Insect Pest Control - Essay Example

?Introduction Insects infest different types of stored products contaminating them and rendering them unsuitable for human or animal consumption. There are different places where insects attack the stored products, including silos, kitchen and bulk handling stores. Besides damaging stored products, insects crawl and fly about in the house and food stores, creating a lot of discomfort to the users. Insect pests infest different types of stored products, including cereals and all varieties of dried food (Heikki, et al, 1996). Due to the heavy economic damage caused by these pests, it is important to identify the biological characteristics of these pests in order to formulate effective strategies of eliminating them in our premises. This paper discuses how understanding of the biology of insect pests assist in the control of stored products pests. Characteristics of insects Entomologists and biologists have researched on different characteristics of insects including those infesting stored products. Examples of insect pests that infest stored products include grain weevils, grain and flour beetles, spider beetles, flour moths, mites and psocids among others (Heikki et al 1996). According to Robinson et al (2007), insects exhibit distinct physical, reproductive, and behavioural characteristics that enable them survive and multiply in different habitats. The major defining characteristics of insects are three pairs of legs, three body regions including the head, thorax and abdomen. In addition, insects’ bodies are usually enclosed in an endoskeleton (Robinson et al 2007). Because they have jointed appendages, insects are classified under bigger animal group called arthropod (Robinson et al 2007). Many insects have wings for locomotion, and others use their legs to crawl on surfaces. Another defining characteristic of insects is that they develop from eggs. They go through different stages called metamorphosis after hatching until they become full-grown adults. Insects undergo complete or incomplete metamorphosis (Isaac, & Rami, 2009). Complete metamorphosis comprises of four stages, namely egg that hatches into larvae, then pupae and later an adult develops from the pupa stage. Incomplete metamorphosis comprises of three stages, namely egg, nymph and adult (Isaac, & Rami, 2009). Another defining characteristic of insects is that they breathe through spiracles that are located in the thoracic and abdominal cavity (Heikki, et al 1996). The body of insects is relatively small and it varies in shape and colour depending on the particular species. In addition, insects have one pair of antennae that is used as sensory organ to detect smell, temperature, and other forms external stimuli (Robinson, et al 2007).Insets have different feeding habits and they have specialized mouthparts adapted to suit a particular feeding method. For instance, insects that suck blood from animals or sap from plants have long sharp proboscis. Others that feed on stored products such as grains have different mouth parts, such as mandibles and sharp tooth like structures to enable them feed on the particular stored food material (Isaac, & Rami, 2009). Methods of controlling stored product pests Entomologists have developed different methods of eradicating insect pests infesting stored products basing on their biological characteristics. However, Jack and Nancy (1999) note that no method is 100% effective and a combination of several techniques are applied. Some of the methods used to control insect pests include insecticides such as fumigants, biological control, sanitation, drying stored products, temperature regulation among other methods. Fumigants work by interfering with respiratory process of insects in large and medium sized storage premises (Jack, & Nancy, 1999). According to Heikki et al (1996), fumigants are volatile and toxic chemicals and they kill the pest by suffocating. Chemicals applied in fumigation are effective at killing insect pests in different stages of metamorphosis. Biological information about these pests is important in order to identify the stages that are most vulnerable to chemical action. In this regard, entomologists recommend application of fumigants and other chemicals during larval, pupae and adult stages. Heikki et al (1996) note that eggs of most insect pests have protective covering that reduces effectiveness of chemicals. Method of locomotion and paths of entry into buildings The biological knowledge of the physical characteristics of insects helps in formulating effective method of control. The method of locomotion used by insects pests helps not only in applying the most efficient method of control, but also in eliminating pathways that they use in getting entrance to storage premises. For instance, flying insect pest that infest stored products normally gain access buildings by flying through ventilation pathways or windows. On the other hand, insect pests that do not fly enter storage facilities through broken fissures and tiny cracks on the walls and floors of structural framework of the building. In addition, crawling insect pests access building by climbing on plants and other vegetations around the premises and then they crawl into the premises through windows and ventilation (Heikki, et al, 1996). The approach used to control and manage insect pests on the basis of their locomotion habits includes closing and blocking the entry points used by the insects, smearing the walls or floors with chemicals and insecticides that kill on contact or repels the insects from climbing on the walls. In addition, entomologists recommend clearance of tall vegetation and other landscaping plants around