eChapters

Introduction

Globally, India takes pride of being one of the world’s largest producers of horticultural and agricultural commodities. The rapid increase in the area under intensive cultivation of crops, introduction of high yielding varieties, lack of natural enemy load of the pests and changing climatic conditions is largely responsible for the severe pest depredations. Pest management in agriculture is a challenging task in the context of increasing agricultural productivity without upsetting the ecological balance and deteriorating the environment. Use of agrochemicals in agriculture though played a significant role to boost the agricultural production is posing enormous problems like environmental pollution, pest resistance, pest resurgence, toxicity hazards, secondary pest outbreaks, residues in feeds, foods, soil and water, destruction of biodiversity of useful natural enemies and some social economic and political problems. In response, there has been increased demand for alternative and selective pest control agents. Biopesticides are advantageous due to their target specificity, eco-safety, no development of resistance, reduced number of applications, yield and quality improvement, higher acceptability and value of produce for exports and suitability for rural areas.

Introduction

Indian agriculture accounts for nearly 65% of the country’s employment, 23% of the total GDP and nearly 20% of total export earning and supplier of raw material to major industries. Agriculture is not only the backbone of Indian economy and food security but also a way of life, a tradition and anchor of overall livelihood opportunity for about 700 million of our one billion populations. Agriculture, therefore, is and will continue to be central to all strategies for planned socio-economic development of the country.

Losses due to insect pests represent one of the single largest constraints to crop productivity estimated at 14% of the total agricultural production. Besides, insects also serve as vectors of plant pathogens. The annual global cost of pest management through insecticides is more than US$10 billion per annum. However, over-reliance of insecticides creates agricultural, environmental and pest management problems, such as frequent evolution of insect resistance, destabilization of multitrophic interactions and environmental contamination. Broad spectrum insecticides often compound these problems. Insecticides often interfere with biological control, causing secondary pest outbreaks or catastrophic resurgence of insecticide resistant herbivores. The vicious cycle of pesticide treadmill effect is observed when more pesticides lead to insects developing resistance, which in turn necessitates use of more and newer pesticides. Therefore, now it is imperative to develop a holistic system of tackling pests to make it more eco-friendly, economically viable and socially acceptable for the farmers.

A pesticide is any material intended to prevent, destroy, repel, or mitigate any pest, which is defined as a living organism that occurs where it is not wanted or that causes damage to crops, humans, or other animals. There are many different types of pesticides, each is meant to be effective against specific pests. The term “-cide” comes from the Latin word “to kill.”

A pesticide may be referred to by several different names, which can cause confusion. The same pesticide may be referred to by a number of different names, or different pesticides may have similar names.

There are broadly five categories of crop protection products

Insecticides: Insecticides provide protection to the crops from the insects by either killing them or by preventing their attack. They can be further classified based on their mode of action:

Proteinase inhibitors (PIs) are small proteins that are quite common in nature. They are natural, defense-related proteins often present in seeds and induced in certain plant tissues by herbivory or wounding (Koiwa et al., 1997). PIs are present in multiple forms in numerous tissues of animals and plants as well as in microorganisms. In plants they can be counted among the defensive mechanisms displayed against phytophagous insects and microorganisms. The defensive capacities of plant PIs rely on inhibition of proteases present in insect guts or secreted by microorganisms, causing a reduction in the availability of amino acids necessary for their growth and development. PIs are of common occurrence in the plant kingdom. Plant PIs (PPIs) are generally small proteins that have mainly been described as occurring in storage tissues, such as tubers and seeds, but they have also been found in the aerial parts of plants (De Leo et al., 2002). One of the important defense strategies that are found in plants to combat predators involve PIs which are in particular effective against phytophagous insects and microorganisms. The defensive capabilities of PPIs rely on inhibition of proteases present in insect guts or secreted by microorganisms, causing a reduction in the availability of amino acids necessary for their growth and development (Lawrence and Koundal, 2002).

