Pollution: Pesticides in Agro-Horticultural Ecosystems
Introduction
Agro-horticultural ecosystems are man-made ecosystems that are greatly influenced by human activities. In the last few decades, agricultural intensification and diversification in most of the developing and developed countries have resulted in high-input farming, i.e., excessive use of pesticides (herbicides, insecticides, fungicides) and fertilizers, which has helped to meet the rising food demand. Agricultural and horticultural ecosystems are now dominated by monoculture and hybrid varieties to enhance crop yields. Hybrid varieties are high yielding and more demanding. The excessive use of inorganic fertilizers results in rapid multiplication and subsequent outbreaks of many pests, simultaneously resulting in enhanced pesticide use. Rice and cotton are important crops grown worldwide, and because of monoculture, they are attacked by hundreds of pests and receive a disproportionately high share of pesticides (17% and 24%) worldwide.1'1 It has been observed that chemicals that have been banned for most of the food crops are still being used on cotton as it is not consumed directly. For example, nearly one-quarter of all pesticides used in the United States are applied to cotton, and the overall amount and intensity per acre are increasing every year. Worldwide, more and extremely toxic pesticides are sprayed on cotton than on any other crop,121 which find an entry in the human body in the form of salad dressings, baked goods, and snacks like Fritos and Goldfish.
Based on the trend of herbicide use in the United States, agriculture accounts for three quarters of total chemical pesticides used. According to the data published by the US Environmental Protection Agency (EPA), in 2001, 675 million lb of chemical pesticides were used in agriculture.131 Thus, horticultural and agricultural ecosystems are highly dependent on pesticides. It is estimated that if pesticides are not used, food supplies would fall to 30%-40% due to the ravages of pests.141 Worldwide, research data show that without effective pest management, preharvest losses in crops would average about 40% and the world’s food and fiber production as well as environmental and human health would be seriously threatened.151
According to market research report, pesticide consumption has been found to be highest in China followed by the United States and Brazil and India ranked 11th after Spain, and as per Tata Strategic Management Group161 (2016), the world agrochemical market is expected to be worth $60 billion in 2016 of which Indian market will account for $6.8 billion of the total revenues and is expected to hike at $8 billion by 2025 in comparison to world market share of $8.0 billion.161
No doubt, pesticides play an important role in enhancing agricultural productivity, but intensive use of pesticides in agricultural and horticultural ecosystems has resulted in degradation of environment, whether it is in the form of development of resistant pests, secondary pest outbreak, or pest resurgence, which leads to changes in ecosystem biodiversity or adverse effects on pollinators, natural enemies, and many incurable human diseases. Several pesticides are known to persist for a longer period in the environment or on the substrate to which they are applied and have long-term side effects on human health and the natural environment. Persistent organic pesticides, especially DDT (dichloro diphenyl trichloroethane) and HCH (hexachloro cyclohexane), have been detected in various systems, even in human blood, fat, and milk samples. Even the soft drinks that are water- based flavored drinks are known to contain pesticides. The hazards of pesticide pollution have been much realized presently, and the demands for their reduction are desired globally in various pesticide monitoring programs.
Pesticide Consumption Trend
By using nonchemical techniques such as sanitation, cultivation, crop rotation, resistant cultivars, and biological control (including introduction of transgenic) for pest control, many pests cannot be controlled adequately. Therefore, there is a continuous need for application of substantial quantities of chemical pesticides, as a result of which crop protection in many developing countries is still dominated by an increasing use of pesticides.
The world pesticide market now amounts $60 billion and is expected to increase to $80 billion in 2025, whereas, Indian market of pesticides is recently reported to be $6.8 billion out of which $2.9 billion is by domestic use and $3.9 billion is earned by export of pesticides to various countries. Both the domestic and the export markets are expected to enhance to $4.0 billion each in 2025, thereby increasing the expected Indian pesticide market to $8.0 billion.161
Globally, pesticide consumption has been found to be highest in China 18,07,000 and 17,72,449 metric tonnes in 2014 and 2015, respectively. In the United States, 4,07,779 metric tonnes of pesticide consumption in 2012 was observed. After China and the United States, next in the list are Brazil (3,52,336 and 3,95,646 metric tonnes in 2014 and 2015), Argentina (2,07,706 metric tonnes in 2014), Mexico (98,814 metric tonnes in 2014), Ukraine (78,201 metric tonnes in 2014), Canada (76,314 metric tonnes in 2014), and France (75,339 and 63,818 metric tonnes in 2014 and 2015)J71
According to the data given by FAOSTAT 2018, the pesticide consumption reported in Europe is 4,36,361,4,28,506,4,49,392, and 3,56,279 metric tonnes in 2012,2013, 2014, and 2015, respectively.171 Out of all European countries, the top five consumers have been France, Italy, Spain, Germany, and Poland with the highest consumption in France, i.e., 63,844, 66,676, 75,339, and 63,818 metric tonnes in 2012, 2013,2014, and 2015, respectively.
The per hectare consumption of pesticides in India is among the lowest in the world and currently stands at 0.6 kg/ha against 5 kg/ha in the UK and at almost 20 times approximately 13 kg/ha in China. In order to increase yield and ensure food security for its enormous population, agrochemical penetration in India is bound to go up.|6J
Further, government policies on subsidies, establishment of market for agrochemicals, availability of technology packet, etc., encourage the farmers to use pesticides excessively. Today, more than 80% of worldwide pesticide sales fall to the share of only six companies. In 2004, three agrochemical companies, each with sales of more than $4 billion, together controlled the global market for pesticides,181 by controlling such a large stake of the market, these companies have a considerable influence on the way in which plant protection is practiced in farming ecosystems.
