PESTICIDES AND THE ENVIRONMENT

Insecticide residues

The toxicant retained for sometime in the environment after application is called insecticide residues and the duration of retention is known as its persistence. Residue tolerances are permissible residues in terms of ppm of actual chemical in the products used by man and animals. The EPA (Environmental Protection Agency) of USA established tolerance level for various pesticides. For example for Malathion, it is 2 ppm in cotton and 8 ppm in vegetable; for carbaryl it is 5 ppm in cotton and 100 ppm in other crops.

Maximum Residue Level (MRL)

            Maximum concentration of pesticide residue in a produce resulting from pesticide usage accepted legally.

Acceptable Daily Intake (ADI)

            Daily Intake of a chemical, which, during entire life time, appears to be without appreciable risk, on the basis of all the facts known at the time. It is expressed in milligrams of the chemical per kilogram of body weight.

            ADIs and MRLs are not permanently fixed values. In India the MRL values for pesticides are prescribed under the Prevention of Food Adulteration Act, 1954.

Good Agricultural Practice:

            GAP (in the use of pesticides) is the officially recommended or authorized use of pesticides, under practical conditions.

 

Waiting periods

The time interval between the spray and harvest of the produces to avoid pesticide toxicity. It varies with insecticides. Normally it is 3 day for Malathion, 7 days for carbaryl and endosulfan and 15 days and above for Monocrotophos.

Environmental pollution

            Improper use of pesticides causes environmental pollution in different ways.  The contamination may be due to drift, leaching, and persistence in soil. The causes are;

1.      Use of non selective insecticide

2.      Non-adoption of application details and guidelines

3.      Not following ETL and indiscriminate use of insecticides.

4.      Choice of wrong dispersing aids.

Systemic poisons are the least contaminants of the environment as they are degraded quickly into harmless compounds. However, persistent Chlorinated hydrocarbons (OC) are mostly responsible for pollution.

Impact of Pesticides on Agroecosystem:

I. Abiotic Environment: Include soil, air and water.

1.      Soil: Source of contamination: Direct application; Fallout from plants; Rain

Reason for persistence: Resist biochemical and microbial degradation

Effect: Affect soil flora and fauna. Get into plants.

2.      Air: Source of contamination: Drift during conventional and aerial application; Volatilization; Thermal decomposition; Evaporation with water vapour.

      Effect: Inhalation toxicity; Enter into soil and water.

3.      Water: Source of contamination: Direct treatment; Surface run off; Aerial spraying; Precipitation.

      Effect: Biomagnification; Reduction of O₂ content; Toxic to fishes.

II. Plants

1.      Presence of residual amount – health hazard.

2.      Damage because of phytotoxicity

3.      Changes in the vegetative development – Etiolation by herbicide

III. Animals:

1.      Domestic Animals; Source: Forage treatment; Direct application

Effect: Chronic poisoning; Storage in fat reserves

2.      Wild Life: Trophic transfer of pesticides through food chain kill wild life eg. Egg shell thinning led non-vitality of bird eggs through D.D.T poisoning.

3.      Natural Enemies: Elimination of parasitoid and predators upset the biotic balance.

Effect:

i)                   Pest resurgence: Recovery of pest population following the application of insecticides to levels higher than before treatment. eg. BPH resurgence after quinalphos application.

ii)                 Secondary pest outbreak: Increase in the population of non-target insect to damaging levels followed by the application of pesticides due to the elimination of natural enemies of minor pests or potential pests eg. Red spider mite outbreak in apple followed by the application of organo chlorines.

4.      Pollinators: Pesticide application during blooming kill honey bees.

IV. Man

1.      Operational hazards: Manufacture – Distribution – Application – Post application.

2.      Accidental and intentional poisoning.

3.      Indirect hazards through food chain – Handigodu syndrome

4.      Diseases: Carcinogenic, Mutagenic and Teratogenic effects

V. Food:

Residues in human food – reason: Use of persistent chemicals; Spraying crops nearing harvest; Excessive use of pesticides.

VI. Target Insect:

Development of resistance to insecticides. Excessive use exert a high selection pressure in selecting resistant strains. eg. Mosquito resistance in DDT; Synthetic pyrethroid resistance in bollworms.

How to avoid pollution?

¨      Choose a selective insecticide

¨      Use only adequate dose

¨      Apply insecticides at a time when drift would be very minimum or nil

¨      Use non persistent soil insecticide whenever necessary

¨      Use sticker or spreader with insecticides

¨      Use correct spraying device

¨      Use an insecticide only when it is absolutely necessary

¨      Do not indulge in dipping the produce in a solution of pesticides

¨      Don't spray before harvest

¨      Don't wash spray equipments, cloths in pods, rivers, irrigation channels etc.,

PESTICIDE HANDLING AND USAGE

Compatibility                         

                                                               Compatibility is combination of insecticides to get higher protection without any adverse effect. As for as possible insecticides should not be mixed, because the mixtures may cause various reactions.

                                                   The incompatibility may be;

1.      Chemical incompatibility (different compounds are formed due to combination).

2.      Phytotoxic incompatibility (mixtures cause injury to plants) and

3.      Physical incompatibility (Physical from chemicals is changed)

Always we should have the compatibility charts.

Handling of pesticides and precautions

Before spraying

Ø  Use pesticides if pest has exceeded to ETL

Ø  Read instructions manual of pesticide and equipment

Ø  Ascertain that all components are clean and perfect

Ø  Test the sprayer for pumping, discharge etc.,

Ø  Calibrate the sprayer with proper nozzle.

