The importance of timing of heat events for predicting the dynamics of aphid pest populations

Abstract

BACKGROUND: Heatwaves are increasing in frequency and there is growing interest in their impact on pest organisms. Previous work indicates that effects depend on the timing of the stress event, whose impact needs to be characterized across the full set of developmental stages and exposure periods of an organism. Here, we undertake such a detailed assessment using heat stress (20-35 ∘ C diurnal cycle) across the nymph and adult stages of the English grain aphid, Sitobion avenae (Fabricius). RESULTS: Stress-related mortality increased with stress duration at all stages; effects were less severe at the late nymphal stage. Effects on longevity adults after stress showed a complex pattern with nymphal heat stress, increasing with stress duration at the late nymphal stage, but decreasing with duration at the early nymphal stage. Longevity was also reduced by adult stress although to a lesser extent, and patterns were not connected to duration. Post-stress productivity decreased following adult and nymphal stress and the decrease tended to be correlated with stress duration. The rate of offspring production was more affected by adult stress than nymphal stress. Productivity and longevity effects, when combined, showed that the largest effect of heat stress occurred at the early nymphal stage. CONCLUSION: These findings highlight the complex ways in which heat stress at a particular life stage influences later fitness and they also emphasize the importance of considering multiple fitness components when assessing stress effects.

Responses ofManduca sextalarvae to heat waves

“…Using an elegant experimental design with aphids, that varied the duration and relative frequency of 'normal' (13-28°C diurnal fluctuation) and 'hot' (20-35°C diurnal fluctuation) time periods, Ma et al (2018) demonstrated that the negative fitness consequences of a HW depend both on its duration (1-3 days) and on its temporal clustering. Responses to high temperature events may also vary with developmental timing and life stage (Zhang et al, 2015b;Banahene et al, 2018;Zhao et al, 2019). Our results for M. sexta similarly show that the consequences of HWs depend on timing within the larval stage, especially when there are multiple HWs.…”

Differential thermal tolerance across life stages under extreme high temperatures crossed with feeding status in corn leaf aphid

“…Ectotherms do not maintain constant body temperature, as they apply behavioural, physiological, and cellular adjustments to maintain thermal homeostasis (Bicego et al ., 2007; Bodlah et al ., 2017; Green et al ., 2019). Extreme high temperature plays a major role in affecting ectotherms (Ma et al ., 2018; Cherif et al ., 2019; Zhao et al ., 2019). It influences the biological functions, geographical distribution, and species richness of insects, especially under climate change scenarios (Hu et al ., 2015).…”

“…Even a brief exposure to extreme temperature could affect organism phenology (Semenov, 2009), species distribution (Overgaard et al ., 2014), population dynamics (Asin & Pons, 2001), community structure (Ma et al ., 2015), and sustained exposure to high temperatures, which may eventually lead to death (Chown & Terblanche, 2006; Hoffmann et al ., 2013). Therefore, determining the thermal tolerance is essential for understanding the effects of extreme heat events on a given population's fitness and dynamics under climate change scenarios (Terblanche & Chown, 2007; Zhao et al ., 2019).…”

“…Severe infestation of this aphid may cause serious yield and economic losses (Xie et al ., 2014). As an ectotherm, the aphid is sensitive to the slight change of the environmental temperatures (Ma et al ., 2018; Zhao et al ., 2019), and is therefore an ideal model for studying thermal adaptation in response to extreme high‐temperature events. In this study, the feeding effect on R. maidis thermal tolerance has been tested.…”

Complex delayed and transgenerational effects driven by the interaction of heat and insecticide in the maternal generation of the wheat aphid, Sitobion avenae

“…The abiotic environment is vital to the development of most organisms, 1–3 and the earlier experience of this environment regulates development, but also partly induces it 4–6 . Previous studies have suggested that earlier experiences of environmental stressors can prompt plasticity responses 7 in fitness traits, including development, longevity and fecundity, 8,9 or induce changes in tolerance to other stressors 10,11 . Thus, exploring how adaptation to one environmental stressor impacts the tolerance and phenotypic plasticity to other stressors requires attention in a rapidly changing world.…”