RESUMO
In this study, insecticide resistance and the mechanisms responsible were characterized in Ae. aegypti of Boyeros municipality from Havana, Cuba. Boyeros represents a high epidemiological risk because it is located near the Havana International Airport, it is highly urbanized, and it has a large influx of people from endemic countries so that it qualifies as a sentinel site for surveillance. The larvae collected from five areas of this municipality showed resistance to temephos associated with metabolic enzymes. The adult mosquitoes displayed a deltamethrin resistance and less distinctly to other pyrethroids associated with a high frequency of sodium channel gene mutations (F1534C and V1016I), detected for the first time in a field population from Cuba. The presence in the field populations of two insecticide resistance mechanisms represents a limiting factor in the success of the control operations of this vector, so other strategies should be considered to preserve the effectiveness of the insecticides available in public health for vector control in Cuba.
Assuntos
Aedes/efeitos dos fármacos , Resistência a Inseticidas , Controle de Mosquitos , Aedes/genética , Animais , Cuba , Piretrinas/farmacologia , Canais de Sódio/genética , Temefós/farmacologiaRESUMO
Dengue (family Flaviridae, genus Flavivirus, DENV) and dengue hemorrhagic fever (DHF) are presently important public health problems in Costa Rica. The primary strategy for disease control is based on reducing population densities of the main mosquito vector Aedes aegypti (L.) (Diptera: Culicidae). This is heavily dependent on use of chemical insecticides, thus the development of resistance is a frequent threat to control program effectiveness. The objective of this study was to determine the levels of insecticide resistance and the metabolic resistance mechanisms involved in two Ae. aegypti strains collected from two provinces (Puntarenas and Limon) in Costa Rica. Bioassays with larvae were performed according to World Health Organization guidelines and resistance in adults was measured through standard bottle assays. The activities of beta-esterases, cytochrome P450 monooxygenases, and glutathione S-transferases (GST), were assayed through synergists and biochemical tests, wherein the threshold criteria for each enzyme was established using the susceptible Rockefeller strain. The results showed higher resistance levels to the organophosphate (OP) temephos and the pyrethroid deltamethrin in larvae. The efficacy of commercial formulations of temephos in controlling Ae. aegypti populations was 100% mortality up to 11 and 12 d posttreatment with daily water replacements in test containers. Temephos and deltamethrin resistance in larvae were associated with high esterase activity, but not to cytochrome P450 monooxygenase or GST activities. Adult mosquitoes were resistant to deltamethrin, and susceptible to bendiocarb, chlorpyrifos, and cypermethrin. Because temephos and deltamethrin resistance are emerging at the studied sites, alternative insecticides should be considered. The insecticides chlorpyrifos and cypermethrin could be good candidates to use as alternatives for Ae. aegypti control.
Assuntos
Aedes/efeitos dos fármacos , Aedes/genética , Resistência a Inseticidas , Inseticidas/farmacologia , Aedes/enzimologia , Animais , Costa Rica , Sistema Enzimático do Citocromo P-450/metabolismo , Eletroforese , Esterases/metabolismo , Feminino , Frequência do Gene , Glutationa Transferase/metabolismo , Proteínas de Insetos/metabolismo , Larva/efeitos dos fármacos , Larva/enzimologia , Larva/genética , Dose Letal Mediana , Organotiofosfatos/farmacologia , Fenilcarbamatos/farmacologia , Piretrinas/farmacologia , Fatores de TempoRESUMO
Aedes aegypti (L.) (Diptera: Culicidae) control programmes in Cuba rely on the application of the organophosphate temephos for larval control. Hence, the monitoring of resistance to this insecticide is an essential component of such programmes. Here, 15 field populations from different municipalities of Havana City were assayed for resistance to temephos. High levels of resistance were detected in all strains and resistance ratios were highly correlated with esterase activity (P = 0.00001). Populations from three municipalities were tested in both 2006 and 2008; resistance and esterase activities both significantly increased during this 2-year period. Synergist studies demonstrated that neither glutathione transferases nor monooxygenases were associated with the increase in resistance to temephos in this period. The duration of the efficacy of commercial formulations of temephos in controlling Ae. aegypti populations in Havana City was reduced by the high level of temephos resistance observed; hence these data are of clear operational significance for the dengue control programme in Cuba. New integrated strategies to avoid further increases in temephos resistance in Cuba are necessary.
