insect pest management

Insect pest management

511 ZooPrepared by: Dr. Reem Alajmi

Insect pests

Pests, by definition, are organisms that come into conflict with humans.

Just one insect is all it takes to cause physical trauma in the form of biting, stinging or disease transmission.

Transportation results in pests becoming translocate into new area. About 40% of major insect pests in North America are not native.

In order to protect our self from biting and disease caring insects, we have devised methods to alter normal population growth of many insect pests by reducing their chance for survival.

The current philosophy of contending with insect pests is to minimize damage using as many different techniques as possible without injuring the environment.

Insect pests

1- Cultural Control

Cultural control involves the manipulation of the environment to make it less favorable for the pest populations.

These techniques are ancient.

Normally, the results are not immediate, and these practices must be applied long before economic damage is evident.

Crop rotation is a common means of minimizing damage by pests.

The timing of plantings to the period when the insect pest is least abundant or absent has proven successful in winter.

Other methods are categorized as cultural control methods and all are based on agricultural procedures.

This type of control is important in controlling pests of livestock and their impact on humans.

For example, the house fly breeds in manure; therefore, proper farm management and disposal of these wasted prevent flies from reproducing and migrating to nearby urban areas.

1- Cultural Control

Host-Plant Resistance

Plant must be capable of resisting the effects of insect herbivores to survive.

Painter 1968 categorized plant resistance into three major types: tolerance, antibiosis, and nonpreference.

Tolerance means the ability of a plant to survive pest infestations that would normally injure or kill similar plants. Environmental factors have a great influence on this type of resistance to pests.

Antibiosis is the ability to induce detrimental effects on the pest and thereby reduce damage by the insects. Effects on the insect pest include causing death, lowering fecundity, lowering survival rated, affecting diapauses, causing behavior or physical aberrations, decreasing size, and lowering food reserve

Nonpreference (now called antixenosis) resistance is somewhat intermediate between the first tow types; plants in this category seem to be ignored or much less preferred by the pest. This maybe caused by modifications in the substances that attract the pests, by the use of repellents or by other factors.


Using genetic engineering, the speed of transferring genes is increased significantly.

At present, genes from bacterium Bacillus

thuringiensis, which produce an insecticidal toxin have been incorporated into various plants, including cotton and corn, and can protect these plants in varying degrees from certain major pests.


2- Biological Control

This strategy is one of the oldest method to control insect pests. It depend on using different predators or parasites in reducing

pest population. It includes different ways: 1- Introduction of exotic beneficial into a new area to control a

specific pest. 2- Increase of releasing laboratory reared beneficial at times

when natural beneficial populations are low. 3- Inundation, which is the release of large numbers of

predators and/or parasites at critical times for short-term results.

The use of biological control is most likely to be effective when coupled with other techniques of regulating pest populations.

Biological control programs require considerable scientific information on population potentials, fluctuations of both pest and control agents, possible ecological ramifications, expected variations from locality to locality, the capability of rear and transfer the agents.

2- Biological Control

The advantages of introducing parasites and predators instead of using insecticide are:

1- These agents are selective. 2- Insect resistance is less evident. 3- The ecosystem is less affected. 4- Parasites and predators are less dangerous than insecticides to humans.

2- Biological ControlAdvantages

1- Difficulty in achieving the requirements for effectiveness.2- Difficulty in meeting government regulations for viruses, fungi, and bacteria.3- Viral and bacterial pathogen must normally be ingested by the target insect.4- Timing of spraying pathogens is often critical.5- It could affect native and pest insects.6- Rearing Beneficial's and maintaining them to have them available at just the right time is difficult.

2- Biological ControlDisadvantages

3- Genetic control

The goal of genetic control is to convert a pest insect to the non-pest status.

Three avenues of accomplishing this include: 1- Sterilizing native pest population through

chemosterilants. 2- Mass sterilizing males and then releasing them. 3- Conferring beneficial advantages such as insecticidal resistance on natural predators or parasites that utilize certain pests.

4- Pheromones and Growth regulator

Pheromones are chemicals released by an organism into its environment enabling it to communicate with other members of its own species.

Pheromones have a means of selectively controlling insects when combined with insecticide and traps.

The strategy is either to confuse the mating behavior or to use different concentrations of pheromones to attract specific pests to a centralized area, thereby reducing the need to spray areas and kill other insects, including predators and parasites.

Some of the attractant pheromones are for beneficial insects, so it should be possible to spray these attractants on the crop to be protected and attract and receive benefits of their activity.

