Photoperiodic cues regulate phenological carry‐over effects in an herbivorous insect

Abstract

Abstract1. To maximise their fitness, organisms need to synchronise their phenology with the seasonal variation in environmental conditions. Most phenological traits are affected by environmental abiotic cues such as photoperiod, temperature and rainfall. When individuals with complex life cycles fail to match one of the stages with the favourable environment, the negative conditions experienced may lead to carry-over effects and, thus, influence fitness in subsequent stages.2. In the winter moth, an herbivorous insect with an annual life cycle, timing of egghatching in spring is strongly influenced by temperature and varies from year to year. To investigate whether the phenological variation in egg-hatching date affects subsequent stages, we analysed data on egg-hatching date and adult catching date (considered here to be a proxy for adult eclosion date) from our long-term study . Furthermore, we experimentally manipulated the photoperiod experienced by newly hatched larvae and recorded the phenology of their subsequent life cycle stages.3. In the long-term field study, we found that the timing of winter moth egg-hatching in spring varied strongly from year to year. Interestingly, however, the timing of adult eclosion date in winter showed little inter-annual variation. In line with these findings, our experimental data showed that the winter moth shortened the duration of their pupal development when they experienced a late spring photoperiod as a larva, and prolonged pupal development when experiencing early spring photoperiod. The effects of the larval photoperiodic treatments persisted during egg development in the following generation.4. The results show that a phenological shift that occurs during an early life stage is partially compensated during subsequent stages and suggest that the mechanism underlying this compensation is mediated by photoperiod. Winter moths regulated their phenology in such a way that the variation in the egg-hatching stage was not carried over to the next life cycle stages. This has strong effects on fitness as it (1) ensures the synchronisation of adult eclosion during the mating period and (2) is likely to reduce potentially negative fitness consequences of phenological mismatches in egg-hatching in the following generation. Overall, these findings stress the importance of understanding phenological carry-over effects to forecast the impact of global change in species with complex life cycles.

Artificial light at night, in interaction with spring temperature, modulates timing of reproduction in a passerine bird

“…, Salis et al. ). A previous study has shown that both green and white light at night advances caterpillar emergence from the pupa stage (van Geffen et al.…”

“…The lack of fitness effects might be expected if the insects that Great Tits rely on to feed their young, caterpillars, also shift in response to light pollution. In fact, the development of Lepidoptera eggs and larvae is also sensitive to both temperature and photoperiod, although the relative importance of each depends on the species examined (Cox 1979, Fantinou et al 1996, Nabeta et al 2005, Tauber et al 2015, Salis et al 2018. A previous study has shown that both green and white light at night advances caterpillar emergence from the pupa stage (van Geffen et al 2014).…”

Dietary restriction and insulin‐like signalling pathways as adaptive plasticity: A synthesis and re‐evaluation

“…spring or wet season) is likely to have major impacts on fitness and be under strong selection (e.g. Salis, Hoorn, Beersma, Hut, & Visser, 2018).…”

Effects of photoperiod on life‐history and thermal stress resistance traits across populations of Drosophila subobscura

“…In contrast to temperature, photoperiod can be defined as a highly reliable environmental cue due to the constant variations in photoperiod across days and seasons for a given latitude and/or altitude (Bradshaw & Holzapfel, 2007;Jackson, 2009;Salis, van den Hoorn, Beersma, Hut, & Visser, 2018). The day length that triggers the incidence of seasonal activities (critical photoperiod) is linked to the length of the growing season and the timing of the onset of a specific season.…”