Environmental Impact of Production Horticulture - Horticulture: Plants for People and Places - page 505

Table 15.3 The list of biological control agents with full registration as pest control agents in
Kenya. (Source: PCPB ( 2011 ))
Source Biological Organism Target pest

Imported Ampelomyces quisqualis Powdery and Downy mildew

Kenya Amblyseius cucumeris Thrips in carnations

Kenya Aphidius transcaspinus Aphids

Kenya Bacillus subtilis Powdery Mildew

Imported Bacillus thuringiensis (var israelensis,

kurstaki and aizawai available)

Caterpillars

Imported Beauveria bassiana Aphids, DBM and sucking

insects

Imported Coccidoxenoides peminulus Mealy bug

Kenya Diglyphus isaea Leaf miner

Kenya Encarsia formusa White fly

Imported Eretnocerus eremicus White fly

Kenya Metarhizium anisopliae Mealy bugs

Kenya and imported Neoseilus californicus Red spider mite

Imported Neoseilus swirskii White fly

Imported Paecilomyces lilacinus Nematodes in roses

Kenya and imported Phytoseiulus persimilis Spider mite

Kenya Steinernema feltiae Nematode

Kenya Trichoderma asperellum Root diseases

Imported Trichoderma harzianum Root diseases

Imported Verticillium lecanii White fly

on Lake Naivasha and its environment, and finally the consideration of air freight
of flowers from Kenya to global markets. The adoption of IPM and the reduction in
pesticides has been a prominent feature of the Kenyan flower industry (Wainwright
and Labuschagne 2009 ). This is also supported by the number of biological control
agents currently approved by government for use in Kenya (Table 15.3 ). Despite
protestations by the popular press there is no scientific evidence that the flower
industry has caused pesticide pollution in Lake Naivasha, a freshwater lake in Ke-
nya, lying north-west of Nairobi, outside the town of Naivasha, where the flower
industry is based (Fig. 15.6 ).
The ecology and exploitation of Lake Naivasha in the context of many human
activities has been reviewed by Harper et al. ( 2011 ). Horticulture is a significant
player in the challenges that interface with the lake's ecosystem. There are some
5,000 ha of horticultural production dependant on the fresh water of the lake or sur-
rounding catchment area. Water extraction has increased not only due to horticul-
tural activity but also geothermal power generation, abstraction from rivers in the
catchment area, and extraction for several large towns for domestic use. The lake
is about a third lower than the predicted level however the nature of the lake has
always been considered hydrologically unstable and fluctuated considerable over
the last 100 years even before the arrival of the horticulture industry. The success of
the horticultural industry has resulted in an increase in human population as a result
of employment opportunities.