Effect of elevated CO2 and temperature on maize resistance against the Asian corn borer

The increasing atmospheric CO₂ concentration and temperature has altered the plant‐insect interactions. However, little is known about the intrinsic mechanisms between plant resistance and insect survival strategies under the combined conditions of elevated CO₂ and temperature. This study investigated the effects of elevated temperature alone and in combination with CO₂ enrichment on the nutrition and resistance of maize (Zea mays L.) to the Asian corn borer (ACB) (Ostrinia furnacalis [Guenée]) and feeding, survival, and physiological response of ACB over 2‐year growing seasons. The maize plants were grown in free‐air CO₂ enrichment connected by infrared heating system with the ambient (control), ~4.0°C increase in air temperature (ET) and ET together with ~700 ppm concentration of atmospheric CO₂ (ETEC). Elevated CO₂ alleviated the effect of ET on total non‐structural carbohydrates (TNC)/N in maize, and thus ETEC did not change this parameter. ETEC enhanced the defensive enzyme activities in maize. Elevated CO₂ enhanced the ET effect on increased total phenolics content in maize. ET and ETEC increased the expression levels of the jasmonic acid (JA) defence‐related genes and JA content in maize. Above insect resistance‐related secondary metabolism in maize was enhanced by ACB damage. Except for amylase, ET and ETEC had no effect on the digestive enzyme activities and food intake of ACB, but enhanced its protective enzyme activities. ET and ETEC decreased the survival rate, overwintering larval body weight and fecundity, increased supercooling point of ACB fed on maize. These findings demonstrate that the combination of elevated temperature and CO₂ did not influence the nutritional metabolism, but enhanced insect resistance‐related secondary metabolism of maize, which could alleviate the occurrence and damage of ACB in maize under the context of future climate change scenarios.