A life table follows a group of eggs at one temperature, humidity and host through to the death of the last adult, recording how many survive each day and how many eggs each female lays. From it come the development time of each stage, adult longevity, fecundity, sex ratio, the net reproductive rate (R0), generation time and the intrinsic rate of increase (r_m), using the method Birch set out in 1948.
In practice
Almost all pest life tables are lab studies on leaf discs or a standard host such as bean, cucumber or rose, not cannabis. They are still the best numbers available. Use them for comparisons and for timing re-applications at your room temperature, and expect real cannabis rooms to run somewhat slower because of predators, plant chemistry and crowding.
Don't confuse with
- Degree-day model: uses only development time, not reproduction.
- Field population count: what is there now, not what could grow.
