Environmental controls on the phenology of moths: predicting plasticity and constraint under climate change

Abstract

Ecological systems have naturally high interannual variance in phenology. Component species have presumably evolved to maintain appropriate phenologies under historical climates, but cases of inappropriate phenology can be expected with climate change. Understanding controls on phenology permits predictions of ecological responses to climate change. We studied phenological control systems in Lepidoptera by analyzing flight times recorded at a network of sites in Finland. We evaluated the strength and form of controls from temperature and photoperiod, and tested for geographic variation within species. Temperature controls on phenology were evident in 51% of 112 study species and for a third of those thermal controls appear to be modified by photoperiodic cues. For 24% of the total, photoperiod by itself emerged as the most likely control system. Species with thermal control alone should be most immediately responsive in phenology to climate warming, but variably so depending upon the minimum temperature at which appreciable development occurs and the thermal responsiveness of development rate. Photoperiodic modification of thermal controls constrains phenotypic responses in phenologies to climate change, but can evolve to permit local adaptation. Our results suggest that climate change will alter the phenological structure of the Finnish Lepidoptera community in ways that are predictable with knowledge of the proximate physiological controls. Understanding how phenological controls in Lepidoptera compare to that of their host plants and enemies could permit general inferences regarding climatic effects on mid- to high-latitude ecosystems.

Northern geometrid forest pests (Lepidoptera: Geometridae) hatch at lower temperatures than their southern conspecifics: Implications of climate change

“…The difference in temperature sum required for hatching of the "early" eggs and eggs placed in climatic chamber one week later is consistent with previous studies showing that the classical +5°C base temperature for the botanical growing season may not be a biologically relevant threshold for the development of moth eggs, at least not for all moth species, and perhaps especially not for species feeding on newly-fl ushed foliage in spring (Embree, 1970;Kimberling & Miller, 1988;Valtonen et al, 2011). In our experiment, both "early" and "late" eggs were transferred to the constant climate chamber while temperatures were still below +5°C and they should have accumulated similar temperature sums above that temperature.…”

“…Photoperiod is known to affect the timing of bud burst in, for example, white birch, Betula pubescens (Caffarra et al, 2011a, b), the main host of both E. autumnata and O. brumata in northern Fennoscandia. It is also an important controller of life cycle events in many moth species, either alone or acting together with temperature (Danks, 1987;Valtonen et al, 2011). Thus the matching of bud burst and hatching of geometrid eggs in a changing climate depends on the extent to which herbivores and their host plants use the same environmental cues for timing their phenology in spring.…”

“…In fact, both trees and moths are likely to rely on a sophisticated combination of environmental cues for their development, with day length taken into account only when certain temperature requirements are already met or the reverse. The previous winter and autumn temperatures would then count towards the accumulating temperature sum in addition to the conditions in spring (Kaitaniemi & Ruohomäki, 1999;Visser & Holleman, 2001;Bale et al, 2002;Valtonen et al, 2011). There is also evidence that not only the temperatures above a certain development threshold count, but that a "chilling sum" of accumulating cold temperatures and the length of the sub-zero chilling period is also important (Kimberling & Miller, 1988;Visser & Holleman, 2001;Hibbard & Elkinton, 2015).…”

Forest pests and their management in the Anthropocene

“…Similarly, increasingly sophisticated understanding of source-sink relations in plant carbohydrates and environmental effects on plant defenses allows informed hypotheses and defensible generalizations regarding phenotypic patterns in phytochemistry and plant susceptibility to herbivory (T-6) (Herms and Mattson 1992;Lombardero et al 2000;Hartmann and Trumbore 2016). Our understanding of climatic effects on the phenology of interacting species (T-3) is at intermediate maturity; we know that interannual variation in weather has strong effects on phenology that can vary among species (Parmesan 2006), and we are beginning to understand interspecific patterns in physiological controls on phenology (Pau et al 2011;Valtonen et al 2011;Buckley and Kingsolver 2012). As examples of theories that are presently immature but relevant to pest management, it is logical but has barely been tested that changing climate leads to physiological mismatch in trees because they grow to match the climate, which can change during their lifetime (T-11) (Zadworny et al 2016).…”

Future changes in the supply of goods and services from natural ecosystems: prospects for the European north

“…3). For example, warmer weather may increase forest pests such as pathogens, diseases, invasive herbivorous insects, and plants (Niemelä et al 2001, Wolf et al 2008b, Valtonen et al 2011. In northern Fennoscandia, northward expanding geometrid moth outbreaks have caused massive devastation of subarctic birch forests (Jepsen et al 2011), most likely owing to warmer winters and springs (Jepsen et al 2008(Jepsen et al , 2011.…”