1. Ripha International University, Lahore Campus
Pesticides By
Dr. Tahir Ali
Ripha International University, Lahore Campus

2. Introduction
Pest is any animal, plant or microorganism that causes trouble, injuries or destruction; therefore, pesticide may be defined simply as chemical agents used to control or eliminate pest. OR
A pesticides is any toxic substance used to kill animals or plants that cause economic damage to crop or ornamental plants or are hazardous to the health of domestic animals or humans.

3. Introduction Conti…
Many kinds of insects transmit serious diseases, such as malaria and typhus. Some insects destroy or cause heavy damage to valuable crops, such as corn, cotton, wheat and rice. Other common pests include bacteria, fungi, rats and such weeds as ragweed and poison ivy.
An understanding of genesis of pest status is important in the design and execution of pest control strategies incorporating the substance of natural origin.
Worldwide, the traditional pesticide represents the big business in which the majority of the synthetic pesticides are utilized for agriculture or other purposes.

5. Types of pests
Rodents
Arthropods
Weeds
Fungi
Mollusk

6. Rodents
Rodents are mammals like rat, mouse, rabbit and monkey ,which have sharp gnawing incisor teeth. In some stores the crude drugs are often contaminated due to fecal pallets and hair from the fur of rats and mice. Rodents are responsible for transmitting diseases from which they are suffering. Biting of rat causes rat-bit fever, an infectious disease caused by microorganisms. A large number of lice infected rodents transmit typhus fever, bubonic plague, and rat leprosy.

7. Arthropods
Arthopods are insects, spiders, ticks, mites, and lice. Some of these cause discomfort only, while other cause fatal diseases. Insects represent the class of the phylum Arthopoda and according to their mouth parts they are divided into two morphologic groups:
Biting and chewing, and
Piercing and sucking
The insect of first category are dependant on the leaves and stems of plants. They are present in excess number to strip a cultivated field. Grasshoppers and locusts destroy the crop during the developmental process and after maturity stages. Tomato horn worms and army worms cause destruction during larva or caterpiller stage.

8. Weeds
Any undesirable plant is known as weed. A weed may be a dandelion in a lawn, a thistle plant in a vegetable garden or mustard in a clove field.
Undesirable plants in gardens interfere in the growth of cultivated plants by consuming most of the available water contents and minerals of the soil.
Weeds grow and flourish in the condition of much sunshine, ample moisture and well-fertilized soil which are provided for cultivation of some ornamental plants and vegetables.
If weed allow to grow , they will soon acquire possession of the garden and gradually destroy the more delicate, cultivated plants. Similarly, the quality of the field crops, specially grains, become poor due to presence of weed seeds.

10. Weeds (Conti..)
A considerable number of weed are toxic in nature. Corn cockle, Agostemma githago, contains a cyanophore type of glycoside, and its seeds cause death when they are present in excessive quantities in wheat flour. A large number of plants give rise to allergic reaction in certain individuals. Once a person has been sensitized to a particular allergen , subsequent exposure to the materials produces an antigen-antibody reaction which results in the liberation of histamine or identical compounds causing allergic symptoms.

12. Fungi parasitic on plants
Various type of fungi growing on plants produces many diseases such as
Wheat rust,
White pine blister rust ,
Dutch elm disease,
Hollyhock rust,
Asparagus rust
Rose rust.

14. Mollusk including Gastropods
The Gastropoda or gastropods, more commonly known as snails and slugs, are a large  taxonomic class within the phylum Mollusca. The class Gastropoda includes snails and slugs of all kinds and all sizes from microscopic to large. There are many thousands of species of sea snails and sea slugs, as well as freshwater snails, land snails and land slugs.