Assuntos
Aedes/efeitos dos fármacos , Esterases/metabolismo , Resistência a Inseticidas , Inseticidas/farmacologia , Temefós/farmacologia , Aedes/enzimologia , Animais , Cuba , Demografia , Larva/efeitos dos fármacos , Fatores de TempoRESUMO
Between the April and December of 2004, an Aedes aegypti (L.) pupal/demographic survey was conducted in the Playa municipality of Havana. The aims were to identify the key types of container in the production of the adult mosquitoes (and so provide a basis for targeted control) and assess transmission risk in terms of the number of pupae/person. Pupal abundance, as measured in the survey, was compared with traditional Stegomyia indices. The immature stages of Ae. aegypti were only found in 70 of the 15,153 containers that were investigated and the pupae of this species were only seen in 52 of the containers. Ground-level water-storage tanks yielded 74.1% of all the pupae, with a further 19.0% found in miscellaneous small containers. The utility of the pupal/demographic-survey methodology in the evaluation of dengue risk in the study area, and other areas of Cuba with low densities of Ae. aegypti, is discussed.
Assuntos
Aedes , Dengue , Insetos Vetores , Animais , Cuba/epidemiologia , Dengue/epidemiologia , Dengue/transmissão , Utensílios Domésticos , Humanos , Controle de Mosquitos , Vigilância da População/métodos , Pupa , Fatores de Risco , Estações do Ano , Saúde da População Urbana , Abastecimento de ÁguaRESUMO
Five strains of Aedes aegypti L. one from Cuba and 4 from Venezuela were evaluated to determine their resistance to organophosphate insecticides (temephos, chlorpiriphos and pirimiphos methyl). In the Venezuelan strains only APURE showed resistance to temephos. In TACHIRA and MIRANDA moderate resistance values were noted (FR50 5 to 10x) for chlorpiriphos and high levels of resistance (FR > 10x) to this insecticide were found in ARAGUA. All the Venezuelan strains showed high levels of resistance to pirimiphos methyl. The Cuban strain from Santiago de Cuba revealed moderate resistance to temephos and pirimiphos methyl, but high resistance to chlorpiriphos. The results of the biochemical tests proved the presence of esterase and glutathione-s-transferase at high frequency in almost every strain. By the polyacrilamide gel electrophoresis, a strongly stained band was observed in all the strains with a Rf value of 0.779; it was named esterase A4 and was not seen in the susceptible reference strain. The meaning of this esterase in the resistance to organophosphate insecticides is yet to be determined. Resistance to these insecticides in Aedes aegypti is a serious problem for the control of this species therefore integrated management strategies were proposed to prevent or delay the appearance of this species in Cuba and Venezuela.
Assuntos
Aedes/efeitos dos fármacos , Aedes/enzimologia , Esterases/metabolismo , Inseticidas/farmacologia , Compostos Organofosforados , Animais , Esterases/análise , Resistência a InseticidasRESUMO
The detection techniques for the activity of non-specific esterases and glutathione-s-transferase in Culex quinquefasciatus were modified to detect such enzymes in Aedes aegypti(L). The optimal concentration values of substrate (saturating concentration) and the optimum reading time for reaction were determined for each enzyme by using 4 Aedes aegypti strains: one from Cuba 2 from Venezuela and one susceptible reference strain. The frequency of non-specific esterases turned out to be 0.76 in MIRANDA 0.42 in ARAGUA and 1 in SANTIAGO DE CUBA in which the highest frequency value of this mechanisms was reached. The frequency of glutathione-s-transferase mechanism was 0.45 in ARAGUA 0.043 in MIRANDA and 1 in SANTIAGO DE CUBA. For the first time in Cuba a set of biochemical techniques was available for detecting the resistance mechanisms of Aedes aegypti which made it possible to create sound foundations for the easy rapid detection of the resistance of this species the main dengue vector in the Americas.
