BIODIVERSITY
Make insects your natural pesticide
A
utumn can be a trying
time on plots due to
the increased numbers
of insects in the vegetable
gardens and fields. As a result,
many smallholders declare
chemical war on these
unwelcome visitors. However,
according to Dr Astrid
Jankielsohn, senior researcher
in entomology at the
Agricultural Research Council,
the use of agrochemicals has
a detrimental effect on insect
biodiversity, an important
component of the overall
health of the environment.
Biodiversity refers to the need
for the variety of plant, animal
and micro-organic life in a
particular habitat and the
ecological complexes of
which they are part. Insects
account for about 66% of all
known species and constitute
more than three-quarters of
global biodiversity.
Insects have many important
One of the spin-offs of mixing it up in your
garden and fields is that it encourages
a range of insects ... many of which prey
on other insects ~ your natural pesticide
roles to play in ensuring the
effective functioning of an
ecosystem. Pollination is the
most obvious. Flowering
plants (Angiosperms) play
critical roles in many natural
and agricultural ecosystems,
providing food, fibre and
shelter for wildlife and
humankind alike. A large
percent of our crops rely on
insects to pollinate them.
Predator insects, both in their
larval and adult stages, prey
on insects that eat plants. For
example, lacewings and
ladybirds eat hundreds of
aphids and other predatory
insects also eat slugs, root-
feeding flies and plant-eating
beetles.
Other insects form a vital link
in the decomposition phase
of the cycle of life and death
in an ecosystem.
Decomposition i s the first
stage in the recycling of
nutrients that have been used
by an organism (plant or
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animal) to build its body, and
are surrendered back to the
ecosystem upon its death.
The insects that help in this
process are called detritivores
and include beetles and their
larvae, flies and maggots,
woodlice, slugs and snails,
millipedes, dung beetles, ants,
termites and earthworms.
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