Effect of diflubenzuron on immature stages of Haematobia irritans (L.) (Diptera: Muscidae) in Uberlândia, State of Minas Gerais, Brazil

Horn fly immatures were raised in media containing different concentrations of diflubenzuron in order to verify their susceptibility to this insect growth regulator (IGR). The 50% and 95% lethal concentrations of diflubenzuron for the population (LC50, LC95) were determined as well as the effect of this IGR on the different immature horn fly stages. The tests were performed using the progeny of adults collected in the field. The immatures were maintained in a growth chamber at 25.0 ± 0.5ºC and 12-12 h photoperiod. IGR concentrations of 300 ppb, 100 ppb and 50 ppb were lethal for 100% of the sample. Pupae malformation occurred in the breeding media containing different diflubenzuron concentrations. Values for LC50 , LC95 (± 95% fiducial limits) and the slope of the regression line were respectively, 25.521 ± 1.981 ppb, 34.650 ± 2.001 ppb and 12.720 ± 1.096. The third larval instar was more sensitive to the sub-lethal concentration of the product than the first and second ones were. The results indicate that this IGR can be an important tool for controlling horn fly populations as well as for managing horn fly resistance to conventional insecticides against Haematobia irritans in Uberlândia, State of Minas Gerais

Susceptibility of Aedes aegypti (L) to the insect growth regulators diflubenzuron and methoprene in Uberlândia, State of Minas Gerais Susceptibilidade de Aedes aegypti (L) aos reguladores de crescimento de insetos diflubenzuron e methoprene em Uberlândia, Estado de 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.<br>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