Effects of elevated CO 2 on feeding responses of biological control agents of Pontederia crassipes

PAPER, M. K.; RIGHETTI, T.; RAUBENHEIMER, S. L.; COETZEE, J. A.; SOSA, A. J.; RIPLEY, B. S. R.; HILL, M. P.

ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA

WILEY-BLACKWELL PUBLISHING, INC

Año: 2023 vol. 171 p. 998 - 1008

0013-8703

Elevated carbon dioxide (eCO2) and rising temperatures will have far-reaching effects onglobal plant-insect interactions, yet their implications for future biological control programsare not fully understood. Studies have shown that elevated CO2 will affect insect feedingguilds differently and these responses can be predicted with some confidence. Water hyacinth,Pontederia crassipes Mart. (Pontederiaceae), is a native and representative species of the DelPlata wetlands (Argentina) that invades outside of its native environment. It is considered oneof the world’s worst aquatic weeds and a target for biological control. In this study, waterhyacinth plants were grown under two CO2 concentrations – current (400 p.p.m.) or elevated(800 p.p.m.) –, with and without two biocontrol agents representing different feeding guilds,the leaf-chewing Cornops aquaticum Brüner (Orthoptera: Acrididae) and the phloem-feedingMegamelus scutellaris Berg (Hemiptera: Delphacidae). Under eCO2 concentration,photosynthetic rate, total dry weight, and relative growth rate of P. crassipes acclimated toeCO2 conditions and plants showed very little CO2 fertilization response in eutrophic water.Insect herbivory varied depending on feeding guilds at eCO2; however, P. crassipes growthresponses increased when exposed to insect herbivory. Chewing herbivory by C. aquaticumwas consistent across CO2 conditions; however, the feeding by M. scutellaris increasedsubstantially at eCO2. These results indicate that successful biological control of P. crassipesunder conditions of elevated CO2 might rely on phloem-feeding insects, with chewers playinga lesser role.