Susceptibility of Aedes aegypti (L) to the insect growth regulators diflubenzuron and methoprene in Uberlândia, State of Minas Gerais

Aedes aegypti (L) (Diptera: Culicidae) was reared in several concentrations of diflubenzuron and methoprene under laboratory conditions in Uberlândia, State of Minas Gerais, southeastern Brazil. Characteristics such as LC50 and LC95, the susceptibility of immature stages of different ages to these insect growth regulators and their residual effects were studied. The LC50 and LC95 of diflubenzuron and methoprene were 5.19 and 12.24 ppb; 19.95 and 72.08 ppb, respectively. While diflubenzuron caused great mortality in all larval instars, methoprene was more effective when the mosquito was exposed from the start of the fourth larval instar onwards. Commercial concentrations of these two insect growth regulators close to LC95 presented greater residual activity than did their respective technical formulations. The parameters were compared with those obtained elsewhere. The characteristics investigated here indicate that these insect growth regulators are effective alternatives for controlling the dengue vector in the Uberlândia region.

Aedes aegypti (L) (Diptera: Culicidae) foi criado em várias concentrações de diflubenzuron e methoprene sob condições de laboratório em Uberlândia, Minas Gerais, sudeste do Brasil. Foram estudados aspectos tais como, CL50 e CL95, suscetibilidade de estágios imaturos de diferentes idades a estes insect growth regulators e seu efeito residual. As CL50 e CL95 de diflubenzuron e methoprene foram: 5,19 e 12,24ppb; 19,95 e 72,08ppb, respectivamente. Enquanto diflubenzuron causou grande mortalidade em todos os estádios larvais, methoprene causou maior mortalidade quando o mosquito foi exposto a partir do início do quarto estádio larval. As concentrações comerciais dos dois insect growth regulators próximas às CL95 mostraram maior atividade residual que suas respectivas formulações técnicas. Os parâmetros são comparados com aqueles obtidos em outros locais. Os aspectos aqui investigados indicam estes insect growth regulators como alternativas efetivas para o controle do vetor da dengue na região de Uberlândia.

Modulatory influence of juvenile hormone analogue (JHa) and 20-hydroxyecdysone on lipophorin synthesis in red cotton bug, Dysdercus cingulatus Fabr.

Topical supply of methoprene, a juvenile hormone analogue (JHa) caused notable morphological disturbance in insects. Topical supply of methoprene to newly emerged adult female D. cingulatus caused notable disturbance and induced a dramatic reduction in the total haemolymph protein pattern and lipophorin production in tissues like fat body, ovary and haemolymph. Total protein concentration in haemolymph also showed significant reduction in 1 day old insects but increased slightly as age advanced. Application of 20-hydroxyecdysone (20-HE) to 2-day-old adult female stimulated protein synthesis intensively. Lipophorin levels in fat body and ovary also simultaneously increased. Densitometric analysis revealed that methoprene inhibits while 20-HE stimulates lipophorin production in D. cingulatus.

Evaluation of methoprene effect on Aedes aegypti (Diptera: Culicidae) development in laboratory conditions

Several Brazilian Aedes aegypti populations are resistant to the larvicidae temephos. Methoprene, that inhibits adult emergence, is one of the alternatives envisaged by the Brazilian Dengue Control Program (PNCD). However, at Brazil vector infestation rates are measured through larvae indexes and it has been claimed that methoprene use in the field could face operational problems. In order to define a standardized protocol, methoprene effect was evaluated in laboratory conditions after continuous exposure of larvae (Rockefeller strain) to a methoprene formulation available to the PNCD. Methoprene-derived mortality occurs mainly at the pupa stage and pupa development is inversely proportional to methoprene concentration. Number and viability of eggs laid by treated and control females are equivalent. A methoprene dose-dependent delay in the development was noted; however, b correlations were found for total mortality or adult emergence inhibition if data obtained when all control mosquitoes have emerged are compared to data obtained when methoprene-treated groups finish development. The cumulative record of total methoprene-induced mortality at the time control adults emerge is proposed for routine evaluation of field populations. Mortality of all specimens, but not of larva, could account for adult emergence inhibition, confirming the inadequacy of larvae indexes to evaluate methoprene effect.

Morphogenetic derangements in the reproductive system of Bracon hebetor, a beneficial parasitoid, bred on juvenoid treated host (Corcyra cephalonica) larvae.

Effect of juvenoids (hydroprene and methoprene) on the ecto-parasite B. hebetor was investigated by rearing them upon the juvenoid treated ultimate instar host larvae of C. cephalonica. Emerged adultoid wasps of either sexes obtained from treated series showed anatomical deformities in the reproductive systems. Ill-developed ovaries with reduced length, terminally free ovarioles and abnormal testicular growth showing non-fusion of lobes were the important abnormal features. Data on measurements of male reproductive system, e.g., width (transverse axis) of testis, length of common vas deferens plus ejaculatory duct and length of accessory gland showed significant difference (P < 0.05) from control.