Assuntos
Aedes/enzimologia , Esterases/metabolismo , Glutationa Transferase/metabolismo , Titulometria/métodos , Animais , Esterases/análise , Glutationa Transferase/análiseRESUMO
A study was conducted on the level of resistance to seven insecticides, namely, 3 organophosphate compounds (malathion, chlorpyrifos and pirimiphos-methyl), one carbamate (propoxur) and 1 pyrethroid (cypermethrin, deltamethrin and lambdacialotrine) of three field-collected strains of Blattella germanica (Linnaeus, 1767) from Santiago de Cuba. These strains showed high resistance levels to malathion, cypermethrin, deltamethrin and lambdacialotrine and low resistance to pirimiphos-methyl, and also they were susceptible to chlorpyrifos and propoxur. The levels of resistance to tested organophosphate insecticides such as malathion and pirimiphos-methyl and to pyrethroid compounds like cypermethrin, deltamethrin and lambdacialotrine may be related to the increased production of esterases as a mechanism of resistance. The value of frequency of the resistant genes for enzyme acetylcholinesterase was very low, therefore, the modified acetylcholinesterase is not involved in resistance to insecticides tested in the studied strains from Santiago de Cuba.
Assuntos
Blattellidae , Inseticidas/farmacologia , Compostos Organofosforados , Piretrinas/farmacologia , Animais , Resistência a Inseticidas , Dose Letal Mediana , Modelos Teóricos , Propoxur/farmacologiaRESUMO
We studied the levels of resistance to seven insecticides: malathion, chlorpyrifos, pirimiphos-methyl, propoxur, cypermethrin, deltamethrin, and lambda-cyhalothrin in nine strains of Blattella germanica (Linnaeus, 1717) collected from sites in Santiago de Cuba and Havana City. The strains from Santiago de Cuba, generally had high levels of resistance to malathion, cypermethrin, deltamethrin, and lambda-cyhalothrin, but only low levels of resistance to pirimiphos-methyl, chlorpyrifos, and propoxur. In the strains from Havana City we found a moderate resistance to the organophosphate insecticides, resistance to the pyrethroids (except for three strains that showed susceptibility to lambda-cyhalothrin), and susceptibility to the carbamate insecticide (propoxur).
Assuntos
Blattellidae , Resistência a Inseticidas , Inseticidas/toxicidade , Animais , Clorpirifos/toxicidade , Cuba , Geografia , Malation/toxicidade , Nitrilas , Compostos Organotiofosforados/toxicidade , Propoxur/toxicidade , Piretrinas/toxicidade , Especificidade da EspécieRESUMO
The use of malathion to control mosquitoes in Cuba during 7 years until 1986 selected 2 resistance mechanisms: that of elevated activity of nonspecific esterases and that of altered acetylcholinesterase (Ache) in Culex quinquefasciatus (Say). In Havana, specifically in the area under study (Quibú River), malathion was replaced by cypermethrin in 1987 and cycles of treatment with cypermethrin have been intensively used since 1987 up to now when the populations of Aedes or Culex increase. In Culex quinquefasciatus (Say) from the Quibú River the resistance levels, mainly to malathion, declined significantly from 1986 to 1997. An increase of resistance to pyrethroid was observed during that period of 11 years. The mechanism of elevated esterases rose to a frequency of 1 and there was also an increase in the frequency of the mechanism of Ache. The esterase B1, responsible for the resistance to malathion, but not to pyrethroid, was selected in this population until 1986. Starting from the use of pyrethroid for the control in this area, 2 new phenotypes of esterases named A6 and B6, apparently related to pyrethroid resistance, were selected.