The document discusses botanical pesticides derived from plants, highlighting their advantages, disadvantages, and specific examples like neem, nicotine, pyrethrum, sabadilla, and rotenone. Each example includes details on chemical properties, modes of action, effectiveness, and potential safety issues, emphasizing their roles in pest management and environmental impacts. Overall, botanical pesticides are portrayed as safer alternatives to traditional chemicals, with considerations for their efficacy and limitations.

1. Botanical Pesticides
By- Yuvraj Singh

2. Botanicals:
Toxicants or chemicals derived from plants parts like leaves,
stems, roots, seeds etc which are used in insect pest and disease
control
Ex. Neem products, Nicotine, Ryania, Rotenone and Pyrethrum
A botanical pesticide is a type of bio pesticide formulation made
up of crude plant extracts or purified compound of plant species
for managing pest and diseases.
• Extracted from plants
• Broad spectrum pesticides
• Low environmental persistence
• Low residual value
• Degrade very fast under the sunlight

3. Advantages:
• Do not leave harmful residues
• Cheaper than chemical
• Safe to user, environment and non target sp.
• Safe for insect enemies – predator, parasitoids
• Prevent resistance and resurgence
Disadvantages:
• Not true pesticides
• Readily degraded by UV rays or sunlight
• Slow speed of action
• High specificity
• Effective period is less – low self life

4. 1. Azadirachtin (Neem): Azadirechta indica
• Almost every part of the tree is bitter and finds its application in
indigenous medicine.
• The refined and purified neem seed oil has many therapeutic
properties.
• Considerable quantities of oil are used in cosmetic preparations.
• The neem cake after oil recovery is used for slow release of
nitrogenous fertilizers.
• Extracts from the neem tree have been reported to control over 200
types of insects, mites, and nematodes.

5. 1.1. Chemical Structure

6. 1.2. Properties:
• Neem oil contains limonoids, a class of compounds that act as
antifeedants or growth regulators in insects.
• They do not kill instantly but wipe out a whole generation of
insects by preventing the young ones from maturing and the
adults from reproducing.
• The most effective of the limonoids is a compound called
azadirachtin.
• The neem spray solution should not be exposed to sunlight and
must be prepared with water having a temperature between 50
and 90°F.
• The solution is effective for only 8 hours after mixing.
• Neem is most effective under humid conditions or when the
insect and plants are damp.
• It has a low toxicity to mammals.

7. 1.3. Mechanism:
• It is similar to the insect hormone ecdysone, which is needed for
moulting during insect development.
• It works at a concentration of 1-10 ppm by blocking ecdysone’s
action, thereby preventing the larvae from shedding their external
skeletons and maturing.
• It also prevents feeding in about 200 insects at a concentration of
10-100 ppm.
• A number of neem formulations are being produced by small-scale
formulators and marketed as insecticides.
• Neemguard, Margocode, Nimbicidine, Neemplus, Sukrina,
Achook etc.

8. 2. Nicotine: Tabacco (T. sativum)
It is the principal alkaloid in tobacco which is very poisonous.
An alkaloid may be defined in general as a naturally occuring
heterocyclic, optically active nitrogenous base of relatively high
molecular weight and having marked physiological activity.

9. 2.1. Properties:
• Nicotine (C10 H14 N2).
• Its chemical name is I-methyl-2,3 (pyridyl) pyrrolidine.
• Nicotine is found in the leaves of Nicotinana tabacam and N.
rustica in the range of 2 to 14 per cent.
• Among the twelve alkaloids present in tobacco nicotine is the
most important one contributing about 97 per cent
• And the other two of insecticidal value are
(i) Nornicotine (C9 H12 N2) 2-(3-pyridyl pyrrolidine)
(ii) Anabusine (Neonicotine, 3-(2-piperdyl) pyridine.

10. 2.2. Chemical Structure

11. 2.3. Mode of action:
In both insects and mammals, nicotine is an extremely
fast-acting nerve toxin.
• It competes with acetylcholine, the major neurotransmitter, by
bonding to acetylcholine receptors at nerve synapses and causing
uncontrolled nerve firing.
• This disruption of normal nerve impulse activity results in rapid
failure of those body systems that depend on nervous input for
proper functioning.
• In insects, the action of nicotine is fairly selective, and only certain
types of insects are affected.
• Nicotine is a fast acting contact killer for soft bodied insects, but
does not kill most chewing insects.
• It is less effective when applied during cool weather.
• Do not spray within 7 days of harvest.
• Commonly sold as 40% Nicotine sulphate concentrate.