Ø  Make sure that appropriate protective clothing is available

Ø  Ensure that soap. Towel, and plenty of water is available

Ø  Never work alone when holding highly hazardous pesticides

Ø  Mix chemicals outside or in a well ventilated area

Ø  Persons engaged in mixing, handling, or applying pesticides should not smoke, eat, or drink while working.

Ø  Don’t use mouth to siphon a pesticide from a container

Ø  Clean up spilled pesticides immediately from skin clothing

Ø  Always use gloves while mixing pesticides

During spraying

Ø  Take only sufficient pesticide for the day’s application from the store

Ø  Recheck the use instructions of pesticide and equipment

Ø  Mix the pesticide thoroughly in correct quantities

Ø  Wear appropriate clothing

Ø  Avoid contamination of the skin especially eyes and mouth’

Ø  Don’t spray in high wind, high temperature and rain

Ø  Spray along the wind, not against the wind

Ø  Never blow out clogged nozzles with mouth

Ø  Never allow children during mixing

Ø  Never leave pesticides un attended in the field

Ø  Newer allow cattle’s near by and never spray if the wind is blowing towards grazing livestock or pastures regularly used.

Ø  Follow correct spray technique and spray crop throughly.

After spraying

Ø  Dispose the pesticide containers in pits in waste lands.

Ø  Never empty the tank into irrigation canals or pods

Ø  Never leave unused pesticides in sprayer

Ø  After spraying clean the sprayer and oil it.

Ø  Don’t use empty containers for any purpose

Ø  Clean buckets, sticks, measuring jars etc.,

Ø  Wash protective clothing and take bath well and put on clean clothing.

Ø  Mark the sprayed plots with a flag

Ø  Keep a accurate record of pesticide usage

Pesticide poisoning and first aid

Pesticide poisoning can happen in

Ø  Deliberate consumption for suicidal purposes

Ø  Working in pesticide manufacturing units

Ø  Using pesticides in farm activities

Clinical features

                                                   OC compounds – Muscle twitching, fits, unconsciousness coma

                                                   OP compounds – Watering eyes, running nose, cough, breathlessness, vomiting,

diarrhea, abdominal pain.

Pyrethroids     - Muscle twitching fits.

First aid

Ø  Remove the victim from the site to fresh air

Ø  Look for the adequacy of breathing. If breathing is is inadequate take steps to restore normal breathing.

Ø  Remove all contaminated cloths and wash the body

Ø  Induce vomiting if swallowed

Ø  Don’t give alcohol in any form

Ø  Give strong tea or coffee

Ø  Take the patient for medical attention

Antidotes

A. General antidotes

a. Removal of poison: Remove poison by inducing  vomiting.

                                                   b. Universal antidote: A mixture of 7g of activated charcoal, 3.5 g of magnesium oxide and 3.5 g fo fannic acid in half glass of warm water to neutralize poisons.

a.      Gastric lavage (Removal of stomach contents): Do gastric lavage to remove poisons from the stomach

b.      Demulcents (Substances having soothing effect) :  After the stomach has been emptied, give raw egg white mixed with water or butter or  milk or cream or masked potato.

B. Specific antidotes

OC- If swallowed give universal antidote, followed by gastric lavage and then give magnesium sulphate in a glass of water, followed by hot tea or coffee. Inject 10 ml of calcium gluconate intravenously.

OP- Give Antropine. Administer artificial respiration in case of respiratory failure.

Advantages of Chemical control

Ø  Insecticides are only means of preventing economic damage

Ø  Insecticides are readily to use

Ø  A range of pesticides are available

Ø  Easy to adopt in larger areas

Ø  Work out under special conditions pest out break, pest complex

Ø  Assured income to farmers

Ø  Compatible with other components

Disadvantages of Chemical control

Ø  High cost

Ø  Toxic to natural enemy, bees etc.

Ø  Cause environmental pollution

Ø  Cause resistance and resurgence in insects

THIRD GENERATION PESTICIDES (BIORATIONALS)

1.      SEMIO CHEMICALS

Definition

                                                   Chemicals that deliver behavioural messages which act either interspecially or intraspecifically.

Interspecific semiochemicals

1.      Allomone -  Interspecific semiochemical that favours the produces  E.g. Repellents, Deterrents (feeding and ovipositional)

2.      Kairomone -  Interspecific semiochemical that favours the receiver E.g. attractants ‘ Food love”

3.      Synamone -  Interspecific semiochemical that favours both the producer and receiver E.g Plant odours attracting natural enemies of pests.

4.      Apneumone: Chemical from non-living materials eliciting behavioural response. E.g. Fish meal attracting sorghum shoot fly

Intraspecific semiochemicals

1.      Pheromone-  Semiochemical used for intraspecific communication which is an exocrine secretion that causes specific reaction in the receiving individuals of the same species.

2.      Sex pheromone- Female produce to attract males E.g. Bombyco (Bombyx mori) Cyplure (gypsy moth) and Gossyplure (Pink boll worm) ( In American boll weevil males produce)

3.      Alarm pheromone- Semiochemicals used to warm other fellow individuals from mandibular glands or anal glands. E.g. honey bees (E) B. Farnesene aphids.

4.      Trailmarking pheromone- Semiochemicals used in route perception. Eg. Ants, termites.

5.      Aggregation pheromone- Semiochemicals which attract other fellow members to a particular spot. E.g. Ferrolure of red palm weevil.