In the national and International scenario weeds continue to cause major problems in agriculture thereby, reducing yield and quality of crops by competing for the water, nutrients and sunlight essential for vigorous crop growth. Holm et al. (1997) listed about 200 weed species that cause 95% of weed problems for humans. As international travel and global trade increased, more plant species with potentially weedy traits are being moved around the world, giving rise to new, invasive weed problems, particularly in non-agricultural or natural ecosystems (Mack et al., 2000). The importance of weeds is reflected by the rapid growth of the use of chemical herbicides in agriculture throughout the world. The effectiveness of herbicides has dramatically increased yields in many cases and, in turn, stimulated development of new chemical herbicides. However, despite massive efforts, weeds continue to cause significant losses. These losses result from the selection and emergence of species that are not controlled by currently available herbicides, the inability of an herbicide to selectively control certain weedy species without injury to crop species, or the development of resistant strains. Among different management practices plant pathogens have also been suggested as one of several possible means of controlling the weeds that remain problematic or even as an alternative to chemical herbicides. Plant pathogens can be used to control weeds in a similar way to chemical herbicides. The term bio herbicide is coined to refer to herbicides based on any living organism (e.g. fungi, bacteria, viruses, protozoans). When the active ingredient used is a fungus, the product is called a mycoherbicide. Mycoherbicides can be applied in many ways, e.g. as aerial sprays, through ‘cut and paste’ application or in a powder form to be applied to the soil.

Plant viruses are ultramicroscopic particles that multiply only within living cells and are potentially pathogenic while composed of nucleic acids surrounded by protein coat.

More than half of the known viruses cause diseases of plants. All plant species are probably susceptible to one or more plant viruses. Symptoms of virus infection may include stunting, yellowing, necrosis, mosaic, mottling, ring spots, or abnormal structures. Economic damage consists of reduced yield and quality.

Viruses neither divide nor produce any kind of specialized reproductive structures such as spores. Instead, they multiply by inducing host cells to form more viruses. Viruses causes disease not by consuming cells or killing them with toxins, but by utilizing cellular substances during multiplication, taking up spaces in cells, and disrupting cellular processes. These in turn upset the cellular metabolism and lead to the development of abnormal substances and conditions injurious to the functions and life of the cells or the organism. The property of transmissibility is an essential criterion for viruses. Plant viruses are transmitted from plant to plant in a number of ways. Mode of transmission includes vegetative propagation, mechanically through sap, seeds, pollen, dodder and by insects.

The label on the pesticide container is the principal source of information about a product. The label has all the fundamental information that is required. If you need information about a pesticide, do not rely on memory as it is very easy to make a mistake. Read the label every time before using a pesticide. The lay-out of the pesticide label varies between countries. However, every label on a pesticide container from a reputable manufacturer or source will have the following information:

Pesticide Resistance

Resistance to pesticides may be defined as ‘a heritable change in the sensitivity of a pest population that is reflected in the repeated failure of a product to achieve the expected level of control when used according to the label recommendation for that pest species.

At times a pesticide application fails to reduce the levels of a pest. Usually, the farmer blames either the pesticide for this or he thinks that the pests have developed resistance. Though, the usual causes of poor results with an application of a genuine pesticide from a reputable source are:

Pesticide poisoning occurs when a pesticide enters the body and interferes with the vital systems of the body. Symptoms can begin anything from 1/2 hour to 24 hours after exposure. The typical symptoms and signs of pesticide poisoning are:

Introduction

Horticulture is an intensive but profitable venture with higher output in terms of yield and income per unit area and time. In order to maximize the output, there has been liberal use of inorganic products like fertilizers, pesticides (insectides, fungicides, nematicides, weedicides) and other chemicals. With the continuous application of these chemicals since the last green revolution, the soil and its fertility is showing the sign of fatigue and plants developing resistance to insects, pests and diseases is breaking down and causing overall pollution to soil and water. There is growing evidence of sterility in humans and various other animals, particularly in males, related to the presence of various chemicals and pesticides in the environment. Hence the demand of the hour is looking for some alternative arrangements which are eco-friendly and moreover safe guarding the quality of the produce, which is essential so far as ornamentals are concerned. This is especially true for cut flowers and potted plants. Visible symptoms of insects, pests and diseases, have a major impact on quality. Direct and indirect effects of infections include reduction in growth, reduction in vigor, costs of attempting to maintain crop health, reduction in quality and/or market value (Hadidi et al., 1998). This may cause serious economic losses. In addition, infected plant material may not be acceptable for export.

Fungi include a large group of organisms and there are about 72,000 described species and the total number of species in the world may be as high as 1.5 million (Hawksworth et al., 1995). The infections that these fungi cause on a group of organisms viz. plants, animals, insects etc. may or may not be beneficial depending upon the type of host infected. With reference to insects, fungal infections in pest insects are beneficial which can be used effectively in biocontrol programmes. On the other hand, fungal infections in beneficial insects are harmful.

