ENVIRONMENTAL IMPACT OF CHEMICAL PESTICIDES

The usage of chemical pesticides increased several folds since 1940s for control of different insect pests and diseases.

Several environmental issues have aroused in recent past regarding the usage of these pesticides with due concern of the public health particularly the children. Many of the pesticides which are under usage for controlling the pests are highly toxic pesticides that can harm not only the humans but even environment. Increased environmental concern as they are nonbiodegradable, attention is directed toward the use of certain natural chemicals which are both effective and ecofriendly. Importance was felt to incorporate these as key elements in the insect management programs to minimize harmful effect on environment.

Several incidences are stating the poisonous effect of DDT as quoted by Hill and Robison (1945), Tschirley (1973), Longnecker et al. (1997), Conis et al. (2010), and Qiu (2013). The farmworkers, people residing near to agricultural areas, small children, and so on, are the victims of hazardous effects of organopliosphates (Landrigan et al., 1999; Eskenazi et al., 1999; Fenske et al., 2000; McCauley et al., 2001; Quandt et al., 2004; Eskenazi et al., 2008). Acute toxicity of organopliosphates and carbamates is a severe problem in under developed countries, ignorance about their hazards and lack of information has led to many deaths among agricultural workers (Konradsen et al., 2003).

Intensified usage of synthetic pesticides in agriculture had changed ecological conditions that had affected soil fauna (Edwards and Thompson, 1973; Tripathi and Sharma, 2005; Frampton et al., 2006; Bezchlebov et al.,

2007). The population of beneficial insects (bees, wasps, and other) involved in pollination had been drastically reduced due to the increased application of pesticides in most of the agriculturally important crops (Gill et al., 2012).

On high pesticide exposure, there is a decline in frog population (Bruhl et al., 2013) Even several species of birds have wiped out or are on the verge of it because of pesticides. The synthetic pesticides have showed devastating effects on ecosystems, due to lack of alternative and it was impossible to diminish their utility and effects (Wu and Chen, 2004; Aktar et al., 2009).

FACTORS FOR THE EMERGENCE OF BIOPESTICIDE MARKET

Increased conscious on environment safety, hike in price of chemical insecticides and increased resistance of insects to these products, to decrease the toxic residual effects of synthetic chemicals in foodstuffs, especially in export markets there aroused a need to their emergence. At an impressive rate of 20%, the consumption of biopesticides is growing globally.

At present the biopesticides cover 2% in the world pesticide market and its share is going to increase tremendously in coming years.

Majority of the consumers have become more health conscious and prefer for organic food. Following are the reasons for which the usage of biopesticides are likely to increase at higher rate: increase in demand for organic food, increasing in number of insects developing resistance to existing chemicals, and increase in cost of developing new chemical pesticides.

FUNDAMENTAL COMPONENTS OF IPM

Sustainable agriculture mainly focus on protecting the environment, public health in addition to animal welfare. It integrates the economic profitability and social equity to cater the needs of future generations. In recent past, most of the growers are working to create sustainable agriculture system as their forefront toward the beneficial organisms.

Generally, an IPM program combines cultural practices, biological controls (i.e., predatory insects, micro-organisms) and chemical control to keep pest populations low and therefore it became a key factor of sustainable agriculture. However, under severe conditions, chemical control may be opted. Most of the biopesticides are environmentally friendly, target specific, enhance the crop growth and also confer resistance to different pests and diseases.

They sustainably balance and maintain the microbial environment and habitat. Thus, they can be integrated as one of the component in IPM program and as such in sustainable agriculture system. There is an urgent requirement for alternative tactics to help make crop protection more sustainable.

BIOPESTICIDES CONCEPT

The inconsistency raised at global level in understanding the term biopesticide given by USEPA, the International Biocontrol Manufactures Association (IBMA) and the International for Biological Control (IOBC,

2008) had promoted to use the term biocontrol agents (BCAs) to biopesticide (Guillon, 2003).

According to IBMA, the BCAs are classified into four groups: (1) rnacro- bials, (2) micorbials, (3) natural products, and (4) semiochemicals. Many of the agricultural crops and other vegetation are susceptible to insect pest and disease infestations. These naturally occurring chemicals or materials are effective and ecofriendly were designated as biopesticides. In other words they are the management tools with beneficial microbial origin, fungi, nematodes, viruses, protozoa, the biologically based active ingredients. The characteristics of commercial ideal biopesticide (Andy Cherry, 2005) are as follows:

  • a) It should possess high efficacy.
  • b) It should be fast acting with consistent results.
  • c) It should exhibit specificity against broad spectrum of pests.
  • d) Manufacturable at low cost.
  • e) It should possess a shelf life of at least one year.
  • f) Should be simple to use.
  • g) The biopesticide should be environmentally friendly and provide beneficial profits to grower.