storage premises and homes (Isaac & Rami, 2009). There are different forms of chemicals and insecticides that are designed to control flying and crawling insects. For instance, Robinson et al. (2007) notes that powdery insecticides are more effective in controlling crawling insect pests such as grains weevils than flying insects. Insecticides in form of sprays are used in control of flying insect pests such as flying moths. Insects are generally small organisms and they can easily be demobilised using traps especially made of adhesives (Robinson, et al 2007). Response of insects to external stimuli Insects respond differently to external stimuli, such as temperature, water, food and light. Combinations of these stimuli affect the behaviour of these pests. In this regard, the pests can be controlled by changing these factors. Presence of food is a natural attraction to insects. Insect pests have different food tastes and eliminating these foods is one method of preventing buildings from being infested by insect pests. For instance, grain weevils like grains or cereals while moths commonly attack powdered foods such as flour. Other insect pests such as ants are attracted to sugary food substances (Jack & Nancy, 1999). Therefore, to prevent insect pests from accessing these buildings, high level of sanitation is required to clear away food remnants in a building. In addition, stored food should be put in airtight containers, with well-secured lids made of materials strong enough to resist insect attacks. Temperature is an important environmental factor that determines survival of insects. According to Heikki, et al (1996) insects require favourable temperatures and moisture because they are cold blooded. Availability of these factors influences survival and reproduction rates of insects. Optimum temperature enhances their metabolism and their activity. Temperatures below 55 degrees Fahrenheit, most insects are inactive (Heikki, et al 1996). In this respect, keeping stored products at low temperatures is an effective method of controlling and managing pests. In addition, food substances should be dried properly before storage, because moisture attracts insects and results into production of heat during fermentation. Insect pests that attack cereal and other stored products are averse to high temperatures and therefore entomologists are currently considering heat application as a potential method of controlling the pests (Jack & Nancy, 1999). Light is another important stimuli that determine behaviour of insect pests. Some pests become attracted to light while others are averse to light. Light averse insect pests move away from sources of light and they hide in dark crevices. This helps in determining locations where they hide buildings, which makes it easier to kill and control them (Heikki, et al 1996). For example, grain weevils are cylindrical shaped and they move away from light, hiding in deep horizons of silos and other storage facilities (Jack & Nancy, 1999). To kill and eliminate grains weevils effectively, storage facilities should be well lit and insecticides placed in strategic positions. Insects attracted to light such as moths can be controlled by bright lamps and then introducing other organisms that feed on the pests when they cluster around the lamps. In this regard understanding their living habits in response to external stimuli is vital in determining where they hide in large numbers in order to apply effective methods of control (Robinson, et al 2007). Establishing predators, pathogens and parasitoids of insect pest Entomologists apply other living organisms to control the spread of another through biological control (Heikki, et al, 1996). Insects play a major ecological role, whereby they are used as a source of food to other insects and vertebrates. Some predators, including insects selectively feeds on insect pests that attack stored products. Biologists have indentified important insect predators that feed on pests that attack stored food. Some of these insect predators include ladybeetles, rove beetles, hover flies, among others (Heikki, et al, 1996). Insects that use another insect host to develop into maturity are called parasitoids (Heikki, et al, 1996). Parasitoids lay their eggs on the body of a particular insect pest and when their eggs hatch, they use the host body for food, eventually killing the insect. For instance, parasitoid wasp such as Bracon hebetor kills particular internal grain weevils, by laying their eggs on the larva of the weevils. When the eggs of the wasp hatch, the wasp larvae feed on that of the weevils (Heikki, et al, 1996). Conclusion Understanding the biology of insect pests enhances implementation of better control and management practices. The knowledge of insects’ physiology, ecological niche and response to stimuli helps pest control specialists to device control measures such as improving sanitation in storage premises, and eliminating factors that enhance breeding and infestation of the pests. In addition, knowledge on the insects’ predators, pathogens and parasitoids enables biologists to control the pests in more environmentally friendly manner than the usual toxic chemicals. References Heikki, M., et al. (Eds). (1996). Biological control: Benefits and risks: Cambridge: Cambridge University Press. Isaac, I., & Rami, H. (Eds). (2009). Biorational control of arthropod pests: Application and resistance management. New York: Springer. Jack, R., & Nancy, R. (1999). Biological and biotechnological control of insect pests. New York: CRC Press. Robinson, A., et al. (Eds). (2007). Area-wide control of insect pests: From research to field implementation. Oxford: Springer. Read More