eChapters

Chemicals are commonly employed to manage plant diseases, pests, and weeds, but they are only effective if administered promptly once an infestation has been discovered. These chemicals must be sprayed, dusted, or misted over the ground and plants. Since the chemicals are expensive, it is important to have tools for applying them evenly and effectively. Crop Protection Products (CPP) like herbicides, pesticides, and fungicides work best when they are used at the right time during the crop’s most productive times. This problem is getting worse because there aren’t enough people to do the work. In this situation, the only choice that makes sense is to automate the application process. Most of the time, poisons are put on with dusters or sprayers. Dusting is the easier way to apply chemicals. It works best with movable equipment and usually only needs simple tools, but it is less effective than spraying because the dust doesn’t stick around as long. High volume spraying is usually efficient and reliable, but it is more expensive than low volume spraying, which fixes some of the problems with the first two methods while keeping the things that work well about them.

Crops are grown with the use of plant protection chemicals to boost production, enhance quality, and lengthen shelf life. Wherein the enormous use of pesticides which are having the longer half life period led to leave the residues in the different bodies of the ecosystem. Pesticide residues refer to the residual presence of pesticide active ingredients, their metabolites, or breakdown products in various environmental components subsequent to their application, accidental release, or disposal.

Analysis of residues gives insight on the type and extent of chemical contamination in an area, as well as how long it has been there. Before governments will approve the use of pesticides, they require comprehensive testing of their efficacy, environmental impact, and toxicology. A possible risk to human health arises from the presence of chemical residues and/or breakdown products in agricultural goods. Selective sampling plans can be used to learn more about pesticide traces in the environment, how they move about, and how quickly they degrade.

Pesticide: The act defines “pesticide” as any substance or other substance or product that is used to stop, kill, repel, or control insects, rodents, fungi, weeds, and other plants and animals that humans don’t need.

i) Silicon Technology

Silicon technology in agriculture refers to the use of silicon-based compounds, primarily silicon dioxide (SiO2 ), in pesticide formulations and as part of integrated pest management (IPM) strategies. Silicon technology is not a pesticide itself but is used to enhance the effectiveness of pesticides and contribute to sustainable pest management. Here are some ways silicon technology is applied in pesticide use:

1. Silicon-Based Adjuvants: Silicon-based adjuvants are added to pesticide formulations to improve their efficacy. These adjuvants can enhance the spreading, wetting, and sticking properties of pesticides, ensuring better coverage of plant surfaces and improving the retention of the active ingredient. This leads to more effective pest control and reduces the need for higher pesticide concentrations.

2. Induced Resistance: Silicon has been shown to induce plant resistance against pests. When plants take up silicon from the soil and deposit it in their cell walls, it can create physical barriers that make it more difficult for pests to penetrate plant tissues. Additionally, silicon can trigger the production of defensive compounds in plants, making them less susceptible to pest damage.

3. pH Buffering: Silicon compounds can act as pH buffers in pesticide formulations, helping to maintain the stability and efficacy of the active ingredients over a broader pH range. This can be particularly useful when mixing pesticides with other chemicals or using them in different environmental conditions.

The role of toxicology in the evaluation of new agrochemicals

The widespread use of agrochemicals for crop protection may expose humans, animals, and the environment to toxic chemicals. Humans may be exposed during manufacture or application, and to a lesser extent as consumers of food products containing trace amounts of residues.

Strategies of toxicity testing

No-Observable-Adverse- Effect-Level (NOAEL)

A level in which the total diet that causes no adverse effect in treated animals when compared to untreated animals maintained under identical conditions. This NOAEL is expressed on a mg/kg of body weight/day basis. Chronic and sub chronic studies are need to be carried out in different species to determine NOAEL values.

It depends on how much of the substance an organism is exposed to, but all chemicals are toxic to some degree. Toxicology studies try to figure out the exact types and amounts of harmful effects, as well as the lowest doses that won’t have any negative effects (called the “No Observed Adverse Effect Level” or NOAEL). Most data come from studies with lab animals and cells that have been grown in a lab. Using these numbers and extrapolation or uncertainty factors, it is possible to figure out an Acceptable Daily Intake (ADI). This is the maximum amount of a substance that a person can take in every day without putting themselves at a very high risk of getting sick. These numbers will be compared to how people might be exposed to a compound in the environment, including through food. This will show if the use of an agrochemical is potentially allowed.

