the ppt provide information about agrochemicals

1. Dr Anita Sharma
Assistant Professor, Entomology

2.  AGROCHEMICALS ; A chemicals which is used increase
the agriculture production such crop Protectors and Soil
supplements are called as “Agrochemicals”
 Agrochemicals were introduced to protect crops from pests
and enhance crop yields

3.  An optimum nutrient level is essential for
productive agriculture. Nutrients can be supplied
either by natural sources or in the form of synthetic
chemical fertilizers. However, the use of both
natural and chemical fertilizers may result in an
excess of nutrients, which can cause problems in
water bodies and to health. This excess use of
various fertilizers may pollute food crops and
groundwater; this process is commonly called
agrochemical pollution

4. Agrochemical
Crop protectors Soil supplements

5. Crop
protectors
Pesticides
Insecticide
s
Herbicides
Fungicides
Algacides
Nematicid
es
Soil
supplements
Fertilizer
Hormones
Growth
agents
liming and
acidifying
Agent

6.  Pesticides: Pesticide is a chemical or a substance used to
destroy or control some types of plants or organisms also
known as pests, which are harmful to cultivated plants or
to animals.
 Insecticides: It is used to destroy insects. Insecticides can
be ovicides that kill eggs, larvicides to kill larvae.
Pesticides examples: Organochlorines, organophosphates,
carbamates, and pyrethroids.
 Herbicides: It is used to control or kill weeds and herbs.
Herbicides examples: Gramoxone and glyphosate.
 Algaecides: used for controlling algae. Also known as
algicides.

7.  Fertiliser: This are chemical compounds used for
promoting plant growth.
 Fertiliser can be categorized into two categories:
Organic
And Inorganic fertilisers.
 Organic fertilisers are naturally existing substances
prepared through natural processes.
 Inorganic fertilisers, also referred to as synthetic fertilizers
are manufactured artificially using chemical processes by
utilizing natural deposits, which are altered chemically.

8.  HORMONES/GROWTH AGENTS :
 Are of Endogenous origin and are synthesised by plants.
 These are Growth regulators performing function in
overall development of the plant
 Liming and acidifying agents:
Soils sometimes can be too acidic or too alkaline for proper
growth of crops. In these cases, liming and acidifying
products are added to soil to adjust its pH. When the soil is
too acidic, calcite on the form of powdered limestone is
added primarily, whereas for more alkaline soil sulfur
compounds are added to neutralize.

9. 1. Effects on soil:
 May kill beneficial bacteria
 Increase nitrate level in soils
 Alter the pH of the soil
 Residual effect
 Kill soil organisms
 Toxicity and reduction in soil quality

10. 2. Effects on water:
 Water becomes unfit for consumption
 Can promote the growth of algae
 Leads to eutrophication due to excessive
chemicals
 Affect aquatic animals due to water pollution

11. 3. Effects on air:
 Residues and particles of these chemicals can
lead to air pollution.
 Pesticides drift happens when air carries
agrochemicals particles from one place to
other.
 More amount of spray evaporation may
happen due to low relative humidity and
higher temperatures.
 Effect surrounding organisms’ health due to
inhalation of polluted air.

12. 4. Effects on human health:
 It causes variety of health effects, from
simple skin and eyes irritation.
 It also effects the nervous system, causes
cancer and also reproductive problems.
 Can cause nerve damage, infertility,
hormones disorders and neurotoxicity.

13.  AIR POLLUTION:
 The pesticides/ herbicides/ insecticides which
are suspended in the air contribute to air
pollution, when they are carried away to other
areas due to wind.
 The phenomenon is also known as pesticide drift.

14.  WATER POLLUTION:
 It refers to pollution of water bodies such as
ponds, lakes or rivers due to unintended mix up of
synthetic herbicides/ fungicides/ pesticides
 SOIL POLLUTION:
 It generally occurs when many of the pesticides/
insecticides/ herbicides is used for a prolonged period
of time which adversely affects the soil quality and
therefore polluting it.

