Pesticides: Types, Advantages, Disadvantages

Pesticides are chemical compounds designed to exterminate or control pests. Broadly speaking, a pesticide can be defined as a substance of either chemical or biological nature, encompassing agents such as viruses, bacteria, antimicrobials, or disinfectants that serve the purpose of deterring, incapacitating, or exterminating organisms considered to be pests. A diverse array of pests has the potential to devastate crops, leading to significant economic ramifications. Several instances of organisms that are considered nuisances in various contexts include insects, rodents, fungi, slugs and snails, bird mites, and weeds.

Because pesticides are used so often, the words “pesticide” and “plant protection products” are often used interchangeably. The utilization of this method is frequently employed to mitigate or regulate a diverse range of agricultural pests that possess the potential to inflict harm upon crops and livestock, thereby diminishing the overall productivity of farms. The prevailing pesticides utilized in various contexts encompass insecticides, herbicides, rodenticides, and fungicides. These substances are employed to eradicate insects, suppress weed growth, eliminate rodents, and manage the proliferation of fungi, mold, and mildew.

Pesticides are a class of biocides that have been specifically formulated to eliminate, deter, attract, or control organisms that pose a nuisance to human beings and their agricultural and hygiene practices. Pesticides encompass a range of chemical compounds that can be classified into three main categories: organic molecules, inorganic synthetic molecules, and biopesticides. The toxicological activities exhibited by pests are contingent upon their chemical composition and the various developmental stages they undergo.

History of Pesticides

• Humans have been using pesticides to protect their crops since before 2000 BC. The use of the first known pesticide dates back approximately 4,500 years to ancient Mesopotamia, specifically ancient Sumer. This pesticide was in the form of elemental sulfur dust.
• During the 15^th century, farmers began using toxic chemicals like arsenic, mercury, and lead to eliminate pests from their crops.
• During the 17^th century, people extracted nicotine sulfate from tobacco leaves to use it as an insecticide.
• During the 19^th century, two additional natural pesticides were introduced: pyrethrum, derived from chrysanthemums, and rotenone, derived from the roots of tropical vegetables.
• Arsenic-based pesticides were the dominant choice until the 1950s. Paul Müller discovered that DDT is an extremely effective insecticide. Chlorinates, like DDT, used to be widely used, but they were phased out in the United States by 1975 and replaced with organophosphates and carbamates. Since their introduction, pyrethrin compounds have emerged as the leading insecticides.
• During the 1960s, herbicides gained popularity, particularly those containing triazine and other nitrogen-based compounds, carboxylic acids like 2,4-dichlorophenoxyacetic acid, and glyphosate.

Types of Pesticides

Pesticides are categorized according to their chemical composition, mechanism of action, formulation, durability, and the specific organisms they aim to control. Some of the major types are discussed here:

Insecticides

• The following are specific categories of pesticides employed for the eradication of insect populations.
• The selection of insecticides ought to consider their origin, whether organic or inorganic in nature.

Neonicotinoids

• Neonicotinoids belong to a class of insecticides known as neuro-active chemicals, which share a chemical resemblance to nicotine.
• Imidacloprid, which belongs to the neonicotinoid family, is currently the most extensively utilized insecticide globally.
• During the late 1990s, neonicotinoids faced growing scrutiny due to their environmental impact.
• Numerous studies linked these pesticides to adverse ecological effects, such as honey-bee colony collapse disorder (CCD) and the decline of bird populations caused by a decrease in insect numbers.
• Certain neonicotinoids were restricted for use by the European Union and a few non-EU countries in 2013.

Organophosphate and Carbamate

• Organophosphate and carbamate insecticides have similar mechanisms of action.
• The substances achieve their impact on the nervous systems of both intended pests and unintended organisms by disrupting the activity of acetylcholinesterase.
• This enzyme is essential for regulating acetylcholine at nerve synapses. The phenomenon of inhibition described here results in a significant increase in synaptic acetylcholine levels.
• This, in turn, causes excessive activation of the parasympathetic division of the autonomic nervous system.
• Many insecticides that were developed in the mid-20th century are highly toxic. In recent times, many chemicals that were once commonly used have been removed from circulation due to their harmful effects on human health and the environment.
• Some notable examples include DDT, chlordane, and toxaphene. Many organophosphates have a short lifespan in the natural environment.

Pyrethroid

• Pyrethroid insecticides were developed as a synthetic alternative to pyrethrin, a natural pesticide found in chrysanthemum flowers.
• The organisms have undergone modifications to improve their stability within their ecological niche.
• Some synthetic pyrethroids have been discovered to have neurotoxic properties, which means they can harm the central nervous system.

Herbicides

• The substances employed for the purpose of eradicating undesirable vegetation within agricultural fields are commonly referred to as herbicides.
• Several herbicides commonly used in agriculture include simazine, 2, 4-dichloro phenoxy acetic acid (2, 4-D), and 2, 4, 5-trichloro phenoxy acetic acid (2, 4, 5-T).

Bio-Pesticides

• Biopesticides refer to a specific category of pesticides that are derived from various natural sources, including animals, plants, bacteria, and specific minerals.
• Canola oil and baking soda possess pesticidal properties and are recognized as biopesticides, exemplifying their potential in the field of pest control.

