| Abstract: | The actions of a number of pyrethroids upon the crural nerve, chordotonal organs and skeletal muscles of the desert locust were investigated. The compounds were principally 3-phenoxybenzyl esters (with or without an α substituent), and particular attention was given to fenvalerate and related compounds. Four different effects were observed, both during the early stages of intoxication of intact locusts and during perfusion of physiological preparations with low concentrations of the pyrethroids. The type of effect produced was determined by the molecular structure of the pyrethroid. Knockdown activity was associated with one particular effect, and it is suggested that it is the type of action caused by a pyrethroid, rather than its rate of penetration into the insect, that determines whether or not it will have knockdown activity. |
