| Bagrada
bug |
Namibian
crop pests # 22
|
| Bagrada hilaris |
Order: Hemiptera |
Family: Pentatomidae |
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Note:
This page is brought to you courtesy of Menno Keizer and Jantien
Zuurbier, who worked at the Kavango Horticultural Production and Marketing
Project. For further information please email them directly at: mennojantien@yahoo.co.uk
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Bagrada bug on cabbage
|
Common names:
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Bagrada bug, Harlequin
bug, Painted bug (English),
Shingurukutu (Gciriku) |
Host:
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Mainly Brassica spp. (cabbage,
Chinese cabbage, kale, rape), but also beetroot, groundnut, potato and
papaya are known to be attacked. |
Pest status:
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A major pest of Cruciferous crops
in many parts of world, including southern parts of Africa. In Namibia
the pest is manifesting itself in the Kavango and Caprivi regions.
The bugs prefer the cooler conditions
of the year and therefore occur in North-eastern Namibia mainly from April/May
onwards up to August/September. Apart from the Tsumeb area, the pest is
less problematic in the NCD regions (Omusati, Ohangwena, Oshana and Oshikoto
regions). |
Description:
|
The eggs are white and turn orange
in a later stage. They are laid in small clusters, on the leaves, but mostly
in the soil underneath. More than 100 eggs may be laid during a period
of 2-3 weeks. The incubation period is 5-8 days.
There are 5 nymphal stages, which
take 2-3 weeks for development. The nymphs are shiny red (± 2 mm),
becoming mahogany in colour in a later stage and can easily be mistaken
for a different insect.
The adult bug is typical shield-shaped,
5-7mm long. The upper surface has a mixture of black, white and orange
markings. The whole life cycle takes only 3-4 weeks and there are several
generations per year. |
Damage:
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Both adults and nymphs feed by sucking
on the foliage of the crop. Starting on the edges of the leaves, white
patches become visible, eventually the leaves wilt and dry. Young plants/seedlings
often die completely. |
Control:
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Use of botanical pesticides:
Natural control methods are currently
tested at Mashare ADI. A mixture of chilli, soap, garlic and paraffin has
shown to be an effective control method in previous trials. A tobacco extract
was less effective, but reduced the population slightly. Further testing
of botanicals will continue this season. For more details contact the Horticultural
section at Mashare ADI.
Cultural practices:
Eggs laid in the soil are readily killed
by cultivation, so frequent light cultivation (once, twice a week) of the
vegetable beds will help greatly in control of this pest. The residues
of all Crucifers (including weeds) should be destroyed to reduce the carry-over
between crops and seasons. Regular monitoring of the crop is important.
Handpicking of the bugs when seedlings are still small helps to reduce
damage to the young and vulnerable plants. A vegetable grower in Tjeye
(Kavango) reported that handpicking the insects, collecting them in a jar,
pound them and sprinkle the remains over the crop, repels other bugs and
can be used effectively in combination with frequent soil cultivation.
Chemical control:
Insecticides such as Malathion and Malasol,
(active ingredient mercaptothion), Carbaryl and Karbaspray (a.i. carbaryl)
can be used to control heavy attacks, but should always be used as a last
resort. Contact your nearest Agricultural Extension office of FSR/E-Unit
for more advice on the safe and effective use of chemicals.
Threshold level:
Research at Mashare ADI has shown that
if the number of bugs/m² exceeds 1, in the early growing stage, control
measurements should start. If the crop has past the early growing
stage, a higher threshold level of 3 bugs/m² can be maintained. The
economical threshold level is the pest density at which control measures
should be initiated to prevent an increasing pest population from reaching
the stage at which the economical loss is higher than the benefits. |
References:
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Keizer, M., J.A.M., Zuurbier, Integrated
Pest Management for Horticultural crops in Namibia, Proceedings of the
National Annual Agricultural Research Reporting Conference, MAWRD, September
1998.
Keizer, M., J., Zuurbier, Pest Manual
for Extension Workers, Mashare Agricultural Development Institute, Rundu,
Namibia, April 1999.
Myburgh, A.C., Crop pests in Southern
Africa, Vol 3 Potatoes and other vegetables, Plant Protection Research
Institute, Bulletin No. 415, Pretoria, 1993.
Varela, A.M., A.A., Seif, Crop protection
manual for Brassicas, ICIPE, Nairobi, Kenya, June 1999. (Photo by: GTZ-ICIPE
IPM Horticultural Project) |
Other pages by the same authors:
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