Insect photoperiodism: Seasonal development on a revolving planet

Abstract

This review starts by comparing photoperiodic diapause with non-photoperiodic quiescence in four representative species, paying particular attention to overwintering in Drosophila melanogaster. In the second part it describes dormancy strategies of insects from the equator to the polar regions, addressing topics such as the role of the circadian system in photoperiodic time measurement, latitudinal clines in diapause-related traits, hourglass-like photoperiodic clocks based on dampening circadian oscillators, and the dormancy strategies of insects close to the equator or at high latitudes where seasonal changes in photoperiod are unreliable or absent. * Note: When reviewing early papers or more general accounts of photoperiodism, the terms daylength, short days, long days, critical daylength (CDL) etc are used (probably because we humans are a day-active species). In later examples, where duration of the dark phase of the daily cycle has been shown to be more important, references are made to nightlength (critical nightlength, CNL etc), hopefully without causing confusion.

Predicting the potential for spread of emerald ash borer (Agrilus planipennis) in Great Britain: What can we learn from other affected areas?

“…There are several potentially important differences in the biophysical environment that could affect this conclusion. GB winters are mild and so may be more conducive to a longer development period enabling completion of life stages into late autumn; however, this effect may be restricted by photoperiod which can also affect the timing of winter dormancy (Saunders, 2020); many of our trees are weakened by ADB with unknown impact on EAB behaviour and development (Dearborn et al, 2018;Showalter et al, 2020); the spatial distribution, mix with other species, and planting density may impact active flight distances; and parasitoids already present in the environment may attack EAB (Bauer et al, 2015). In addition, based on the variation in reported degree days at emergence and at peak flight activity, the link between degree day accumulation and behaviour does not appear to be as strong as reported for many other species.…”

Effect of temperature on the development and reproduction of Thrips flavus (Thysanoptera: Thripidae)

“…This is possibly owing to disadvantageous factors of high temperature on its development. To simulate the natural temperature, it also takes into account that lower temperatures and/or short‐day photoperiods may induce diapause or morphological polymorphism, such as with the grass thrips ( Thrips setosus ) (Bale, 1996; Jiang et al, 2016; Nakao, 1993, 1998; Saunders, 2020). Therefore, the development and reproduction at lower temperatures were not tested.…”

Effects of Constant versus Fluctuating Temperatures on Fitness Indicators of the Aphid Dysaphis plantaginea and the Parasitoid Aphidius matricariae

“…Of course, in natural contexts, it is not only the temperature that varies over time, but also the humidity, light, food availability, plant quality, etc. These are parameters that are rarely studied in the laboratory under fluctuating conditions, because they are often considered less important than temperature, despite their great importance on the traits of individuals, on the dynamics of populations, and on species' interactions within communities [52][53][54][55]. Finally, it is not only the fluctuation itself that is important to consider, but also the amplitude of the variation and the type of temperature change (smooth variations in a sinusoidal design, gentle slope in a triangle design like ours, or sharp change in a rectangle design), which are issues that should be further addressed in future studies [29,47].…”