Appendix B. Equation for calculating λ', a composite index of population performance based on r', which estimates the realized per capita rate of population change (dN/N dt = r, the exponential growth rate) for each replicate cohort (Livdahl and Sugihara 1984).
where No is the initial number of females in a cohort (assumed to be 50% of the initial cohort); Ax is the number of females eclosing on day x; wx is a measure of mean female size on day x; f(wx) is a function relating fecundity to female size (see text); and D is the estimated time (in days) required for a newly eclosed female to mate, obtain a bloodmeal, and oviposit. D is assumed to be 12 days for A. aegypti (Grill and Juliano 1996) and 14 days for A. albopictus (Juliano 1998). The estimated finite rate of increase, λ’ = exp(r’), is often preferable to r’ in demographic analyses because λ’ is estimable even if no individuals survive to reproductive age (l' = 0) whereas r' is not estimable in that case (r' = -∞) (Lenski and Service 1982).
Grill, C. P., and S. A. Juliano. 1996. Predicting species interactions based on behaviour: predation and competition in container-dwelling mosquitoes. Journal of Animal Ecology 65:6376.
Juliano, S. A. 1998. Species introduction and replacement among mosquitoes: interspecific resource competition or apparent competition. Ecology 79:255268.
Lenski, R. E., and P. M. Service. 1982. Statistical analysis of population growth rates calculated from schedules of survivorship and fecundity. Ecology 63:655662.
Livdahl, T. P., and G. Sugihara. 1984. Non-linear interactions of populations and the importance of estimating per capita rates of change. Journal of Animal Ecology 53:573580.