Comparaçao da efectividade dos insecticidas abate e altosid no controle do aedes aegypti: Linnaeus 1762 / Effectivity comparison 2 insecticides abate and altosid in the control of aedes aegypti: Linnaeus 1762

Atualmente a Fundaçao Nacional de Saúde, a nivel nacional, utiliza o Abate no controle de aedes aegypti na dosagem de 1,0 ppm no tratamento focal. Esta concentraçao representa uma margem de segurança de 100 por ciento aproximadamente, porém na base deste programa estao certamente os problemas relacionados com a possível resistência e eliminaçao dos inimigos naturais em meio aquático. Estando atento a esse possível acontecimiento é que procurou-se alternativa capaz de garantir a mesma eficácia. Sendo assim, desenvolveu-se um experimento para analisar e comparar a efetividade dos insecticidas Abate e Altosid. Estuou-se a efetividade e o desenvolvimento das larvas durante 11 semanas em três concentraçoes a saber: Abate - 1,0 ppm, 0,77 ppm e 0,5 ppm; Altosid - 1,3 ppm, 0,65 ppm e 0,32 ppm. Neste período observou-se que o Abate apresentou 100 por ciento de efetividade nas três concentraçoes durante todo o teste. Já o Altosid, teve sua efetividade reduzida gradativamente a partir da 4º semana chegando na 11º na maior, 1,67 por ciento na intermediária e 10,0 por ciento na menor concentraçao. Concluiu-se que o Abate ainda oferece melhores resultados que o Altosid. Em relaçao ao Abate acredita-se que o uso de uma concentraçao menor oferecería as mesmas perspectivas que a usada pela FNS atualmente. Quanto ao Altosid, nao podemos considerálo como boa alternativa

report on field testing of methoprene [IGR] for mosquito control [Pakistan]

A large scale field trial under natural conditions was conducted to observe biological effects of methoprene on mosquito immature and mature stages. In addition non-target invertebrates [N. T. Os] in the treated breeding places were also checked for any adverse effect. One dose of Altosid briquet formulation one briquete per 100 sq. ft. and two dosages 250 ml/hect. and 300 ml/hect. of liquid SR-10 methoprene were tested. Negligible% [less than 1%] adult mosquitoes emerging from pupae were observed during the first week after treatment with briquets or 300 ml/hect. On 18

h day of observation after treatment only 50% adults emerged from breeding places treated with 300 ml/hect. and same% from treated with briquets but on the 21

t day after treatment. Morphological abnormalities were noticed among the surviving adults, emerging between 6-15 days after treatment. Significant sex proportion distortion was also noticed among the apparent normal adults emerging between 3-12 days after treatment. Both the formulations of methoprene were found to be very safe in handling and for N. T. Os

Effects of cyromazin and methoprene on the developmental stages of Anopheles dirus, Aedes aegypti and Culex quinquefasciatus (Diptera : Culicidae).

The effects of two chemical compounds, cyromazin and methoprene, on the developmental stages of Anopheles dirus, Aedes aegypti and Culex quinquefasciatus were investigated under laboratory conditions, with the mean temperature of 24 degrees +/- 1 degree C and the relative humidity at 65-75%. Both compounds were tested against the second, third and fourth instar larvae. The concentrations of cyromazin used for An. dirus and Cx. quinquefasciatus ranged from 0.0008 to 0.5 mg/l; and for Ae. aegypti from 0.004 to 2.5 mg/l. The concentrations of methoprene used for An. dirus, Ae. aegypti and Cx. quinquefasciatus ranged from 0.00016 to 0.1 mg/l. The mortality rates were found to be relatively high in larval and pupal stages when treated with cyromazin and methoprene. The primary toxic effects of cyromazin were on the second stage larvae. The LC50 values for cyromazin on the second, third and fourth stage larvae were, respectively, 0.0027, 0.0042 and 0.0114 mg/l for An. dirus, and 0.1662, 0.2307 and 0.3005 mg/l for Ae. aegypti. Cx. quinquefasciatus was the most sensitive species to cyromazin with LC50 values for second, third and fourth stage larvae of 0.0015, 0.0068 and 0.0130 mg/l, respectively. The primary toxic effects of methoprene were in the fourth stage larvae. The LC50 values for methoprene on the second, third and fourth stage larvae were, respectively, 0.0110, 0.0041 and 0.0022 mg/l for An. dirus, and 0.0077, 0.0034 and 0.0025 mg/l for Ae. aegypti. Cx. quinquefasciatus was the most sensitive species to methoprene, with LC50 values for second, third and fourth stage larvae of 0.0013, 0.0008 and 0.0006 mg/l, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)