Internal Clocks and Insect Diapause

Abstract

ier mean ion mass at high latitudes. At low latitudes the topside measurements have shown the detailed latitudinal structure of the equatorial anomaly, demonstrating control by the geomagnetic field.A variety of electron-density irregularities have been studied. Most are greatly elongated along the magnetic field, and produce echoes either by lateral scattering, if they are thin, or by longitudinal ducting, if they are thick. Some of the thick irregularities are continuous between the hemispheres and support conjugate echo propagation.The topside sounders have revealed the complex structure of the ionosphere near the auroral zone and at higher latitudes. At night an east-west trough of greatly reduced electron density occurs equatorward of the auroral zone. At the auroral zone itself the electron density is high and quite variable, both in space and time. The electron density at the polar cap within the auroral zone is often uniform and smooth. Ionospheric irregularities are common in the area of the trough and the auroral zone.Among other satellites, the topside sounders have been used in various plasma studies involving the excitation and propagation of waves. These studies suggest that the ionosphere is an appropriate region for future plasma physics investigations, especially with rocket and satellite payloads designed specifically for that purpose. ier mean ion mass at high latitudes. At low latitudes the topside measurements have shown the detailed latitudinal structure of the equatorial anomaly, demonstrating control by the geomagnetic field.A variety of electron-density irregularities have been studied. Most are greatly elongated along the magnetic field, and produce echoes either by lateral scattering, if they are thin, or by longitudinal ducting, if they are thick. Some of the thick irregularities are continuous between the hemispheres and support conjugate echo propagation.The topside sounders have revealed the complex structure of the ionosphere near the auroral zone and at higher latitudes. At night an east-west trough of greatly reduced electron density occurs equatorward of the auroral zone. At the auroral zone itself the electron density is high and quite variable, both in space and time. The electron density at the polar cap within the auroral zone is often uniform and smooth. Ionospheric irregularities are common in the area of the trough and the auroral zone.Among other satellites, the topside sounders have been used in various plasma studies involving the excitation and propagation of waves. These studies suggest that the ionosphere is an appropriate region for future plasma physics investigations, especially with rocket and satellite payloads designed specifically for that purpose. References 1. J. A. Ratcliffe, Physics of the Upper Atimosphere (Academic Press, New York, 1960); K. Davies, Natl. Bur. Std. U.S. Monograph 80, "Ionospheric Radio Propagation" (1965); C. 0. Hines, I. Paghis, T. R. Hartz, J. A. Fejer, Physics of the Earth's Upper Atmosphere (Prentice-Hall, Englewood Cliffs, N.

Artificial light at night causes diapause inhibition and sex‐specific life history changes in a moth

“…). In many moth species, caterpillars use day length as the main environmental cue for the decision to initiate pupal diapause, where short days trigger diapause (e.g., Adkisson ; Huang et al. ; Xiao et al.…”

“…; Xiao et al. ), ensuring that late generation caterpillars or pupae overwinter in diapause so that the imago life stage is synchronised with favourable seasons (Adkisson ). Light at night can disturb the reliability of this cue (Gaston et al.…”

Insect Diapause, the Seasonal Synchronization of Life Cycles, and Management Strategies

“…The laboratory finding that insects exposed during their sensitive pre-diapause stages to correctly timed light breaks in the night avert diapause (Adkisson, 1966) has been tested under field conditions. In addition, field population of insects have been exposed to non-inductive conditions by artificially extending the natural daylength to avert their diapause.…”

Photoperiodic determination of insect development and diapause

“…In the case of developmental photoperiodism (diapause and form determination), systematic responses to scotophasic light pulses have also been observed (Biinning and Joerrens, 1960;Beck, 1962;Adkisson, 1964Adkisson, , 1966Lees, 1965;Saunders, 1968). The interpretation of the experimental results has been both difficult and mildly controversial, because a relationship between the measured response (developmental state) and any postulated driving circadian oscillator has not been demonstrable; neither an overt nor covert rhythm is apparent in the response curves obtained.…”

“…Successively later pulses again induce a maximum incidence of diapause, but pulses occurring late in the scotophase result in relatively low incidences (Beck, 1962;Adkisson, 1966;Saunders, 1975). A light pulse occurring in the early hours of the long scotophase of an asymmetrical skeleton photoperiod usually results in a relatively low incidence of diapause.…”