PHEROMONES IN INSECT PEST MANAGEMENT

                                                   The synthetic pheromones are used to monitor pest population attract and kill insects and confuse male from mating (mating disruption). Lures are available for following pests

1.      Helicoverpa armigera                    - Heli lure

2.      Tobacco caterpillar S. litura      - Spode lure/Pherodin SL

3.      Pink boll worm Pectinphora gossypiella – Pectinolure/Gossyplure

4.      Rhionceros beetle Orycetes rhinoceros – Sime RB  or Rhinolure

5.      Red palm weevil – Rhynchophorus ferrungineus – Ferrolure

6.      Spoted boll worm Eavis – Erin lure.

7.      β Farnescene (EBF) has been identified as alarm pheromone of aphids – Aphis gossypii.

The number of traps required for monitoring is  12 /ha.

 Set up at 1-2’ inch above the crop level

Types of pheromone trap 

1.      Funnel trap for mamy insects

2.      Sticky trap / delta trap for pink boll worm

3.      Bucket trap – red palm weevil & rhinoceros beetle

2.      STERILITY METHOD/ STERILANTS

Sterility method envisages the use of insects to bring down the population. Insects are used against members of their  own species to reduce the populations and hence called as autocidal control. Autocidal control received siginificance after E.F. Knipling, a USDA scientist in the 1950’s when the population of screw wormfly Cochliomyia homvinvorax, a parasite of cattle was eradicated in Curaca island in United State.

Principles of Autocidal control

1.      Flooding a population with sterile males which mate with normal females

2.      Such mating result in inviable eggs

3.      With continued sterile male releases the population declines

4.      The ratio of sterile to normal males increases until virtually no normal males remain

5.      Population becomes extinct for lack of progeny

Release of sterile males in the ratio of 9:1 of the wild populations of male for successive generations results in the population reaching zero in F4 generations (This is called male sterile technique)

Methods of sterilization

A.    Ionizing radiation

Electromagenetic radiation such as gamma rays and X rays cause sterilization in insects. At 200-500 kiloroads (k rads) ionizing radiation brings about complete death. At 100 krads ionizing radiation causes sterilization and subsequent death. At 8-10 krads ionizing radiation causes sterilization

B.     Chemosterilants

 Chemicals which deprive insect species of their ability to reproduce chemosterilants are dangerous and carcinogenic or mutagenic.

They are classified into

a.      Alkalating agents.  E.g. TEPA and Metapa. Tepa 0.025% ina protein hydrolysate trap is used for sterilizing the  Mexican fruit fly.

b.      Antimetabolities.  E.g Amethopterin and

c.       Miscellaneous compounds. E.g. Hempa and Hemel. They are effective against housefly.

The chemosterilants could be applied in traps containing attractants, so that the lured insects pick up the chemical and sterilized.  Housefly, Mosquito, fruit fly, screw worm fly etc. are controlled by this male sterile technique.

3        INSECT GROWTH REGULATORS (IGRs)

IGRs are chemical that alter normal growth and development by interfering with the insect endocrine systems. Synthetic compounds possessing activities of juvenile hromone and moulting hormone of insects, often termed as ‘ miimics’ or insect growth regulants.

JH analogues (interfere with the growth and development)

1.       Methoprene (Altosid)   - JH analogue effective against many dipeterans (Mosquito larvae)

2.      Knioprene (Enstar) – JH analogue effective against whiteflies and mealy bugs.

Moulting inhibitors (inhibit chitin synthesis and moulting)

3.      Diflubenzuron (Dimilin)- Inhibits chitin synthesis and thus affects the moulting effectice agaisnt Le. 2 col. Insects.

4.      Buprofezin (Applaud) – Mould inhibitors effective agaisnt sucking pests (BPH)

5.      Lufenuron – Available as Match 5 EC or ‘ Rimon’ 10 EC (Especially for Helocverpa and Diamond Black moth)

Advantages : Low mamalion toxicity, environmentally compatible.

4. ATTRACTANTS (Kairomone)

                                                               Chemicals substances which elicit oriented movements by insects towards their sources are called attractants. These are mainly food attractants and oviposition attractants. Baits are prepared with these products and laced with insecticides to attract and kill insects. Example;

                                                   Methyl eugenol for fruit flies

                                                   Fish meal for shoot flies

                                                   Ricebran + jaggery for Spodaptera  larvae.

                                                   The pheromones are also attractants.

                                                  Advantages : Specific and thus no harmful effects.

5. REPELLENTS (Allomone)

                                                               Chemicals which cause insects to move away from their sources are called repellents. Repellents are usually volatile chemicals. Example;

                                                               Citronell oil   - mosquito repllent

Neem oil        - feeding and oviposition repellent for insects

Bordeaux mixture- was the first synthetic chemical repellent for chewing insects and leaf hoppers.

Advantages                              : Low toxicity to higher animals and no  resistance development

Disadvantages                         : Complete coverage required and possibility of increasing infestation near by.

6.      ANTIFEEDANTS OR FEEDING DETERRANTS (Allomone)

Chemicals which inhibit feeding of insects on a treated surface without necessarily killing or repelling them are called antifeedants. Antifeedants inhibit the taste receptors of mouth region and in the absence of gustatony stimulus, the insects fails to recognize the treated leaf as food.

Carbamate – Arprocarb is a systemic antifeedant against boll weevil,  Anthonomous grandis

Botanical extracts – Pyrethrum. Azadirachtin  and Many plant products / extracts are found to be repellents and antifeedants against many pests

NEWER INSECTICIDES / COMPOUNDS

I.                   Naturalytes

A.    Avermectins : They are discovered  from Streptomyces avermetilis by Merck & Co. . The analogue  Avermectin B1 (Commercially available as Abamectin) is insecticidally most active (systemic ). 

