Geographic variation in the effects of temperature and photoperiod on dormancy induction, development time, and predation in the tree-hole mosquito, Toxorhynchites rutilus septentrionalis (Diptera: Culicidae)

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Abstract
Critical daylength for dormancy induction was similar for laboratory colonies of a northern (Delaware) and a southern (Louisiana) [USA] population of T. rutilus septentrionalis. The threshold daylength for dormancy induction was greater in the northern population, and the photoperiodic response of the northern population was less affected by high temperature. Although photoperiod did not affect duration of preadult development in the southern population, duration of preadult development of the northern population varied in a nonlinear fashion with photoperiod at 27.degree. C and increased with decreasing daylength at 19.degree. C. Duration of the 3rd instar was consistently longer in dormant than active larvae of both populations. The pattern of prey consumption during larval development was similar in dormant and active larvae. Prey consumption terminated 24 h prior to pupation in active larvae; dormant larvae continued to feed at a low rate. Similar numbers of prey were consumed during development by active and dormant larvae. Differences in the biologies of the 2 populations are discussed in relation to climatological differences in the environments from which each population was derived.