FUNGAL ATTACKS ON FROG EGGS

John W Wilkinson

Like Clive Cummins in Newsletter No. 32, I remove the eggs of my Dendrobatids (largely D. truncatus at the moment) for improved hatching and metamorphosis as I find them to be poor parents. Their eggs seem to suffer from the following if left in situ: -

(1) small (nematode?) worms which live in the vivarium substrate are attracted to the eggs after laying and can be found happily munching through healthy and infertile eggs alike if left in place for more than a couple of days;

(2) the eggs are attacked by a fungus such as the one Clive describes in his article.

The first problem is overcome by careful provision of oviposition sites and I have abandoned the traditional half-coconuts in favour of plastic "Aquarian" fishfood tubs turned on their lids. These have a hole of about 20mm cut about midway "up" the tub and the lid acts as a shallow Petri dish. They have the disadvantage of being bright blue but they can be roughened with sandpaper and painted in a suitable natural colour with enamel paint or coated with silicone sealant and a layer of fine bark chippings to make a very unobtrusive oviposition hut. Neither of these camouflage techniques are necessary for the method to be effective. Both the D. truncatus and my Mannophryne trinitatis use these for egg-laying in preference to other sites such as shaded leaves etc. The warms, the villains of the story, take much longer to seek out the eggs using this method and the atmosphere inside the tubs is humid without there being anywhere for mould to grow. The tubs can be sterilized and reused to prevent bacteria accumulating.

As Clive suggests, fungal problems are alleviated by simulating the movements of a parent frog (cleaning the egg surface?). In the plastic boxes I use for keeping the developing eggs, the atmosphere is very humid and must be fairly stale. The eggs are lightly sprayed daily with aged, room-temperature water and this agitates their surface sufficiently to prevent fungus developing, as well as maintaining the humidity.

I hope these two methods are of interest to members. I would be interested to hear from anyone who keeps D. truncatus and leaves the eggs to be cared for naturally. It has been suggested to me that their parenting skills might develop and improve over time so that the need for the removal of eggs is ultimately removed.