B.     Spinosyns : In 1994 Dow Elango – announced a new class of insect control active molecules called ‘ spinosyns’. They are naturally derived from a new species of Actinomycetes, Saccharopolyspora spinosa. Commercially available as spinosad. It shows both contact and stomach activity against different types of insects. Spinosad causes persistent activation of Ach receptors in the insect nervous system.

C.     Cartap hydrochloride: It is extracted from a marine annelid, Lumbriconereis heteropoda.It has systemic, contact and stomach poisons. It is effective against chewing and sucking pests. Commercially available as Caldan 50SP.

II.                 Neo nicotinoids

a.       Chlornicotynyl compounds

The chemical Imidocloprid (Bayer) is available as Goucho 70WS for seed treatment and Confidor 200SL for spray application.

b.       Thionictoynyl compounds

The chemical Thiomethozam (Syngenta)  is  available as Cruiser 70WS for seed treatment and Actara 25WG for spray application.

c.        Thionictoynyl compounds : Chemical is yet to come in this group

MOA : Neo nicotinoids bind the receptor portion of synape

III.             Organophosphates

a.      Profenofos

It is contact and stomach poison insecticide and also having translaminar in action. It is mainly targeted against suking pests, bollworms and mites in different crops. Commercially available as Curacron 50EC.

b.     Triazophos

It is an effective acaricide and targeted against sucking and chewing insects. It is contact and stomach poison. Commercially available as Hostathion 40 EC

c.       Carbamates: The following are the newer carbamates 

Indoxacarb                -           Avaunt 14.5 SC

Thiocarb                    -           Larvin 75 WP

Carbosulfan              -           Marshal 25 EC

These carbamates are contact and stomach poisons. Their effective against sucking and chewing insects.

d.     Synthetic Pyrethroids

The following are the two newer synthetic pyrethroids having contact and stomach poison. They are effective against sucking and chewing insects.

Lamda cyhalothrin              -           Karate 5 EC, Kungfoo 2.5 EC

Beta cyfluthrin                      -           Bulldock 0.25 SC

Lamda cyhalothrin is alo having phytotonic effect.

INTEGRATED PEEST MANAGEMENT

INTEGRATED PEEST MANAGEMENT

            " It is a broad ecological pest control approach aiming at best mix of all known past control measures to keep the pest population below ETL.

            It is the pest management system that utilizes all suitable techniques and methods in a compatible manner as possible and maintains pest populations at levels below those causing economic injury.

Why IPM?

            It is an economically justified and sustainable system of crop protection that leads to maximum productivity with the least possible adverse impact on the total environment.

Objectives of IPM  

v  To keep the pest numbers below ETL instead of their eradication.

v  To protect and conserve the environment including bio-diversity.

v  To make plant protection feasible, safe and economical even for the small farmers.

History

Ø  Chinese discovery of the use of soap to control pests in 1101 A.D.

Ø  Concept of plant resistance in 1700 s

Ø  In early 1900s rapid development of insecticides like DDT, organo phosphates etc.,

Ø  The insecticidal approach become a major preoccupation in pest control

Ø  The total use of pesticides was 434 tones in 1954 and now it is > 1,00,000 tons in 2000-2001

Ø  Pesticide usage solved pest problems initially but has given rise to development of resistance, resurgence, destruction of beneficial organisms, besides affecting human health and degrading quality of the environment.

Ø  After 1970s IPM gained momentum with the concept of integration of control techniques.

Strategies

Ø  Do nothing when pest densities are below ETL.

Ø  Reduce pest population numbers- usually when pest densities reach ETL

Ø  Reduce crop susceptibility to pest injury -most effective and environmentally desirable strategy HPR and environmental manipulation.

Ø  Reduce both population numbers and crop susceptibility.

Components IPM

            These are cultural, physical, mechanical, biological, HPR and insecticidal control methods.

Definitions of IPM

            The concept of 'IPM' from pest control has emerged during late 1960's. IPM is an ecologically based system approach by harmonious of carefully selected pest control practices based on economical and social consequences.

Smith, 1978 defined IPM as a multi-disciplinary ecological approach to the management of pest populations, which utilizes a variety of control tactics compatibly in a single coordinated pest management system.

Frisbie and Adikisson (1985) defined IPM as a pest population management system that utilizes all suitable techniques in a compatible manner to reduce pest populations and maintain than at levels below those causing economic injury.

Luckman and Metcalf (1994) defined IPM as the intelligent selection and use of pest control tactics that will ensure favourable economical, ecological and sociological consequences.

Objectives of Integrated Pest Management (IPM)

v  To keep the pest numbers below ETL instead of their eradication.

v  To protect and conserve the environment including bio-diversity.

v  To make plant protection feasible, safe and economical even for the small farmers.

Constraints (demerits) of IPM

v  Institutional constraints : like lack of coordination among faculties, institutional barriers to research scientists.

v  Informational constraints: Lack of IPM technology among farmers.

v  Sociological constraints: Coordinating of most farmers to use insecticides, lack of coordination in society.

v  Economic constraints: Farmers depend on shopkeepers or pesticide dealers for pesticides on credit and for information about the p

PESTICIDES AND THE ENVIRONMENT

Insecticide residues

The toxicant retained for sometime in the environment after application is called insecticide residues and the duration of retention is known as its persistence. Residue tolerances are permissible residues in terms of ppm of actual chemical in the products used by man and animals. The EPA (Environmental Protection Agency) of USA established tolerance level for various pesticides. For example for Malathion, it is 2 ppm in cotton and 8 ppm in vegetable; for carbaryl it is 5 ppm in cotton and 100 ppm in other crops.

