Action of major insecticide groups on insect cell lines of the beet armyworm, Spodoptera exigua, compared with larvicidal toxicity.
In a first series of experiments, the biological response of a continuous cell line of the beet armyworm, Spodoptera exigua, was tested with different groups of insecticides with different modes of actions: acetylcholinesterase inhibitors, acetycholine receptor agonists, inhibitors and uncouplers of oxidative phosphorylation, site I electron transport inhibitors, gamma-aminobutyric acid receptor inhibitors, chitin synthesis inhibitors, and juvenile hormone analogues. From the concentration response curves, 50% inhibition concentration (IC(50)) values were calculated. The most active compound in vitro was pyridaben with an IC(50) value of 0.0083 ppm. In a second series of experiments, the toxicity of these insecticide groups was determined on third-instar larvae of S. exigua, and lethal concentration with 50% kill (LC(50)) values were used in the evaluation of their in vivo biological activity. Toxicity bioassays showed that lufenuron was the most toxic (LC(50) = 0.098 ppm). To explain the discrepancies in biological responses in vitro with insect cells compared with in vivo conditions with whole third-instar larvae, the significance of different detoxifying enzyme systems was tested. P(450) monooxygenases, esterases, and glutathione S-transferases were measured in third-instar larvae and cells of S. exigua. Data are discussed in terms of the usefulness of insect cell cultures as tools in the screening for novel insecticide actions.
Decombel
Luc
L
Laboratory of Agrozoology, Department of Crop Protection, Faculty of Agricultural and Applied Biological Sciences, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium. luc.decombel@ugent.be
Smagghe
Guy
G
Tirry
Luc
L
D000818:Animals; D001681:Biological Assay / Q000379:methods; D002460:Cell Line / Q000187:drug effects*; D006801:Humans; D007300:Insect Control / Q000379:methods; D007306:Insecticides / Q000494:pharmacology / Q000633:toxicity; D007814:Larva / Q000187:drug effects* / Q000378:metabolism; D007928:Lethal Dose 50; D018411:Spodoptera / Q000187:drug effects* / Q000502:physiology
D007306:Insecticides