12. 3. Pyrethrum : Chrysanthemum cinraerifoilum
• The insecticidal principle in pyrethrum is found in the flower heads
of certain plants of chrysanthemum genus, family compositeae.
• Pyrethrin is a fast acting contact poison derived from the pyrethrum
daisy.
• It is very toxic to cold blooded animals.
• Some people and most cats have allergic reactions to it.
• Pyrethrin is effective on most insects, but does not control mites.
• It rapidly breaks down in sunlight, air and water.
• the term “pyrethrins” refers to the six related insecticidal
compounds that occur naturally in the crude material, the
pyrethrum flowers.
• They are extracted from crude pyrethrum dust as a resin that is used
in the manufacture of various insecticidal products.

13. 3.1. Chemical Structure

15. 3.2. Mode of action:
• Pyrethrins exert their toxic effects by disrupting the sodium and
potassium ion exchange process in insect nerve fibers and
interrupting the normal transmission of nerve impulses.
• Pyrethrins insecticides are extremely fast acting and cause an
immediate “knockdown” paralysis in insects.
• Despite their rapid toxic action, however, many insects are able to
metabolize (break down) pyrethrins quickly.
• After a brief period of paralysis, these insects may recover rather
than die.
• To prevent insects from metabolizing pyrethrins and recovering
from poisoning, most products containing pyrethrins also contain
the synergist, piperonyl butoxide (PBO).
• Without PBO the effectiveness of pyrethrins is greatly reduced.

16. 4. Sabadilla (veratrine alkaloids):
Schoenocaulon
officinale
Source :
• Sabadilla is derived from the ripe seeds of Schoenocaulon officinale, a
tropical lily plant which grows in Central and South America.
• Sabadilla is also sometimes known as cevadilla or caustic barley.
• When sabadilla seeds are aged, heated, or treated with alkali, several
insecticidal alkaloids are formed or activated.
• It is a broad spectrum contact poison, but has some activity as a
stomach poison.
• It is most effective against true bugs such as harlequin bugs and
squash bugs.
• Sabadilla degrades rapidly in air and sunlight, and has little residual
toxicity.
• It is very toxic to honey bees.

18. 4.1. Chemical Structure

19. 4.2. Mode of action:
• In insects, Sabadilla’s toxic alkaloids affect nerve cell membrane
action, causing loss of nerve cell membrane action, causing loss of
nerve function, paralysis and death.
• Sabadilla kills insects of some species immediately, while others
may survive in a state of paralysis for several days before dying.
• Sabadilla is effectively synergized by PBO or MGK 264

20. 5. Rotenone: Lonchocarpus sp. And Derris
sp.
• Source: Rotenone is insecticidal compound that occurs in the roots
of Lonchocarpus species (Cube Root) in South America, Derris species
in Asia, and several other related tropical legumes.
• Rotenone is extracted from cube roots in acetone or ether.
• Extraction produces a 2-40% rotenone resin which contains several
related but less insecticidal compounds known as rotenoids.
• The resin is used to make liquid concentrates or to impregnate inert
dusts or other carriers.
• cube roots may be dried, powdered and mixed directly with an inert
carrier to form an insecticidal dust.

21. Lochocarphus plant and roots

22. 5.1. Roteneone chemical structure

23. 5.2. Properties:
• It has a short residual.
• Rotenone is a broad spectrum poison mainly used to control leaf-
eating caterpillars and beetles.
• Direct contact may cause skin and mucous membrane irritation.
• It is more toxic when inhaled.
5.3. Mode of action:
• Rotenone is a powerful inhibitor of cellular respiration( the
process that converts nutrient compounds into energy at the
cellular level).
• In insects rotenone exerts its toxic effects primarily on nerve and
muscle cells, causing rapid cessation of feeding.
• Death occurs several hours to a few days after exposure.
• Rotenone is extremely toxic to fish, and is often used as a fish
poison (piscicide) in water management programs.
• It is effectively synergized by PBO or MGK 264.

24. Generic Name Oral LD50 Dermal LD50 Signal Word
Pyrethrins 1,200-1,500 >1,800 Caution
Rotenone 60-1,500* 940-3,000 Caution
Sabadilla 4,000 — Caution
Ryania 750-1,200 4,000 Caution
Nicotine 50-60 50 Danger
d-Limonene >5,000 — Caution
Linalool 2,440-3,180 3,578-8,374 Caution
Neem 13,000 — Caution