Maximum Residue Level (MRL)

            Maximum concentration of pesticide residue in a produce resulting from pesticide usage accepted legally.

Acceptable Daily Intake (ADI)

            Daily Intake of a chemical, which, during entire life time, appears to be without appreciable risk, on the basis of all the facts known at the time. It is expressed in milligrams of the chemical per kilogram of body weight.

            ADIs and MRLs are not permanently fixed values. In India the MRL values for pesticides are prescribed under the Prevention of Food Adulteration Act, 1954.

Good Agricultural Practice:

            GAP (in the use of pesticides) is the officially recommended or authorized use of pesticides, under practical conditions.

 

Waiting periods

The time interval between the spray and harvest of the produces to avoid pesticide toxicity. It varies with insecticides. Normally it is 3 day for Malathion, 7 days for carbaryl and endosulfan and 15 days and above for Monocrotophos.

Environmental pollution

            Improper use of pesticides causes environmental pollution in different ways.  The contamination may be due to drift, leaching, and persistence in soil. The causes are;

1.      Use of non selective insecticide

2.      Non-adoption of application details and guidelines

3.      Not following ETL and indiscriminate use of insecticides.

4.      Choice of wrong dispersing aids.

Systemic poisons are the least contaminants of the environment as they are degraded quickly into harmless compounds. However, persistent Chlorinated hydrocarbons (OC) are mostly responsible for pollution.

Impact of Pesticides on Agroecosystem:

I. Abiotic Environment: Include soil, air and water.

1.      Soil: Source of contamination: Direct application; Fallout from plants; Rain

Reason for persistence: Resist biochemical and microbial degradation

Effect: Affect soil flora and fauna. Get into plants.

2.      Air: Source of contamination: Drift during conventional and aerial application; Volatilization; Thermal decomposition; Evaporation with water vapour.

      Effect: Inhalation toxicity; Enter into soil and water.

3.      Water: Source of contamination: Direct treatment; Surface run off; Aerial spraying; Precipitation.

      Effect: Biomagnification; Reduction of O₂ content; Toxic to fishes.

II. Plants

1.      Presence of residual amount – health hazard.

2.      Damage because of phytotoxicity

3.      Changes in the vegetative development – Etiolation by herbicide

III. Animals:

1.      Domestic Animals; Source: Forage treatment; Direct application

Effect: Chronic poisoning; Storage in fat reserves

2.      Wild Life: Trophic transfer of pesticides through food chain kill wild life eg. Egg shell thinning led non-vitality of bird eggs through D.D.T poisoning.

3.      Natural Enemies: Elimination of parasitoid and predators upset the biotic balance.

Effect:

i)                   Pest resurgence: Recovery of pest population following the application of insecticides to levels higher than before treatment. eg. BPH resurgence after quinalphos application.

ii)                 Secondary pest outbreak: Increase in the population of non-target insect to damaging levels followed by the application of pesticides due to the elimination of natural enemies of minor pests or potential pests eg. Red spider mite outbreak in apple followed by the application of organo chlorines.

4.      Pollinators: Pesticide application during blooming kill honey bees.

IV. Man

1.      Operational hazards: Manufacture – Distribution – Application – Post application.

2.      Accidental and intentional poisoning.

3.      Indirect hazards through food chain – Handigodu syndrome

4.      Diseases: Carcinogenic, Mutagenic and Teratogenic effects

V. Food:

Residues in human food – reason: Use of persistent chemicals; Spraying crops nearing harvest; Excessive use of pesticides.

VI. Target Insect:

Development of resistance to insecticides. Excessive use exert a high selection pressure in selecting resistant strains. eg. Mosquito resistance in DDT; Synthetic pyrethroid resistance in bollworms.

How to avoid pollution?

¨      Choose a selective insecticide

¨      Use only adequate dose

¨      Apply insecticides at a time when drift would be very minimum or nil

¨      Use non persistent soil insecticide whenever necessary

¨      Use sticker or spreader with insecticides

¨      Use correct spraying device

¨      Use an insecticide only when it is absolutely necessary

¨      Do not indulge in dipping the produce in a solution of pesticides

¨      Don't spray before harvest

¨      Don't wash spray equipments, cloths in pods, rivers, irrigation channels etc.,

PESTICIDE HANDLING AND USAGE

Compatibility                         

                                                               Compatibility is combination of insecticides to get higher protection without any adverse effect. As for as possible insecticides should not be mixed, because the mixtures may cause various reactions.

                                                   The incompatibility may be;

1.      Chemical incompatibility (different compounds are formed due to combination).

2.      Phytotoxic incompatibility (mixtures cause injury to plants) and

3.      Physical incompatibility (Physical from chemicals is changed)

Always we should have the compatibility charts.

Handling of pesticides and precautions

Before spraying

Ø  Use pesticides if pest has exceeded to ETL

Ø  Read instructions manual of pesticide and equipment

Ø  Ascertain that all components are clean and perfect

Ø  Test the sprayer for pumping, discharge etc.,

Ø  Calibrate the sprayer with proper nozzle.

Ø  Make sure that appropriate protective clothing is available

Ø  Ensure that soap. Towel, and plenty of water is available

Ø  Never work alone when holding highly hazardous pesticides

Ø  Mix chemicals outside or in a well ventilated area

Ø  Persons engaged in mixing, handling, or applying pesticides should not smoke, eat, or drink while working.

