Spartina spp. have
been introduced to estuaries around the world.
They can decrease the rate of tidal flow, accrete and hold sediment in
intertidal areas, change the communities of intertidal algae, benthic
invertebrates and shorebirds, and outcompete native salt marsh plants confining
the native to a narrow intertidal zone. Spartina
invasions have resulted in massive habitat alteration with ramification for
wildlife, fisheries, native vegetation, geology, and hydrology. Two sap-feeding
Spartina specialists, Prokelisia marginata and Prokelisia dolus, were used to
test the impacts of insect herbivory on introduced intertidal cordgrass,
Spartina
anglica in a greenhouse.
The vegetative growth rate, total plant biomass, mortality, and
herbivores density were investigated in this study. Prokelisia spp. had
significant impacts on the growth of S. anglica plants.
The S. anglica plants exposed to P. marginata herbivores averaged 37% of
the total plant biomass of herbivory free controls after one season of herbivory,
and the plants exposed to P. dolus averaged 45% of the total plant biomass of
controls. All of the herbivory free plants survived the next spring
while the plants exposed to P. marginata suffered 92% mortality and the plants
exposed to P. dolus suffered 93% mortality.
The impacts of both Prokelisia spp. on S. anglica plants were similar,
and they both successfully killed the plants in this greenhouse experiment.
The results suggest that Prokelisia spp. could be used as biological
control agents to limit the growth of S. anglica plants.
A future prerelease investigation is strongly recommended.
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