Detoxifying enzymes and the effects of temperature on the toxicity of malathion to Oncopeltus fasciatus (Heteroptera) and Tenebrio molitor (Coleoptera)

Punzo, Fred; Kirk, A.

doi:10.1016/0742-8413(92)90025-3

Cited by 3 publications

(2 citation statements)

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“…Insects have been observed to recover even weeks after insecticide poisoning 19. The KD 50 values determined for the insecticides used were very close to the LD 50 values reported elsewhere for susceptible strains of other insects, including coleopteran, heteropteran and dipteran species 20. 21…”

Section: Discussionsupporting

confidence: 78%

“…The difference in tolerance was about fourfold in respect of paraoxon‐methyl and far greater in the case of malaoxon, since a dose sufficient to knock down 50% of the pupae was never reached. Punzo and Kirk20 have also reported the pupal stage of T molitor to be the most tolerant to malathion. Stage‐dependent susceptibility has been observed in several insects 22.…”

Section: Discussionmentioning

confidence: 95%

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The role of glutathione S‐transferases in the detoxification of some organophosphorus insecticides in larvae and pupae of the yellow mealworm, Tenebrio molitor (Coleoptera: Tenebrionidae)

Kostaropoulos

Papadopoulos

Metaxakis

et al. 2001

Pest Management Science

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The correlation between the natural levels of glutathione S-transferase (GST) and the tolerance to the organophosphorus insecticides parathion-methyl and paraoxon-methyl, as well as the interaction of affinity-purified enzyme and the insecticides were investigated in order to collect further information on the role of the glutathione S-transferase system as a mechanism of defence against insecticides in insects. The studies were carried out on the larvae and pupae of the coleopteran Tenebrio molitor L, which exhibit varying natural levels of GST activity. Stage-dependent susceptibility of the insect against insecticides was observed during the first 24 h. However, 48 h after treatment, the KD50 value increased significantly due to the recovery of some individuals. Simultaneous injection of insecticide with compounds which inhibit GST activity in vitro caused an alteration in susceptibility of insects 24 or 48 h post-treatment, depending on stage and insecticide used. Inhibition studies combined with competitive fluorescence spectroscopy revealed that the insecticides probably bind to the active site of the enzyme, thus inhibiting its activity towards 1-chloro-2,4-dinitrobenzene in a competitive manner. High-performance liquid chromatography and gas chromatography revealed that T molitor GST catalyses the conjugation of the insecticides studied to a reduced form of glutathione (GSH). From the above experimental results, it is considered that GST offers a protection against the organophosphorus insecticides studied by active site binding and subsequent conjugation with GSH.

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Section: Discussionsupporting

confidence: 78%

Section: Discussionmentioning

confidence: 95%