Ø  Don’t use mouth to siphon a pesticide from a container

Ø  Clean up spilled pesticides immediately from skin clothing

Ø  Always use gloves while mixing pesticides

During spraying

Ø  Take only sufficient pesticide for the day’s application from the store

Ø  Recheck the use instructions of pesticide and equipment

Ø  Mix the pesticide thoroughly in correct quantities

Ø  Wear appropriate clothing

Ø  Avoid contamination of the skin especially eyes and mouth’

Ø  Don’t spray in high wind, high temperature and rain

Ø  Spray along the wind, not against the wind

Ø  Never blow out clogged nozzles with mouth

Ø  Never allow children during mixing

Ø  Never leave pesticides un attended in the field

Ø  Newer allow cattle’s near by and never spray if the wind is blowing towards grazing livestock or pastures regularly used.

Ø  Follow correct spray technique and spray crop throughly.

After spraying

Ø  Dispose the pesticide containers in pits in waste lands.

Ø  Never empty the tank into irrigation canals or pods

Ø  Never leave unused pesticides in sprayer

Ø  After spraying clean the sprayer and oil it.

Ø  Don’t use empty containers for any purpose

Ø  Clean buckets, sticks, measuring jars etc.,

Ø  Wash protective clothing and take bath well and put on clean clothing.

Ø  Mark the sprayed plots with a flag

Ø  Keep a accurate record of pesticide usage

Pesticide poisoning and first aid

Pesticide poisoning can happen in

Ø  Deliberate consumption for suicidal purposes

Ø  Working in pesticide manufacturing units

Ø  Using pesticides in farm activities

Clinical features

                                                   OC compounds – Muscle twitching, fits, unconsciousness coma

                                                   OP compounds – Watering eyes, running nose, cough, breathlessness, vomiting,

diarrhea, abdominal pain.

Pyrethroids     - Muscle twitching fits.

First aid

Ø  Remove the victim from the site to fresh air

Ø  Look for the adequacy of breathing. If breathing is is inadequate take steps to restore normal breathing.

Ø  Remove all contaminated cloths and wash the body

Ø  Induce vomiting if swallowed

Ø  Don’t give alcohol in any form

Ø  Give strong tea or coffee

Ø  Take the patient for medical attention

Antidotes

A. General antidotes

a. Removal of poison: Remove poison by inducing  vomiting.

                                                   b. Universal antidote: A mixture of 7g of activated charcoal, 3.5 g of magnesium oxide and 3.5 g fo fannic acid in half glass of warm water to neutralize poisons.

a.      Gastric lavage (Removal of stomach contents): Do gastric lavage to remove poisons from the stomach

b.      Demulcents (Substances having soothing effect) :  After the stomach has been emptied, give raw egg white mixed with water or butter or  milk or cream or masked potato.

B. Specific antidotes

OC- If swallowed give universal antidote, followed by gastric lavage and then give magnesium sulphate in a glass of water, followed by hot tea or coffee. Inject 10 ml of calcium gluconate intravenously.

OP- Give Antropine. Administer artificial respiration in case of respiratory failure.

Advantages of Chemical control

Ø  Insecticides are only means of preventing economic damage

Ø  Insecticides are readily to use

Ø  A range of pesticides are available

Ø  Easy to adopt in larger areas

Ø  Work out under special conditions pest out break, pest complex

Ø  Assured income to farmers

Ø  Compatible with other components

Disadvantages of Chemical control

Ø  High cost

Ø  Toxic to natural enemy, bees etc.

Ø  Cause environmental pollution

Ø  Cause resistance and resurgence in insects

THIRD GENERATION PESTICIDES (BIORATIONALS)

1.      SEMIO CHEMICALS

Definition

                                                   Chemicals that deliver behavioural messages which act either interspecially or intraspecifically.

Interspecific semiochemicals

1.      Allomone -  Interspecific semiochemical that favours the produces  E.g. Repellents, Deterrents (feeding and ovipositional)

2.      Kairomone -  Interspecific semiochemical that favours the receiver E.g. attractants ‘ Food love”

3.      Synamone -  Interspecific semiochemical that favours both the producer and receiver E.g Plant odours attracting natural enemies of pests.

4.      Apneumone: Chemical from non-living materials eliciting behavioural response. E.g. Fish meal attracting sorghum shoot fly

Intraspecific semiochemicals

1.      Pheromone-  Semiochemical used for intraspecific communication which is an exocrine secretion that causes specific reaction in the receiving individuals of the same species.

2.      Sex pheromone- Female produce to attract males E.g. Bombyco (Bombyx mori) Cyplure (gypsy moth) and Gossyplure (Pink boll worm) ( In American boll weevil males produce)

3.      Alarm pheromone- Semiochemicals used to warm other fellow individuals from mandibular glands or anal glands. E.g. honey bees (E) B. Farnesene aphids.

4.      Trailmarking pheromone- Semiochemicals used in route perception. Eg. Ants, termites.

5.      Aggregation pheromone- Semiochemicals which attract other fellow members to a particular spot. E.g. Ferrolure of red palm weevil.

PHEROMONES IN INSECT PEST MANAGEMENT

                                                   The synthetic pheromones are used to monitor pest population attract and kill insects and confuse male from mating (mating disruption). Lures are available for following pests

1.      Helicoverpa armigera                    - Heli lure

2.      Tobacco caterpillar S. litura      - Spode lure/Pherodin SL

3.      Pink boll worm Pectinphora gossypiella – Pectinolure/Gossyplure

4.      Rhionceros beetle Orycetes rhinoceros – Sime RB  or Rhinolure

5.      Red palm weevil – Rhynchophorus ferrungineus – Ferrolure

6.      Spoted boll worm Eavis – Erin lure.

7.      β Farnescene (EBF) has been identified as alarm pheromone of aphids – Aphis gossypii.

The number of traps required for monitoring is  12 /ha.

