"In my next life, I will study biocontrol" – Rhodes University Vice-Chancellor champions sustainable biological control solutions

By Siqhamo Jama

Three years ago, Rhodes University and the Centre for Biological Control introduced a tiny natural enemy to the Makana Botanical Gardens. Today, and coinciding with the 120th birthday of Rhodes University’s Zoology and Entomology Department, that small intervention is yielding remarkable results in the battle against an aggressive aquatic invader.

In October 2023, the Listronotus appendiculatus weevil was first released to combat Sagittaria platyphylla, commonly known as the delta arrowhead. Fast forward to March 2026, and the University community has gathered once again at the very same streamside for a second targeted release. The goal is to bolster the existing population of these biocontrol agents and further protect local waterways from being choked by the invasive weed.

The science in action

The aquatic weevils have been hard at work since their initial introduction. Researchers at the Centre for Biological Control have observed that the insects successfully travelled downstream from the original release site to establish new colonies.

During the recent excursion, Master's student Eden Rhys Hendricks and the dedicated rearing team explained the fascinating life cycle of the weevil to Vice-Chancellor Professor Sizwe Mabizela. The adult insects fly and hop between plants, feeding on healthy flowers and laying their eggs. The hatched larvae then burrow deep into the fruit and stems, eating the seeds from the inside out and effectively destroying the reproductive capabilities of the weed.

The research has also uncovered vital insights into how the weevils adapt to local climates. In the Eastern Cape, the insects enter a state of dormancy during the colder winter months when the host plant dies back. Furthermore, researchers have discovered that the weevils can reach adulthood in just ten days under optimal temperatures of 30 degrees Celsius. To ensure continuous control, the team is already testing two additional biocontrol agents that target the roots and leaves of the delta arrowhead.

Cultivating articulate leaders

The success of this biocontrol programme extends well beyond environmental conservation. It actively reflects the commitment of Rhodes University to nurturing exceptional scientific talent from across the nation. The Centre for Biological Control recently welcomed new postgraduate students from Mpumalanga, Limpopo and the University of Zululand. Professor Mabizela praised the calibre of these young scientists and the expanding national footprint of the programme.

He shared a heartwarming tale with the team about recently hearing a Rhodes University biocontrol student interviewed on the SAFM radio station.

"I could have jumped out of my car," Professor Mabizela recalled enthusiastically. "The person was just so articulate, so clear thinking, and I said well, that could only be a Rhodes University graduate. Thank you for making us proud."

Standing at the edge of the water to assist the researchers with the latest release, the Vice-Chancellor marvelled at the dedication of the group and the fascinating science behind their work. "In my next life I will study biocontrol," he declared, praising the team for their crucial contributions.

This enthusiasm perfectly illustrates why such research is so vital. By continuously developing innovative and environmentally safe solutions with a passion for developing young scientists, Rhodes University remains at the forefront of protecting South African biodiversity while shaping the leaders of tomorrow.