Farmers still rely heavily on insecticides because of their efficiency, portability, and speedy returns on investment. Although synthetic organic insecticides are highly efficient, their widespread usage has led to toxicity to natural enemies, toxic residues in plants and the environment, insect resistance, and a resurgence in insect populations. Ripper (1956) first time recognized the problem of resurgence in plant protection.

Metcalf (1986) distinguished between two types of resurgence: primary insect resurgence, in which populations of target insects that had been suppressed by insecticide application quickly recover to excessive levels (Fig. 1.A), and secondary insect outbreak, in which non-target species develop into serious insect s after insecticide application (Fig. 1.B).

Primary insect resurgence

Primary insect resurgence occurs when the target insect population increases to at least as high (Hajek, 2004) or higher (Hardin et al., 1995) than in an untreated control or higher than before the treatment (Pedigo and Rice, 2006).

Secondary insect resurgence/ secondary insect outbreak (Type II resurgence)

The phenomenon known as replacement of a primary insect with a secondary insect, or secondary insect outbreak, occurs when the population of a non-target insect, which is harmful to the crop, experiences a surge following the application of a insecticide aimed at controlling the population of the primary insect. A second insect outbreak is also called resurgence. A secondary insect outbreak is the rise of a non-target species after an insecticide has been used.

Insecticide resistance is a growing concern for those who need insecticides for medical, veterinary, and agricultural control of insect pests. In response to the introduction of DDT resistance in 1947, the incidence of resistance has increased annually by an alarming amount. Resistance is “the inherited ability of a strain of some organism to survive doses of a toxicant that would kill the majority of individuals in a normal population of the same species” (WHO, 1957).

As a result of continued insecticide application, the proportion of resistant insects increases compared to that of susceptible and the population becomes increasingly difficult to control

Above photograph theoretical example illustrating the increase of insecticide resistance levels in a pest population. Some individuals (black) with genetic traits allowing them to survive insecticide applications can reproduce; if the selection pressure is frequent, they easily become the preponderant part of the population (Fig. 1).

An adaptation to a pesticide leads to reduced susceptibility to it among the pest population targeted by that pesticide. In nature, pests develop resistance to chemicals through natural selection. In the most resistant organisms, their genetic traits are passed on to their descendants. Since 1945, at least 500 species of pests have developed resistance to pesticides (Anonymous, 2007), but other sources estimate as many as 1000 species (Miller, 2004).

Synergists are chemicals that significantly increase the toxicity of an insecticide while being nearly non-toxic on their own. Thus, non-toxic chemicals that contribute to the increased toxicity of insecticides are referred to as synergists. Many chemical substances have the potential to synergize with poisons. Some enzyme inhibitors work well synergistically by inhibiting enzymes that metabolize pesticides, particularly in insecticide-resistant strains. When mixed with other insecticides, some insecticides increase the toxicity of the latter at non-toxic dosages. When a mixture is more harmful than expected based on the sum of its separate efficacies when administered alone, the interaction between substances is known as synergy. Antagonistic interactions among components reduce a mixture’s efficacy.

Synergism can also develop between two or more poisons. Several statistical methods have been proposed to quantify the synergy of both non-toxic and hazardous substances. Toxin interactions are assessed using bioassays, which involve mixing toxicants (two or more) in a specific ratio. The combination is then used to prepare serial dilutions. Alternatively, the poisons can be supplied sequentially in the same amounts as in the mixture. Bioassays are also used to determine the dose-mortality response of each toxin on the same insect strain. The data are subjected to probit analysis, and the toxin interactions can be evaluated using the statistical methods listed below.

Insecticide mode of action is divided in to four major chapters 1. Nerve & Muscle 2. Growth & development 3. Respiration & Energy production 4. Metabolic process 5. Unknown or Non-Specific (multisite inhibitors) (Source: IRAC). To understand the mode of action of insecticides, it is necessary to understand the function of nervous system and how it works in insect. The nervous system functions transmits information throughout the body. This system has three components: 1) Peripheral nervous system (PNS) to receive and transmit incoming signals (taste, smell, sight, sound, and touch) and to transmit outgoing signals to the muscles and other organs, effectively communicating them how to respond, and 2) Central nervous system (CNS) to interpret the signals and coordinate the body’s responses and movements. 3) Visceral or sympathetic nervous system (VNS) directly connected with the brain that supplies nerves to the anterior part of the alimentary canal (foregut and midgut), heart, and spiracles. Some additional nerves arise from posterior compound ganglion of ventral nerve cord (VNC) which supply nerves to the posterior part of gut and reproductive system.