15. METHODS OF PEST CONTROL

16. Biological Controls
Nature is full of the example of prey–predator relationships.
E.g. Ladybugs :- These common insects consume aphids, mites, whiteflies and scale. 
Cats, owls, and hawks are enemies of mice and rats.
Certain flies and wasps lay eggs on the body of large destructive insects like slow moving larvae.
Microorganisms may be used to kill by causing fatal disease in insects. For example, Bacillus thuringiensis selectively kills only larvae of butterflies and moths

17. Environmental method By changing environmental conditions of pest
E.g. Mosquito larvae in water are killed by spreading a layer of oil.

18. Agriculture method
Agriculture control is the oldest in its approach. Deep plugging for the eradication of weeds and early stages of insects, alternate crop rotation or changing environmental conditions are some methods that leads to obstruction of the life cycle of pests.
Nowadays advanced plant breeding techniques like hybridization, mutation, and biotechnological manipulations are greatly used for the production of pest resistant species.

19. Mechanical control
Mechanical control: It employs manual labour as well as mechanical devices for collection or destruction of pest.
Techniques, such as handpicking, pruning, trapping and burning are employed for the destruction of eggs, larvae, pupae and adult insects.

20. Chemical controls
Chemical controls: Chemical agents are the major pesticides agents used for the control of pest throughout the world.
These are the materials used for the purpose of killing pests or for protecting crops, animals or other properties against the attack of the pest.
Insect repellents, attractants, fumigants like insecticides, parasiticides are used for killing mites, ticks, and sterilizing agents which employ radioisotopes or chemicals to interfere with reproductive capabilities are nowadays widely used.

21. ESSENTIALS OF A GOOD PESTICIDE
1. A pesticide should have a high margin of safety for plants and animal causing very little or no damage to the foliage or livestock, respectively. 2. It should be safer. 3. It should be easier to handle and easy for application. 4. It should not show toxicity in case of warm blooded animals. 5. It should not have flammable or explosive character. 6. It should have safety and palatability of the food products exposed to insecticides and should not show the residual effects of pesticides. 7. It should be available easily at affordable cost.

22. CLASSIFICATION of Pesticides
Pesticides are classified according to the pest they control. The four most widely used types of pesticide are :
Rodenticides
Insecticides
Herbicides
Fungicides

23. Other types

24. 1. Rodenticides
These agents are used especially in urban areas where rats and other rodents are a major problem.
Warfarin-related compounds: Warfarin ,Coumarins
Thallium
Sodium monofluoroacetate
Strychnine
Zinc phosphide
Yellow phosphorus
Arsenic
Alpha-naphthyl-thiourea (ANTU) 
DDT (dichloro-diphenyl-trichloroethane) 
Norbomide

25. RODENTICIDES Red squill:
Red squill and white squill are both varieties of Urginea maritima (Liliaceae). The red squill may be distinguished in either the whole or powdered state by the reddish- brown outer scales and the white to deep purple inner ones.
In addition to other cardioactive glycosides, the bulb of the red squill also contains the glucosides scilliroside and scillirubroside.
Unlike other mammals rodents do not regurgitate the squill bulb, and death follows convulsions and respiratory failure.

26. 2. Insecticides
Farmers use insecticides to protect their crops from insect damage.
In urban localities, public health officials use these chemicals to fight mosquitoes and other insects.
Insecticides are widely utilized in homes and other outdoor conditions to control such pests as ants, moths, cockroaches and termites.

28. PYRETHRUM FLOWERS Synonym Biological Source
Insect flowers, Pyrethrum flowers.
Biological Source
dried flower heads of:
Chrysanthemum cinerariaefolium
Family: Composite

29. Cultivation and Collection
Pyrethrum is a perennial plant propagated by seeds and pieces of stems bearing roots known as splits.
Attitude of 1,900–2,700 m and an annual rainfall of 76–180 cm.
First collection of flower heads is made after about 4 months, but the best time for collection is when two-third of the disc florets are open.
Collection is generally done by hand pickers at roughly 3-week intervals.
The flowers are dried immediately after collection in the sun or in drying chambers at a temperature not exceeding 50°C.
In Kenya, after gradation, the flowers are compressed into bales and exported.
The flowers are directly exported or made into powder or standard liquid extract.

