cyhalothrin and bendiocarb

We evaluated the susceptibility status of Anopheles gambiae in two communities of Ikorodu, Lagos, Nigeria to DDT, deltamethrin, lambda cyhalothrin and bendiocarb.. Resistance to DDT (40% and 86%) and lambda cyhalothrin (75% and 84%) in Oke-Ota and Majidun respectively. Suspected resistance to deltamethrin (94.9%) and bendiocarb (93.5%) was recorded in Oke-Ota community and the mosquitoes were susceptible to malathion in both communities. KDR mutation (L1014F) from resistance samples from both locations though with a low frequency that significantly departs from Hardy-Weinberg's probability (P> 0.01). PBO synergized bioassay was able to increase knockdown, percentage mortality and restore full susceptibility to deltamethrin and bendiocarb.. Results from this study indicates that the metabolic resistance mechanism is highly implicated in the resistance to different classes of insecticide in Ikorodu and this should be taken into consideration when implementing vector control activities in this area.

Topics: Animals; Anopheles; DDT; Female; Humans; Insecticide Resistance; Insecticides; Malathion; Mosquito Vectors; Mutation; Nigeria

Biting midges (Culicoides spp.) are vectors of bluetongue and Schmallenberg viruses. Treatment of mesh barriers is a common method for preventing insect-vectored diseases and has been proposed as a means of limiting Culicoides ingression into buildings or livestock transporters. Assessments using animals are costly, logistically difficult and subject to ethical approval. Therefore, initial screening of test repellents/insecticides was made by applying treatments to mesh (2 mm) cages surrounding Onderstepoort light traps. Five commercial treatments were applied to cages as per manufacturers' application rates: control (water), bendiocarb, DEET/p-menthane-3,8-diol (PMD) repellent, Flygo (a terpenoid based repellent) and lambda-cyhalothrin. The experimental design was a 5 × 5 Latin square, replicated in time and repeated twice. Incongruously, the traps surrounded by DEET/PMD repellent-treated mesh caught three to four times more Obsoletus group Culicoides (the commonest midge group) than the other treatments. A proposed hypothesis is that Obsoletus group Culicoides are showing a dose response to DEET/PMD, being attracted at low concentrations and repelled at higher concentrations but that the strong light attraction from the Onderstepoort trap was sufficient to overcome close-range repellence. This study does not imply that DEET/PMD is an ineffective repellent for Culicoides midges in the presence of an animal but rather that caution should be applied to the interpretation of light trap bioassays.

Topics: Animals; Bluetongue; Ceratopogonidae; Cyclohexane Monoterpenes; DEET; Insect Repellents; Insect Vectors; Insecticides; Menthol; Nitriles; Phenylcarbamates; Plant Extracts; Pyrethrins; Sheep; Terpenes

Long-lasting insecticide treated nets (LLINs) and indoor residual house spraying (IRS) are the main interventions for the control of malaria vectors in Zanzibar. The aim of the present study was to assess the susceptibility status of malaria vectors against the insecticides used for LLINs and IRS and to determine the durability and efficacy of LLINs on the island.. Mosquitoes were sampled from Pemba and Unguja islands in 2010-2011 for use in WHO susceptibility tests. One hundred and fifty LLINs were collected from households on Unguja, their physical state was recorded and then tested for efficacy as well as total insecticide content.. Species identification revealed that over 90% of the Anopheles gambiae complex was An. arabiensis with a small number of An. gambiae s.s. and An. merus being present. Susceptibility tests showed that An. arabiensis on Pemba was resistant to the pyrethroids used for LLINs and IRS. Mosquitoes from Unguja Island, however, were fully susceptible to all pyrethroids tested. A physical examination of 150 LLINs showed that two thirds were damaged after only three years in use. All used nets had a significantly lower (p < 0.001) mean permethrin concentration of 791.6 mg/m2 compared with 944.2 mg/m2 for new ones. Their efficacy decreased significantly against both susceptible An. gambiae s.s. colony mosquitoes and wild-type mosquitoes from Pemba after just six washes (p < 0.001).. The sustainability of the gains achieved in malaria control in Zanzibar is seriously threatened by the resistance of malaria vectors to pyrethroids and the short-lived efficacy of LLINs. This study has revealed that even in relatively well-resourced and logistically manageable places like Zanzibar, malaria elimination is going to be difficult to achieve with the current control measures.

