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Slugs and snails occasionally cause serious damage to seedlings, tender, lowgrowing leafy vegetables; or ripening fruit that are on the ground. Feeding damage, hollowed-out areas, can be found anywhere on fruit, but is usually concentrated near the stem. Slugs leave a tell tale slime trail (silvery trail) behind on the surface of fruit or leaves.

Abstract
Pesticides, which are extensively employed in agriculture and pest management, pose serious dangers to the environment and public health because they frequently enter aquatic ecosystems through runoff, leaching, and inappropriate disposal. Acute and chronic toxicity in aquatic creatures caused by pesticide poisoning in water bodies can disturb ecosystem services and biodiversity. As sentinel species, fish have immune-toxic consequences, such as impaired immune function and increased vulnerability to illness. Aquatic animals and human health are at risk due to the bioaccumulation of pesticides in fish tissues and their subsequent biomagnification in the food chain. In order to control pesticide exposure and guarantee safety, important parameters such as Maximum Residual Limits (MRLs) and Acceptable Daily Intake (ADI) are essential. In order to control pesticide, use and lessen its negative effects, government regulations and international standards are essential. In order to protect aquatic ecosystems and human health, future research should give priority to environmentally suitable pesticide substitutes and strong regulatory frameworks.
Keywords: Pesticides, Toxicity, Aquatic Environment, Bioaccumulation and Biomagnification.

Pesticides are used to control plant growth (herbicides), insects (insecticides), worms  (vermicides), bacteria (bacteriocides), fungi (fungicides), and other organisms. Almost without exception, pesticides are used to benefit humans by the control of unwanted species of plants (e.g. weeds in a lawn), disease-causing bacteria (e.g., Pneumococcus, the causative agent of pneumonia), disease-carrying insects (e.g. malarial or yellow fever mosquitoes) or in controlling destruction of agricultural products by disease-causing organisms (e.g., corn-borers, the virus of anthurium blight). Although they are by and large mostly beneficial, pesticides used both properly and improperly are also “resources out of place”, that is pollutants, that are subject to normal ecological processes.

The Insecticides Act, 1968 and Insecticides Rules, 1971 regulate the import, registration process, manufacture, sale, transport, distribution and use of pesticides with a view to prevent risk to human beings or animals and for all connected matters, throughout India. However, recently the Union Cabinet gave its approval for the introduction of the Pesticides Management Bill with the aims of improving the quality of pesticides available to Indian farmers and introducing new, safe and efficacious pesticides. This bill will replace the existing Insecticide Act 1968.The pesticides’ regulations in India are governed by two different bodies:

10.1. Classification of pesticides

10.1.1. Based on organisms

Introduction

Pesticide in broad term refers to “killer of pests” but is an agent used to control, prevent, destroy, repel and mitigate a pest. Pesticides are thus poisonous substances intentionally applied in situations, which harbour so-called pests. Agriculture including poultry and veterinary (i.e. raising of crops and protection of produce and storage), health (public places-hospitals, restaurants, gardens cinema halls etc.), transportation (shipment, air rail and road transport) are some areas where pesticides are used extensively as spot application, fumigation, aerial and field sprays, soil treatments etc. Plant protection comes to be recognized as an equally important factor of agriculture production as improved seeds, fertilizers and irrigation. Pesticides over time get accumulated in the environment and contaminate all systems i.e. air, water, soil, plants, animals and micro-organisms on being transported from one system to another leading to biomagnifications.

The fate of a pesticide in the environment and the entities, which come in contact, is depicted in the Fig. 1 reflecting the pollution and contamination. Pesticides during manufacturing, transportation, storage and actual use enter the biotic and abiotic components of the environment through air, water and soil and disturb the cohesion causing great disaster sometimes. Pollution is defined as undesirable change in physical, chemical and biological characteristics of air, land and water. This change may or will harmfully affect human life or that of desirable species, industrial process, living conditions and cultural assets. It may or will waste or deteriorate our raw material resources. Pollution increases burden of human society causing loss of resources through unnecessary wasteful exploitation, the cost of pollution abatement and deterioration of human health.

The chemicals, which can destroy pests or prevent their occurrence by their chemical action, are known as ‘pesticides’. Pesticides include ‘insecticides’, ‘acaricides’, ‘nematicides’, ‘rodenticides’, ‘molluscicides’ etc., which are used to destroy insect pests, mites, nematodes, rodents, slugs and snails respectively.

Pesticides have been used even before the time when man never knew how to read or write. Even before 200 BC, several substances were known to control pests. Sulfur, arsenic poisons, fluorine poisons, as well as some plant extracts and oils were used to control pests. However, these substances could destroy only a few specific pests.

