Bio Control Project

Current Activities

As of May 2019, the extent of spread of the weevils is at an average of 21m from each of the October 2018 points of release, a much higher extent as compared to 5m to 9m in December 2018 and March 2019 respectively. These results are obtained from site monitoring activities [A1] that are focused on observing the extent of spread of the weevil spread, the browning score of the Salvinia and as well as recording any effect of the weevil on other plants apart from the Salvinia.

Eight control points (Non-weevil release sites) have been selected and georeferenced in Waya and Chiyuni. These are used for comparison with the weevil release sites.

Weevil mass rearing has been escalated with 13 mass rearing avenues in comparison to the 6 at start of 2019; two troughs at the BirdWatch Office, four troughs in Chilwa, two troughs in Chiyuni, two concrete ponds in Waya and three concrete ponds at Chilanga Fisheries Headquarters.  The mass rearing is done so as to increase the weevil population prior to introduction into additional points in the swamp.

Cyrtobagous salviniae performs better in a temperature range of between 25.5°C and 33.5°C with a good supply a fresh green Salvinia molesta. In an effort to maintain the water temperature at optimum in the mass rearing troughs, the project team has employed the use of warm water, heated by floating elements. Waterproof thermometers are used to ensure that water temperature is optimum. At the optimum temperatures (25.5°C to 33.5°C), the feeding and breeding rate of the weevils is at its peak thus increasing chances of reproduction and ultimately Salvinia molesta control.

Additionally, the use of a water soluble nitrogen-rich fertilizer promotes the speedy development of Salvinia molesta growth tips.  The fertilizer improves the health and growth rate of Salvinia molesta which ultimately produces lots of healthy weevils as a result of an improved food supply. In addition to that, nitrogen is known to increase the size of females thus leading to large egg clutches.

Awareness raising to stakeholders and the local community remains a vital aspect of this project. The target groups are the fishermen, traders, pupils and traditional leaders and relevant stakeholders. At present, a total of 1110 individuals, comprising of a total 777 males and 330 females have been reached. These talks are centered on discussing the purpose of the weevils, the weevil mechanism as well as the Dos and Don’ts with regards to good weevil management to improve the rate of success. These are usually interactive talks with visual awareness raising materials [A2] such as posters, a banner, invasive species guide and weevil lifecycle leaflets.

Project Update Timeline[A3] 

  • November 2019 – Weevil monitoring in Chilwa and Chiyuni, awareness raising in Chiyuni and at Liutebm University, weevil introduction in Chilwa
  • October 2019 – Weevil monitoring in Waya, radio appearance, 5th Project Steering Committee meeting
  • September 2019 –Pond nurturing and maintenance in Waya, Impact/Extent Survey, Mass rearing at Chilanga fisheries, Enhanced mass rearing techniques.
  • August 2019- Pond nurturing and monitoring Waya, trough monitoring activities in all sites
  • July 2019 – Trough monitoring Activities, 4th Project Steering Committee Meeting,
  • June 2019 – Biodiversity Survey in Lukanga.
  • May 2019 – Weevil monitoring activities, introduction of weevils in Chilwa, awareness raising talks, trough monitoring.
  • April 2019- Weevil introduction in Chilwa and Waya, awareness raising in Chilwa and Waya.
  • March 2019 – Quarterly Project Steering Committee meeting, invasive species talk at Rusangu University, Participation at the invasive species symposium in Gaborone, Botswana.
  • February 2019 – Weevil monitoring activities, awareness raising
    talks, pond managers training, weevil introduction into troughs in
    Chilwa and in pond 2 in Waya.
  • January 2019 – Construction works on Pond 2, completion of weevil
    Introduction and weevil monitoring reports.
  • December 2018 – Weevil introduction into Pond 1, Weevil monitoring activities.
  • November 2018 –Weevil monitoring activities, weevil mass rearing pond construction, steering committee meeting and site visit.
  • October 2018 – Weevil shipment received, Weevil introduction
  • September 2018 – Pond management training, Selection of weevil introduction sites
  • August 2018 – Weevil importation procedures
  • July 2018 – EPB approved
  • June 2018 – ZEMA site inspection, Post baseline survey
  • May 2018 – Courtesy call on traditional leaders
  • April 2018 – Submission of final EPB report
  • March 2018- Inception meeting for Monitoring and Evaluation Steering Committee.
  • February 2018- Traditional leaders courtesy call
  • January 2018- Zambia Environmental Management Agency (ZEMA) report reviews
  • December 2017- Environmental Project Brief (EPB) activities
  • November 2017- Baseline survey
  • October 2017- Project inception meeting