RESUMO
Due to the lack of informations concerning Urbanus acawoios (Williams, 1926) (Lepidoptera: Hesperiidae), and the severe damage caused by it in Clitoria racemosa trees in Manaus, AM, the present research was conducted, under semi-natural conditions, in order to obtain data about its biology and development. The occurrence of phytophagous pests in urban environments, in addition to causing troubles and problems, it needs special control methods, at least safety for the public health. Three consecutive generations were studied in the present work. As a multivoltine insect, the whole life cycle was observed to vary between 36 and 50 days, with an average of 41.89 ± 0.98 days. The oviposition behaviour, as well as the egg morphology were described. The embryonic development lasted between 3 and 4 days. External and internal alterations during the egg development were determined. The initial larval instars showed to be of aggregated habit, while the others were solitary. The larval stage, consisting of 5 instars, lasted an average of 18.46 ± 1.28 days, with a minimum of 19 and a maximum of 26 days. The biology of each instar and its duration time were also determined. The mid-gut pH of the larval stage varied between 8.4 and 9.2, with an average of 8,7. The pupal stage lasted an average of 9.96 ± 1.05 , with a minimum of 8 and a maximum of 12 days for its development. The mated adult longevity varied between 9 and 22 days, with an average of 13.47 ± 0.27 days.
Devido aos danos dos ataques de Urbanus acawoios (Williams, 1926) (Lepidoptera: Hesperiidae) em palheteiras (Clitoria racemosa) (Leguminosae) em Manaus, AM e a total ausência de qualquer informação a respeito desta espécie, o presente trabalho foi desenvolvido visando a obtenção de conhecimentos que facilitem a identificação de métodos seguros e eficientes para o seu controle. Os estudos biológicos revelaram que este inseto é multivoltino, tendo duração média de 41,89 ± 0,98 dias por geração. As condições climáticas na cidade de Manaus, a disponibilidade de alimentos, e possivelmente a ausência de inimigos naturais eficientes, parecem ser os fatores principais responsáveis pela ocorrência de erupções populacionais desta espécie. Enquanto o estágio larval consiste de 5 fases (ínstares) e dura em média 18,46 ± 1,28 dias, o da pupa necessita 9,96 ± 1,05, e o adulto 13,47 ± 0,27 dias, sob condições de 30°C e 85% UR. Estudos morfológicos foram incluídos.
RESUMO
Due to the lack of information concerning Urbanus acawoios (Williams, 1926) (Lepidoptera: Hesperiidae), and the severe damage caused by it in Clitoria racemosa trees in Manaus, AM, the present research was conducted. The study was undertaken under laboratory conditions, in order to investigate the possibility of its microbial control, utilizing a commercial formulation, Dipel, based on Bacillus thuringiensis var. kurstaki (H-3a:3b). The larval mid-gut contents of this insect species showed to be highly alkaline, with a pH varying between 8.4 and 9.2, with an average of 8.7, indicating initially, a possible susceptibility of the larval stage to such a pathogen. Posteriorly, Such an indication, was confirmed by bioassays. During the preliminary tests, a dosage, equivalent to 110 g / ha (17.40 IU/cm2 of leaf-covered area) was utilized and resulted in median lethal times (LTs50) of 42.28, 37.18, 28.00 and 51.87 hours for the 3rd, 4th, beginning of the 5th and end of the 5th instar, respectively. Giving more attention for the 3rd instar larvae, three dosages were applied: 80 g/ha (13 IU/cm2), 150 (25 IU/cm2) and 280 g/ha (45 IU/cm2). In this case, the LTs50 were calculated as 42.62, 30.77 and 30.06 hours, for each dose, respectively. External symptoms of the bacterial disease were studied among 5th instar infected larvae. Detailed description of these symptoms is given. The mid-gut histopathological changes caused by the d-endotoxin of B. thuringiensis are also described. The results obtained during the present work could indicate applications of B. thuringiensis, as a promising method for the microbial control of this urban pest.
Devido à falta de informações sobre Urbanus acawoios (Williams, 1926) (Lepidoptera: Hesperiidae), e pelos danos severos por ele causados em árvores de Clitoria racemosa, o presente trabalho foi desenvolvido sob condições de laboratório para verificar a possibilidade de utilizar Bacillus thuringiensis var. kurstaki (H-3a:3b) como agente microbiano para o seu controle. O pH do intestino médio do hesperídeo mostrou ser bastante alcalino, variando de 8,4 a 9,2 (média de 8,7), indicando a possibilidade das larvas serem susceptíveis ao patógeno. Os ensaios confirmaram a alta susceptibilidade a dosagens equivalentes a 110 g / ha, resultando em tempos letais medianos (TL50) de 42,28, 37,18, 28,00 e 51,87 horas para larvas de 3o, 4°, início e final do 5º ínstares, respectivamente. Três outras dosagens (80, 150 e 280 g/h) foram aplicadas para larvas do 3º ínstar, resultando em TLs50 de 42,62, 30,77 e 30,06 horas, respectivamente. Descrições detalhadas sobre os sintomas externos nas larvas infectadas foram dadas. As alterações histológicas do intestino médio afetado pela d-endotoxina de B. thuringiensis foram descritas. Os resultados obtidos no presente trabalho revelam a grande possibilidade de controlar esta praga utilizando-se produtos e formulados à base desta bactéria.