Paarl, Banhoek and Sir Lowry’s Pass, as well as Franschhoek by 2004. These are all
centres in agricultural landscapes that sequentially border the first Boland population
detected in 2002 (Haupt 2015). It is thus clear that the species suddenly underwent a
rapid range expansion after being isolated on the Peninsula for many years. The species
now has a much larger distribution that can increase further over time.
Polistes dominula is a more recent invader but has already spread approximately
100 km from its point of introduction near Cape Town in 2008. It is now common
throughout the Cape Town Metropolitan Region, Somerset West, Stellenbosch,
Paarl, Wellington, Franschhoek and parts of Grabouw (Veldtman et al. 2012;
Benadé et al. 2014; van Zyl et al. 2018).
From 2014 the City of Cape Town, in partnership with Stellenbosch Municipality, SANBI and Stellenbosch University researchers, initiated nest removal
programmes for V. germanica and P. dominula (van Zyl et al. 2018). Due to the
similar appearance of the two wasp species and the seriousness of their stings
(particularly V. germanica), the public were invited to inform the City of nests on
private property, and staff were dispatched to remove nests in response. The aim of
the programme was not to eradicate, but to provide a service to residents who were
experiencing problems with invasive wasps on their properties. In April 2015, the
City of Cape Town Invasive Species Unit reported that 6142 nests had been removed
and 691.5 person days worked. At that time, members of the Invasive Species Unit
noted the high volume of requests and that the extent and density of the invasion was
worse than expected, and concluded that a piecemeal approach of treating individual
houses would never be effective. There are however far fewer cases of V. germanica
reports and the destruction of nests as reported could help curb the impacts experienced by residents from this species. The V. germanica control programme is
therefore still ongoing.
From 2016 November to February 2017, SANBI initiated a systematic trial to
eradicate P. dominula at its range edge in the Franschhoek and Grabouw areas using
contractors. After training by researchers these contractor teams (three teams of five
people per area) set out to visit residential properties in a 3 month period in each area
to systematically record and destroy all detected P. dominula nests. During this
period 3708 homes were checked and 15,008 nests removed in Franschhoek, while
in Grabouw 3370 homes were checked and 7029 nests were removed. This equates
to 1890 persons days (30 people  63 days) spent on inspecting 7078 homes and
destroying 22,037 nests. The area-wide coverage and clearing effectiveness was
better in Franschhoek than Grabouw, possibly because of communication difficulties
in communities that speak several languages (Simakani 2017). There was no follow
up work done in these areas to establish whether fewer nests were present the
following season, so the effectiveness of the intervention is unknown.
For V. germanica 232 nests were destroyed between 2014 and 2018 across its
distributional range (in 2014, 56; 2015, 12; 2016, 80; 2017, 23, and 2018, 61) by
researchers based at Stellenbosch University, wine farms, pest control companies
and the City of Cape Town. Spatial records for each of these nests will be used to
model the fine scale distribution of this species (Veldtman et al. unpublished data) as
a potential aid to future control strategies. The climate in the current range of
640
S. J. Davies et al.
centres in agricultural landscapes that sequentially border the first Boland population
detected in 2002 (Haupt 2015). It is thus clear that the species suddenly underwent a
rapid range expansion after being isolated on the Peninsula for many years. The species
now has a much larger distribution that can increase further over time.
Polistes dominula is a more recent invader but has already spread approximately
100 km from its point of introduction near Cape Town in 2008. It is now common
throughout the Cape Town Metropolitan Region, Somerset West, Stellenbosch,
Paarl, Wellington, Franschhoek and parts of Grabouw (Veldtman et al. 2012;
Benadé et al. 2014; van Zyl et al. 2018).
From 2014 the City of Cape Town, in partnership with Stellenbosch Municipality, SANBI and Stellenbosch University researchers, initiated nest removal
programmes for V. germanica and P. dominula (van Zyl et al. 2018). Due to the
similar appearance of the two wasp species and the seriousness of their stings
(particularly V. germanica), the public were invited to inform the City of nests on
private property, and staff were dispatched to remove nests in response. The aim of
the programme was not to eradicate, but to provide a service to residents who were
experiencing problems with invasive wasps on their properties. In April 2015, the
City of Cape Town Invasive Species Unit reported that 6142 nests had been removed
and 691.5 person days worked. At that time, members of the Invasive Species Unit
noted the high volume of requests and that the extent and density of the invasion was
worse than expected, and concluded that a piecemeal approach of treating individual
houses would never be effective. There are however far fewer cases of V. germanica
reports and the destruction of nests as reported could help curb the impacts experienced by residents from this species. The V. germanica control programme is
therefore still ongoing.
From 2016 November to February 2017, SANBI initiated a systematic trial to
eradicate P. dominula at its range edge in the Franschhoek and Grabouw areas using
contractors. After training by researchers these contractor teams (three teams of five
people per area) set out to visit residential properties in a 3 month period in each area
to systematically record and destroy all detected P. dominula nests. During this
period 3708 homes were checked and 15,008 nests removed in Franschhoek, while
in Grabouw 3370 homes were checked and 7029 nests were removed. This equates
to 1890 persons days (30 people  63 days) spent on inspecting 7078 homes and
destroying 22,037 nests. The area-wide coverage and clearing effectiveness was
better in Franschhoek than Grabouw, possibly because of communication difficulties
in communities that speak several languages (Simakani 2017). There was no follow
up work done in these areas to establish whether fewer nests were present the
following season, so the effectiveness of the intervention is unknown.
For V. germanica 232 nests were destroyed between 2014 and 2018 across its
distributional range (in 2014, 56; 2015, 12; 2016, 80; 2017, 23, and 2018, 61) by
researchers based at Stellenbosch University, wine farms, pest control companies
and the City of Cape Town. Spatial records for each of these nests will be used to
model the fine scale distribution of this species (Veldtman et al. unpublished data) as
a potential aid to future control strategies. The climate in the current range of
640
S. J. Davies et al.