Advances in the invention of pesticides

The invention of many of the present day pesticides started only after 1867. Paris green, a synthetic chemical was the first pesticide used to control the Colorado beetles of potato.  Up to  1939,  only  a few inorganic  chemical compounds and plant poisons were used as pesticides. Only after the Second World War much advances were made in chemical research. After the invention of DDT in 1939, a revolution had started in the field of pest control.  Following the introduction of DDT,  several other pesticides were identified and introduced for pest control. In 1941, BHC was invented by the British and French scientists. During the same period, organophosphorus pesticides were invented by the German scientists and parathion, malathion, demeton etc. were introduced.

The chemicals, which can destroy pests or prevent their occurrence by their chemical action are known as ‘Pesticides’. Pesticides include ‘insecticides’, acaricides’, ‘nematicides’, rodenticides’, molluscicides’ etc., which are used to destroy insect pests, mites, nematodes, rodents, slugs and snails respectively. Pesticides have been used even before the time when man never knew how to read and write. Even before 200 BC, several substances were known to control pests. Sulfur, arsenic poisons, fluorine poisons, as well as some plant extracts and oils were used to control pests. However, these substances could destroy only a few specific pests only to some extent.

Advances in the invention of pesticides

The invention of many of the present day pesticides started only after 1867. ‘Paris green’, a synthetic chemical was the first pesticide used to control the ‘Colorodo beetles’ of potato. Up to 1939, only a few inorganic chemical compounds and plant poisons were used as pesticides. Only after the Second World War much advances were made in chemical research. After the invention of DDT in 1939, a revolution had started in the field of pest control. Following the introduction of DDT, several other pesticides were identified and introduced for pest control. In 1941, BHC was invented by the British and French scientists. During the same period, organophosphorus pesticides were invented by the German scientists and parathion, malathion, demeton etc. were introduced.

Bougainvillea is relatively pest-free. Worms, aphids, and moths might be an issue. Sometimes it gets attacked by spiders which can be controlled by using miticide and by the fungus Phytophthora which is checked by spraying Blitox (copper oxychloride) (Sharma 1996, Banerji 2010). Although it is normally pest-free plants, but may suffer from worms, snails and aphids. The larvae of some Lepidoptera species also use them as food plants, for example the giant leopard moth (Hypercompe scribonia). Leaf spot disease caused by Cercosporidium bougainvillea has been reported in the U.S.A. (Sobers and Martinez 1966, Sobers and Seymour 1969). When compared to B. spectabilis, B. glabra has been reported to be resistant or only slightly susceptible to the leaf spot disease (Pal and Swarup 1974). Cercosporidium bougainvillea has been reported in Colombo by Pardo-Cardona (1998) and in Indonesia by Kobayashi and Oniki (1994). The disease can be controlled by spraying copper Carbendazim at the rate of 1 g/l at an interval of 10-15 days. Fusarium wilt caused by Fusarium oxysporum in bougainvillea has been reported in Italy (Polizzi et al., 2010). Bacterial leaf spot caused by Pseudomonas andropogonis has been reported in Brunei, Darussalam (Peregrine and Ahmad 1982, Sivapalan and Hamdan 1997) and U.S.A. (Walker 1991, Walker and Hodge 1991). This can be controlled by spraying copper oxychloride at the rate of 3 g/l at intervals of 10-15 days.

Tropical tuber and root crops are subjected to the depredation of a number of insect and non insect pests. Comprehensive studies revealed that cassava is attacked by a wide range of arthropod and rodent pests. An exhaustive global account of cassava pests and their management was given by Anon (1978), Bellotti and Schoonhoven (1978) and Bellotti et al. (1999). Lal and Pillai (1982); Pillai and Palaniswami (1984), Pillai (1994) and Palaniswami (1999) reviewed the pests of cassava in India. Anon (1978), Sutherland (1986) and Jansson and Raman (1991) covered world sweet potato pests. Palaniswami (1999) detailed the pests attacking sweet potato in India. Pests of edible aroids, yams and chinese potato were comprehensively reported by Anon (1978); Mitchell and Maddison (1983) and Palaniswami (1994, 1999). In India about 34 species of insects and non-insect pests infest cassava, 80 species attack sweet potato, 46 species on edible aroids, 21 on yams and 10 on chinese potato. One of the main factors for the low productivity of these crops in India is attributed to the pest complex attacking them (Chadha, 2001).

