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A CO2-induced Influence on Aphid Life Parameters

Paper Reviewed
De Paulo, P.D., Pereira, E.J.G., Oliveira, E.E., Fereres, A. and Garzo, E. 2020. Indirect effect of elevated CO2 concentration on Bemisia tabaci MEAM1 feeding on Bt soybean plants. Journal of Applied Entomology, doi: 10.1111/jen.12822.

The aphid whitefly Bemisia tabaci causes widespread economic damage to crops worldwide, particularly in soybean. However, rising levels of atmospheric CO2 have been shown to alter the production of secondary plant metabolites that enhance plant defenses against insect attack. Such alterations can lead to changes in insect feeding behavior, biology and ability to transmit pathogens.

Against this backdrop, De Paulo et al. sought to investigate the potential effects of CO2 on B. tabaci whiteflies feeding on soybean (Glycine max) plants grown at two CO2 concentrations. Their experiment was conducted in environment-controlled growth chambers at the Institute of Agricultural Sciences of the Spanish National Research Council (Madrid, Spain). The two CO2 concentrations utilized were 450 ppm (ambient) and 700 ppm (elevated). In each CO2 treatment a portion of the soybean plants were infested with ten B. tabaic eggs per plant that were monitored for duration of the egg stage and other developmental life history traits, as well as adult fecundity and fertility. In addition, the authors examined whitefly feeding behavior.

In describing their findings De Paulo et al. report that "elevated CO2 increased the egg to adult development time and reduced the reproductive responses (fecundity and fertility) of B. tabaci." More specifically, as illustrated in Figure 1, elevated CO2 increased the embryonic period of the laid eggs by 14%, the nymphal development period (1st to 3rd instars) by 11%, total development time to adulthood by 9%, and reduced fecundity (number of eggs per female) and fertility (percent of hatching eggs) by 21% and 5%, respectively. With respect to feeding behavior, the authors found this parameter "was negatively influenced by several traits related to the host plant resistance [under elevated CO2], such as the time spent on phloem sap ingestion," where the whiteflies needed more time to start phloem activities.

Commenting on their several findings, De Paulo et al. conclude, "taken together, our results indicate that Bt plants cultivated under elevated CO2 inhibit B. tabaci feeding, which can reduce whitefly infestations of the soybean fields." And that is wonderful news with great implications for future agriculture yields in regions of high whitefly infestations.

Figure 1. Indirect effect of ambient (aCO2 = 450 ppm) or elevated (eCO2 = 700 ppm) CO2 level on various life parameters of B. tabaci feeding on the soybean plants. Mean ± SE of (a) number of days required for eggs to emerge and for the development of immature stages [eggs, 1st to 3rd instar, 4th instar (pupa) and number of days required for emergence of adults from eggs]; (b) fecundity and (c) fertility. The symbol (*) indicates significant differences (p < .05). Source: De Paulo et al. (2020).

Posted 4 November 2020