[Pyrethroid resistance in human lice (Anoplura, Pediculidae): toxicological and molecular genetic methods].

The paper gives the data obtained in toxicological experiments versus analysis by a real-time polymerase chain reaction assay in permethrin-resistant human lice (VSSC1 gene kdr mutations leading to the amino acid replacements T9171 and L920F have been found). It is shown that the results of toxicological experiments may be indirectly indicative of the genetic composition of a study sample of lice.

[Peculicidal activity of plant essential oils and their based preparations].

The peculicidal activity of eight plant essential oils in 75% isopropyl alcohol was in vitro investigated. Of them, the substances that were most active against lice were tea tree (Melaleuca), eucalyptus, neem, citronella (Cymbopogon nardus), and clove (Syzygium aromaticum) oils; KT50 was not more than 3 minutes on average; KT95 was 4 minutes. After evaporating the solvent, only five (tea tree, cassia, clove, anise (Anisum vulgare), and Japanese star anise (Illicium anisatum) oils) of the eight test botanical substances were active against lice. At the same time, KT50 and KT95 showed 1.5-5-fold increases. Citronella and anise oils had incomplete ovicidal activity. Since the lice were permethrin-resistant, the efficacy of preparations based on essential oils was much higher than permethrin.

[Pyrethroid resistance mechanisms in the body lice Pediculus humanus humanus L.: detoxification enzyme systems].

Synergists (piperonyl butoxide, MGK-264 (N-octyl bicycloheptene dicarboximide), DEF (S, S, S, tributyl phosphorotrithioate), and diethylmaleate) were used to investigate the metabolic resistance of body lice to permethrin. Instances of the synergistic activity ofpermethrin when combined with enzyme system inhibitors have been identified. The synergic ratios were 3.3 to 52.0 for monooxygenase inhibitors; 5.2 to 7.4 for esterases, and about 4 for glutathione-S-transferases. Since the use of the synergists did not lead to full inhibition of resistance, it was concluded that the lice had also a kdr-like type of resistance.

[Comparative activity of different groups of insecticides against permethrin-resistant lice (anoplura: pediculidae)].

The activity of insecticides (CK50, CK95 ) from different chemical classes against permethrin-resistant body and head lice was investigated. Having developed resistance to pyrethroids (permethrin, d-phenothrin, cypermethrin, and deltamethrin), the lice remain susceptible to organophosphorus compounds, phenylpyrazoles, neonicotinoids, and avermectins. The susceptibility of lice to the insecticides having a mechanism of action that is different from that of pyrethroids does not depend on the level of their resistance to permethrin.

[The systemic effects of imidacloprid and fipronil on Xenopsylla cheopis fleas (Siphonaptera) and blood-sucking Ornithonyssus bacoti gamasid mites (Gamasina: Macronyssidae)].

The systemic effects of imidacloprid and fipronil on Xenopsylla cheopis fleas and blood-sucking Ornithonyssus bacoti gamasid mites were studied under laboratory conditions. Albino rats were forcibly administered insectoacaricides per os in doses of 1, 10, 30 mg/kg or fed with dietary bait (the doses of fipronil and imidacloprid were 10-33 and 18-70 mg/kg/day, respectively) for 3 or more days. Fipronil had a pronounced systemic effect on both X. cheopis and O. baconi. Imidacloprid was markedly active against the fleas and, on the contrary, inactive against the mites.

[Insecticide resistance in lice collected from homeless people in Moscow].

Permethrin and malathion resistance in body and head lice collected from homeless people in Moscow was investigated in March 2009 to March 2010. Most micropopulations were found to have permethrin-resistant individuals. Their proportion varied from 8.7 to 100%. Cross resistance of body lice to 5 insecticides (the pyrethroids permethrin, d-phenothrin, cypermethrin, deltamethrin, and the organic chlorine compound DDT) was revealed in one case. The lice remained susceptible to organic phosphorus insecticides (fenthion, malathion). The data on permethrin resistance in the lice, obtained by the standard method (immersion of the insects into an insecticide solution), correlated with those yielded by the modified WHO method.