15. Merits and demerits of Agrochemicals

16. Organochlorine Pesticides
This group consists of, the polychlorinated derivatives of cyclohexane
(Lindane), polychlorinated biphenyls (DDT, dicofol) and polychlorinated
cyclodiene (Endosulfan).
DDT was first synthesized by O. Ziedler in 1874 and insecticidal properties
was discovered by Paul Muller in 1939.
Properties
Physical: Solids which possess low volatility
Low solubility in water
High solubility in oils, fats,lipids etc.,
Not prone to environmental degradation.
Chemical: Isomerism is a common phenomenon,
Ex. Gamma HCH Stable over a wide range of pH
Toxicity: Possess a high acute toxicity as well as chronic toxicity
Compound LD50 (oral) mg/Kg
HCH 1000
Dicofol 684-809
Lindane 88-91
Endosulfan 70-110

17. Biological stability: Not rapidly degraded by the enzyme, not rapidly
exerted, but get stored in the fatty tissues.
Behaviour in the field: These chemicals are non systemic, act as contact
and stomach poisons. Lindane exhibits slight fumigant action. Persist in the
environment for long time, results in pesticide residue problem in the
environment and bio magnification.
Effect of OC’s in the environment: Insecticides can kill bees, pollination
decline and the loss of bees that pollinate plants, and colony collapse
disorder (CCD).
A number of the organochlorine pesticides have been banned from most
uses worldwide, and globally they are controlled via the Stockholm
convention on persistent organic pollutants. (POP’s)
These include: aldrin, chlordane, DDT, dieldrin, endrin,heptachlor, mirex
and toxaphene, endosulfan also banned in the country from 2011.

18. Organo phosphorous pesticides
These are the esters of derivatised phosphoric acid, thiophosphoric acid
and dithio phosphoric acids which are called phosphates, thiophosphates
and dithiophosphates respectively. Some of the examples of each class of
pesticides are as follows:
Group Example
i. Phosphates - Monocrotophos,phosphamidon, DDVP
ii. Thiophosphates or - Methyl parathion, fenitrothion,
Phosphorothiate oxy demeton methyl
iii. Dithiophosphates or
phosporodithioates - Dimethoate, phorate, Phosalone
Based on the organic moiety attached to the phosphoric acid these
grouped can also be classified in to aliphatic, phenyl and heterocyclic
derivatives.

19. Properties
Physical: These compounds are available as liquids or semi solids and
posses significant vapour pressure and comparatively volatile. Some
compounds have slight solubility in water (MCP and Phosphamidon are
soluble in water). Sunlight brings about modification of the toxicity of
these molecules either way. Some of insecticide show systemic action Eg.
Schradan (1st OP).
Chemical: These compounds which are esters of phosphoric acid are not
stable in alkaline pH, but stable over narrow range of pH. Thiophosphates
and dithiophosphates undergo molecular rearrangements. Forms isomers
with increased toxicity( (may take place in storage as well as on application
in the field) and under go oxidation to give oxo compounds with increased
toxicity. Sulphur atoms in side chain may be oxidised to sulfoxide or
sulfones which more toxic than parent molecule.
The organo phosphorous pesticides under go conversion of one pesticide
in to another pesticides also takes place. The following are some of the
examples.
Trichlorfon Dichlorvos
Formothion Dimethoate
Acephate Methamidophos

20. Toxicity:
Exhibits acute extreme toxicity to slight toxicity (Phorate1.5 to 3.7
mg/Kg, temephos 8600mg/Kg). LD50 values may change with the purity
of the compound (as the impurities present some times are more toxic
than the parent compd.) and they do exhibit low chronic toxicity. The
undergo rapid conversion in to low fat soluble metabolites which are
excreted.
Biological stability: The OP compounds undergo enzymatic degradation
and the metabolites are fat insoluble and easily excreted. Bio
magnification is almost absent and chronic toxicity is in significant
Behaviour in the field: Some of the OP compounds show systemic activity
and chemicals like dichlorvos exhibits fumigant action too. Persists for
shorter duration and do not pose environmental problem like organo
halogen pesticides.

