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Junie 2018
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migration patterns
of aphids explained
A
phids are important transmitters of plant viruses attacking
different crops. Knowledge of their migration and seasonal
presence could enable us to make decisions on when to
control the aphids to prevent virus transmission to crops.
A suction trap network was started by potato producers in
2005, who have since 2013 been joined by the wheat industry. The
network currently consists of 13, 12,2 m high suction traps in the
major potato and wheat production areas of the country.
These traps continuously collect all flying insects on a weekly
basis. In collaboration with the Department of Zoology and Entomol
ogy at the University of Pretoria, all aphids are sorted, counted and
identified and data made available on a weekly basis to producers
via the internet.
One trap was moved to Cookhouse during May last year, since the
producers in that area were complaining about the presence of bar
ley yellow dwarf virus on wheat (
Photo 1
). This became the first
suction trap to monitor insects in the Eastern Cape.
At the same time, a 1,8 m high suction trap was installed on a farm
near Hofmeyr in the same province, to get an indication of aphids
infesting crops in that area.
Aphids migrating on air currents
It is known that aphids migrate between areas on air currents moving
at or above 12 m from the soil surface, hence the height of the suc
tion traps. Therefore, aphids feeding on a crop infected with a virus
could migrate to another area within hours and when landing on a
suitable crop, could transmit the virus.
on farm level
Aphids migrating / Suction traps
Integrated pest control
Dr Goddy Prinsloo,
ARC-Small Grain, Bethlehem
Figure 1: Air current patterns over South Africa during mid-November last year.
1
1: A suction trap at Cookhouse.