Botanical insecticides and their future perspectives

By,Bharati Singh

Characteristics of botanical insecticides

• Fast breakdown, Fast action

• Phyto toxicity, selectivity

• IPM friendly, cost and availability

Just because a pesticide is natural, does not mean it is safe

Limonene and linalool

• Extracted from orange and other

citrus fruits

• Limonene , a terpene, and purified

by steam distillation

• Linalool, a terpene alcohol, found

in small quantities in citrus peel

d- limonene

• Limonene often applied with PBO (pyperonil butoxide)

• Target pests: Fleas, aphids, mites, flies, paper wasp

• Mode of action:

• Act as nerve toxin and stomach poisons(limnonene)

• Affects ion transport and release of acetyl choline esterase(linalool)

Rotenone

• Isolated from the roots of two tropical legumes Lonchocarpus or Derris

• Extremely toxic to fish

Root of the Tuba

roots of the legume family (Fabaceae).

Rotenone structure

Deguelin structure

• Target pests: caterpillers, aphids, suckers and other pests found in fruits and vegetables , certain beetles

• Mode of action- inhibits the electron transport chain in the mitochondria

Electron Transport Chain

Rotenone’s safety is somewhat controversial

Sabadila

• Extracted from the seeds of the sabadilla

lilly (Schoenocaulon officinale)

• cevadine + veratridine = veratrine

2 : 1

White hellebore

S. Officinale

Mode of action• Similar to that of the pyrethrins as it affects

the voltage dependent sodium channels of nerve axons.

• Veratridine causes an increase in the duration of the action potential

Ryania

• Obtained from the roots and stems of a South American herbs (R. speciosa)

• contain alkaloids with insecticidal activity, collectively known as ryanoids

mode of action • Slow acting stomach poison• Block neuromuscular junction

Most active ryanoid is ryanodine and 9,21-dehydroryanodine

Ryanodine

Neuromuscular junction

Future Perspectives

• Botanical insecticides (BI) were major weapons (before 1940’s)

• Use of BI in California grew by almost 50% between 2006 and 2011

• Quite logical to expect coexistence of the two kinds of compounds i.e synthetic and natural insecticides

• Barrier to commercialization

scarcity of natural resources

standarization and quality control

Regulatory approval

References• Dayan et al (2009), Bioorganic and medical chemistry 17, 4022- 4034, Natural

products in crop protection

• Isman (1997) Phytoparasitica 25 (4): 339-344, Neem and other botanical insecticides:Barriers to commercialization

• Isman, Annu. Rev. Entomol.2006.51:45-66

• Martina et al, Agriculturae conspictus scientificus .Vol. 78 (2013) No .2 (85-93),Botanical insecticides in plant protection

• Nikoletta et al, pesticides laboratory,Pesticides of botanical origin: A promising tool in plant protection

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