21. Classification of OPS
1. Phosphorohalides and cyanides:They are commonly known as nerve gases
because they used in the form of mist. E.g. sarin, tabum and soman.
2. Phosphorothioates: This group are converted to phosphates in the insect
body and become much toxic. E.g. Malathion, Phorate, Dimethoate,
Disulfoton, Methyl parathion (Banned from 2018)
3. Phosphates: e.g. Dichlorvos, Monocrotophos, Phosphamidon
4. Phosphorothionate: Chlorpyriphos (for termite control), Quinalphos,
Diazinon
5. Phosphorothiolate: e.g. Oxydemeton-methyl
6. Phosphoroamidate: e.g. Acephate, Schradan, phosphoran
The Ops which have systemic actions are-
Dichlorvas, Monocrotophos, phorate (Banned from 2018), oxydemeton
methyl, schradan, phosphamidan.

22. Carbamates
The Carbamates are esters of either carbamic acids or thiocarbamic acids.
And the Carbamates may be further subdivided in to three sub-groups as
given under,
Group Example
i. Aryl N methyl carbamate Carbaryl, Propoxur
ii. Hetero cyclic mono or
dimethyl Carbamates Carbofuran
iii. carbamoylated oximes Methomyl
iv. Thiocarbamates Cartap hydrochloride
(Neriestoxin group of insecticide)
Properties :
Physical : The organo carbamates are available as non volatile solids.
carbaryl, carbofuran have very low water solubility (40-6000ppm) where
as Cartaphydrochloride is hygroscopic. And these compounds under go
degradation by the environmental factors

23. Chemical : These compounds are unstable in alkaline medium.
Toxicity: The OC compounds exhibit moderate to extreme toxicity. And they
do not display chronic toxicity.
Carbaryl -Moderately toxic
Propoxur and cartap- Highly toxic
Methomyl & carbofuran -Extremely toxic
Biological stability :The OC compounds undergo enzymatic degradation and
rapidly metabolised and excreted. Bio magnification is almost absent and
Chronic toxicity is in significant.
Behaviour in the field:
Carbaryl (banned from 2018) & Propoxur - contact pesticides
Carbofuran, methomyl & - systemic pesticides
Cartap
Methomyl is well taken up by leaves
Carbofuran is well taken up by the roots (soil applied) Widely used carbamates
for borers and also for nematodes.
Cartap is taken by both roots and leaves.

24. Insect Growth Regulators
The possibility that JH analogs may have potential as insect control was
first recognized by Williams (1965). The compounds showing JH activity,
‘Juvenoids’. Four types of JHs (JH= 0, I, II, and III) are known with their
structural variations.
JH-0 is known from the eggs of Manduca sexta only.
JH-I & JH-II are from all lepidopterans and are said to be morphogenetic in
action i.e to retain the larval characters.JH-III present in all insect orders
and are said to be gonado tropic i.e. for stimulating the ovaries to mature
in the female.
Juvenile hormone analogs and mimics when applied to an insect, an
abnormally high level of juvenilizing agent will produce another larval
stage or produce larval-pupal intermediates.
Juvenoid IGRs can also act on eggs, can cause sterilization, disrupt
behavior and disrupt diapauses.

