Toxicity caused by pyrethroid pesticides mainly to the aquatic animals.

1. STRUCTURE AND TOXICITY OF
PYRETHROID PESTICIDES TO
AQUATIC ANIMALS
PREPARED BY: ISHITA MAJI

2. CONTENT
1.PYRETHROIDS AND PYRETHRINS
2. STRUCTURE & EVOLUTION OF PYRETHROIDS
3. CLASSIFICATION OF MODERN PYRETHROIDS:
TYPE-I & TYPE-II PYRETHROIDS
4. EFFECTS OF TYPE II PYRETHROIDS ON AQUATIC
ORGANISMS
(i) ACUTE TOXICITY
(ii) HAEMATOLOGICAL PARAMETERS
(iii) BIOCHEMICAL PARAMETERS

3. INTRODUCTION
 Pyrethrum’s insecticidal properties have been
known for over 150 years.
 Jumticoff discovered it’s use for the control of body
lice.
 In 1917, the U.S. military made the first pyrethrum
extracts.
Chrysanthemum
flower

4.  The commercial limitations of pyrethrum -pyrethrins
 High rate of photodegradation and a short "knockdown"
effect
 The advantages of pyrethrins and pyrethroids –
highly lipophilic
short half-life in the environment
low toxicity to terrestrial vertebrates
do not biomagnify

5. How do pyrethroids kill insects?

6.  pyrethroids are used in India on a large scale
under different trade names (Roy 2002).

7. STRUCTURE AND EVOLUTION OF
PYRETHROIDS
 ‘Pyrethroid’ -designate a synthetic insecticide
 Pyrethrins are esters of a cyclopropanecarboxylic acid
and a cyclopentenolone alcohol
 Structures of the six natural pyrethrins

8. Essential features of pyrethroid structure –
activity relationships
 Permethrin proved to be the first synthetic pyrethroid

9. CLASSIFICATION OF MODERN
PYRETHROIDS: TYPE-I & TYPE-II
PYRETHROIDS
 Pyrethroids are categorized according to their structure
and toxicology(Schleier and Peterson 2011).
Type I
Type II
Type-I (without α-cyano
group)
Permethrin
Type-II (with α-cyano group)
Cypermethrin

10. TYPE I TYPE II
Lacking the α-cyano group on the
phenoxybenzyl moiety
Those with a α-cyano group on
the phenoxybenzyl moiety
Compounds are generally
considered to produce the T
syndrome of intoxication
Compounds are considered to
produce the CS syndrome
(Lawrence and Casida, 1982).
Not so potent in depolarizing the
nerves
More potent toxicant in
depolarizing the nerves
Type I pyrethroids modify the
sodium channels in the closed
state
While type II pyrethroids modify
the open but not inactivated
sodium channels.
Not so potent (Thatheyus and
Deborah GnanaSelvam 2013).
More potent enhancers of Ca2+
influx and glutamate release
under depolarizing conditions

12. Types of synthetic pyrethroids:

13. EFFECTS OF TYPE II PYRETHROIDS ON AQUATIC
ORGANISMS
ACUTE TOXICITY
o Not toxic to any terrestrial vertebrate ?
o toxic to fishes
o Deltamethrin - first Type II group pesticide
o Cypermethrin
o Fenvalerate -lipophilicity

14. HAEMATOLOGICAL PARAMETERS
o Total erythrocyte count, total leucocyte count, and
haemoglobin and haematocrit content in major indian
carps - found to decrease on cypermethrin exposure .
o Decrease in hemoglobin content, total erythrocyte count,
packed cell volume, mean corpuscular volume, and
mean corpuscular hemoglobin concentration and an
increase in total leukocyte count, mean corpuscular
volume, erythrocyte sedimentation rate, and clotting time
-exposed to deltamethrin
o Acute toxicity of fenvalerate remains persistent for a
long duration in air breathing cat fishes.

15. BIOCHEMICAL PARAMETERS:
o Chronic effects of pyrethroids - growth retardation,
behavioral, blood profile and histopathological changes,
compromised immune system and endocrine disruption
– DELTAMETHRIN
o Significant inhibition of AChE (Acetylcholine esterase)
and elevation of acetylcholine content in all tissues viz.
gill, brain, liver and muscle of Cyprinus carpio with
response to exposure of technical grade cypermethrin

16. o Cypermethrin was also reported to cause significant
alteration in the levels of ammonia and urea in
freshwater fish, C. mrigala
o Fenvalerate-induced changes in the activity and
isoenzyme pattern of lactate dehydrogenase (LDH) in
the liver, gill, muscle and brain of the freshwater teleost,
Oreochromis mossambicus
o Exposure to fenvalerate gradually decreased the activity
of glucose-6-phosphate dehydrogenase in brain, liver
and skeletal muscle up to 21 days

17. Toxicity studies on the effects of type-II pyrethroids on various fish
species

18. REFERENCES
O Lawrence L. J. and Casida J. E. (1982), Pestic. Biochem
.Phvsiol., 18, 9.
O Prusty A.K., Meeena D.K., Mohapatra S., Panikkar P.,
Das P., Gupta S. K., Behera B.K. Synthetic pyrethroids (
Type II) and freshwater fish culture : perils and
mitigations. Int Aquat Res (2015) 7:163-191
O Roy. N. K (2002) Chemistry Of Pesticides, CBS
Publishers, New Delhi.
O Schleier III, J.J. and Peterson, R.K (2011) Pyrethrins and
pyrethroid insecticides, In Lopez, O and Fernandez-
Bolanons, J.G (eds), Green Trends in Insect Control, pp
94-121, Royal Society of Chemistry London.
O Thatheyus A.J., Debrorah GnanaSelvam A (2013)
Synthetic pyrethroids : toxicity and biodegradation ,
Applied ecology and environmental Sciences.,Vol. 1. No.
3, 33-36