncommon. Maybe it is not a fungal disease? Any comments/info gratefully recd
M

PS I was unsure as to whether to post this on this subforum or on "water life", but thought there may be more insect pathogen experts on this one

[The Woodman]

Looks like Saprolegnia fungus to me. It's common in freshwater and will attach its filaments onto just about any organic substance.

Have a look at the fish keeping sites for easy and cheap remedies e.g. salt solutions

[Malcolm Banks]

Thanks for the steer Woodman. My thoughts were that, since it only appears towards the end of the life of the backswimmers, perhaps it was an opportunistic growth enhanced by their failing immunity. So this chimes with your Saprolegnia spp. suggestion.
They don't appear to be affected by the fungus. I certainly don't intend to intervene since despite the fungus also being present in N.g. from 2008 over into 2009, there was still a good healthy crop of young produced in Spring 09 that (as they do) "bossed" the pond for most of the season.
M

[The Woodman]

It's certainly more visible at this time of year when dissolved oxygen levels are higher, BOD is low and the Ng's are failing. Perhaps it infiltrates necrotic tissue in the first instance.