Factors militating against pest control in the environment

Introduction

Gillion (2007) described pest as an organism with characteristics, which people see as damaging or unwanted, as it harms agricultural through its feeding on plants and animal can also be a pest when it causes damage to a wild ecosystem or carried germs. The term pest is used to refer to specifically to harmful animals but it also relate other harmful organism including fungi and virus. It is possible for animal to be a pest in one setting but beneficial or domesticated in another; many weeds (plants pest) are also seen as useful under certain conditions.

Crops need to be protected from a variety of different pests, organisms that present in a threat to the crops. Woody (2010), opined that pest control is at least as old as agriculture, as there has always been a need to keep crops from pest. In order to maximize food production, it is advantageous to protect crops from competing species of plant as well as from herbivores competing with human.

In the 18^th and 19^th century, the introduction of the insecticides, such as pyrethrum and derries are use as pest control chemicals, and they also become widespread in the 20^th century. The discovery of several synthetic insecticide, such as DDT (dichlorodipheny trichloroethane) and herbicide boosted this development.

Chemical pest control is still the predominate types of pest control today, although its long term effects led to a renewed interest in traditional and biological pest control towards the end of the 20^th century (Pedersen, 2007).

Methods of pest control

Physical control method: These are methods that physically keep insect pests from reaching their host, barrier include window screens for keeping health and nuisance pests out of buildings and plant pest out green houses, floating  row covers for many horticultural crops and  plant cottars to keep ct worms from attacking plants such as tomatoes. Various types of traps can be used for control, such as cockroach traps in home, codling moth larvae can be trapped under cardboard bands wrapped around apple trees, the bands are removed and destroyed (Gillion, 2007).

Chemical control method: This is the use of chemicals in the control of pest. It involves using natural or artificial pesticide for the destruction of these pests; these pesticides are properly formulated into solid, liquid and gaseous form during application; when applying pesticides, extreme care must be taken to prevent accident during the exercise. These method is very effective but if not properly handled could cause adverse effect to the environment at large (Woody, 2010).

Biological control method: This is the use of beneficial organism to control pest. It has been identify as one of the major approach to pest management and microbial control is a form of biological control that uses insect pathogens, such as viruses, bacteria and fungi to control pests (Gillion, 2001).

Culture control method:  This involves a method of pest control adopted long ago by farmers, it involves the planting of healthy crops materials/ proper soil cultivation, crop rotation and correction harvesting at the right time, etc. (Atikpekpe, 2013).

Integrated pest management:   According to Hockings (2004), this is the blending of all effective, economical and environmentally sound pest control methods into a single but flexible approach to manage pest. Those who practice integrated pest management realize that, it is neither possible nor economically feasible to eliminate all pests; instead pest populations should be managed below economically damaging levels. Users of integrated pest management approach realize and understand the importance of the controls provided by nature, when human integration is necessary, the resistance, biological control and cultural control should be used because these are the practices that fit best into sustainable agriculture. Highly disruptive or environmental damaging practices should be used only as a last resort; chemical pesticides should be used only when necessary, based upon frequent and routine monitoring of pest populations. Natural enemy population should also be monitored so that their impact on pests can be determined when pesticides are necessary, if possible, only those products that are not detrimental to natural enemies should be used (Alan, 2011).

Chemicals used as pesticides

Chemical used as pesticides are often selected to according to the type of pest they control. Pesticides can also be considered as either biodegradable pesticides, which will be broken down by microbes and other living beings into harmless compounds, or persistent pesticides, which may take months or years before they are broken down: it was the persistence of DDT, for example, which led to its accumulation in the food chain and its killing of birds of prey at the top of the food chain. Another way to think about pesticides is to consider those that are chemical pesticides or are derived from a common source or production method.

Some examples of chemically-related pesticides according to Goldman (2007) are:

Organophosphate pesticides: Organophosphates affect the nervous system by disrupting the enzyme that regulates acetylcholine, a neurotransmitter. Most organophosphates are insecticides. They were developed during the early 19th century, but their effects on insects, which are similar to their effects on humans, were discovered in 1932. Some are very poisonous. However, they usually are not persistent in the environment.

Carbamate pesticides: Carbamate pesticides affect the nervous system by disrupting an enzyme that regulates acetylcholine, a neurotransmitter. The enzyme effects are usually reversible. There are several subgroups within the carbamates.

