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A CO2-induced Herbivory Decline of the Corn Leaf Aphid on Barley

Paper Reviewed
Chen, Y., Serteyn, L., Wang, Z., He, K. and Francis, F. 2019. Reduction of plant suitability for corn leaf aphid (Hemiptera: Aphididae) under elevated carbon dioxide condition. Plant-Insect Interactions 48: 935-944.

The corn leaf aphid (Rhopalosiphum maidis) is an herbivore pest that causes significant damage worldwide on key cereal crops, including maize, barley, wheat, millet, sorghum and broad bean. It also acts as a vector to spread plant viruses such as sugarcane mosaic virus and maize dwarf mosaic virus, causing significant yield losses annually.

Writing as background for their work, Chen et al. (2019) say that "in the current context of global climate change, atmospheric carbon dioxide (CO2) concentrations are continuously rising with potential influence on plant-herbivore interactions." And thus they purposed to investigate the impacts of elevated CO2 on corn leaf aphids feeding on young barley plants.

The study was conducted in controlled-environment chambers using two CO2 treatment concentrations, ambient (450 ppm) and elevated (800 ppm). As noted by the authors, "virus free aphid and barley seedlings were reared under ambient CO2 and/or elevated CO2 chambers [for] more than 10 generations." Thereafter, aphids were allowed to feed on two week old healthy barley seedlings in each of the CO2 treatments, with the authors performing a series of measurements to evaluate the plant-herbivore interactions.

When all was said and done, Chen et al. report "R. maidis feeding on elevated CO2 barley seedlings showed significantly decreased body weight, fecundity, and intrinsic rate of population increase, which may result in decreased population abundance under elevated atmospheric CO2." And to this they add in the final sentence of their paper "further studies will be required to determine the defense mechanisms including epidermal integrity, defense proteins, and secondary metabolites of plants which might also hinder the penetration of [aphid] stylets." For now, however, farmers can be thankful for the good news that corn leaf aphid herbivory will likely cause less damage and crop yield loss in the years and decades ahead as the air's CO2 concentration continues to rise!

Posted 1 July 2020