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Sunday, October 16, 2011

The Hybrid Onion Seed Production Region of South Africa

Hybrid onion seed are produced mainly in the Klein Karoo and partly in some areas in the greater Karoo in the Western Cape province.  The seed companies are mostly situated in Oudtshoorn.

The Klein Karoo is a longitudinal area of about 23 500 km2 situated between two mountain ranges parallel to the southern coastal shores of South Africa (the Langeberg-Outeniqua mountain range in the south and the Witteberg-Swartberg mountain range in the north).  The soils of the lowlands are generally clayey and nutrient-rich while the mountains typically have sandy, nutrient-poor soils.  Soil surfaces in the lowland areas are dependent on a living soil crust, formed by small organisms like lichens, mosses, fungi and bacteria, to insure water infiltration, erosion control and nutrient cycling.  The Klein Karoo has a semi-desert climate with higher rainfall in the mountainous areas.  The diversity of environmental factors merging in the Klein Karoo is the reason for the very rich plant diversity.  About 3 200 plants have been identified in the region with 400 of them being endemic to the region.  Four vegetation types are recognized namely, subtropical thicket, succulent karoo, transitional shrubland and fynbos (Vlok & Schutte-Vlok, 2010).

Two of the four vegetation types found within the Klein Karoo, the fynbos and succulent karoo vegetation types, form part of two of the world’s 34 biodiversity hotspots (the Cape Floristic Region and Succulent Karoo).  The Cape Floristic Region is home to the greatest non-tropical concentration of higher plant species in the world.  (Ref: http://www.biodiversityhotspots.org/xp/hotspots/cape_floristic/Pages/default.aspx)  While the Succulent Karoo boasts the richest succulent flora on earth.  (Ref: http://www.biodiversityhotspots.org/xp/hotspots/karoo/Pages/default.aspx)

The ecosystems in the mountain ranges, which also serve as water catchment areas, are largely protected and unaltered in protected areas.  However, the lowland landscapes have been altered considerably over the years by agricultural practices.  One of the main farming practices in the region is ostrich farming that started between 1857 and 1860, which also impelled the cultivation of lucerne as ostrich fodder (Beyleveld, 1967). 

Ostrich farming in the Klein Karoo, near Calitzdorp
The topology of the Klein Karoo landscape where hybrid onion seed are produced, is largely characterized by undulating hills interchanged with historical floodplains along rivers and streams.  These floodplain areas is suitable for crop cultivation, while the hilly areas are mostly used for livestock grazing.



View of the Swartberg mountain range from the Klein Karoo, showing the hilly landscape in the foreground with a historical riverine floodplain in between.

Not much work has been done on the insect diversity found in the Klein Karoo.  Some work has been done on the occurrence and diversity of pollen wasps in the region and elsewhere by Fred and Sarah Gess from the Albany Museum in Grahamstown.  But the area remains largely under-sampled in terms of insect, and especially pollinator insect diversity, says Jonathan Colville, my promoter and entomologist at SANBI.  Thus, my work will be a valuable contribution to the knowledge base of pollinator insect diversity and distribution within the area covered in the study.  



Even the casual collection of insects can bring about new species being discovered.  Jonathan is particularly interested in monkey beetles, members of the family Scarabaeidae, which are largely endemic to southern Africa and important pollinators of many flowers.  He asked me to be on the look-out for them and collect them if I find some.  So, while we were busy data capturing on a site in the greater Karoo, a rather large monkey beetle came landing on the ground in front of me.  I picked it up, and pickled it in some alcohol.  It turned out to be a new species!  Needless to say, the monkey beetle specialists were ecstatic about the new discovery.  The trick is to be on the right place at the right time.