[Interaction with esterases and mechanism of synergistic action of thio- and dithiophosphates containing the fragments of N-acylated glycine and beta-alanine]. / Vzaimodeistvie s ésterazami i mekhanizm sinergisticheskoi aktivnosti tio- i ditifosfatov, soderzhashchikh fragmenty N-atsilirovannykh glitsina i beta-alanina.

We studied the interaction between O,O-diethyl-S-[(N-acyl-N-alkoxycarbonylalkyl)aminomethyl]thiophosphates and mammalian cholinesterases as well as esterases from insect tissue extracts by kinetic methods and disc electrophoresis. The coefficients of combined effect of these compounds or their dithioanalogs with permethrin were determined. The obtained data suggest that the synergistic effect on the common cockroaches and houseflies is chiefly due to carboxylesterase inhibition by monothioderivatives and monooxygenase suppression by dithioderivatives, respectively.

[Specific interaction between esterases and 2-butylthio-2-thio-1,3,2-oxazaphosphorynane and its cyclic and acyclic analogs]. / Osobennosti vzaimodeistviia s ésterazami 2-butiltio-2-tio-1,3,2-oxsazafosforinana i nekotorykh ego tsiklicheskikh i atsiklicheskikh analogov.

We studied the anticholinesterase and anticarboxylesterase effects of 1,3,2-oxazaphosphorynane derivatives and certain cyclic and acyclic analogs on the two enzymes of homoiotherms (ACE from human erythrocytes and BuCE from horse serum) as well as the enzymes from insect tissues (the nerve cord of the American cock-roach and the cephalic region of the domestic fly). The differences in in vitro antiesterase activity of cyclic thionic and the corresponding oxo derivatives of phosphorinane were revealed. The mechanism of the esterase active center phosphorylation not only splitting off the outgoing group (in vivo) but also opening the cycle by P-O bond (in vitro and possibly in vivo) is usually proposed to explain the higher inhibiting activity of the thionic compounds compared to the oxonic ones. The possible involvement of this phosphorylation mechanism in the synergistic activity of the studied compounds is discussed.

[Mechanism of action of 2-aryloxy-2-thio-1,3,2-oxazaphosphorinane pesticides]. / Issledovanie mekhanizma deistviia pestitsidov riada 2-ariloksi-2-tio-1,3,2-oksazafosforinana.

The interaction of 2-aryloxy-2-thio-1,3,2-oxazaphosphorinanes exhibiting nematocide, insecticide/acaricide, and synergetic activities with monoamine oxidases and the interaction of the corresponding oxones, 2-aryloxy-2-oxo-1,3,2-oxazaphosphorinanes, with various cholinesterases, carboxyl esterases, and monoamine oxidases were studied. We showed that the thioderivatives inhibited monoamine oxidases, whereas oxones, which are, as a rule, weak cholinesterase inhibitors, strongly inhibited carboxyl esterases of the American cockroach and were transformed with monoamine oxidases into the strong cholinesterase inhibitors, acyclic phosphamidates. This allowed us to explain the low toxicity of the thioderivatives, the high toxicity of the oxoderivatives, and the great difference in toxicities of thio- and oxocompounds in the 1,3,2-oxazaphosphorinane series. The capacity of thioderivatives to inhibit monoamine oxidases and of oxoderivatives and their further activation products to inhibit carboxyl esterases, i.e., both enzymes responsible for pyrethroid detoxication in insects, explains the synergetic activity of the 1,3,2-oxazaphosphorinane series.

[A method of using synergists in studying the level of activity of enzyme systems and their participation in the mechanism of action of insecticides on insects]. / K metodike ispol'zovaniia sinergistov pri izuchenii urovnia aktivnosti nekotorykh fermentnykh sistem i ikh uchastiia v mekhanizme deistviia insektitsidov na nasekomykh.