25. Mode of Action
i) Antimorphic effect: Do not allow Metamorphosis to take palace there by
forcing larva to continue as a larva. Therefore if the Juvenoids are
provided exogenously the larvae will undergo an extra larval moult
(change in to super larva) or moult in to defective intermediate forms
which may suffer from a failure to successfully moult, feed or mate.
ii) Larvicidal effect
iii) Ovicidal effect.
iv) Diapause disrupting effect
v) Embryogenesis inhibiting effect.
 Juvenoids acts as ovicides when applied directly on eggs and indirectly
on ovipositing females. They block embryogenic development of
blastokinesis stage. When applied before hatching, they show
morphogentic effect at the time of metamorphosis. They inhibit
ecdysone synthesis by effecting prothorasic glands. If applied to the last
instar larvae, they could prevent pupa from entering in to diapause.
They could terminate pupal diapause by activating the inactive PTG of
diopausing pupa.
Juvenoids:
i) Juvabione (Fernesol - extracted from excreta of Tenebrio sp)
ii) Methoprene (Altosid ) (iii) Hydroprene (Gentrol, Altozar (iv) Kinoprene
(Enstar)

26. Anti-juvenile hormone
Anti JH agents cancel the effect of juvenile hormone, an early instar treated
with an anti-juvenile hormone molts prematurely into a nonfunctional
adult. Some of the examples are methoprene, kinoprene, hydroprene,
pyreproxyfen, fenoxycarb etc.
Precocenes are the compounds which would antagonize the JH activity
and dearrange the insect development. These compounds induce the
precocious metamorphosis of immature insects. Precocenes affect insect
diapause, reproduction and behaviour. These compounds first extracted
from the plant Ageratum houstonium. It contains two simple chromene
compounds precocene –I and II. 1)
 Fenoxycarb (Insegar 50 % WP, Award,Comply Logic, Torus, Pictyl and
Varikill) @ 0.025 %
 Pyriproxyfen (Tiger 10 % EC, Distance, Esteem, Archer Knack, Sumilarv
and Admiral) @ 0.0125 %

27. Ecdysone or Moulting Hormone
(MH) Agonists MH contains two hormones, α -Ecdysone and β - Ecdysone.
The α - ecdysone is a prohormone produced by PTG which is converted into
β - ecdysone in the peripheral tissues of the gland and is also called 20-
Hydroxy Ecdysone, which actually brings about molting in insects and is the
true MH.
Synthetic analogues of ecdysones are called ecdysoids .After absorption into
haemolymph it binds the ecdysone receptor proteins which initiates moulting
process .The normal moulting process is disrupted. Larvae is prevented from
shedding of old cuticle and it will die due to dehydration and starvation.
a) Tebufenozide (Mimic, Confirm and Romdan) b) Halofenozide (Mach)
c) Methoxyfenozide (Prodigy), chromafenozide, difenolan etc.

28. Chitin synthesis inhibitors
Chitin synthesis inhibitors disrupt molting by blocking the formation of
chitin, the building block of insect exoskeleton. Without the ability to
synthesize chitin, molting is incomplete, resulting in malformed insects
that soon die. It suppresses egg-laying and causes egg sterility in treated
adults through secondary hormonal activity.

29. Name & Mode of action Tradename &Formulation LD50 mg/kg
Diflubenzuron: Stomach and contact
poison that acts by inhibiting chitin
synthesis so it interferes with formation of
cuticle.
Dimilin 25 WP 4640
Flufenoxuron : Broad spectrum Insect and
mite growth regulator with contact and
stomach action.
Cascade 10 WDC 3000
Chlorfluazuron: Chlorfluazuron is used in
subterranean termite baiting stations.
Atabron 5 SC 8500
Triflumuron: Broad spectrum Insect growth
regulator
Alsystin , Baycidal
Starycide25 WP
>5000
Teflubenzuron: It is effective against
Lepidoptera, Coleoptera, Diptera,
Hymenoptera Aleyrodidae, and Psyllidae
Nomolt,Dart, Nemolt 15
SC
2250
Novaluron: It acts mainly by ingestion, but
has shown some contact activity. It does
not have ovicidal activity, but a high
percentage of mortality of first instars
hatching from eggs laid on sprayed foliage
occurs.
Rimon 10 EC 5000
Buprofezin: Contact and stomach,
persistent chitin synthesis inhibitor with
miticidal action. Effective against
Applaud 25 SC, 70 WP 2198