Though a large number of insect pests are reported to attack mango, which cause considerable damage to mango crops in India. More than 492 species of insects, 17 species of mites and 26 species of nematodes have been reported to be infesting mango trees, about 45 per cent of which have been reported from India. Almost a dozen of them have been found damaging the crop to a considerable extent causing severe losses and, therefore, may be termed as major pests of mango. These are hopper, mealy bug, inflorescence midge, fruitfly, scale insect, shoot borer, leaf webber and stone weevil. Of these, insects infesting the crop during flowering and fruiting periods cause more severe damage. The insects other than those indicated above are considered as less injurious to mango crop and are placed in the category of minor pests. A brief description of the biology and control of major pests of mango is given below. Mango suffers from several diseases at all stages of its life. All the parts of the plant, namely, trunk, branch, twig, leaf, petiole, flower and fruit are attacked by a number of pathogens including fungi, bacteria and algae. They cause several kinds of rot, die back, anthracnose, scab, necrosis, blotch, spots, mildew, etc. Some of these diseases like powdery mildew are of great economic importance as they cause heavy losses in mango production. Major pests and diseases of mango and their control measures are discussed below.

Anar butterfly, Deudorix isocrates (Fab.)

The pest has been found boring into fruits of pomegranate. Besides it may attack guava, aonla, apple, ber, citrus, litchi, loquat, sapota, etc., pomegranate is the most preferred host for this pest. It may destroy up to 50 percent fruits. The female lays eggs singly on calyx of flowers or small fruits. On hatching, the caterpillars bore inside the developing fruits and are usually found feeding on pulp and seeds just below the rind; subsequently bacteria and fungi causing fruit rot also attack the infested fruits. The conspicuous symptoms of damage are offensive smell and excreta of caterpillars coming out of the entry holes, the excreta is found stuck around the holes. The affected fruits ultimately fall down and are of no use; even if the fruits be picked before falling down, these fruits have no market value.

Cashew (Anacardium occidentale L.) is one of the most important commercial crops of India. The crop is grown on commercial scale in coastal Maharashtra and other states of the country. The main reason for the low productivity is the pest incidence. The insect pests cause crop loss ranging from 30 to 40 per cent in cashew (Satapathy, 1993). Keeping in view, the strategy of increasing production, one of the important aspects is to develop technologies to save the crop from the pest incidences.

Cashew is attacked by around 180 species of insect and non-insect pests in India resulting in substantial yield loss (Sundararaju, 1993b). Godse et al. (2004) reported over 58 species of insects and pests on cashew crop in the Kokan region of Maharashtra region. The infestations of insect pests have been identified as one of the major factor responsible for low productivity. The most important pests that limit production are the cashew stem and borer (CSRB) and the tea mosquito bug (TMB). In addition, leaf and blossom webber, shoot tip caterpillar, and apple and nut borer cause damage. Recently, apple and nut borer and leaf miner are emerging as major pests and they also occasionally becoming serious in some orchards.

Amaranthus is an important leafy vegetable and is grown all over the Indian subcontinent. Amaranthus tricolor Linn and A. blittum Linn. are the common varieties cultivated. These herbaceous annuals are a rich source of proteins, vitamins A and C, and iron. The foliage is a good source of calcium, iron, and vitamins A, B, and C. In contrast, grains are good sources of important amino acids, particularly lysine, and are rich in dietary fibre, calcium, and minerals such as iron, magnesium, phosphorus, copper, and manganese. It enhances the body’s immune system and antioxidant status while lowering blood pressure and cholesterol. Fresh leaves and tender stems are used as vegetables. Production of amaranthus is affected by the incidence of pests. Cultivated amaranth is currently infested by a total of 92 different insect pests. (Rajeshkanna et al., 2017) among which the leaf webbers and amaranthus stem weevil are the most important pests.
Biology: Black moth with dark brown wings bearing white wavy markings on wings. Eggs are laid singly on leaves. Egg period 3 to 4 days. Larval duration will be completed within a period of 2 weeks. Pupation occurs among the leaf webbings and pupal duration lasts for 10 days. Several larvae can be seen inside each leaf web.

The Indian gooseberry or amla (Phyllanthus emblica Linn.; Family: Euphorbiaceae) is a deciduous fruit largely cultivated in the Indian subcontinent for its fruits. Amla is native to the tropical South Eastern Asia, particularly the Central and Southern India (Mortan, 1960), where the plants are often seen to grow in the wild up to an elevation of 1800 m (Firminger, 1947). In India, amla is mostly cultivated in the semi-arid regions of Maharashtra, Gujarat, Rajasthan, Andhra Pradesh, Karnataka, Tamil Nadu, and the Aravalli ranges in Haryana, Punjab and Himachal Pradesh (Pathak, 2003). The tree attains a height of 8 to 18 m, with a crooked trunk and spreading pattern of branching. The branchlets are glabrous or finely pubescent; leaves are simple, nearly stalkless, set along the branchlets resembling pinnate type. 

