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ARS Home » Southeast Area » Fort Lauderdale, Florida » Invasive Plant Research Laboratory » Research » Publications at this Location » Publication #262317

Title: Effect of an Herbivorous Stem Mining Midge on the growth of hydrilla

item CUDA, J - University Of Florida
item COON, B - University Of Florida
item DAO, Y - University Of Florida
item Center, Ted

Submitted to: Journal of Aquatic Plant Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/7/2011
Publication Date: 7/1/2011
Citation: Cuda, J.P., Coon, B.R., Dao, Y.M., Center, T.D. 2011. Effect of an Herbivorous Stem Mining Midge on the growth of hydrilla. Journal of Aquatic Plant Management. 49:83-89. 2011.

Interpretive Summary: Hydrilla is a submersed aquatic weed that grows from the bottom of water bodies to the water surface. It clogs waterways and interferes with virtually all uses of water resources. An insect that damages the growing tips was discovered in the Crystal River in Florida. Research indicated that this insect could potentially prevent hydrilla from growing to the water surface and thereby alleviate many of the problems it causes.

Technical Abstract: Hydrilla (Hydrilla verticillata (L.f.)Royle: Hydrocharitaceae) is one of the worst invasive aquatic weeds in the US, with millions of dollars spent annually to control large infestations in all types of water bodies. A major factor contributing to the invasiveness of hydrilla is its pattern of growth. The characteristic dense surface mats that are produced impact native plant and animal communities, navigation and flood control, and water quality. An adventive tip mining midge Cricotopus lebetis Sublette (Diptera: Chironomidae) was discovered attacking hydrilla in Florida’s Crystal River watershed. Larvae of C. lebetis mine the apical meristems of the plant and in the process severely injure or kill the plant’s growing tips. Results of field and laboratory studies showed that larval feeding damage changed the plant’s architecture by preventing new hydrilla stems from reaching the surface of the water column. In King’s Bay, the average water depth to the top of the hydrilla bed from April through December 1998 was 41.9 ± 5.8 cm. Regression analysis also indicated a positive correlation between larval density and meristem damage. Approximately 200 larvae/m2, or the equivalent of 1.5 eggs masses, were capable of damaging 50% of hydrilla’s apical meristems. In the laboratory, 99% of the standing biomass of hydrilla was reduced by larval feeding activity. This type of damage is desirable for hydrilla management because it could eliminate most of the environmental and navigational problems caused by the formation of the dense surface mats.