PEST RISK ANALYSIS (PRA) TRAINING Group Exercises Manual

PEST RISK ANALYSIS TRAINING - GROUP EXERCISES MANUAL APPENDIX 8
160 African Entomology Vol. 9, No. 2, 2001
Figs 4-5. Numbers and species of thrips recorded from yellow card traps in mango orchards. Horizontal lines indicate
the phenology of flowering and fruiting. 4, Numbers of Scirtothrips aurantii, Thrips acaciae and Thrips tenellus recorded
from yellow card traps in a Zill orchard at Friedenheim during 1996; 5, numbers of S. aurantii, T. acaciae and T. tenellus
recorded from yellow card traps in a Sensation orchard at Friedenheim during 1996.
numbers of S. aurantii were present during both
flowering and fruit set.
Scirtothrips aurantii, T. acaciae or T. tenellus
were the most abundant species in the flowers.
However, abundance of thrips species in the
flowers varied seasonally and between orchards.
Monitoring thrips with DIE traps
The D/E traps yielded similar abundance
patterns to yellow card traps, with high numbers
of T. tenellus and T. acaciae present during the
flowering period which declined when fruit were
setting and developing (Figs 6, 7). However, in
the Zill orchard, thrips numbers peaked about
three weeks earlier on the card traps than on the
D/E traps. Very low numbers of S. aurantii were
present during the flowering period and when fruit
were small.
Scirtothrips aurantii was the most widely
distributed species in the survey when considering
results from flowers, leaves and fruit. It was also
one of only two species found to cause lesions on
the fruit. Although S. rubrocinctus caused fruit
damage, it was much less abundant than S.
aurantii and did not seem to be of economic
importance. When using both trapping techniques,
S. aurantii was the second most abundant thrips
during flowering and the most abundant after
flowering. Based on these observations, S.
aurantii is considered to be the most economically
important thrips species on mangoes in South
Africa.
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