Autogenous and anautogenous mosquitoes: a mathematical analysis of reproductive strategies.

A mathematical model is presented to compare the relative advantage of an anautogenous mosquito population (in which females blood feed throughout life) with an obligate autogenous population (in which females do not feed on blood for the first oviposition). The advantage is measured by the intrinsic rate of natural increase. Autogeny was more advantageous than anautogeny when host searching time (ts), the ratio of the fecundity of the first autogenous to anautogenous oviposition (p), the fecundity in one anautogenous oviposition (n), or the instantaneous death rate of the adult population (D) was large, or when the preimaginal period (xo), the instantaneous death rate during the preimaginal period (D'), or survival during blood feeding (s) was low. The parameters most sensitive to the advantage of autogeny were ts, p, and s. The value of n was insensitive, and xo, D, and D' were intermediately sensitive to autogeny. Conditions when autogeny was advantageous were equivalent to conditions conducive to high autogeny rates in facultatively autogenous species, which alter the expression of autogeny depending upon environmental stimuli. Data on several facultatively autogenous species are discussed qualitatively and quantitatively to demonstrate the utility of our model in considering the evolution of autogeny and the autogeny rate.