PEST CONTROL.

Eastern and Southern Africa are characterized by cultivation of Cabbage (Brassica oleracea L.var.capitata). Pests, chiefly, the Diamond black moth {DBM: Plutella xylostella (L.)}, Cabbage Aphid and Cutworm jeopardize good production.

DBM

The pests quickly develop resistance to pesticides. (Geernter and Lomer, 2000). The farmers end up increasing quantity of pesticides and spray frequency. (Varela et al., 2003). This overuse certainly has negative effects on human and environmental health. Worse still, in Africa it is reported that most of the available pesticides cannot do much to control pests.

DBM LAVA

However, in the highland areas of Tanzania, Kenya and Uganda, the DBM nightmare is almost over now!

Classical Biological control (BC), the introduction of an exotic natural enemy into a new environment, was introduced. It involves release of an appropriate BC agent which spreads on its own and is ubiquitous when successfully established. It requires no investment hence effective poor farmers. (Hajek, 2004).The method has been working well in areas such as Asia.

Consequently, a parasitoid -Diadegma semiclausum (Hellén) - was imported from Taiwan and introduced by the International Centre of Insect Physiology and Ecology (Icipe) in 2001.It was used in the chosen research areas of Central Province and Northern Province; their dry and rainy seasons. In Kenya, 634 farmers were sampled and 616 in Tanzania. The BC was used on 850 of all the farms while 400 were left without.

The findings showed that other physical and biological within the eco system needed to be controlled for the BC to be effective. (Blackwell and Pagoutlatos, 1992) For example the temperature had to be like that within an altitude of 800 and 2000m. (Macharia et al., 2005).

Also, this parasitoid is complementary. It counters the effect of DBM only. Other methods of pest management have to be incorporated so as to enhance production. This includes use of biological pesticides and spot spraying. Furthermore, other chemical pest controls have to be used properly to enhance performance of this BC. The relationship between parasitism and effectiveness of the control are directly proportional.

Production of cabbage, in the end, was US $198/ha with the BC whereas without it was US $ 99/ha in Kenya. Use of pesticides accounts for up to US $ 15/ha (Asfaw et al., 2009). Use BC, save up!

Reference

• Carpentier and Weaver, R.D 1997 damage Control productivity.
• Why econometrics matters American journal of Agricultural Economics 79(1), 47-61.