ABSTRACT
ABSTRACT: The objective of this study was to evaluate the synergy and response homogeneity of the Spodoptera frugiperda larvae population to the Piper aduncum essential oil in combination with pyrethroid insecticides (alpha-cypermethrin, beta-cypermethrin, fenpropathrin, and gamma-cyhalothrin) compared to piperonylbutoxide (PBO) as positive control. Synergism (SF) comparisons were obtained using lethal concentration (LC50) and lethal dose (LD50) ratios of insecticides individually and in their respective synergistic combinations with essential oil and PBO. Dose/concentration-mortality slope curves were used to establish relative toxicity increase promoted by synergism. They also determined homogeneity response. Residual contact revealed significant potentiation for commercial insecticides formulated with beta-cypermethrin (SF=9.05-0.5) and fenpropathrin (SF=34.05-49.77) when combined with the P. aduncum essential oil. For topical contact, significant potentiation occurred only for alpha-cypermethrin (SF=7.55-3.68), fenpropathrin (SF=3.37-1.21), and gamma-cyhalothrin (SF=5.79-10.48) insecticides when combined with essential oil. With the exception of fenpropathrin and gamma-cyhalothrin, insecticides synergistic combinations presented homogeneous response by topical as well as residual contact at least with essential oil. The SF significance values of the P. aduncum essential oil combined with alpha-cypermethrin, beta-cypermethrin, fenpropathrin, and gamma-cyhalothrin insecticides indicated potential for this oil to be used as an alternative to PBO.
RESUMO: O objetivo deste trabalho foi avaliar a sinergia e homogeneidade de resposta de lagartas de Spodoptera frugiperda ao óleo essencial de Piper aduncum, em combinações com inseticidas do grupo dos piretroides: alfa-Cipermetrina, beta-Cipermetrina, Fenpropatrina e gama-Cialotrina, em comparação ao butóxido de piperonila (PBO controle positivo). Por meio da relação das CL50 e DL50 dos inseticidas tomados isoladamente e de suas respectivas combinações sinérgicas com o óleo essencial e o PBO, foram obtidos os fatores de sinergismo (FS) para comparação entre si. O coeficiente angular das curvas de dose/concentração-mortalidade foi utilizado no estabelecimento do aumento de toxicidade relativa, promovida pelos sinérgicos e determinação da homogeneidade de resposta. Por contato residual, evidenciou-se significativa potencialização dos inseticidas comerciais formulados com beta-Cipermetrina (FS=9,05-0,5) e Fenpropatrina (FS=34,05-49,77), quando combinados com o óleo essencial de P. aduncum. Já por contato tópico, ocorreu significativa potencialização somente dos inseticidas alfa-Cipermetrina (FS=7,55-3,68), Fenpropatrina (FS=3,37-1,21) e gama-Cialotrina (FS=5,79-10,48) quando em combinação com o óleo essencial. Com exceção da Fenpropatrina e gama-Cialotrina, as demais combinações sinérgicas apresentaram homogeneidade de resposta tanto por contato tópico como residual, para pelo menos uma combinação sinérgica com o óleo essencial de P. aduncum. A significância dos valores do FS das combinações do óleo essencial de P. aduncum com os inseticidas a base de alfa-Cipermetrina, beta-Cipermetrina, Fenpropatrina e gama-Cialotrina pode indicar que esse óleo essencial é uma alternativa ao PBO.
ABSTRACT
Despite the recommendations by interpretation of resistance ratios obtained in laboratory bioassays, little is known about the actual impact of these results in the effectiveness of vector control activities in the field. In this context, our objective was to determine the mean value of different resistance ratios obtained by laboratory bioassays performed as part of the chemical control strategies of
Field bioassays were developed in Monte Azul and Coração de Jesus (Southeast, Brazil). In each location, samples were formed with three domestic units treated with alpha-cypermethrin 20.0% (Alfatek (r) 200 SC). One day after spraying, 10 fifth-instar nymphs remained in contact with the surfaces treated (adobe with plaster, adobe without plaster, or wood) with insecticide in plastic cones for 72h. Three cones were exposed inside the intradomicile and the peridomicile. The insects in the control group were exposed to an insecticide-free piece of cardboard. Mortality was measured 72h after removal of the insects from the treated surfaces. The tests were realized in triplicate.
