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)

Abstract

TRIMBLE, R. M., and S. M. SMITH. 1979. Geographic variation in the effects of temperature and photoperiod on dormancy induction, development time, and predation in the tree-hole mosquito, Toxorhynchites rurilus septentrionulis (Diptera: Culicidae). Can. J. Zool. 57: 1612-1618. Critical daylength for dormancy induction was similar for laboratory colonies of a northern (Delaware) and a southern (Louisiana) population of Toxorhynchire.~ 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 the duration of preadult development in the southern population, the duration of preadult development of the northern population varied in a nonlinear fashion with photoperiod at 27' C and increased with decreasing daylength at 19°C.The duration of the third instar was consistently longer in dormant than in active larvae of both populations.The pattern of prey consumption during larval development was similar in dormant and active larvae. Prey consumption terminated 24h 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.The differences in the biologies of the two populations are discussed in relation to climatological differences in the environments from which each population was derived. TRIMBLE, R. M., et S. M. SMITH. 1979. Geographic variation in the effects of temperature and photoperiod on dormancy induction, development time, and predation in the tree-hole mosquito. Toxorhynchites rurilus septentrionalis (Diptera: Culicidae). Can. J . Zool. 57: 1612-1618. Chez Toxorhynchires rutilus septentrionalis, le declenchement de la dormance est fonction d'une photoperiode critique qui est la mCme chez les colonies experimentales issues d'une population du nord (Delaware) et chez celles issues d'une population du sud (Louisiane). Chez la population nordique, la photoperiode-seuil est plus longue et la reaction i la photoperiode est moins affectee par des temperatures elevees.La photoperiode n'affecte pas la duree du developpement pre-adulte, chez la population du sud, mais, chez la population nordique, la duree du developpement pre-adulte varie avec la photoperiode selon une fonction non lintaire a 2PC, alors qu'8 IYC, cette duree augmente a mesure que diminue la photoperiode.Chez les deux populations, la duree du troisieme stade est toujours plus longue chez les larves en dormance que chez les larves actives.La consommation des proies se fait selon des courbes semblables chez les larves en dormance et chez les larves actives. La consommation de proies cesse 24 h avant la nymphose chez les larves actives; les larves en dormance continuent de se nourrir un peu. Durant le developpement, les larves actives et les larves en dormance consomment B peu pres le mCme nombre de proies.La discussion porte sur les differences biologiques des deu...

Predator-mediated, non-equilibrium coexistence of tree-hole mosquitoes in southeastern North America

“…One cannot examine the effect of T. rutilus' predation on itself in the same manner as we did above Table 6. A Proportion of total development time of T. rutilus spent in each stage at 19 ~ or 27 ~ C (spanning the temperature prevailing in tree holes at Tall Timbers May to October, 1978); calculated from Trimble and Smith (1979). B Observed and expected frequencies of each stage of T. rutilus found in 340 wet-holes during censuses 5-17; expected number = (relative duration of the stage from (A)) times total number of all stages) A.…”

“…B Observed and expected frequencies of each stage of T. rutilus found in 340 wet-holes during censuses 5-17; expected number = (relative duration of the stage from (A)) times total number of all stages) A. % total development time (L: D = 15 : 9) first instar to adult for other prey; rather, assuming no other source of mortality, we estimated the impact of cannibalism first by comparing expected instar ratios from developmental rates and second by pupae:egg ratios 9 Trimble and Smith (1979) provide data on the duration of pre-adult development in T. rutilus from southern Louisiana. While temperature has a profound effect on the total duration ofpre-adult development, the ratio of the duration of a given instar to the total remains surprisingly constant at 19 ~ and 27 ~ (Table 6A).…”

“…If cumulative mortality increased with developmental age, then there should be a progressive departure from these frequencies, i.e., younger instars should be uniformly more abundant and older instars uniformly less abundant than expected. To avoid the effects of photoperiod which may modify the rates of larval development or induce diapause in later instars (Bradshaw and Holzapfel 1975;Holzapfel and Bradshaw 1977;Trimble and Smith 1979) and thus bias our assumptions, we examined the instar distribution and egg abundances from late April (census 5) through mid-October (census 17) while oviposition ( Fig. 16) and pupation (Fig.…”

INTRA- AND INTERPOPULATION VARIATION IN THE THERMAL CHARACTERISTICS OF PREADULT DEVELOPMENT OF TWO LATITUDINALLY DIVERSE POPULATIONS OF TOXORHYNCHITES RUTILUS SEPTENTRIONALIS (DIPTERA: CULICIDAE)

“…The developmental thresholds of Delaware 1st-(i.e. Both Delaware and Louisiana T. r. septentrionalis overwinter as 4th-instar larvae in a facultative, photoperiodically induced state of diapause (Trimble and Smith 1979). 8.9"C) instar larvae were significantly different (t-test, P < 0.05) as were the thresholds of the 2nd-(i.e.…”

Is the mechanism present in Asellus aquaticus (L.) an evolutionary stage towards an endogenous calendar?1

“…This implies that the organism has "continued" its development. In some cases the larva feeds (VINAGRADOVA 1962;TRIMBLE and SMITH 1979) or increases in weight (INEICHEN et al 1979). This indicates that it was not in a state of total arrest.…”