RESUMO
The generalist predator Ceraeochrysa cincta (Schneider) (Neuroptera: Chrysopidae) is an important biological control agent of several arthropod pests in different agroecosystems. This study assessed the lethal and sublethal effects of six insect growth regulators sprayed on first-instar larvae of C. cincta. Lufenuron and diflubenzuron were highly harmful to first-instar larvae of C. cincta, causing 100 % of mortality before they reached the second instar. Buprofezin caused ~25 % mortality of the larvae and considerably reduced the fecundity and longevity of the insects, but substantially increased the proportion of females in the surviving population of C. cincta. Methoxyfenozide and tebufenozide did not affect the duration and survival of the immature stages, but methoxyfenozide significantly reduced the fecundity and longevity of the insects. Pyriproxyfen reduced the survival of the larval stage by 19.5 %, but did not affect the development, survival and reproduction of the surviving individuals. Based on reduction coefficient, the insecticides diflubenzuron and lufenuron were considered harmful to C. cincta, whereas buprofezin and methoxyfenozide were slightly harmful and tebufenozide and pyriproxyfen were harmless. The estimation of life-table parameters indicated that buprofezin and methoxyfenozide significantly reduced the R o , r and λ of C. cincta, whereas pyriproxyfen and tebufenozide caused no adverse effect on population parameters, indicating that these insecticides could be suitable for use in pest management programs towards the conservation and population increase of the predator in agroecosystems. However, more studies should be conducted to evaluate the compatibility of these insecticides with the predator C. cincta under semi-field and field conditions.
Assuntos
Insetos/efeitos dos fármacos , Inseticidas/toxicidade , Hormônios Juvenis/toxicidade , Animais , Diflubenzuron/toxicidade , Hidrazinas/toxicidade , Insetos/fisiologia , Piridinas/toxicidade , Tiadiazinas/toxicidade , Testes de Toxicidade/métodosRESUMO
The effect of several alkyl-linked bis tetrahydro-(2H)-1,3,5-thiadiazine-2-thione (bis-THTT) on Leishmania donovani, Trypanosoma brucei rhodesiense, and Plasmodium falciparum is reported. Most of the compounds exhibited a potent activity against the three parasitic strains but the best in vitro activity profiles were found against T. b. rhodesiense with IC(50) values ranging between 0.3 and 4 microM for the most active compounds.
Assuntos
Tiadiazinas/síntese química , Tiadiazinas/farmacologia , Tripanossomicidas/síntese química , Tripanossomicidas/farmacologia , Alquilação , Animais , Ácidos Carboxílicos/química , Leishmania donovani/efeitos dos fármacos , Estrutura Molecular , Plasmodium falciparum/efeitos dos fármacos , Relação Estrutura-Atividade , Tiadiazinas/química , Tiadiazinas/toxicidade , Tripanossomicidas/química , Tripanossomicidas/toxicidade , Trypanosoma brucei rhodesiense/efeitos dos fármacosRESUMO
In a search for antichagasic drugs, 14 new 4-(nitroarylidene)-1,2,6-thiadiazin-3,5-dione 1,1-dioxide derivatives were synthesized and tested in vitro against the epimastigote form of Trypanosoma cruzi and some of them showed important antiprotozoan activity. Attempts to synthesize new 4-(nitroarylidene)-3,5-diamino-1,2,6-thiadiazine 1,1-dioxides were unsuccessful. The antichagasic properties of nitroarylidene-malononitrile and nitroarylidene-cyanoacetamide derivatives, thus obtained, were also tested. The cytotoxic properties against Vero cells of compounds which showed remarkable in vitro antichagasic activity were evaluated. All compounds tested exhibited high toxicity percentages at 100 micrograms/ml. However, compound 3c showed in vitro antichagasic and cytotoxic properties such as nifurtimox at the dose of 10 micrograms/ml.
Assuntos
Tiadiazinas/síntese química , Tripanossomicidas/síntese química , Animais , Chlorocebus aethiops , Humanos , Espectroscopia de Ressonância Magnética , Nifurtimox/química , Nifurtimox/farmacologia , Nifurtimox/toxicidade , Nitroimidazóis/química , Nitroimidazóis/farmacologia , Nitroimidazóis/toxicidade , Espectrofotometria Infravermelho , Tiadiazinas/farmacologia , Tiadiazinas/toxicidade , Tripanossomicidas/farmacologia , Tripanossomicidas/toxicidade , Trypanosoma cruzi/efeitos dos fármacos , Células VeroRESUMO
The insecticide buprofezin was examined for its genotoxicity in cultured Syrian hamster embryo cells in order to better understand the mechanisms underlying the genotoxicity of the compound in mammalian cells. Exposure to buprofezin concentrations of 12.5-100 microM did not significantly affect the colony-forming ability of the cells, but did result in increased frequencies of morphologically transformed colonies. Treatment with buprofezin did not cause a detectable induction of DNA repair synthesis, an indicator of DNA damage, but significantly increased the frequency of micronuclei. Immunostaining of the cells with antikinetochore antibody (CREST antibody) showed that essentially all of the buprofezin-induced micronuclei were kinetochore-positive. The results suggest that morphological transformation of Syrian hamster embryo cells by buprofezin results from an interaction of the compound or a metabolite of it with the mitotic apparatus rather than from DNA damage.