Abstract:
Thaumastocoris peregrinus is a sap-sucking
insect that infests non-native Eucalyptus plantations in
Africa, New Zealand, South America and parts of Southern
Europe, in addition to street trees in parts of its native range
of Australia. In South Africa, pronounced fluctuations in
the population densities have been observed. To characterise
spatiotemporal variability in T. peregrinus abundance
and the factors that might influence it, we monitored
adult population densities at six sites in the main eucalypt
growing regions of South Africa. At each site, twenty
yellow sticky traps were monitored weekly for 30 months,together with climatic data. We also characterised the
influence of temperature on growth and survival experimentally
and used this to model how temperature may
influence population dynamics. T. peregrinus was present
throughout the year at all sites, with annual site-specific
peaks in abundance. Peaks occurred during autumn (February–
April) for the Pretoria site, summer (November–
January) for the Zululand site and spring (August–October)
for the Tzaneen, Sabie and Piet Retief monitoring sites.
Temperature (both experimental and field-collected),
humidity and rainfall were mostly weakly, or not at all,
associated with population fluctuations. It is clear that a
complex interaction of these and other factors (e.g. host
quality) influence population fluctuations in an annual,
site specific cycle. The results obtained not only provide
insights into the biology of T. peregrinus, but will also be
important for future planning of monitoring and control
programs using semiochemicals, chemical insecticides or
biological control agents.
