Pest control is a broad spectrum term. Some pests require specialty
services while others can be controlled as a group. We classify general
crawling insects as one group for basic maintenance control. This group
includes silverfish, roaches, ants, and crickets. Insects such as
Mosquitoes are not included as crawling insects. Spiders are not
technically insects and the Brown Recluse is a specialty problem.
Perma dust is an aerosol containing boric acid. Using the crack and
crevice tip that comes with it, you can apply the chemical to those
areas where roaches tend to hide. The residual is excellent and it is
safe for home use. It does dry pure white, so be careful where it is
applied. However, it can be wiped off with a disposable rag.
A wide range of pest control techniques is available to farmers. Some of
them are as old as agriculture itself – rotating a crop, for example, to
avoid a build-up of host-specific pests. Some are new – in recent years,
genetic engineering has opened up many possibilities in pest control
that were unavailable to agriculturalists even a decade ago.
PEST CONTROL TECHNIQUES
Integrated pest management involves
the integrated use of four basic control techniques. Physical
controls
Physical controls are those that can be carried out by the farmer to
alter environmental factors in a way that reduces pest populations. A
simple and common example of this is crop rotation, which is the
practice of planting different crops each year in a given paddock. This
interrupts the normal life cycle of some pests by changing their
environment to one in which their favorite host plant does not feature.
It is a strategy that has been used successfully for years by Australian
gardeners against tomato nematodes.
Another physical control method sometimes called 'mating disruption'
involves the use of sex pheromones. These chemicals are produced by
female insects to attract males for mating. For many insects, scientists
have been able to analyze the chemistry of the sex pheromones and
reproduce them synthetically in the lab. Quantities of the chemical
placed around an orchard can disrupt mating – male insects become
confused and are less likely to find a mate.
Biological control
The principle behind biological pest control is that a given pest has
enemies – predators, parasites or pathogens. By introducing or
encouraging such enemies, the population of pest organisms should
decline. It is not a new concept. The ancient Chinese encouraged ants in
citrus orchards because they attacked many citrus pests.
There are three general approaches to biological pest control. The first
of these is importation of a biological agent. For example, the Mexican
prickly pear once covered 250,000 square kilometers, mostly in
Queensland, greatly reducing the land's carrying capacity for sheep and
cattle. It was brought under control very effectively by the
introduction of an Argentinean moth, Cactoblastis cactorum, the larvae
of which eat the leaves of the offending plant.
But there are dangers with this approach. When the cane toad (Bufo
marinus) was introduced to north Queensland to reduce populations of the
cane grub, Bufo failed to have any impact on the grub. Not only that, it
has become a major pest itself, spreading through much of northern
Australia and threatening the survival of several native animal species.
Nowadays biologists are required to carry out extensive research before
a control organism is released because it is important to find out
whether it will attack species other than the pest species.
The second approach to biological control is augmentation, which is the
manipulation of existing natural enemies to increase their
effectiveness. This can be achieved by mass production and periodic
release of natural enemies of the pest, and by genetic enhancement of
the enemies to increase their effectiveness at control.
The third approach is conservation. This involves identifying and
modifying factors that may limit the effectiveness of the natural enemy.
In some situations, this may include reducing the application of
pesticides, since such pesticides may kill predators at the same time as
killing the pests (Box 2). Sometimes part of a crop area is left
untreated so that natural enemies will survive and recolonise the
treated areas.
Genetic modification
Crop plants can be bred to be resistant to pests. Farmers and
orchardists have been doing this for centuries, selecting the seeds of
those plants least affected by a pest for use in the next year's crop.
This preferential selection is a form of genetic modification.
With advances in biotechnology and molecular biology, it is becoming
increasingly easy to transfer resistance genes into a plant – this is
called gene transformation or genetic engineering. An example of genetic
engineering is the insecticide-producing Bt gene in cotton. Scientists
took the gene from a bacterium and inserted it into a plant, making the
plant resistant to insect attack. Similarly, potato plants have been
genetically modified to increase their resistance to potato leaf roll
virus.
Another technique is the genetic modification of the pest itself. The
idea is to engineer a disadvantageous trait in a pest and then release
modified individuals into the outside world. The sterile insect release
method is an example of this approach.
The genetic engineering of organisms is controversial. Some people argue
that toxins produced as a result of gene transfer may have harmful
effects on beneficial organisms or on human health, while others suggest
that the transferred gene might 'escape' into wild, related species of
the modified organism, with possible ecological implications.
Chemical control
The use of chemical pesticides often forms part of an integrated pest
management strategy. The key is to use pesticides in a way that
complements rather than hinders other elements in the strategy and which
also limits negative environmental effects. It is important to
understand the life cycle of a pest so that the pesticide can be applied
when the pest is at its most vulnerable – the aim is to achieve maximum
effect at minimum levels of pesticide.
