During the past two decades, resistance to pyrethroids within the cattle tick genus Boophilus has caused tick control problems in various tropical countries, mainly in Latin America, southern Africa, Australia, and New Caledonia. A Rhipicephalus (Boophilus) microplus (Canestrini) strain from Costa Rica, exhibiting resistance to the pyrethroid deltamethrin but only a very low resistance to organ...

In both tetrodotoxin-resistant (TTX-R) and tetrodotoxin-sensitive (TTX-S) sodium channels, deltamethrin greatly prolonged the current during step depolarizing pulse and caused a large and prolonged slow tail current. The activation was shifted by 20 mV in the hyperpolarizing direction. These changes in channel kinetics account for the prolongation of action potential, membrane depolarization an...

To explore if trypsin could catalyze the degradation of non-protein molecule deltamethrin, we compared in vitro hydrolytic reactions of deltamethrin in the presence and absence of trypsin with ultraviolet-visible (UV/Vis) spectrophotometry and gas chromatography-mass spectrometry (GC/MS). In addition, acute oral toxicity of the degradation products was determined in Wistar rats. The results sho...

Acaricide resistance is a major problem that hinders the control of the tropical cattle tick, Rhipicephalus (Boophilus) microplus (Canestrini), in many parts of the world where cattle production continues to suffer severe economic losses to tick infestation. Deltamethrin and amitraz have been used alone to control R. microplus in New Caledonia for the past decade, and tick populations have deve...

The pyrethroid insecticide-deltamethrin [(S)-alpha-cyano-3-phenoxybenzyl-(1R)-cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane carboxylate] is widely used throughout the world in agricultural applications. It is also used to treat humans, thereby creating a possible public health concern. The toxic effects of deltamethrin in mammals include choreoathetosis, hyperexcitability and salivation. Th...

The in vivo effects of deltamethrin on Helicoverpa armigera cytochrome 450s were investigated by the measurements of cytochrome P450 content and two enzymatic activities. Deltamethrin showed dose-, tissue-, and exposure way-specific effects on cytochrome P450 monooxygenases, ranging from induction to repression. Topical deltamethrin (0.1 and 1.0 g insect) significantly decreased cytochrome P450...

In the present study we identified the degeneration and apoptotic cell death in rat brain after deltamethrin treatment. By hematoxylin-eosin (H&E) staining, a large number of degenerative cells (pyknosis of nuclei, disruption of eosinophilic cytoplasm) were seen in the hippocampus and cortex at 24 and 48 h after deltamethrin treatment at a dose of 12.5 mg/kg (i.p.) in corn oil. The similar morp...