31. Characteristics
Pyrethrum flowers have a slight aromatic odour and a bitter acrid taste. It is interesting to note that before drying the flower heads are not toxic to insect.
The powder of pyrethrum flowers shows the presence of parenchymatous tissues, with aggregate crystals, sclerenchymatous tissues, t-shaped hairs and spherical pollen grains.
Dried flowers or powder should be stored in wellclosed container, protected from air and light and should not be kept for more than two years.
Pyrethrum extract is comparatively more stable than pyrethrum flowers.

32. Chemical Constituents
Pyrethrum flowers have its insecticide properties due to two groups of esters: the first group consists of:
Pyrethrin I
Jasmolin I
Cinerin I
Second group of esters:
Pyrethrin II
Jasmolin II
Cinerin II

33. Uses
Pyrethrum brings about its pesticide activity by an instantaneous knock down action on insects within few seconds.
It has no appreciable effect on insects as a stomach poison but acts by contact, producing a characteristic effect on the nervous system that results in muscular excitation, convulsion and paralysis.
Pyrethrum is widely used in domestic and agricultural insecticidal sprays, dusting powders and aerosol preparations for controlling a variety of garden pests ,lice and ticks on pets.
A noninflammable preparation is used as a spray in aircraft to kill insect vectors and so prevent the transmission of insect borne diseases.

34. DERRIS ROOTS Synonym Derris roots, Tuba roots Biological Source
Derris root consists of the dried rhizomes and roots of Derris elliptica
Family: Leguminoseae.

35. Chemical Constituents
Derris roots contains about 3–10% of a flavone derivative, rotenone. It is colourless to brownish crystalline compound or a white to brownish white odourless tasteless crystalline powder. It is insoluble in water but soluble in alcohol, acetone and other organic solvents.

36. Uses
Derris is a widely used agricultural and horticultural insecticide and larvicide. It is a contact and stomach poison.
Its action is more persistent but less rapid than pyrethrum.
The insecticidal preparations of rotenoids at concentrations ranging from 0.75 to 1.0% are effective against a wide range of insects, such as Mexican bean beetle, cabbage worms, leaf hoppers and other insects attacking a variety of vegetable.

37. TOBACCO Synonym Tobacco. Biological Source
dried leaves of Nicotiana tabacum
Family Solanaceae.
Geographical Source
Tobacco is indigenous to tropical America. It is cultivated on large scale in China, United States and India. It is also produced in Brazil, Turkey, Russia, Italy, India and Pakistan.

38. Curing
Tobacco is subjected to curing by any of the three procedures, namely
flue curing,
sun curing
air curing,
which modifies the aroma and flavour characteristics of tobacco. Loss of nicotine during flue-curing is negligible but sun-curing causes considerable loss of nicotine content.

39. Characteristics
Tobacco is a crop which is mostly used for the preparation of Cigarettes, bidi, cigar, cherrot, hookah, snuff and chewing tobacco. Nicotine is the characteristic alkaloid prepared commercially from waste material of tobacco industry.
Nicotine is a colourless to pale yellow, very hygroscopic, oily liquid with an unpleasant pungent odour and a sharp burning persistent taste. It gradually becomes brown on exposure to air or light. It is soluble in water, alcohol, chloroform, kerosene and fixed oils. It should be stored in airtight containers.

40. Chemical Constituents
Levels of nicotine content in various tobacco types vary drastically, but it is in the range of about 1–10% .Nicotine is a pyridine–pyrolidine group of alkaloid mainly responsible for its pesticidal activity.
Along with nicotine, tobacco leaf has several other alkaloids especially nornicotine and anabasine which may have some insecticidal properties in association with nicotine.