Using Juvenile hormones can be mimicked by different synthesizing chemicals which affects insect development.


Some artificial substances used to interfere with the titer of JH by destroying cells of the corpora allata.

Chitin-formation inhibitors are another method with some prospects.

The previous methods in controlling the pest insects by using pheromones and growth regulators were used, but further imagination and much testing must be conducted to refine these techniques for integration into pest management programs.


5- Mechanical and physical control

These techniques have been used for thousand of years.

For example, slapping at a mosquito or stepping on a pest.

During the locust or grasshopper plagues in the US in the 1800s and early 1900s, elaborate devices were constructed to mechanically harvest or kill the invaders.

Light traps are used as mechanical control but for limited potential.

Microwaves and other radio-frequency energy devices have been used experimentally to kill some pests, but heir cost for large-scale operations is currently prohibitive.

Freezing also has been used to control certain pests; for example, a few libraries have large walk-through freezers into which they rotate their old classic books to periodically expose the guild of book pests to lethal temperature.

Physical control are an important method in the management of both medical and crop pests because other alternative techniques often not available.

5- Mechanical and physical control

6- Insecticides

Insecticides are chemicals used to kill insects with no apparent or at least only minimal effect on animals at the recommended dosage levels and conditions of use.

These chemicals are proven to be extremely effective in controlling many pests.

The use of chemicals to kill insects dates back some 3,000 years to the use of sulfur and arsenic compounds.

Each insecticide must be registered for specific use, and label must state detailed instructions for use, including the pest, habitat or substrate, and any restrictions.

Much scientific research on the insecticides reliability, ability of selectively ill insects, safety to humans, and rated of use.

The process of registering new chemical takes approximately 7 years, and it is expensive.

Most insecticides have a varying effect on other animals especially when

1- The concentration are increased by improper formulation of spays.

2- Carelessness cause continual exposure. 3- The insecticides are used in prophylactic regimens 4- Buildups occur in the soil because of poor drainage. 5- There are runoffs fro sprayed areas into streams 6- Insecticides concentrate in some food chains.

6- Insecticides

Different mode of entry of insecticides into the insects

1- Some act after being ingested with food. These poisons are often used on insects that have chewing mouthparts. A few insects that have piercing-sucking mouthparts take in toxins carried within the plant sap.

2- The direct contact between insect and insecticides, so it can enter the body through the integument and often affect the nervous system. This is often used with insects that have piercing-sucking mouthparts.

3- Enter the body through the tracheal system, but this often requires the environment to be enclosed as in fumigation.

Each insecticide has a different toxicity level for each pest; this is measured b the point where the lethal dose (LD) of toxicant kills 50% of the pest population (the LD50).

Different mode of entry of insecticides into the insects

What insects are the target of insecticides??

Much of the use is in agriculture with 1- Lepidopteran species the most common target (35%). 2- Followed by Hemiptera (20%) 3- Coleoptera (15%) 4- Diptera (10%) 5- The remainder among scattered groups. Insecticides are also used against medically important insects

(mainly Diptera, Anoplura, and Siphonaptera) to prevent diseases transmission; on insects of veterinary and domestic animal importance; and the remainder on household and garden insects.

An insecticide can best be used for only a year and achieve its maximal result, but more than 95% of a population of insect pests must be killed to have a decrease in next years numbers.

Because normally this is not possible, yearly spray schedules were often institute in the past. However, insect pests that survives such a regimen were genetically better adapted for withstanding subsequent applications and thus resistance developed within populations, particularly when high levels of kill were achieved. In many instances, resistance has come not from new mutations but because of the close chemical similarities between the pesticide and naturally existing insecticides produced by plants, the allelochemicals, which the herbivorous insects has had to cope with during the evolutionary past.


More than 500 insect species have been tested and show resistance, including 20 of the worst agricultural and medical pests that are resistance to nearly all types of insecticides.


Types of insecticides

Insecticides are often grouped into botanicals, inorganics, microbial, and synthetic organic.

Of the botanicals, both nicotine and pyrethrines are contact poisons and are available on the market today.

Inorganic compounds were far more toxic, but they must be ingested to kill. For example, Paris green, arsenates, fluorides, sulfur. These inorganic poisons have been banned from use.

Microbes can produce insecticides. These microbes can be applied directly to crops in similar manner as other insecticides.

The last group of insecticides are the synthetic organics. DDT, the first of the new synthetic organic insecticide, where introduced extensively at the end of the World War 2. It was very effective for killing insects

Types of insecticides

Any questions??

insect pest management

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