Biopesticides can be categorized into three primary classes:

Microbial Pesticides

• Microbial pesticides encompass a diverse array of biological agents, namely bacteria, entomopathogenic fungi, and viruses, occasionally accompanied by the inclusion of bacterial or fungal metabolites.
• Entomopathogenic nematodes are frequently categorized as microbial pesticides, despite their multicellular nature.

Biochemical Pesticides

• Biochemical pesticides, colloquially known as herbal pesticides, comprise naturally occurring compounds that exhibit potent control over pest populations and microbial diseases.
• Additionally, these compounds serve as pheromonal agents for the purpose of monitoring.

Plant-Incorporated Protectants (PIPs)

• Plant-Incorporated Protectants (PIPs) refer to agricultural organisms that have undergone genetic modification, leading to the assimilation of genetic material from distinct species into their own genetic composition.
• The aforementioned crops have undergone genetic modification to acquire augmented defensive characteristics.
• The employment of these entities has engendered substantial discourse, particularly within various European nations.

Different Types of Pesticides And Their Use

Types of Pesticides Based on Chemical Structures

Advantages of Pesticides

There are several advantages linked to pesticides some of which are discussed here:

Optimize the Crop Yield

• Pesticides play a crucial role in cost optimization by enabling farmers to achieve higher crop yields on a given plot of land.
• The cultivation of organic vegetables necessitates a greater financial commitment owing to the manual removal of weeds, in contrast to the utilization of herbicides in the growth of conventionally farmed vegetables.

Control Transmittable Diseases

• Pesticides play a crucial role in mitigating the prevalence of waterborne diseases and those transmitted by insects.
• The implementation of preventive measures aids in mitigating the transmission of diseases attributable to insects and rodents.

Environmental Conservation

• Pesticides serve as valuable tools for environmental preservation and protection, as they contribute to the mitigation of deforestation, soil pollution, and the conservation of natural resources.

Increase in Productivity

• The utilization of pesticides has the potential to enhance agricultural productivity, leading to a subsequent increase in the financial gains of farmers.
• The implementation of this initiative is expected to enhance the socioeconomic conditions and overall well-being of farmers.

Time-Saving

• Pesticides serve as a time-saving tool for farmers as they effectively safeguard crops against weed infestations, thereby obviating the need for labor-intensive manual weed removal efforts.
• When farmers have successfully protected their crops from pests, it is no longer necessary to engage in repetitive tilling of the land in order to cultivate their crops.

Crop Security

• In developing countries, the use of pesticides has facilitated a transformational process that is best exemplified by India, where these nations have evolved into significant contributors to global food production.
• The implementation of crop protection measures serves to safeguard agricultural produce and ensure a substantial harvest for the populace.

Food Storage

• Pesticides play a crucial role in extending the longevity and viability of food products within storage chambers or warehouses.
• In addition, they serve to mitigate substantial post-harvest losses resulting from the presence of plant diseases and pests, thereby safeguarding the consumable food and ensuring its safety for human consumption.

Disadvantages of Pesticides

Pesticides exert a multitude of impacts on our surrounding ecosystem, human well-being, and even the confines of our domestic abodes. The aforementioned effects can be enumerated as follows:

Impact on Environment

• The utilization of chemical pesticides during agricultural practices has been identified as a significant contributor to environmental pollution.
• While the immediate impact of these phenomena may be fleeting, their prolonged presence in the environment can potentially give rise to deleterious consequences for both the ecosystem and human well-being.
• The application of chemical pesticides to agricultural crops has the potential to result in unintended dispersion to adjacent regions.

Impact on Crop and Soil

• The utilization of pesticides has been found to have a detrimental impact on soil quality, subsequently leading to further degradation in both the nutritional value of food and overall crop yield.
• Chemical pesticides have been observed to diminish the nutritional composition of food items while concurrently introducing contamination.
• Upon consumption of various food items, including but not limited to apples, lettuce, potatoes, and strawberries, the presence of pesticides within these edibles permeates our bodily systems, potentially giving rise to a multitude of health-related concerns.
• Although chemical pesticides are primarily designed to eliminate organisms present in crops, their usage can have detrimental effects on various other forms of life.

Impact on Health

• The encounter with diverse pesticides has the potential to induce transient health complications of immediate onset (acute), as well as enduring ailments of extended duration (chronic).
• The immediate consequences encompass a range of physiological manifestations, such as dermatological eruptions, gastrointestinal distress, vertigo, respiratory impairment, ocular inflammation, and other related symptoms.
• The long-term consequences of chronic exposure may manifest as various adverse health outcomes, including but not limited to congenital abnormalities, oncogenic transformations, neurologic impairments, and reproductive impairments.
• The manifestation of symptoms associated with chronic health conditions may require a considerable span of time, ranging from several months to even multiple years.

Frequently Asked Question

Video on Pesticides

References

• https://www.who.int/news-room/questions-and-answers/item/chemical-safety-pesticides#:~:text=Pesticides%20are%20chemical%20compounds%20that,kill%20pests%20that%20damage%20crops.
• https://www.sciencedirect.com/topics/nursing-and-health-professions/pesticide
• https://ipm.ucanr.edu/PMG/PESTNOTES/pn74126.html
• https://www.theguardian.com/environment/pesticides
• https://www.toppr.com/guides/chemistry/chemistry-in-everyday-life/pesticides/
• https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1006&context=usfda