Elevated CO2 impacts bell pepper growth with consequences in the feeding behaviour and performance of the green peach aphid, Myzus persicae

Abstract

Future CO₂ predictions estimate an increase up to 550 ppm within only few decades away. Among the observed effects on plants, increasing CO₂ stimulates growth, reduces stomatal conductance and transpiration, improves water-use efficiency and induces photosynthesis. These changes have an indirect impact on pest biology and behaviour, e.g. altering their population growth or feeding habits.

Our first aim was to study the effect of ambient (400 ppm) (aCO₂) and elevated CO₂ (650 ppm) (eCO₂) on pepper (Capsicum annuum L.). Height, leaf area, dry weight and leaf temperature by thermal imaging were measured. Chlorophyll was measured in SPAD units as an indirect indicator of nitrogen foliar content. Peppers under eCO₂ were significantly taller although they had the same number of leaves than under aCO₂. SPAD was significantly lower under eCO₂. Leaf, stem and above-ground dry weight were significantly higher under eCO2. There was a significant decrease in specific leaf area under eCO₂. Canopy temperature was 1.2 °C higher under eCO₂.

Secondly, pepper plants were used to assess the development and fecundity of M. persicae. The pre-reproductive period was 11% longer in eCO₂ peppers. Aphids grew significantly slower and produced fewer nymphs under eCO₂. Lastly, aphid feeding behaviour was studied using the Electrical Penetration Graph (EPG) technique, which provides a live visualization and recording of plant penetration by aphid mouthparts. EPG results will be presented and discussed.