 Set up at 1-2’ inch above the crop level

Types of pheromone trap 

1.      Funnel trap for mamy insects

2.      Sticky trap / delta trap for pink boll worm

3.      Bucket trap – red palm weevil & rhinoceros beetle

2.      STERILITY METHOD/ STERILANTS

Sterility method envisages the use of insects to bring down the population. Insects are used against members of their  own species to reduce the populations and hence called as autocidal control. Autocidal control received siginificance after E.F. Knipling, a USDA scientist in the 1950’s when the population of screw wormfly Cochliomyia homvinvorax, a parasite of cattle was eradicated in Curaca island in United State.

Principles of Autocidal control

1.      Flooding a population with sterile males which mate with normal females

2.      Such mating result in inviable eggs

3.      With continued sterile male releases the population declines

4.      The ratio of sterile to normal males increases until virtually no normal males remain

5.      Population becomes extinct for lack of progeny

Release of sterile males in the ratio of 9:1 of the wild populations of male for successive generations results in the population reaching zero in F4 generations (This is called male sterile technique)

Methods of sterilization

A.    Ionizing radiation

Electromagenetic radiation such as gamma rays and X rays cause sterilization in insects. At 200-500 kiloroads (k rads) ionizing radiation brings about complete death. At 100 krads ionizing radiation causes sterilization and subsequent death. At 8-10 krads ionizing radiation causes sterilization

B.     Chemosterilants

 Chemicals which deprive insect species of their ability to reproduce chemosterilants are dangerous and carcinogenic or mutagenic.

They are classified into

a.      Alkalating agents.  E.g. TEPA and Metapa. Tepa 0.025% ina protein hydrolysate trap is used for sterilizing the  Mexican fruit fly.

b.      Antimetabolities.  E.g Amethopterin and

c.       Miscellaneous compounds. E.g. Hempa and Hemel. They are effective against housefly.

The chemosterilants could be applied in traps containing attractants, so that the lured insects pick up the chemical and sterilized.  Housefly, Mosquito, fruit fly, screw worm fly etc. are controlled by this male sterile technique.

3        INSECT GROWTH REGULATORS (IGRs)

IGRs are chemical that alter normal growth and development by interfering with the insect endocrine systems. Synthetic compounds possessing activities of juvenile hromone and moulting hormone of insects, often termed as ‘ miimics’ or insect growth regulants.

JH analogues (interfere with the growth and development)

1.       Methoprene (Altosid)   - JH analogue effective against many dipeterans (Mosquito larvae)

2.      Knioprene (Enstar) – JH analogue effective against whiteflies and mealy bugs.

Moulting inhibitors (inhibit chitin synthesis and moulting)

3.      Diflubenzuron (Dimilin)- Inhibits chitin synthesis and thus affects the moulting effectice agaisnt Le. 2 col. Insects.

4.      Buprofezin (Applaud) – Mould inhibitors effective agaisnt sucking pests (BPH)

5.      Lufenuron – Available as Match 5 EC or ‘ Rimon’ 10 EC (Especially for Helocverpa and Diamond Black moth)

Advantages : Low mamalion toxicity, environmentally compatible.

4. ATTRACTANTS (Kairomone)

                                                               Chemicals substances which elicit oriented movements by insects towards their sources are called attractants. These are mainly food attractants and oviposition attractants. Baits are prepared with these products and laced with insecticides to attract and kill insects. Example;

                                                   Methyl eugenol for fruit flies

                                                   Fish meal for shoot flies

                                                   Ricebran + jaggery for Spodaptera  larvae.

                                                   The pheromones are also attractants.

                                                  Advantages : Specific and thus no harmful effects.

5. REPELLENTS (Allomone)

                                                               Chemicals which cause insects to move away from their sources are called repellents. Repellents are usually volatile chemicals. Example;

                                                               Citronell oil   - mosquito repllent

Neem oil        - feeding and oviposition repellent for insects

Bordeaux mixture- was the first synthetic chemical repellent for chewing insects and leaf hoppers.

Advantages                              : Low toxicity to higher animals and no  resistance development

Disadvantages                         : Complete coverage required and possibility of increasing infestation near by.

6.      ANTIFEEDANTS OR FEEDING DETERRANTS (Allomone)

Chemicals which inhibit feeding of insects on a treated surface without necessarily killing or repelling them are called antifeedants. Antifeedants inhibit the taste receptors of mouth region and in the absence of gustatony stimulus, the insects fails to recognize the treated leaf as food.

Carbamate – Arprocarb is a systemic antifeedant against boll weevil,  Anthonomous grandis

Botanical extracts – Pyrethrum. Azadirachtin  and Many plant products / extracts are found to be repellents and antifeedants against many pests

NEWER INSECTICIDES / COMPOUNDS

I.                   Naturalytes

A.    Avermectins : They are discovered  from Streptomyces avermetilis by Merck & Co. . The analogue  Avermectin B1 (Commercially available as Abamectin) is insecticidally most active (systemic ). 

B.     Spinosyns : In 1994 Dow Elango – announced a new class of insect control active molecules called ‘ spinosyns’. They are naturally derived from a new species of Actinomycetes, Saccharopolyspora spinosa. Commercially available as spinosad. It shows both contact and stomach activity against different types of insects. Spinosad causes persistent activation of Ach receptors in the insect nervous system.

C.     Cartap hydrochloride: It is extracted from a marine annelid, Lumbriconereis heteropoda.It has systemic, contact and stomach poisons. It is effective against chewing and sucking pests. Commercially available as Caldan 50SP.

