Necessarily derived experimentally, this value will vary by stage of development and strain, but from Lim et al.;
http://genesdev.cshlp.org/content/17/8/991.long
a value of 19ng total RNA per 2 day old glp-4 adult hermaphrodite worm was suggested.
(This value was calculated as the average of three independent extractions of synchronised worms).
Others have suggested a lower value of ~9ng but this was not qualified;