Topics: Animals; Anopheles; Female; Geography; Humans; Insect Bites and Stings; Insect Vectors; Insecticide Resistance; Insecticide-Treated Bednets; Insecticides; Malaria; Mosquito Control; Nitriles; Phenylcarbamates; Pyrethrins; Tanzania; Time Factors

We studied the susceptibility to organophosphate, carbamate and pyrethroid insecticides of Aedes aegypti from different regions of high transmission risk for dengue in Panama.. To evaluate the susceptibility to organophosphate, carbamate and pyrethroid insecticides in Ae. aegypti from eight sites belonging to seven municipalities in Panamá.. We collected Ae. aegypti larval populations in different types of breeding sites located in urban areas. Insects were reared in laboratory control conditions. With the F 1 generation of each strain we performed susceptibility bioassays using WHO standardized methodology for larvae and adults.. The eight Ae. Aegypti strains were susceptible to the pyrethroid insecticides: deltamethrin, lambdacyhalothrin and cifluthrin, to the organophosphate fenitrothrion, and to the carbamates propoxur and bendiocarb. Only the CHITRE strain exhibited a moderate resistance to the insecticide deltamethrin in larvae (FR 50 =5x). However, adults were susceptible.. It is necessary to perform periodic surveillance to evaluate the susceptibility of Ae. aegypti populations in the studied municipalities with the purpose of preserving their susceptible. The insecticides applied for Ae. aegypti control can still be used in the evaluated municipalities; however it will depend on the susceptibility of the mosquitoes in the specific area.

Topics: Aedes; Animals; Dose-Response Relationship, Drug; Female; Fenitrothion; Insecticide Resistance; Insecticides; Larva; Nitriles; Panama; Phenylcarbamates; Propoxur; Pyrethrins

Determination of residual activity of insecticides is essential information for the selection of appropriate indoor spraying operation. The present study was undertaken to evaluate the residual effect of three candidate insecticide formulations on different indoor surfaces in order to guide future interventions, in the context of Cameroon and other African countries.. The study was conducted in the Ntougou neighbourhood in Yaoundé (capital city of Cameroon). Bendiocarb WP, lambda-cyhalothrin CS and deltamethrin WG were sprayed on the indoor wall surfaces of local cement, wood and mud houses. Their effects on the knockdown and mortality of the Kisumu susceptible strain of Anopheles gambiae s.s were assessed each month from March to September 2009, using the WHO plastic cones test. Knockdown and mortality rates were compared between different surfaces using Chi-square test. A Kaplan-Meir model was used to estimate the time of treatment failure.. With bendiocarb WP, the knockdown rates were frequently above 98% during 13 weeks after spraying, except on mud walls where it significantly decreased at the 13th week (P < 0.05). With lambda cyhalothrin CS, the knockdown rates remained 100% on wood surfaces during the 26 weeks trial. However, it significantly decreased on concrete and mud surfaces from the 11th (83%) and the 20th (88%) weeks respectively (P < 0.05). With deltamethrin WG, it remained high on concrete surfaces during 26 weeks (> 98%); while it varied between 60 and 100% on wood or mud surfaces. The survival estimates of bendiocarb WP treatments remaining effective in killing An. gambiae s.s. (mortality rate ≥ 80%) was > 13 weeks on cement and wood surfaces and 13 weeks on mud surfaces. Those of lambda-cyhalothrin CS were > 26 weeks on wood surfaces, and 20 weeks on concrete and mud surfaces. By contrast, those of deltamethrin WG were 26 weeks on concrete, 20 weeks on mud surfaces and 15 weeks on wood surfaces.. Current data suggest variable durations of spray cycles for each product, according to the type of wall surfaces, highlighting the importance of testing candidate products in local context before using them in large scale.

Topics: Animals; Anopheles; Cameroon; Construction Materials; Female; Insect Vectors; Insecticides; Longitudinal Studies; Mosquito Control; Nitriles; Phenylcarbamates; Pyrethrins; Survival Analysis; Time Factors

In a laboratory study, the irritancy of bendiocarb, lambda-cyhalothrin and DDT to Anopheles gambiae was evaluated at field, 1/3 field and 1/10 field rates using WHO conical exposure chambers and excito-repellency test boxes. Bendiocarb was the least irritant insecticide at all rates, inducing levels of takeoff, flight and exiting behavior similar to those of a distilled water control treatment. Of those mosquitoes introduced to the bendiocarb-treated boxes, not more than 1% exited and survived at any dose rate. Lambda-cyhalothrin and DDT were highly irritant to An. gambiae, inducing a strong stimulation to take off and fly and also a high level of exiting. Exiting-survival rates associated with lambda-cyhalothrin and DDT were between 15 and 51%. The relevance of these findings to the control of mosquito populations and the prevention of malaria transmission is discussed.

Topics: Animals; Anopheles; Carbamates; DDT; Mosquito Control; Nitriles; Phenylcarbamates; Pyrethrins