Pesticides Use Pattern in India
In many cases, farmers go for prophylactic applications, whether they are required or not. India was one of the first countries in the third world to start large-scale use of pesticides for the control of insect pests of public health as well as of agricultural importance, initially DDT and HCH were imported soon after independence. A moderate beginning in indigenous manufacture of pesticides was made with the setting of the plant to produce HCH in 1952 at Rishra (West Bengal). This was followed by the indigenous production of DDT.|9)
The export of various pesticides from India has been higher than their import. In 2010, pesticides of SI.14 billion were exported which gradually increased to $1.38, $1.66, and $2.13 billion in 2011, 2012, and 2013, respectively, whereas the export of pesticides from India was decreased after 2013 and was nearly of $1.94 and $1.93 billion in 2014 and 2015, respectively. The amount of pesticides imported into India increased from $0.63 (in 2010) to $0.99 billion (in 2014) and somewhat decreased to $0.89 billion in 2015Я
Considering the pesticide consumption and area under cultivation in 2016-2017 in different states, the consumption of pesticides (kg per hectare) has been found to be highest in Jammu and Kashmir (1.89) followed by Tripura (0.78), Punjab (0.74), Haryana (0.62), Telangana (0.61), and Maharashtra (0.58). The pesticide consumption in Kerala, Uttar Pradesh, Himachal Pradesh, Tamil Nadu, Jharkhand, and West Bengal was found to be 0.41, 0.39, 0.36, 0.34, 0.32, and 0.27 kg/ha, respectively.1101
In India, Kerala is one of the leading agricultural states of India, and currently, India is the leading manufacturer of basic pesticides in Asia and ranks 12th globally. Compiling the data on the consumption level of pesticides in agriculture in Kerala (1995-1996 to 2007-2008), the total quantity is estimated at 462.05 metric tonnes (2007-2008). Pesticide application in the state is prophylactic and is one of the most important risk management strategies; e.g., pesticide application on bitter gourd starts from the time of transplanting. The prophylactic application of the pesticides is resorted to at an interval of 2 weeks initially, which gets reduced to 2 days as the crop nears flowering and fruit set. There is a tendency among farmers to change the chemicals in each spray. Thus, on an average, acetamiprid is sprayed 6 times, phorate and dimethoate 5 times each, quinalphos and indoxacarb 4 times each, and the rest 3-4 times each. During a crop cycle of 90 days in bitter gourd, farmers apply pesticides as many as 50 times.111!
The pesticides that are used in the state include chemicals that are banned for sale in Kerala (endosul- fan), banned for use in fruits/vegetables (monocrotophos), and those permitted for restricted use only (methyl parathion, lindane, and methoxy ethyl mercury chloride). The farmers are investing a large portion of their income on pesticides, and pesticide consumption is reported to be the primary method of suicide in Kerala. Of the 900-1000 suicides per year, 60% are by consuming poisons. The commonly used poisons are furadan, malathion, and rat poison.1121 Moreover, farmers also go for suicide because of indebtedness due to purchase of chemicals and sometimes due to complete failure of crops in spite of heavy investment.1121
Impact of Pesticide Use on the Pollinators
Wild bees, bumblebees, honeybees, and solitary bees are well known and valued as important pollinators of crops/plants and are in commercial use for pollination. About 33% of all crops require pollination. Intensive cultivation and excessive use of pesticides lead to a sharp decline in the population of these pollinators, which is one of the major causes of low productivity of agricultural and horticultural crops. Pesticides, such as DDT, benzene hexachloride (BHC), cyclodiene, and most of the organophos- phorus and carbamate compounds are highly toxic to bees. Although endosulfan is listed as a persistent organic pollutant, it is the only available pesticide known to be safe for honeybees and other beneficial insects and is still extensively used in many countries. Health and environmental causalities related to excessive use of this pesticide are reported from many parts of the world and European countries withdrew its registration in 2005. Still, there are many instances where most of the pesticides fail to be effective and endosulfan is recommended. For example, in 2008, there was heavy weevil infestation on hazelnut crops in Italy, and the Italian government had to prescribe the use of endosulfan for 120 days although it endangered the health of its citizens. Pesticides like neonicotinoids used as a substitute for endosulfan in agricultural ecosystems in countries such as Germany, France, UK, and the United States have resulted in mass bee killing and colony collapse disorders. In 1959, carbaryl was used against certain orchard pests and later registered for many other crops. In 1967, it caused the destruction of an estimated 70,000 colonies of honeybees in California from use in cotton and an estimated 33,000 colonies in Washington from use in corn. The estimated national loss from all pesticide poisoning from the same year was 500,000 colonies. Carbaryl is still one of the most destructive bee-killing chemical.1131
A horticultural ecosystem, particularly the apple ecosystem, is heavily polluted with pesticides. Apple is one of the important commercial horticultural crops grown in temperate regions of the world. Honeybees are important pollinators of this crop, and quality beehives are placed in apple orchards for enhancing apple productivity. Since the crop is important from an economic point of view, much attention is paid to it. In India, the temperate northern regions of the country (Himachal Pradesh, Jammu, and Kashmir) are known for quality apple production. To obtain quality fruits in Himachal Pradesh, a number of pesticides, which affect the pollinators, are applied on the crop right from fruit set to harvest. The situation has reached an alarming level in the state, and if required measures are not initiated to conserve and rear the population of these pollinators, it could impinge on the total agricultural and fruit production in the years to come. Currently, about 943,000 ha of land is under fruit cultivation in the state, and it requires at least 5 lakh colonies of honeybees alone for pollination to enhance the production. There is a great need to encourage organic farming to enhance the population of natural pollinators and avoid pesticide applications when crops, cover crops, weeds, and wildflowers are in bloom in the treatment area or nearby.
