Stoichiometric composition of host plants can potentially limit the ability of phytophagous insects to obtain physiologically required resources, thus negatively affecting insect performance. Nitrogen limitation in insects is well documented, however the effects of phosphorus limitation have not been well studied. The key role phosphorus plays in protein synthesis suggests that phosphorus availability may be important to insect growth and performance. Thus, changes in the elemental composition resulting in the reduction of nitrogen and/or phosphorus in host plants may dramatically influence insect performance. We investigated the effect of host plant elemental composition on insect performance and stoichiometry by rearing two monophagous planthoppers, the flightless Prokelisia dolus and the migratory P. marginata on differentially fertilized (N and P) Spartina alterniflora in the lab. We then determined if variation in host plant stoichiometry affects insect elemental composition and growth. Both species showed greater responses to changes in nitrogen composition of the host plant than to changes in phosphorus, suggesting that nitrogen plays a more significant role than phosphorus in insect performance. Additionally, the species responded differently to the elemental composition of the host plant. P. marginata, a predominantly flight capable species, was more sensitive to changes in host plant elemental composition than it's congener, and largely flight incapable, P. dolus. These results suggest that differences in insect life history strategy, such as migratory ability, may allow insects to obtain the needed nutrients for protein synthesis from sub-optimal diets.
Species 1: Hemiptera Delphacidae Prokelisia dolus
Species 2: Hemiptera Delphacidae Prokelisia marginata
Keywords: plant-insect interactions, life history
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