Pesticide use in agriculture has evolved at several stages in the last few decades. Pesticides, as defined by the FAO, are any substance or mixture of substances intended to prevent, destroy, or control any pest, including vectors of human or animal disease, unwanted species of plants or animals causing harm during or otherwise interfering with the production, processing, storage, transport, or marketing of food, agricultural commodities, wood and wood products, or animal feedstuffs, or substances that may be administered to animals. A plant growth regulator, defoliant, desiccant, or agent used to thin or prevent premature fruit fall, as well as substances applied to crops before or after harvest to prevent them from deteriorating during storage and transportation, are included in this category.

Today’s agrochemistry has a massive challenge: ensuring the availability of high quality active ingredients to enable long-term control of pest species, weeds, and agricultural diseases. The differential uptake and transfer of the active ingredient by target and non-target organisms can contribute to diverse biological activity.

The way a chemical moves, persists, and behaves in its surroundings is known as its behaviour. A chemical’s behaviour will dictate both its residual properties and field efficacy. The behaviour of insecticides is determined by their chemical and physical characteristics as well as the interaction of environmental elements. Our capacity to comprehend and forecast how insecticides will behave in the environment will determine our ability to keep utilizing insecticides.

Important features of systemic insecticides

1. They are not susceptible to wash off by rain

2. By virtue of their movement inside plants, they can afford to protection to regions where they have not been sprayed

3. They are often been transported towards region of growth

4. Since they have very weak contact action, safe to beneficial organism.

Insecticide classification majorly divided into three categories. A. based on chemical group, B. mode of entry in the insect, C. based on toxicity.

A. Classification of Insecticides based on chemical group

Historians have traced the use of pesticides to the time of Homer around 1000 B.C. earliest records of insecticide use pertain to the burning of “brimstone” (Sulfur) as a fumigant. Pliny the Elder (A.D. 23-79) recorded most of the earlier insecticide uses in his Natural History and included among these was the use of gall from a green lizard to protect apples from worms and rot. Later, a variety of materials used viz., extracts of pepper and tobacco, soapy water, whitewash, vinegar, turpentine, fish oil, brine, lye and many others. At the beginning of World War II (1940), insecticide selection was limited to several inorganic compounds, arsenicals, petroleum oils, nicotine, pyrethrum, rotenone, sulfur, hydrogen cyanide gas, and cryolite. It was during World War II that opened the Chemical Era with the introduction of a totally new concept of insect control.

Introduction

Analysis of insecticide formulations are critical for the availability of quality insecticides in the market for ultimate benefit of farmers and ecosystem health. This chapter highlights the significance of comprehensive insecticide formulation analysis protocols, encompassing methods for determining active ingredient and assessing physical and chemical parameters. Employing advanced analytical techniques such as spectroscopy and chromatography for insecticide formulation analysis will eventually maintain the quality of insecticides for the sustainable management of pests.

In India, over 339 pesticides are registered that includes insecticides, fungicides, herbicides (DPPQS, 2024). The current market of non-genuine insecticide is INR 3,200 crores (USD 525 Million) which constitutes 25 per cent by value and 30 per cent by volume of the total domestic market of agrochemicals in India as per Industry reports, primary interviews, news articles and Tata Strategic analysis (FICCI, 2015). Monitoring registration and regulation of insecticides is governed by the Insecticide Management Bill 2020, which replaced the Insecticide Act 1968 (DPPQS, 2023). The Insecticide Act of 1968 established the Central Insecticide Laboratory, Faridabad, under section 16 with two regional insecticide testing laboratories at Chandigarh and Kanpur (DPPQS, 2023). Current Quality Control of Insecticides in States/UTs during the last five years shows that 68078 insecticide samples were analysed (DPPQS, 2023). In the beginning, these laboratories involved in analysing insecticide samples drawn by any officer or the body authorized by the Central or State Governments and submit certificates of analysis to the concerned authority. Regional Pesticide Testing Laboratories (RPTLs) had a huge target of analysis of 1550 samples per annum that necessitated the establishment of 71 State Pesticide Testing Laboratories (SPTL) spread across India of which 14 are NABL accredited (DPPQS, 2023).

