PhD Student The University of British Columbia Richmond, British Columbia, Canada
Xylem-feeding insects must contend with a unique problem: the xylem sap within the vascular tissue of plants consists mostly of water and is also under tension (i.e., negative pressure) that can exceed 1MPa. To extract the large quantities of this nutrient-poor liquid required to sustain their metabolism, these insects have evolved a greatly enlarged muscular cibarial pump. But how the capacity of this pump changes across the insect’s ontogeny, and how it varies between species, is unknown. Micro-CT scans of the cibarium and measurements of cibarial dilator muscle sarcomere length have already revealed one particular xylem feeder – the meadow spittlebug (Philaenus spumarius) – to generate a maximum tension of 1.3 ± 0.2 MPa within its cibarium. We now broaden this study to quantify the maximum cibarial tension for four other xylem-feeding species: Aphrophora permutata, Neophilaenus linneatus, Graphocephala fennahi, and Magicicada septendecim. Micro-CT imaging and muscle histology performed across the nymphal and adult stages of each species will be used to determine if certain morphological parameters of the cibarial pump vary across ontogeny or scale isometrically.
