Figure 2: Incidence of brown locust swarms in South Africa, ran
(3). Information sources were a) 1797–1909, the number of mun
application; c) 1988–2006, records of swarms subjected to cont
Gregaria eat indiscriminately, and when
they have depleted their food, they fly
away in search of more. Disturbances
caused by insecticide application on
locust swarms animates surviving Gregaria
to move even further. Given their
extraordinarily high reproductive potential,
especially when they reach superabundant
crops, swarms escalate,
famines follow.
Thus, poor rangeland management in
arid lands impacts crop production in
distant areas. This connection clarifies
why locust plagues have shadowed humanity
since the First Agricultural Revolution.
Local impact
In South Africa, the last significant outbreaks
of brown locusts, Locustana pardalina,
were a decade ago. Many may
have forgotten their existence, and the
Locust Research Unit of the Agricultural
Research Council (ARC) shut down after
a century of its existence.
Preliminary analyses by SAEON of ARC
records show that two-thirds of locust
hopper bands and swarms occur in
the Bushmanland region of the Nama-
Karoo. The mean annual precipitation
in this area is only about 100 mm but is
highly variable (CV=49%).
Figure 3: ARC recor
different Karoo vege
ticlockwise progress
types: SANBI
Drought, heat waves and wet or warm
winters inhibit hatching and allow egg
banks to grow over many years. Mass
hatching of Bushmanland eggs is preceded
by good late
dry cold winter and i
in early summer. Suc
pand across South A
It remains impossib
triggers mass outb
custs, and when an
occur, even though y
out outbreaks corre
nental climatic phas
That makes it com
because of the pote
of ecosystem statu
custs offer us natura
Solitaria deploy “sm
banks that record
Grassroots Vol 20 No 2 June 2020