Biopesticides are used successfully for managing the pesticide resistance, used with other products either alone or in mixtures, at early crop growth stage under low pest pressure, late in the season with short preharvest intervals, at critical field events (multiple harvests), and to manage pesticide residue.

The benefits of biopesticides are as follows:

  • a) Inherently biopesticides are less toxic than conventional synthetic pesticides,
  • b) Target specific (pest),
  • c) Requires in small amounts,
  • d) Quick decomposition and Pollution free,
  • e) Greatly reduces the usage of chemical pesticides with increased crop yields,
  • f) Used effectively and safely,
  • g) They are environment safe,
  • h) Act as an important pest management tool (pest resistance, environmental concern) limits the use of chemical pesticides, and
  • i) Resistance development toward these pesticides is difficult.

DEVELOPMENT OF BIOPESTICIDES

The biopesticides development on commercial basis depends on different fields namely, application technology, operational execution, microbiology, manufacturing and packaging technology, fermentation technology, formulation technology, regulatory, and also the quality control (Andy, 2005).

Biopesticides developed in Africa under public research sector (Andy,

  • 2005):
  • 1. Beauveria and Metarhizium are developed against insect pests namely, Banana weevil (Cosmopolites sordidus), Larger grain borer (Pros- tephanus truncates), Locusts and grasshoppers, Tennites (Macrotennes spp. and Odontotennes spp), Coffee beny borer (Hypothanenuis truncates), Cowpea beetle (Callosobruchus maculatus), Chilo, and Sesamia (stem borers).
  • 2. Viruses: (a). Nucleopolyhedroviruses against cotton bollwonn (Heli- coverpa armigera), Annywonn (Spodoptear exempta), (b) Granulo- viruses developed against Diamondback moth (Plutella xylostella), potato tuber moth (Phthorimoea opercida), (c) Cypoviruese- developed against Cowpea pod borer (Marnea testularies) and Pink borer (Sesamia xylostella).

BROADLY USED BIOPESTICIDES

The strains of bacterium Bacillus thuringiensis are the most widely used microbial pesticides which control pests of cabbage and other solanaceous crops. The biofungicides are the microbial biopesticides such as Trichoderma spp., Bacillus subtilis, Pseudomonas fluorescens, biohencides-Phytohthora spp., and bioinsecticides (Bt), and so on, are effective against specific pathogens and insect pests (Gupta and Bikshit, 2010).

14.9.1 UTILITY OF В10PESTICIDES

From the total biopesticide market inclusive of all types biopesticide products share for, bacterial biopesticides (74%); fungal biopesticides (10%); viral biopesticides (5%); predator biopesticides (8%); predator biopesticides (8%); and others (3%) (Thakore, 2006). By 2008, there were approximately 73 microbial active ingredients that were registered by USEPA which include 35 bacterial products, 15 fungi, 6 nonviable (genetically engineered) microbial pesticides, 8 plant incorporated protectants, 6 viruses and one each for protozoan and yeast (Steinwand, 2008).

  • 14.9.2 MICROBIAL PESTICIDES
  • 14.9.2.1 MODE OF ACTION

Different biopesticides have their distinctive mode of action. They suppress the pests either by synthesizing the toxic metabolites against their target pest or prevent the establishment of pathogens through mechanisms like competition hyperarasitism antibiosis, and so on (Clemson, 2007).

14.9.2.2 MONITORING OF MICROBIAL PESTICIDES

Continuous monitoring of the microbial pesticides is essential for ensuring their ineffectiveness against the nontarget organisms, including humans.

BIOPESTICIDES SCENARIO IN INDIAN AGRICULTURE

Biopesticides and bio-control agents are used successfully in Indian agriculture (Kalra and Khanuja, 2007). The biocontrol agent Bacillus thuringi- ensis effectively controls diamondback moths (cabbage), Heliothis in cotton, pigeon pea and many of solanacous crops; Beauveria against mango hoppers, coffee pod borer and mealy bugs; Products of neem are effective on cotton White fly; NPV against Helicoverpa in gram; Trichogramma controls sugarcane borers; while Trichoderina-based products against soil borne diseases in different crops.

Biopesticides registered under Insecticide Act of 1968 in India (Gupta and Dikshit, 2010) are as follows:

(1) Bacterial biopesticides—B. thuringiensis var. israeleusis, B. rgy'eub- juwbaua var. galleriae, B. sphaericus, P. fluoresens, (2) Entomopathogenic fungi—Beauveria bassiaua, (3) Virus based biopesticides—NPV of H. armigera, NPV of S. litura, and (4) Botanical biopesticides—Neem based pesticide, Cymbopogan.

 
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