EVOLUTIONARILY STABLE SEASONAL TIMING FOR INSECTS WITH COMPETITION FOR RENEWABLE RESOURCE

I study the evolutionarily stable seasonal patterns of hatching and pu pation for herbivorous insects that engage in exploitative competition for a renewable resource. A longer larval feeding period enhances fem ale fecundity, but also causes a higher mortality by predation and par asitism. Previously, it was shown that the evolutionarily stable popul ation exhibits asynchronous starting and ending of the larval feeding period in a model in which larval growth rate decreases with the total larval biomass in the population due presumably to interference compe tition. Here I study the case in which resource availability changes n ot only with environmental seasonality but with the depletion by the f eeding of larvae. I find that if the impact of the herbivory is strong , both hatching and pupation should occur asynchronously in the evolut ionarily stable population. And if the favourable season for the host plant is short the ESS population may include synchronous timing of pu pation. If the timing of hatching and pupation occurs asynchronously, in the first day of each interval some fraction of the population hatc h or pupate, respectively and the rest do so gradually over the interv al. In addition, if the environmental variable changes as a symmetric function of time, the length of the period in which hatching occurs te nds to be much shorter than the period in which pupation occurs.