Jm. Wierenga et Rm. Hollingworth, INHIBITION OF ALTERED ACETYLCHOLINESTERASES FROM INSECTICIDE-RESISTANT COLORADO POTATO BEETLES (COLEOPTERA, CHRYSOMELIDAE), Journal of economic entomology, 86(3), 1993, pp. 673-679
Insecticide-resistant and susceptible strains of the Colorado potato b
eetle, Leptinotarsa decemlineata (Say), were assayed to confirm the oc
currence and define the specificities of altered acetylcholinesterases
. Organophosphate and carbamate insecticides caused widely varying deg
rees of inhibition, with no clear pattern of cross-resistance. In all
strains, oxime carbamates were 5- to 10-fold less potent acetylcholine
sterase inhibitors compared with arylcarbamates. One strain was relati
vely insensitive to inhibition by eserine (4-fold). Acetylcholinestera
ses exhibited the highest insensitivity to the insecticides used to se
lect for resistance in each strain. Acetylcholinesterase from one stra
in was insensitive to carbamates, and that from the other strain was i
nsensitive to organophosphates. Inhibition curves were typically nonli
near, indicating the presence of multiple acetylcholinesterase activit
ies. Penetration studies showed no differences between strains in upta
ke of carbofuran.