Introduction to Pyrethroid Insecticides:
Chemical Structures, Properties, Mode
of Action and Use
Ò. Aznar-Alemany and E. Eljarrat
Contents
1 History and Impact . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . . 2
2 The Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3 Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . 4
4 Metabolisation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
5 Toxicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
6 Legislation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Abstract During the 1920s, pyrethrin was studied because of its potential as a
precursor for synthetic organic pesticides. The first pyrethroid pesticide, allethrin,
was identified in 1949. It is a type I pyrethroid because of a carboxylic ester of
cyclopropane. Type II was created with the addition of a cyano group in α position.
Some phenylacetic 3-phenoxybenzyl esters missing the cyclopropane but with the
cyano group are also considered type II. In the 1970s, pyrethroids transitioned from
mere household products to pest control agents in agriculture. Later, pyrethroids
have replaced organophosphate pesticides in most of their applications the same way
the latter had replaced organochlorinated pesticides before. Works on the optimisation of pyrethroids has granted them better photostability without compromising
their biodegradability, as well as selective toxicity, metabolic routes of degradation
and more effectivity, translating into the use of smaller amounts. Most pyrethroids
present different isomers, each with different biological activity and, therefore,
different toxicity. Pyrethroids account for a quarter of the pesticides used nowadays.
Pyrethroids’ relative molecular mass is clearly above 300 g mol
À1
; they are highly
hydrophobic, photosensitive and get easily hydrolysed, with degradation times
below 60 days. They are not persistent and mammals can metabolise them.
Ò. Aznar-Alemany (*) and E. Eljarrat
Department of Environmental Chemistry, IDAEA-CSIC, Barcelona, Spain
e-mail: oscar.az.al@gmail.com
Ethel Eljarrat (ed.), Pyrethroid Insecticides,
Hdb Env Chem (2020) 92: 1–16, DOI 10.1007/698_2019_435,
© Springer Nature Switzerland AG 2020, Published online: 22 February 2020
1
Chemical Structures, Properties, Mode
of Action and Use
Ò. Aznar-Alemany and E. Eljarrat
Contents
1 History and Impact . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . . 2
2 The Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3 Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . 4
4 Metabolisation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
5 Toxicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
6 Legislation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Abstract During the 1920s, pyrethrin was studied because of its potential as a
precursor for synthetic organic pesticides. The first pyrethroid pesticide, allethrin,
was identified in 1949. It is a type I pyrethroid because of a carboxylic ester of
cyclopropane. Type II was created with the addition of a cyano group in α position.
Some phenylacetic 3-phenoxybenzyl esters missing the cyclopropane but with the
cyano group are also considered type II. In the 1970s, pyrethroids transitioned from
mere household products to pest control agents in agriculture. Later, pyrethroids
have replaced organophosphate pesticides in most of their applications the same way
the latter had replaced organochlorinated pesticides before. Works on the optimisation of pyrethroids has granted them better photostability without compromising
their biodegradability, as well as selective toxicity, metabolic routes of degradation
and more effectivity, translating into the use of smaller amounts. Most pyrethroids
present different isomers, each with different biological activity and, therefore,
different toxicity. Pyrethroids account for a quarter of the pesticides used nowadays.
Pyrethroids’ relative molecular mass is clearly above 300 g mol
À1
; they are highly
hydrophobic, photosensitive and get easily hydrolysed, with degradation times
below 60 days. They are not persistent and mammals can metabolise them.
Ò. Aznar-Alemany (*) and E. Eljarrat
Department of Environmental Chemistry, IDAEA-CSIC, Barcelona, Spain
e-mail: oscar.az.al@gmail.com
Ethel Eljarrat (ed.), Pyrethroid Insecticides,
Hdb Env Chem (2020) 92: 1–16, DOI 10.1007/698_2019_435,
© Springer Nature Switzerland AG 2020, Published online: 22 February 2020
1