Analysis of the operation of the photoperiodic counter provides evidence for hourglass time measurement in the spider miteTetranychus urticae

Nunes, Marlies Vaz

doi:10.1007/bf00615076

Cited by 56 publications

(33 citation statements)

References 23 publications

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“…noncircadian or 'hourglass') mechanism (Veerman & Vaz Nunes, 1987), which, in terms of the pacemaker-slave model (Vaz Nunes et al, 1991), would mean that coupling between the pacemaker and the slave is so weak, that the resulting clock is indistinguishable from an 'hourglass'. The negative results of the present bistability experiments agree with this conclusion and give, therefore, further support in favour of the non-circadian nature of the photoperiodic clock in T. urticae.…”

Section: Resultsmentioning

confidence: 99%

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‘Bistability’ experiments and the photoperiodic clock in the spider mite Tetranychus urticae

Nunes

Veerman

1997

Entomologia Exp Applicata

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Section: Resultsmentioning

confidence: 99%

“…Another experimental protocol had already shown, that the mite's clock is based on a non-circadian, or 'hourglass', mechanism (Veerman & Vaz Nunes, 1987). It was expected, therefore, that bistability would not occur in photoperiodic induction in this species.…”

Section: Introductionmentioning

confidence: 99%

‘Bistability’ experiments and the photoperiodic clock in the spider mite Tetranychus urticae

Nunes

Veerman

1997

Entomologia Exp Applicata

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“…For example, a long day of 18 h followed by a dark period of 6, 30 or 54 h would count as a single cycle under either the hourglass or external coincidence model but would count as 1, 2 or 3 cycles, respectively, under the internal coincidence model. This comparison has been used to determine the role of light in single populations (Veerman and vaz Nunes 1987) but, to our knowledge, no study has considered how the role of light in the photoperiodic counter varies among populations representing climatic extremes due to latitude and altitude within the species' range. It is important to use geographic variation in the photoperiodic counter in these studies to show that the results are not specific to single populations, but rather generally applicable to the species as a whole.…”

Section: Introductionmentioning

confidence: 99%

Extrinsic light:dark cycles, rather than endogenous circadian cycles, affect the photoperiodic counter in the pitcher-plant mosquito, Wyeomyia smithii

et al. 2008

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A wide diversity of organisms use photoperiod (daylength) as an environmental cue to anticipate the changing seasons and to time various life-history events such as dormancy and migration. Photoperiodic time measurement consists of two main components, (1) the photoperiodic timer that discriminates between long and short days, and (2) the photoperiodic counter that accumulates and stores information from the timer and then induces the phenotypic output. Herein, we use extended night treatments to show that light is necessary to accumulate photoperiodic information across the geographic range of the mosquito, Wyeomyia smithii and that the photoperiodic counter counts extrinsic (external) light:dark cycles and not endogenous (internal) circadian cycles.

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“…Saunders, 1982;Beach, 1978) as well as in T. urticae (Veerman and Vaz Nunes, 1987), it has been found that there exists a photoperiodic "counter", which accumu lates the effect of short-day photoperiods until an internal threshold is reached after which diapause induction is complete. Recently, it was found that the diapause-terminating effect of long-day pho toperiods is similarly accumulated as in diapause induction (Koveos and Veerman, 1994).…”

Section: Variation In the Number Of Long-day Cycles Required For Diapmentioning

confidence: 99%

Geographic Variation of Diapause Induction and Termination in the Spider Mite Tetrαnychus urticαe: Α mini-review

Koveos

Veerman

2017

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In eight strains of the spider mite Tetranychus urticae Koch (Acari: Tetranychidae), originating from different localities in Europe, the critical daylength for diapause induction and termination was almost the same in each strain hut varied with the latitudinal origin of the strains; critical daylength was shorter in strains originating from lower latitudes and longer in those from higher latitudes. Diapause intensity, measured as the period of chilling required for diapause termination under a short day photoperiod (LD 10:14) and 19°C, again varied with the latitudinal origin of each strain, being higher the more northern the origin of the strain. An exception were two mountain strains which showed a longer critical daylength and a deeper diapause than expected on the basis of their latitudinal origin. The number of longday (LD 17:7) cycles required for 50% diapause termination after a certain period of chilling was higher in the northern and lower in the southern strains. These results indicate that geographic strains of T. urticae may differ considerably in their diapause attributes, which may be explained as an adaptation to local climatic conditions. The great plasticity of the diapause response may, among other factors, have been responsible for the wide distribution of this mite species.

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Analysis of the operation of the photoperiodic counter provides evidence for hourglass time measurement in the spider miteTetranychus urticae

Cited by 56 publications

References 23 publications

‘Bistability’ experiments and the photoperiodic clock in the spider mite Tetranychus urticae

‘Bistability’ experiments and the photoperiodic clock in the spider mite Tetranychus urticae

Extrinsic light:dark cycles, rather than endogenous circadian cycles, affect the photoperiodic counter in the pitcher-plant mosquito, Wyeomyia smithii

Geographic Variation of Diapause Induction and Termination in the Spider Mite Tetrαnychus urticαe: Α mini-review

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