Phenological responses in a sycamore–aphid–parasitoid system and consequences for aphid population dynamics: A 20 year case study

Abstract

Species interactions have a spatiotemporal component driven by environmentalcues, which if altered by climate change can drive shifts in community dynamics.There is insufficient understanding of the precise time windows during which inter-annual variation in weather drives phenological shifts and the consequences for mismatches between interacting species and resultant population dynamicsparticularly for insects. We use a 20 year study on a tri-trophic system: sycamore Acer pseudoplatanus, two associated aphid species Drepanosiphum platanoidis and Periphyllus testudinaceus and their hymenopteran parasitoids. Using a sliding window approach, we assess climatic drivers of phenology in all three trophic levels. We quantify the magnitude of resultant trophic mismatches between aphids and their plant hosts and parasitoids, and then model the impacts of these mismatches, direct weather effects and density dependence on local-scale aphid population dynamics.Warmer temperatures in mid-March to late-April were associated with advanced sycamore budburst, parasitoid attack and (marginally) D. platanoidis emergence.The precise time window during which spring weather advances phenology varies considerably across each species. Crucially, warmer temperatures in late winter delayed the emergence of both aphid species. Seasonal variation in warming rates thus generates marked shifts in the relative timing of spring events across trophic levels and mismatches in the phenology of interacting species. Despite this, we found no evidence that aphid population growth rates were adversely impacted by the magnitude of mismatch with their host plants or parasitoids, or direct impacts of temperature and precipitation. Strong density dependence effects occurred in both aphid species and probably buffered populations, through density-dependent compensation, from adverse impacts of the marked inter-annual climatic variation that occurred during the study period. These findings explain the resilience of aphid populations to climate change and uncover a key mechanism, warmer winter temperatures delaying insect phenology, by which climate change drives asynchronous shifts between interacting species. K E Y W O R D Semergence, hymenopteran parasitoids, pests, phytophagous insects, population size, woodland | 2815 SENIOR Et al.

Precipitation change accentuates or reverses temperature effects on aphid dispersal

“…Our climate–aphid phenology models predicted that, by 2080, early activity of A. glycines and R. padi could occur earlier by up to 2–4 months, with flight durations extended as much as 3 months, although such large changes will depend on concomitant shifts in phenology of crop and primary host plants. Large shifts in herbivore phenology can disrupt the synchrony with host plants and natural enemies (Thomson et al, 2010), dramatically changing communities (Visser & Both, 2005; Forrest & Miller‐Rushing, 2016; Senior et al, 2020). In agriculture, advancing pest arrival could increase crop damage due to higher pest numbers and/or virus transmission on vulnerable young plants (Harrington et al, 2007; Kieckhefer et al, 1995).…”

The Use of Regression Method on Simple E for Estimating Electrical Energy Consumption

“…The trend coefficient values obtained from the Simple E application are shown in Table 3. From the trend coefficient values obtained, the best regression method used is Growth Trend [35]. This is due to the forecast percentage (1.23%) being close to the real data growth percentage (1.21%).…”

Modeling Climatic Influences on Three Parasitoids of Low-Density Spruce Budworm Populations. Part 1: Tranosema rostrale (Hymenoptera: Ichneumonidae)

“…Thus, it is conceivable that SBW may survive better under climate warming because of decreased attacks by natural enemies [68]. However, evidence for temperature-driven mismatches between parasitoids and their hosts is scarce [16,69], and it has been demonstrated that even if present, mismatches in the phenology of interacting species may not have consequences at population levels [18]. Additional complexity is added to our host-parasitoid system because T. rostrale is generalist to a certain extent [24,33] and may therefore not necessarily be affected by changes in the distribution of the two hosts modelled here.…”