Organochlorine insecticides: They were commonly used in the past, but many have been removed from the market due to their health and environmental effects and their persistence (e.g., DDT and chlordane).

Pyrethroid pesticides: They were developed as a synthetic version of the naturally occurring pesticide pyrethrin, which is found in chrysanthemums. They have been modified to increase their stability in the environment. Some synthetic pyrethroids are toxic to the nervous system.

Biopesticides: Biopesticides are certain types of pesticides derived from such natural materials as animals, plants, bacteria, and certain minerals. For example, canola oil and baking soda have pesticidal applications and are considered biopesticides. At the end of 2001, there were approximately 195 registered biopesticide active ingredients and 780 products. Biopesticides fall into three major classes:

• Microbial pesticides consist of a microorganism e.g., a bacterium, fungus, virus, or protozoan as the active ingredient. Microbial pesticides can control many different kinds of pests, although each separate active ingredient is relatively specific for its target pest. For example, there are fungi that control certain weeds, and other fungi that kill specific insects. The most widely used microbial pesticides are subspecies and strains of Bacillus thuringiensis, or Bt. Each strain of this bacterium produces a different mix of proteins, and specifically kills one or a few related species of insect larvae. While some Bt’s control moth larvae found on plants, other Bt’s are specific for larvae of flies and mosquitoes. The target insect species are determined by whether the particular Bt produces a protein that can bind to a larval gut receptor, thereby causing the insect larvae to starve.

• Plant-Incorporated-Protectants (PIPs) are pesticidal substances that plants produce from genetic material that has been added to the plant. For example, scientists can take the gene for the Bt pesticidal protein, and introduce the gene into the plant’s own genetic material. Then the plant, instead of the Bt bacterium, manufactures the substance that destroys the pest.

• Biochemical pesticides are naturally occurring substances that control pests by non-toxic mechanisms. Conventional pesticides, by contrast, are, in general, synthetic materials that directly kill or inactivate the pest. Biochemical pesticides include substances, such as insect sex pheromones that interfere with mating as well as various scented plant extracts that attract insect pests to traps.

Factors militating against pest control   

The following factors inhabit the effectiveness of pest control measures;

1. Poor storage condition: The temperature and humidity conditions under which an insecticide is stored is a major consideration, to ensure that pesticides held over for use (or sale) for another season remain effective, they must be properly stored. Certain pesticide formulations, for example have a shorter shelf life than others. Dry pesticides formulations (dust, granules, wettable powders) tend to degrade in storage more rapidly than pesticides formulated as emulsions. This is more of a problem with organophosphate insecticides. However, under adequate storage conditions, dry insecticide formulations will normally hold up to at least three years (Dean, 2010). Another problem with dry formulations is that if they are stored under a conditions of high humidity, they will tend to become lumpy or ‘’cakey’’. If this occurs, many times the dry insecticide is ruined and will have to be discarded often, when attempts are made to use lumpy, dry formulations plugging of application equipment occurs resulting in uneven application which will ultimately result in deficient insect control (Dean, 2010).
2. Wrong timing of pesticides application: A basic knowledge of the life cycles and habits of common crops insects is extremely useful in terms of pest control. All insects have a ‘’weak link’’ in their life cycle or feeding habits which makes them more susceptible to insects control at certain times or stages than others, one of the key factors in successful insects control is knowing when to time an insecticidal application to coincide with the stage of insects development or feeding which is most susceptible. Common failures insects control efforts sometimes occur as a result of making insecticide applications prior to or after a stage of insect susceptibility or a time or day or season when insects are protected from insecticidal application (Woody, 2010).