41. Uses
Nicotine acts by its triple action insecticidal property, acting as stomach, contact and fumigant poison.
Its free base is more toxic than the sulphate or hydrochloride salt. It is mostly effective against minute soft bodied insects, such as aphides and also against white flies, red spidermites, leaf rollers, moths, fruit tree borers, termites, cabbage butterfly larvae, etc.
One of the advantages of the insecticidal use of nicotine is its high margin of safety for plants. Nicotine preparations are safer, easier to handle and much less toxic to warmblooded animals.

42. RYANIA Synonym Ryania. Biological Source
Ryania consists of the roots and stems of Ryania speciosa
Family  Flacourtiaceae.
Geographical Source
Ryania is indigenous to South America.
Collection
The roots and stem of Ryania are collected after flowering and fruiting. It is the most expensive material and is not as readily available as rotenone or pyrethrin.

43. Chemical Constituents
Ryania contains about 0.16–0.2 % of alkaloids. Ryanodine is the major pyrrole alkaloid that is esterified with a complex polyhydroxy diterpenoid.

44. Uses
Ryania extracts containing the alkaloid ryanodine are used as insecticide for various lepidopterous larvae which attacks fruits. It is also used for controlling moths and corn borer.
It is toxic to fish.

45. 3. Herbicides
The groups of pesticide agents control weeds or eliminate plants that grow where they are not wanted. OR
A substance that is toxic to plants, used to destroy unwanted vegetation.

46. Classification Selective herbicides Non-Selective herbicides
Pre-emergence herbicides
Emergence herbicides
Soil applied herbicides
Foliar applied herbicides

47. Selective & Non-Selective herbicides
Selective herbicides: They control or suppress certain plants without affecting the growth of other plants species. Selectivity may be due to translocation, differential absorption, physical (morphological) or physiological differences between plant species. 2,4-D (2,4- dichlorophenoxyacetic aic), mecoprop, dicamba control many broadleaf weeds.
Non-selective herbicides: These herbicides are not specific in acting against certain plant species and kill all plant material with which they come into contact. They are used to clear industrial sites, waste ground, railways and railway embankments. Paraquat, glufosinate, glyphosate are non-selective herbicides

48. Preemergence & Postemergence
Preemergence: Preemergence herbicides are applied before the weed seedlings emerge through the soil surface. Herbicides do not prevent weeds from germinating but they kill weeds as they grow through the herbicide treated zone by affecting the cell division in the emerging seedling. Dithopyr and pendimethalin are preemergence herbicides.
Postemergence: These herbicides are applied after weed seedlings have emerged through the soil surface and generally require multiple applications for adequate control. They can be foliar or root absorbed, selective or nonselective, contact or systemic. Liquid formulations of herbicides are more effective than granular formulations. 2,4-D is a selective, systemic, foliar absorbed postemergence herbicide

49. Foliar-Applied Herbicides
Foliar-Applied Herbicides - Foliar-applied herbicides are applied directly to the weeds and kill them primarily by being absorbed into the foliage. For this reason, they are often referred to as contact herbicides. In addition, some of the contact herbicides have a relatively short-lived soil activity.
Exp:  Glyphosate, 2,4-D and dicamba

50. Soil-Applied Herbicides
Soil-Applied Herbicides - As the name implies, soil applied herbicides are applied to the soil, although some require incorporation into the soil. They are carried into the soil by water and absorbed by the roots of weeds. These herbicides effectively control weeds for a few weeks to several months, with the exact time depending on the particular herbicide, rate and time of application, weather and type of soil. Because of this long-term residual effectiveness, soil-applied herbicides are sometimes referred to as residual herbicides. Examples of soil-applied herbicides currently used by Christmas tree growers include simazine, atrazine, pronamide and hexazinone.

51. 4. Fungicides
Many of the fungi are pathogenic and many infect both plants and animals including human beings. Fungicides are used to control fungal diseases of plants and food crops. Most disinfectants used in homes, hospitals and restaurants contain fungicides.
Neem products
Copper sulphate
Tea tree oil
Cinnamaldehyde
Citronella oil
Jojoba oil
Rosemary oil

52. Other types of pesticide