Elevated CO2 concentration improves the performance of an agricultural pest: a worrisome climate crisis scenario
2021
Arantes‐Garcia, Lucas | Maia, Renata A. | Oki, Yumi | Cornelissen, Tatiana | Fernandes, Geraldo Wilson
Carbon dioxide (CO₂) emissions are central to the climate crisis and their consequences indiscriminately affect natural and anthropogenic ecosystems. Among ecological interactions, those between plants and insects are among the most impacted by the elevation in CO₂ concentration (eCO₂). We selected a plant and an herbivore species of worldwide relevance and tested the hypothesis that eCO₂ affects leaf quality and defences of sunflower, Helianthus annuus L. (Asteraceae), and negatively impacts the larval preference and performance of the important pest Helicoverpa armigera Hübner (Lepidoptera: Noctuidae). Plants and insects developed inside open‐top chambers under ambient CO₂ (ca. 400 ppm) and eCO₂ (ca. 800 ppm). Sunflowers under eCO₂ grew more (e.g., increased height and had more leaves) but were of lower nutritional quality at an early developmental stage (e.g., lower nitrogen content, greater leaf thickness, and higher flavonoids content). Despite showing no preference for either treatment, H. armigera larvae performed better when fed with leaves from eCO₂ plants. We argue this was observed because larvae under eCO₂ sustained a greater leaf consumption, even when sunflower leaf quality became similar between treatments (by the 11th week after germination). Besides, they overcompensated a more deficient diet during early developmental stages and presented a higher growth rate; ca. 2.5× more individuals reached the pupal stage, and 4× more individuals became adults. The improvement in H. armigera larval performance under eCO₂ indicates a worrisome scenario in which a species that already exerts a significant impact on ecosystems would increase its consumption, develop faster, and support a larger population size.
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