The biological control insect numbers on the hyacinth on Hartbeespoort Dam have increased dramatically and the Centre for Biological Control of Rhodes University hopes to see the plants dying off soon.
“Due to the combined efforts of the residents and the CBC, the numbers of the biocontrol agents have been increasing, following patterns typical of the last three summer seasons. We have been recording populations of the water hyacinth planthopper between 3 000 to 4 000 insects per square meter. As a result of the high numbers of insects, we project that changes should become evident in the plant population in the coming weeks.”
Representatives of the CBC will be continually monitoring the situation as it unfolds.
“We are optimistic about the outcome, but given the variable weather over the summer, it will be difficult to predict when changes in the plants will become noticeable.”
As the insect population increases, their feeding will significantly damage the plants. The combination of the plants’ nutritional quality decreasing and the insects’ crowding, can prompt them to leave the dying plants to seek quality hyacinth elsewhere.
The CBC says during this time, the insects could be attracted to lights and fly into residential areas. “We ask that residents be patient at this time, as this will be short-lived and will subside in the coming weeks. Reducing the amount of light around residences will prevent large numbers of insects accumulating.”
These insects are plant-specific and will not complete their lifecycles on native, garden, or crop plants.