Abstract
BackgroundDrought may become one of the greatest challenges for cereal production under future warming scenarios, and its impact on insect pest outbreaks is still controversial. To address this issue, life-history responses of the English grain aphid, Sitobion avenae (Fabricius), from three areas of different drought levels were compared under three water treatments.ResultsSignificant differences were identified in developmental time, fecundity and adult weight among S. avenae clones from moist, semiarid and arid areas under all the three water treatments. Semiarid and arid area clones tended to have higher heritability for test life-history traits than moist area clones. We identified significant selection of water-deficit on the developmental time of 1st instar nymphs and adult weight for both semiarid and arid area clones. The impact of intermediate and severe water-stress on S. avenae’s fitness was neutral and negative (e.g., decreased fecundity and weight), respectively. Compared with arid-area clones, moist- and semiarid-area clones showed higher extents of adaptation to the water-deficit level of their respective source environment. Adult weight was identified as a good indicator for S. avenae’s adaptation potential under different water-stress conditions. After their exposure to intermediate water-deficit stress for only five generations, adult weight and fecundity tended to decrease for moist- and semiarid-area clones, but increase for arid-area clones.ConclusionsIt is evident from our study that S. avenae clones from moist, semiarid and arid areas have diverged under different water-deficit stress, and such divergence could have a genetic basis. The impact of drought on S. avenae’s fitness showed a water-level dependent pattern. Clones of S. avenae were more likely to become adapted to intermediate water-deficit stress than severe water-deficit stress. After continuous water-deficit stress of only five generations, the adaptation potential of S. avenae tended to decrease for moist and semiarid area clones, but increase for arid area clones. The rapid shift of aphids’ life-history traits and adaptation potential under drought could have significant implications for their evolutionary dynamics and outbreak risks in future climate change scenarios.
Highlights
Drought may become one of the greatest challenges for cereal production under future warming scenarios, and its impact on insect pest outbreaks is still controversial
Comparison of life‐history traits Population source, water treatment, clone nested in population source, and interactions between the first two factors all showed significant effects on total developmental time of the nymphal stage (DT5), 10 d fecundity and adult weight of S. avenae clones (Table 1)
Interactions between population source and water treatment contributed little to the total variance
Summary
Drought may become one of the greatest challenges for cereal production under future warming scenarios, and its impact on insect pest outbreaks is still controversial. Modified plant physiology under drought has been found to have positive, negative or neutral consequences on the performance of aphids [18, 22, 25,26,27] It remains controversial whether water-deficit stresses can increase aphid outbreaks, even though several hypotheses (e.g., ‘plant stress hypothesis’, ‘plant vigor hypothesis’, and ‘pulsed stress hypothesis’) [21, 28, 29] have been suggested to explain the conflicting results in terms of aphid population dynamics under drought
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