• Application of wrong formulation: Pederson (2011), observed that failure in insect control can sometimes be attributed to the fact that the wrong insecticide was used for insect to controlled, since various types or groups of insecticides are selective in their modes of action and entry, proper selection of an insecticide extremely important.
• Wettable powder: They are powders in form of dust which cannot easily mixed with water i.e. which do not resist penetration of water when mixed, they do not form a true solution, so agitation is required in the spray tank to keep the formulation in suspension for a considerable period of time when mixed with water, additive can be added to the formulation of wet-able powder to prevent sedimentation e.g. methylcellose (Erutase, 2014)
• Solution: Solutions are made or prepared by dissolving the active ingredients in a liquid solvent due to high insolubility of many pesticides or insecticides in water most solutions are prepared in organic solvent such as kerosene, diesel or fuel. The active ingredient can either be solid or liquid form e.g. Sherpa plus (Erutase, 2014).
• Emulsification concentrate: These are chemicals in solution form; they are prepared when a solution concentrate which contains emulsion is added to water or mixed with water to give a desire volume. Emulsifiers are active surface agents that allow liquids to be mixed with liquids. In this way, the emulsifying agents prevent the oil from separating into water and oil but avoid the spread pesticide or insecticides throughout the water e.g. Karate, Basudin, etc. (Erutase, 2014).

• Dust: This preparation is formulated by mixing pesticide active ingredient with suitable finely divided carrier powder such as talc, calcite, clay etc to increase the magnitude of their potency and to prevent excessive drift of the chemicals (Erutase, 2014).
• Aerosol: The active ingredient is dissolved in a volatile solvent and then pressurized into a can by a propellant gas such as carbon-dioxide. When released through a small hole, the pressure releases a fine like air fog with rapid evaporation of fine gas. The content of the active ingredient is very low and is mostly used in household pest control because they are available in container solid as in ready for use e.g. Mobil, Raid, Baygon, etc. (Erutase, 2014).
• Fumigant: These are liquid or dust which change into gas when released. It kills both insects and rodents through inhalation e.g. paradichloro, benzene and naphthalene (Erutase, 2014).
• Granules: These are bigger than dust. These formations varies in shape, size and are made up of porous materials such as corn cobs or walnut shells to which the active ingredient has been applied. They are use in soil treatment and safer to apply than dust e.g. Pirimicarb, Phorate, Diazinon, etc. (Erutase, 2014).
• Baits: These are composed of toxicants in small quantities mixed with foods or a material (Solid or liquids) attractive to the target pest and that can cause their death after ingestion; they can be used in whole area or for spot treatments, indoors or out-doors (Erutase, 2014).

• Environmental conditions: According to Olufemi, (2009) the following environmental factors can influence the effectiveness of pesticides:
• Temperature: Quick acting poisons are more effective at high temperatures, but breakdown much more easily, while slow-acting ones are effective and persistent at lower temperature. There are two possible reasons for increase in toxicity of pesticides at low temperature.
  1. There is faster detoxification of pesticides with increase in temperature.
  2. Nerve endings are more sensitive to pesticides at low temperature than at high temperatures.
• Rain: Rain could wash off sprays and dust pesticides.
• Sunlight: Many botanical insecticides are photo-labile I.e. they decompose rapidly when expose to sun.

Measures that promote the practice of pest control

According to Speiser (2002) the following measures can help to promote pest management;

1. Public awareness: Public awareness and knowledge of pest must be raised to increase the capacity and willingness of individuals to manage pests.
2. Commitment: Effective pest management requires a long-term commitment to management by the community, industrial groups and government entities.
3. Consultation and partnership: Consultation and partnership arrangement between local communities, industrial groups, state government agencies and local governments must be established to achieve a collaborative approach to pest management (Hockings, 2014).
4. Planning: Pest management planning must be consistent at local, regional, state and national levels to ensure resources target priorities for pest management identified at each level (Hocking, 2014).

Dean (2010) stated that preventive pest management is achieved by the following; Preventing the spread of pests especially by human activities early detection and intervention to control pests.

1. Best practice: Alan (2011) stated that pest management must be based on ecological and socially responsible pest management practices that protect the environment and productive capacity of natural sources.
2. Improvement: Research about pest and regular monitoring evaluation of pest control activities if necessary to improve pest management practice (Alan, 2011).

According to Hockings (2014), chemical pesticides play an important role in providing Americans with an abundant and inexpensive food supply. However, these chemicals can have adverse effects on human health and the environment, and pest continue to develop resistance to them; thus, the implementation of integrated pest management practice has yielded significant environmental and economical benefits in certain crops and it has lead to a better long-term pest management than chemical control alone. However the federal government’s commitment to integrated pest management has waned over the years. The integrated pest management initiative is missing several key management identified in the government Performance and Result Act. Specifically, no one is effectively in charge of federal integrated pest management efforts; but with the adequate involvement of three tiers of government in the integrated pest, the activities of pest in our farm-land will be brought to its barest minimum (Pedersen, 2007).