II.                 Neo nicotinoids

a.       Chlornicotynyl compounds

The chemical Imidocloprid (Bayer) is available as Goucho 70WS for seed treatment and Confidor 200SL for spray application.

b.       Thionictoynyl compounds

The chemical Thiomethozam (Syngenta)  is  available as Cruiser 70WS for seed treatment and Actara 25WG for spray application.

c.        Thionictoynyl compounds : Chemical is yet to come in this group

MOA : Neo nicotinoids bind the receptor portion of synape

III.             Organophosphates

a.      Profenofos

It is contact and stomach poison insecticide and also having translaminar in action. It is mainly targeted against suking pests, bollworms and mites in different crops. Commercially available as Curacron 50EC.

b.     Triazophos

It is an effective acaricide and targeted against sucking and chewing insects. It is contact and stomach poison. Commercially available as Hostathion 40 EC

c.       Carbamates: The following are the newer carbamates 

Indoxacarb                -           Avaunt 14.5 SC

Thiocarb                    -           Larvin 75 WP

Carbosulfan              -           Marshal 25 EC

These carbamates are contact and stomach poisons. Their effective against sucking and chewing insects.

d.     Synthetic Pyrethroids

The following are the two newer synthetic pyrethroids having contact and stomach poison. They are effective against sucking and chewing insects.

Lamda cyhalothrin              -           Karate 5 EC, Kungfoo 2.5 EC

Beta cyfluthrin                      -           Bulldock 0.25 SC

Lamda cyhalothrin is alo having phytotonic effect.

INTEGRATED PEEST MANAGEMENT

INTEGRATED PEEST MANAGEMENT

            " It is a broad ecological pest control approach aiming at best mix of all known past control measures to keep the pest population below ETL.

            It is the pest management system that utilizes all suitable techniques and methods in a compatible manner as possible and maintains pest populations at levels below those causing economic injury.

Why IPM?

            It is an economically justified and sustainable system of crop protection that leads to maximum productivity with the least possible adverse impact on the total environment.

Objectives of IPM  

v  To keep the pest numbers below ETL instead of their eradication.

v  To protect and conserve the environment including bio-diversity.

v  To make plant protection feasible, safe and economical even for the small farmers.

History

Ø  Chinese discovery of the use of soap to control pests in 1101 A.D.

Ø  Concept of plant resistance in 1700 s

Ø  In early 1900s rapid development of insecticides like DDT, organo phosphates etc.,

Ø  The insecticidal approach become a major preoccupation in pest control

Ø  The total use of pesticides was 434 tones in 1954 and now it is > 1,00,000 tons in 2000-2001

Ø  Pesticide usage solved pest problems initially but has given rise to development of resistance, resurgence, destruction of beneficial organisms, besides affecting human health and degrading quality of the environment.

Ø  After 1970s IPM gained momentum with the concept of integration of control techniques.

Strategies

Ø  Do nothing when pest densities are below ETL.

Ø  Reduce pest population numbers- usually when pest densities reach ETL

Ø  Reduce crop susceptibility to pest injury -most effective and environmentally desirable strategy HPR and environmental manipulation.

Ø  Reduce both population numbers and crop susceptibility.

Components IPM

            These are cultural, physical, mechanical, biological, HPR and insecticidal control methods.

Definitions of IPM

            The concept of 'IPM' from pest control has emerged during late 1960's. IPM is an ecologically based system approach by harmonious of carefully selected pest control practices based on economical and social consequences.

Smith, 1978 defined IPM as a multi-disciplinary ecological approach to the management of pest populations, which utilizes a variety of control tactics compatibly in a single coordinated pest management system.

Frisbie and Adikisson (1985) defined IPM as a pest population management system that utilizes all suitable techniques in a compatible manner to reduce pest populations and maintain than at levels below those causing economic injury.

Luckman and Metcalf (1994) defined IPM as the intelligent selection and use of pest control tactics that will ensure favourable economical, ecological and sociological consequences.

Objectives of Integrated Pest Management (IPM)

v  To keep the pest numbers below ETL instead of their eradication.

v  To protect and conserve the environment including bio-diversity.

v  To make plant protection feasible, safe and economical even for the small farmers.

Constraints (demerits) of IPM

v  Institutional constraints : like lack of coordination among faculties, institutional barriers to research scientists.

v  Informational constraints: Lack of IPM technology among farmers.

v  Sociological constraints: Coordinating of most farmers to use insecticides, lack of coordination in society.

v  Economic constraints: Farmers depend on shopkeepers or pesticide dealers for pesticides on credit and for information about the pest control methods.

v  Political constraints: Subsidy by government for insecticides major constraints to farmers acceptance of IPM.

Potential (merits) of IPM

v  Sustainability

v  Economics -lower economic costs

v  Health - low health hazards

v  Environmental quality- environmental safety to non-targets organisms- no environmental pollution.

v  Social and political stability-through utilization of local inputs.

v  Local knowledge -indigenous farming, traditional cultivation, practices can also be integrated.

v  Export of agricultural commodities - produced through organic farming.

v  No chance for resurgence or resistance.

v  Well suited for rural areas.

 est control methods.

v  Political constraints: Subsidy by government for insecticides major constraints to farmers acceptance of IPM.

Potential (merits) of IPM

v  Sustainability

v  Economics -lower economic costs

v  Health - low health hazards

v  Environmental quality- environmental safety to non-targets organisms- no environmental pollution.

v  Social and political stability-through utilization of local inputs.

v  Local knowledge -indigenous farming, traditional cultivation, practices can also be integrated.

v  Export of agricultural commodities - produced through organic farming.

v  No chance for resurgence or resistance.

v  Well suited for rural areas.