I am comparing the survival of 2 insect larvae under identical conditions. I have the cumulative survival rate (%) for each day. In my case, I have 100% survival on day 0 (start of test) and survival goes down from there. When I plot this for both insects, I get 2 curves with cumulated survival on the Y axis and the number of days since the start of the test on the X axis. What test should I use to see if these curves are significantly different from each other.
Are all larvaes dead i.e. all survival times known? If yes, you can use any suitable two-sample test, e.g. Wilcoxon's rank-sum test (to see if survival times tend to be larger for one type of insect) or Kolmogorov-Smirnov test (to see if your curves are different). Otherwise, if you have censored times, the log-rank test might be more appropriate.
PS: one Michael was faster than the other ;-)
If you are using Kaplan-Meier estimates for the survival curves you can use the log rank test for determining whether the two survival curves are different.