Socio-economic benefits of pest control

1. Increased food production: Among the benefits of using pesticides for crops protection is that these products are vital to increasing food production. About 20 to 40 percent of the world’s potential crop production is loss annually because of the effects of weeds pests and diseases (according to the Food and Agriculture Organization  of the United Nations or FAO), these crop losses would be doubled if existing pesticides uses were abandoned, significantly raising food prices. Even after harvest, crops are subject to attack by pests or disease, such as bugs, rodents or molds can harm grains (Alan, 2011).
2. Prolong viable life of farm produce: In addition to increasing crop production, pest control has also help to prolong the viable life of produce, prevent huge post–harvest losses from pests and diseases, and protect food, to enable it safe to eat. The crop protection industry’s primary aim is to enable farmers to grow an abundant supply of food in a safe manner and prevent costs from increasing (Alan, 2011).
3. Protection of food quality: Consumers expect high quality fruits and vegetables; this means produce free of insect blemishes and insect contamination. Before the introduction of insecticides, holes, scars and surface tunnels made by insects feeding on crops could often be found in produce sold to consumers, in addition to insect fragments in canned products. Before the introduction of insecticides blue berries often contained maggots, aphids also known as plant lice could be found in canned spinach and fruit worm in tomatoes. Insecticides reduces and in some cases, eliminate, insect damaging allowing the consumer to purchase blemish-free high quality produce (Ranshaw, 2012)
4. Maximization of profit: The ultimate pest management goal of a rational farmer, trader and /or miller /processor is to maximize profit (if he / she is market oriented or to produce enough for his /her needs (if he is a subsistence farmer), this is done through selective reduction or increase of chemical use, selective use of pesticides with a broad action spectrum, and the use of new biological and other control methods. This is where the importance of studying  the socio- economic component  of integrated pest management technology is highlighted, where farmer, traders and/ or millers practice pest management strategies according to their resources  capacity , their objectives and  their perception of the integrated pest management technology will be partly conditioned by the physical and economic environment within which they operate and these includes the size or scale of their operation, access to capital, infrastructural support and services etc. (Gillion, 2007)

Conclusion/recommendations

From the research carried out on factors militating against pest control in environment, and from the socio-economic damage cause by pest on our farm produce. I hereby recommend that farmers in should implement the practice of integrated pest control in the management of pest in their farmland in other to increase their farm produce.

References

Alan, M. & Joe, E. (2011). Evaluation of Chelmosterilant for rat control; Journal of Wildlife management. 34(4) 75-81.

Atikpekpe, C. (2013). Community Sanitation and Housing Inspection in Environmental Health Management. Ughelli; George Publishers.

Cranshaw, W. (20120. Pest Control at Home – National Institute of Environmental Health. Retrieved on 13^th September, 2014 from http://www.wikipedia.com

Dean, K. (2010). Factors Influencing Insect Control. Retrieved 5^th August, 2014 from http://www.sbreb.org/research/ento/ento_75/

Erutase, J. (2014). Pesticides [EHT 408] (Lecture Note). Department of Environmental Health. Delta State College of Health Technology.

Gillion, R. (2007). The Role of Pest Management in Protecting Public Health. Retrieved on 5^th August, 2014 from http://www.cieh.org/policy_in_pap_publication.html

Goldman L.R. (2007). “Managing pesticide chronic health risks: U.S. policies”. Journal of Agromedicine 12 (1): 57–75.

Hockings, F, (2014). Pest, Diseases and Beneficial Aspect of Pest Control. Melbourne; Ciro’s Press.

Olufemi, P. (2009). Introduction to Public Health Pest Management. Lagos; Wright Press.

Pederson, T. (2007). Pesticides Residues in Drinking Water. Retrieved on 5^th August, 2014 from http://www.extoxirorst.edu.

Speiser, B. (2002). Increasing Food Production and Crop Yields. Retrieved on 13^th September, 2014 from http://www.croplife_ameria.org/crop_production/benefits/increase_food_production.

Woody, T. (2010). A Crop Sprouts Without Soil or Sunshine. The New York Times. Retrieved on 19^th August, 2014 from http://www.nytimes.com.