An indirect toxicology method was used to assess the monooxygenase (MO) and nonspecific esterase (NE) activities in three synanthropic cockroach species and four races of houseflies with the help of common and novel organophosphorus and pyrethroid synergists: piperonyl butoxide (PB), S,S,S-tributyltrithiophosphate (TBTP), Kitazin-P, Karesan, butylmercapto-2-thio-1,3,2-oxazaphosphorinan (AO-6), and 2-phenylmercapto-2-thio-1,3,2-oxazaphosphorinan (AO-2). The relationship between the coefficient of synergistic effect (CSE) and the concentrations of MO and NE inhibitors was described, and the minimum effective concentrations with the highest synergistic effect were determined. These concentrations are advisable for use in the insect enzyme assays and studies of insecticide detoxification and insect resistance to them.

[The interaction of phoscarban with the esterases of houseflies and synanthropic cockroaches]. / Vzaimodeistvie foskarbana s ésterazami komnatnykh mukh i sinantropnykh tarakanov.

Interactions of phoscarban and its "oxon" with the esterase complex of the house-fly imago and four species of synanthropic cockroaches were studied. Phoscarban and its oxon have a wide spectrum of effects on the esterase complex in cockroaches and flies. These compounds are not specific inhibitors of any of the zones of esterase activity. Their insecticide effect depends on their ability to inhibit both choline esterases, which are responsible for nervous activity, and carboxyl esterases, which are involved in the detoxication of these compounds. We studied the species specificity of the esterase complex, including individual types and fractions, to phoscarban and its oxon in the order Dictyoptera. It was especially distinct for membrane-bound and water-soluble forms of choline esterases.

[The mechanism of action of permethrin on house dust mites]. / Izuchenie mekhanizma deistviia permetrina na kleshchei domashnei pyli.

The mechanism of permetrin action on two home dust mite species: Dermatophagoides farinae and D. pteronyssinus. Both species turned out to be resistant to permetrin under different conditions of toxicity evaluation. A factor of cuticle permeability was investigated. The impact of monoxygenases and esterases in the permetrin detoxication mechanism was shown. The spectra of esterase complexes of enzymes was examined by means of electrophoresis in PAAG; in addition, the zones of esterase activity were identified with the help of two substrates: 2-NA and ATI. The qualitative differences of the esterase complexes of enzymes of both species were found.

[The enzyme systems in natural populations of the housefly Musca domestica highly resistant to organophosphate insecticides]. / Izuchenie nekotorykh fermentnykh sistem u prirodnykh populiatsii komnatnykh mukh Musca domestica, vysokorezistentnykh k fosfororganicheskim insektitsidam.

Two natural population of house flies from the Podol'sk District, Moscow Province have been studied. The both natural populations proved to be highly resistant to organophosphorus insecticides and sensitive to pyrethroids. The activity of esterases and glutathione-S-transferase has been studied, as well as the sensitivity of the enzymes of esterase complex in vitro to TBTP, DDVP and paraoxon, as compared with that of the sensitive strain SRS. Reliable differences have been established in the sensitivity of non-specific esterases to organophosphorus compounds. The esterase spectrum of enzymes from heads and abdomens of house flies has been studied by electrophoresis in PAAG and the zones of esterase activity have been revealed in the presence of two substrates: 2-HA and ATX. Differences in the activity of catecholamine esterase and cholinesterase and inn the sensitivity of cholinesterase from the natural populations to organophosphorus compounds have been established.

[Insecticidal activity of pyrethroids for houseflies and German cockroaches]. / Insektitsidnaia aktivnost' piretroidov dlia komnatnykh mukh i ryzhikh tarakanov.

Insecticidal and knock-down effects of eight pyrethroids, belonging to 2 types as to their chemical structure and specific action towards the nervous system, on the domestic flies' and German cockroaches' imago were assessed comparatively. Pyrethroids of the 2nd type, especially deltametrine, proved to be more effective against domestic flies as well as German cockroaches. Activity of the pyrethroids of the 1st type featured rapid knock-down effect and was practically independent from varying concentrations. The knock-down was reversible even at high concentrations. In case of the 2nd type of pyrethroids, the knock-down effect was concentration-dependent. Domestic flies, on the whole, were more sensitive to the effect of pyrethroids of the 1st type. The use of pyrethroids of the 2nd type against nonflying sinathropic insects would be advisable because they produce a higher insecticidal effect as well as irreversible knock-down.