# 4.1.2. Analysis of generated data

In order to evaluate compiled experimental data, two different analyses
to measure virulence can be performed. The first virulence indicator is the
lethal concentration (LC) value (Thomas and Elkinton, 2004), which indicates
the spore concentration at which 50 % (LC_{50}) or 100 % (LC_{100})
of the individuals are killed. To calculate this measure, the proportion of
dead larvae from the number of exposed larvae is plotted against spore
concentration. From such graphs, one can to estimate the spore concentration
needed to kill a given proportion of the exposed population. These graphs also
allow to deduce - for a certain analysed strain - the approximate spore
concentration present when a specific percentage of the exposed population is
dead.

Another measure of virulence is the lethal time (LT)
(Thomas and Elkinton, 2004) which is the time it takes the pathogen to kill 50 %
(LT_{50}) or 100 % (LT_{100}) of the infected animals. In order
to obtain this measure, the time course of infection must be determined.
Cumulative mortality per day is calculated as percentage of all individuals
which died from *P. larvae*
infection during the course of the experiment (total number of *P. larvae*-killed animals until the end
of the experiment). Average values are calculated every day from at least three
independent replicates, and plotted against every time point (day
post-infection).