Formulation is a word that can be used in a lot of different ways, but at its core, it means putting things together in the right way, usually by following a formula. Insecticides come in different forms, which are called formulations. A formulation is just the way a product is used. The chemical or biological makeup of a pesticide and its active ingredient (also called the active substance) determine how it works on living things. Most of the time, the active ingredient is mixed with other things, and the product as it is sold will need to be weakened even more before it can be used. Formulation makes a drug easier to handle, store, and use. It can also have a big effect on how well it works and how safe it is.

Insecticides come in many different forms because the active ingredients vary in how easily they dissolve, how well they kill pests, and how easy they are to handle and move. The pesticide is made up of both active and non-active (used to be called “inert”) chemicals. The manufacturer will need to know the identity of the pest, as well as details about its feeding behavior, reproduction, and life cycle, in order to create an effective formulation. Manufacturers also take into account factors including surface and equipment type, runoff and drift rates, pest habits, and safety when formulating insecticides. Inactive materials (adjuvants/ additives) are often added to insecticides to make them stick to the application surface or spread out over leaves. There are solvents (liquids) that dissolve the active ingredient, carriers (liquids or solids) that aid in the delivery of the active ingredient, etc.. Boosting the efficacy of active ingredients requires additives, such as spreaders, stickers, wetting agents, compatibility agents, foaming agents, etc.

A bioassay, also known as a biological assay, is a scientific experiment used to quantify the impact of a substance on a living organism. According to Finney (1952), bioassay is defined as measurement of potency of any stimulus (physical, chemical, biological, physiological) by means of reactions which it produces in living matter. It is an essential procedure in insecticide development and the assessment of environmental pollutants, as well as the evaluation of the effects of interventions viz. pesticides and herbicides on the environment. In the field of biostatistics, a bioassay refers to a set of techniques used to determine the quantity or intensity of an agent or stimulus based on the response of the subject. Typically, many methods are employed to assess the strength or effectiveness of an insecticide by examining its impact on living organisms.

An insecticide is a pesticide used to kill or eliminate insect pests in agriculture, households, and industries. Judicious use of insecticides may be a factor in the increase of agricultural productivity, but by their nature of having high toxicity to non target organisms and capability to develop resistance through widespread use, most insecticides have high potential to significantly affect and alter ecosystems. Many are toxic to humans and animals (both domestic and wildlife), and can accumulate as concentrates in the food chain and water resources, giving rise to serious environmental contamination and pollution.

History of Chemical Control, Insecticide Toxicology and Properties

History of pest control probably started when the first person swatted a mosquito or pulled off a tick, the battle for the control of our planet didn’t start until organized agriculture, when pests attacked the plants, and we grew to eat and threatened our very survival.

A pesticide is any substance or mixture of substances used to stop, kill, avoid, or lessen the effects of a pest (insects, mites, nematodes, weeds, rats, etc.). This includes insecticide, herbicide, fungicide, and many other substances used to control pests. Pesticide was defined in different ways at different times and in different places. But pesticide is still generally the same: it is a (mixed) substance that is poisonous and effective on target organisms but safe for non-target organisms and environments.

Chemical control, commonly known as pest control, is the use of chemicals to reduce insect populations. Herbicides, fungicides, insecticides, rodenticides, acaricides, nematodes, and fungicides are all examples of pesticides. Insecticides are a class of chemicals used to combat insect pests. A substance or combination of compounds used to kill, repel, or otherwise prevent insects is called an insecticide. When it comes to controlling pests, insecticides are most powerful tools available for management. They have a wide range of positive effects, including high efficiency, speed of healing, general applicability, adaptability to different settings, adaptability to shifting agronomic and ecological conditions, and low cost. When insect pest numbers approach or surpass the economic threshold, insecticides are the sole viable instrument for emergency action in pest management. The usage of pesticides, a widely used method, can be central to such a system. The use of chemical pesticides will remain pivotal in these initiatives. In many cases, chemical control of pests is the best option available. Some people’s view of pesticide use for pest management as an ecological sin is incorrect. Chemical pesticides are a reliable and useful tool for the biologist, so long as they are used in accordance with good ecological principles.

Objective: To identify agriculturally important insect orders and understand their key morphological characteristics relevant to their impact on agriculture.

Objective: To study and document the taxonomic characteristics of Siphonaptera and Trichoptera, emphasizing their unique morphological features and ecological adaptations.

Objective: To explore and document the taxonomic characteristics of Strepsiptera and Mecoptera, highlighting their unique morphological features and biological adaptations.

Objective: To identify and understand the taxonomic status and relationships of orders within Endopterygota, focusing on their distinct larval and adult stages and current sister group hypotheses.