Stoichiometric mismatches between plants and phytophagous insects can potentially limit an herbivore's ability to obtain physiologically required nutrients (N and P). Two possible methods of coping with stoichiometric inequalities are compensatory feeding or dispersal to better quality plants. We investigated the stoichiometric relationship between host plants and insects by altering the C:N:P composition of a host plant, Spartina alterniflora, and measuring insect growth rate of the flightless (brachypters) and flight-capable (migratory) wing forms of Prokelisia dolus and P. marginata, two species of flight-dimorphic planthoppers, to determine if N or P limitation in Spartina causes a decrease in Prokelisia performance. Growth rate of brachypters of the sedentary species (P. dolus) was not affected when reared on low N and P plants, whereas macropters of both species and the brachypters of the migratory species (P. marginata) showed slower growth rates. A possible trade-off in cibarial muscle versus flight muscle production explains the discrepant growth rate results between P. dolus and P. marginata. P. dolus (brachypterous) is able to effectively extract nutrients and maintain body C:N:P composition on low quality plants due to greater cibarial muscle allocation (compensatory feeding), whereas P. marginata (macropterous), with its greater allocation to flight exhibits slower growth rates and altered body composition when exposed to low quality plants. Variation in host plant C:N:P also affects the probability of nymphs becoming migratory or sedentary individuals, thus influencing the dispersal ability of both species.
Species 1: Homoptera Delphacidae Prokelisia dolus
Species 2: Homoptera Delphacidae Prokelisia marginata
Keywords: plant-insect interactions, nutritional ecology
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