worms not reproducing?

I transferred worms to freshly seeded NGM plates as usual a few weeks ago. They crawled around like normal, matured into adults but did not produce any offspring. Does anyone know what might have caused this? It happened to two different strains at about the same time. I have since recovered these two strains from frozen stocks and they seem to be doing fine. But I’d like to avoid having this happen again because it has messed up my research timeline.

Any chance that you omitted the cholesterol from your NGM plates? We did that once and N2 worms grew okay, but reproduced poorly - some progeny, but few grandkids. Some of our mutants stocks were much more severely impacted and needed to be restarted. I suspect omission of other components of the plates might lead to similar results. Another possibility is that your incubator experienced a heat or cold surge at just the wrong time. Or maybe it’s just bad karma.

First thing I would like to ask you…is which strain is it ? And hopefully you are growing them as permissible temperate as some strains are sterile at certain temperature. If you dont think thats the case then, check the temp. of the incubator to see is that the cause. Plus…once you let me know which strain you are working with, I guess it would be easier to suggest some more solutions

The worms weren’t on a new batch of plates, so I don’t think that lack of cholesterol is the problem. Can NGM plates go bad?
The strains were N2 and gas-1. We don’t have them in an incubator, but the lab is ~20 °C.

I have used (unseeded) NGM plates that were kept in the cold room for up to 6 months and they were fine, as long as they well wrapped and not contaminated to begin with. We just seed them within ~1 month of use. On the other hand, we have gotten our OP-50 contaminated with another bacteria that was, apparently, inedible. In that case, the worms ‘failed to thrive’ and we restarted our OP-50 from the freezer.

If you are using old seeded plates that have worked before, I would suspect a problem with the lab temperature.