Anthurium is a famous decorative cut flower and pot plant in the Araceae (order Spathiflorae) genus because of its extended vase life and beautiful, long-lasting inflorescences. After orchids, anthurium sales are the second-highest in the world.
Anthurium Thrips : Chaetanaphothrips orchidii Moulton
Order : Thysanoptera
Family : Thripidae
Biology: Chaetanaphothrips orchidii are small, pale yellow thrips commonly found in unopened anthurium buds and flowers. These pests are also commonly found in orchids. Females reproduce parthogenetically and on an average 80-100 eggs are laid by each female (Hata and Hara, 1998). Eggs are inserted inside the flower bud or leaf sheath. Nymphs are light yellowish in colour and are similar to the adults. Pupation takes place beneath the host plant in the soil or growing media. The entire life cycle lasts approximately 28 to 32 days but can extend up to 3 months, depending on the temperature. Increased temperatures and humidity, along with new growth of host plants, seem to promote thrips feeding and reproduction, resulting in heavier infestations and greater damage during the summer months

Apple (Malus pumila, though erroneously and commonly called Malus domestica) is a deciduous plant and considered to be the world’s one of the oldest fruit crops. The tree originated from Central Asia where M. sieversii, wild ancestor of cultivated apple is still found today. It is one of the most important table fruits of the world and excels other fruits in having prolonged keeping quality and wide variety of flavour and taste. It is a highly remunerative crop and is grown in all temperate regions of the world. In India apple is mostly grown in Jammu and Kashmir, Himachal Pradesh, Uttarakhand and some parts of Arunachal Pradesh.

Banana is the eighth most important food crop in the world. It is widely cultivated in over 130 countries in the tropics and sub tropics of Asia, Africa and the United States. Plantains and bananas are next important to major cereals, forming a key component in food security and agricultural sustainability in the developing economics (Patel and Shukla, 2009, Shukla, 2010; Deepah and Paranjothi, 2010). Banana ranks fifth in the global market of agricultural commodities and is one of the largest traded fruit crops. It is popularly known as “Apple of the Paradise ”. The per capita starch output of banana from unit cultivated area is almost near cassava and sweet potatoes (Choudhary, 2015).

Ber (Ziziphus mauritiana Lam.) is one of the most ancient and important fruit crops. It is considered as the “King of arid zone fruits”, due to its adaptations to tolerate the biotic and abiotic stresses prevailing under rainfed conditions (Anbu et al., 2009). It is also called as desert apple, jujube, Badari (Sanskrit), Chinee apple, Ber (Hindi), Kul or Boroi (Bengali), Indian plum, Boroi, Beri, Permseret (Anguilla) etc. It is a tropical fruit tree that belongs to the family Rhamnaceae. Ber is rich in amino acids, protein, sugar, calcium, phosphorus, carbohydrates, iron, vitamin A, ascorbic acid. The fruit contains from 70 and 165 mg ascorbic acid per 100 gm of pulp, which is two to four times higher than the vitamin C content of citrus fruits. The mineral content of phosphorus, calcium and iron in Z. mauritiana fruit is also reported as being higher than in apples and even oranges (Morton et al., 1987, Jawanda and Bal,1978).

Black pepper, popularly known as the “King of spices”, is the most popular spice crop in the world, and the crop originated in the Western Ghats and Malabar coast of India. India was the centre of pepper trade from time immemorial. Recently, black pepper production in the country remained stagnant at around 90000 tonnes in the last few years. Hence, India is losing its status as a leading producer and exporter of black pepper. Kerala accounts for 75 per cent of total black pepper production in the country. It has been noted that the increase in area under cultivation is not in tune with the increase in production. Low productivity is mainly due to the incidence of pests and diseases.
Black pepper is infested by 56 species of insects in India; among these, pollu beetle, (Lanka ramakrishnae Prathapan & Viraktamath), top shoot borer (Cydia hemidoxa Meyr), scale insects (Lepidosaphes piperis and Aspidiotus destructor) are considered as major pests (Devasahayam, 2000).
It is one of the most destructive pests of black pepper and the infestation is severe in plains of Malabar region (20-30 %) and low in hilly tracts (Wayanad and Idukki) and South Kerala.
Distribution: Tamil Nadu, Karnataka and Kerala.
Host plants: Castor, turmeric, guava, mulberry, etc.