A small insect, native to South America, has been brought to California waterways thanks to its voracious appetite for water hyacinth, an invasive aquatic plant that chokes the sloughs and canals of the San Joaquin/Sacramento River Delta.

Scientists with the California Department of Food and Agriculture (CDFA) have begun releasing hundreds of water hyacinth plant hoppers in the Delta to reduce infestations of the hearty and troublesome plant. The floating, exotic weed can grow so densely that thick “rafts” of the plants can completely cover a waterway’s surface, preventing access by boats and clogging water intake systems.

“Water hyacinth is a serious problem not just for agriculture and our state’s water supply, but for anyone who appreciates the natural beauty and recreational value of our waterways,” said CDFA Secretary Karen Ross.  “CDFA’s new biocontrol project will help reduce the impacts of this invasive weed in the Delta.”

Initial releases of 750 water hyacinth plant hoppers were made earlier this month in three locations:  Whiskey Slough in San Joaquin County, Willow Creek in eastern Sacramento County, and Seven Mile Slough in western Sacramento County.  Secondary releases have since been made in Whiskey Slough (1,500 insects) and Willow Creek (3,000 insects).  Scientists hope the plant hoppers will thrive in their new home, eventually resulting in self-sustaining colonies. This project shows CDFA’s ongoing commitment to the principles of integrated pest management – considering physical and biological approaches and using them whenever possible.

Before a biological control agent like the water hyacinth plant hopper can be released in California, the organism must be cleared by both federal and state regulatory officials through an exhaustive analysis that weighs risks. Biological control agents from outside the U.S. are shipped to a domestic quarantine facility where they are subjected to a series of tests. Only those organisms with high specificity to the target weed are approved for use as biological control agents.  The results of the pre-release tests are summarized into a petition requesting permission to release the organism into the field.  Once approved, the permitted biological control organism can be mass-reared to high numbers and released at field sites established by biologists.