The entomopathogenic or entomogenous fungi mainly include those genera of fungi that associate with insects and some arthropods in a variety of ways. The association with the insects may be saprophytic, commensalistic, parasitic or pathogenic with the insect host. Some entomopathogenic fungi like Coelomomyces are obligate pathogens which can’t be cultured outside a living host, but most of them are however, facultative pathogens capable of growing without host insect. More than 750 spp of fungi, mostly deuteromyctes and entomophthorales from about 100 genera are pathogenic on insects and many of them offer great potential for pest management. The entomopathogenic fungi which have been most intensively investigated include Beauveria, Metarrhizum, Paecilomyces, Entomophthora, Verticillium, Hirsutella, Eryina, Mefarrhizium etc. Out of them Beauveria and Mefarrhizium have been extensively used in large scale for the control of several crop pests.

Introduction

Worldwide damage due to insect pest attack accounts for 15 per cent crop losses, despite the use of insecticides which represents over US $100 billion (Krattiger, 1997). The annual cost of insect control itself amounts to US $8 billion, thus warranting immediate and economical control measures. The crop varieties developed in the past 30 years were high yielders, but unfortunately had poor storage characteristics and were highly susceptible to pest damage. Insect-pests are capable of evolving to biotypes that can adapt to new situations, for instance they overcome the effect of toxic materials or bypass natural or artificial plant resistance, which further confounds the problem (Roush and McKenzie, 1987). Under these circumstances, provision of food to the rapidly expanding population has always been a challenge facing mankind. This problem is more acute in the tropics and sub-tropics, where the climate provides a highly conducive environment for a wide range of insects and necessitates massive efforts to suppress the population densities of different pests in order to achieve an adequate supply of food. In developing countries, the problem of competition from insect-pests is further complicated with a rapid annual increase in human population (2.5-3.0 percentage) against a meager 1.0 per cent increase in food production. In order to feed the ever expanding population, crop protection plays a vital and integral role in the present day agricultural production to minimize yield losses. Currently, the crop protection practice in agricultural systems relies exclusively on the use of agrochemicals, although a few specific cases do exist, where inherent varietal resistance and biological control have been successfully employed. The exclusive use of chemical pesticides not only results in rapid build-up of resistance to such compounds, but their non-selectivity affects the balance between pests and natural predators, and is generally in favour of pests (Metcalf, 1986).

Pesticides can cause three types of harmful effects – Acute, Delayed and Allergic.

Acute effects: Are those that occur immediately after the exposure, within minutes or hours.

Definition

Adjuvants are chemicals incorporated in a pesticide formulation or added to the tank mix, to increase effectiveness and safety. They generally have no effect on pests in themselves.

There is a common practice of using the terms spurious, counterfeit, misbranded, illegal, sub-standard and others interchangeably and this often creates confusion among scientist, industrialist and extension officer. Spurious and counterfeit pesticides are the two major words used to describe all kind of anomalies in the pesticides. Hence, there is a need to have a clear understanding of these and differences between them.

Introduction

Biotechnology, in the recent years, has created unprecedented opportunities not only for the manipulation of biological systems for the benefit of mankind, but also to understand studies for better understanding of the fundamental life processes. Consequently, it has become the fastest and most rapidly growing technology in the world. As per US National Science Foundation, “Biotechnology is defined as any technique that uses living organisms or parts of organisms to make or modify products, to improve plants, amend animals or to develop microorganisms for specific uses”. Biotechnology offers new strategies that can be used to develop transgenic crop plants with improved growth, yield and quality and tolerance to biotic and abiotic stresses. By transgenic crop, we mean any plant containing a gene(s) which have been artificially inserted instead of the plant acquiring them through pollination. A plant in which a foreign gene has been transferred through genetic engineering is called transgenic plant and the gene so transferred is called transgenic. The inserted gene sequence known as transgene may come from another unrelated plant or from completely different species. Plants containing transgene are often called genetically modified or GM crops. Transgenic technologies have opened up many exciting possibilities to improve products with added value having application in food, agriculture, animal husbandry, environment, medicine and industry. It also offers uncommon opportunities for improvement in genetic potential of plants and animals by introduction or removal of gene(s) that regulate a specific trait.

Introduction

Vegetables are preferable host to many insects because of their succulence and suitable nutritional status. All vegetables are attacked but degree of damage and number of pests varies depending upon the crop, variety and climate. Pest infestation in vegetables has been the main bottleneck in their economical production. The problem has more socio-economic dimensions because of rapid expansion of area under vegetables, intensive cultivation, round the year cultivation, export enhancement and health consciousness among the people.

The diamondback moth (DBM), Plutella xylostella (L.), is a major pest of brassica crops worldwide. DBM has been estimated globally to cost US$ 1 billion in direct losses and control costs. (Grzywacz et al., 2010)