Mortality was 100.0% in all locations, except for Monte Azul; Landinho (96.6%) and Coração de Jesus; Barriguda (96.6%).
Although the resistant populations in laboratory tests proved to be susceptible in the field, this observation is not sufficient to suggest that the cut-off points used to justify the resistance ratio should be changed. In this sense, we recommend that laboratory and field bioassays are carried out with a greater number of Triatominae populations to allow more in-depth consideration of the subject.
Subject(s)
Animals , Ecosystem , Insect Vectors , Pyrethrins , Triatoma , Biological Assay , Chagas Disease/transmission , Insecticide ResistanceABSTRACT
Evaluation of effectiveness of house spraying with Ale 10SC/m2 in malaria mosquitoe prevention by testing bioassay and etomological indicators as well as side effects in the community in implemented area from 11/2003-11/2004 at Quyet Chien commune, Tan Lac District, Hoa Binh province shows that using Ale 10SC spraying with 30mm/m2 with 6 months of residual on wooden and brick wall and the mosquitoe death rate is 51.3-52.6%. Ale 10SC spraying decreased the density of An.minimus domestically daytime and seeking blood. Ale 10SC spraying with 30mg/m2 in malaria transmitted mosquitoes does not have side effects on people using it directly and the community
Subject(s)
Malaria , Culicidae , PyrethrinsABSTRACT
The evaluation trial was conducted from August 2004 to March 2005 in the laboratory of the National Institute of Malariolgy, Parasitology and Entomology, Ha Noi. Bioassays with An.dirus and Ae.aegypti (reared mosquitoes) were made according to the WHO method for evaluation of susceptibility and residual effects of the insecticide on the painted and nylon wall surface. Ale lose sprayed at the dose of 30mg ai/m2 were found to produce residual effect for 6-7 months on the painted wall surfaces (mosquito mortalities: 51.1%-67.8%) and for 4-5 months on nylon wall surface (mosquito mortality: 55.6%-67.8%).
Subject(s)
Malaria , Pyrethrins , LaboratoriesABSTRACT
The study was designed to evaluate the effectiveness of bed-net impregnation with Ale l0SC at a dose 25mg a.i/m2 based on bioassays, entomological indices and to evaluate side effects and the influence of washing of bed-nets in terms of insecticide residual effects. The trials were conducted from November 2003 to November 2004 in Quyet Chien commune, Hoa Binh province's Tan Lac district. Polyester bed-nets impregnated with Ale l0SC at dose of 25mg ai/m2 were found to have 6-month residual effects and to remain effective in malaria vector control after one wash (60 days after treatment). Ale l0SC bed-net impregnation were found to reduce the density of day time indoor resting and human biting anopheline mosquitoes. There are unsignficant side effects among spraymen, dippers and villagers in the treatment areas caused by bed-net impregnation at dose of 25mg ai/m2 were observed.
Subject(s)
Malaria , PyrethrinsABSTRACT
We sprayed, in three groups of Domiciliary Units, 10 and 15 g of alphacypermethrin and 31.3 g of cypermethrin per pump of 10 liters, equivaling, if applied on 250 [squared meters), respectiveliy, to 60 and 40 mg of a alphacypermethrin [per squared meter] and 125,2 mg of cypermethrin [per squared meter]. The invasion, colonization and cumulative indices in the houses and the positivity index in shelters near houses were very low and similar in the three groups, in the 15 months of evaluation, indicating that alphacypermethrin can replace cypermethrin. Triatoma infestans predominated in the Domiciliary Units before treatment and T. brasiliensis and T. pseudomaculata predominated after it.