ABSTRACT
O estudo foi realizado bimestralmente entre agosto de 2006 e maio de 2007 na Região Sul Fluminense do Estado do Rio de Janeiro. As armadilhas, modelo Carvalho-47, foram adaptadas e posteriormente montadas às 9 horas e retiradas 48 horas depois. Em cada ponto de coleta foram montadas 4 armadilhas, totalizando 20 armadilhas em toda a trilha. Durante o experimento, oito operárias de Lestrimelitta rufipes (Friese) foram capturadas, sendo sete atraídas por salicilato de metila e uma por cineole. Além dessas essências, foram utilizadas mais duas essências, eugenol e vanilina, porém essas duas essências não atraíram nenhum indivíduo. Todas as abelhas foram coletadas ao longo de novembro de 2006. Mesmo com ampla distribuição geográfica, L. rufipes não havia sido registrada na região Sul Fluminense, sendo também o primeiro registro de coletas dessa espécie através de armadilhas com iscas odoríferas. Não foi possível identificar o porquê da atração das operárias de L. rufipes ao salicilato de metila e cineole, uma vez que essas abelhas não visitam flores nem ninhos que poderiam conter tais fragrâncias. O método de coleta através de armadilhas com iscas odoríferas poderá ser empregado com diversos objetivos, entre eles, o de conhecer a riqueza e a distribuição desse gênero em diversas áreas.
This study was done each two months between August 2006 to May 2007 in a South Region in the State of Rio de Janeiro. The traps, a (Carvalho-47) model, were adjusted, then assembled at 9 o'clock and finally removed 48 hours after. In each place of the extraction, 4 traps were assembled, in a total of 20 in all the trail. During the experiment, eight worker bees of Lestrimelitta rufipes, were captured, and seven of them were attracted by methyl salicilate and one by cineole. Beside this essences, two more were used, eugenol and vanillin, but these two ones didn't collect any bees. All the bees were collected during November 2006. Even with such geographical distribution, L. rufipes hasn't been registered in this south region, and this is also the first registered collection of this specie using scent traps. It was not possible to identify the cause of the bee workers L. rufipes attraction by methyl salicilate and cineole, because these bees do not visit flowers, neither nets that could have this fragrance. The method of collection used by scent traps can be used for many purposes and among them the objective of knowing the richness and distribution of these types in different areas.
ABSTRACT
The fish Trachelyopterus striatulus (Siluriforms: Auchenipteridae) used to sample insects in a tropical reservoir. The study of aquatic environments is sometimes difficult to do with normal sampling methods that use gears. Insectivorous fishes represent good users of these ecosystems and analyzing the aquatic organisms present in fish stomachs, is an alternative way to determine resource abundance and utilization. In this paper, the potential of Trachelyopterus striatulus as an insect sampler was examined through dietary analyses of 383 individuals caught between April 1999 and March 2000 in Lajes Reservoir, a 30 km² oligotrophic impoundment in Southeast Brazil. We estimated frequency of occurrence and Schoeners index of similarity. Diet changes among seasons and reservoir zones were addressed with DCA and ANOVA analyses. Its diet was 92.1% insects (ten orders and nine families). Hymenoptera (57.90%), Odonata (39.76%), Trichoptera (27.41%), Ephemeroptera (26.25%) and Coleoptera (28.96%) were the most common groups. Highest insect occurrence and richness were recorded in autumn-summer, a period of greater rainfall and insect activity. Formicidae, the dominant prey item in all seasons, appeared to be especially important in spring, a season marked by shortness of food resources. Trichoptera and Ephemeroptera were the most consumed prey items in the other seasons. Highest insect occurrence and richness were recorded in the middle and upper reservoir zones, respectively. Trichoptera and Ephemeroptera prevailed in the upper zone, where small pristine rivers and tributaries are abundant, whereas Formicidae and Belostomatidae predominated in the lower and middle zones. Because of its abundance in many freshwater ecosystems of Brazil, the ubiquity of insects in its digestive tract and the low level of prey degradation, T. striatulus has potential as an insect sampler of Neotropical reservoirs. However, conventional sampling in Lajes Reservoir is necessary to compare the effectiveness of T. striatulus with other insect sampling methods. Rev. Biol. Trop. 57 (4): 1081-1091. Epub 2009 December 01.
El objetivo de este trabajo fue hacer un levantamiento entomofaunístico, en un embalse Tropical, utilizando como organismo indicador al pez Trachelyopterus striatulus. Fue analizada la dieta de 383 T. striatulus, muestreados desde abril de 1999 hasta marzo de 2000. La Frecuencia de presencia y el porcentaje de similitud de Schoener fueron aplicados para analizar la dieta. Para identificar variaciones de la entomofauna entre las estaciones del año y las zonas del embalse fueron aplicadas estadísticas univariadas y multivariadas. La dieta estuvo compuesta principalmente por insectos (92.14%) siendo los más frecuentes (%FO): Hymenoptera (57.90%), Odonata (39.76%), Trichoptera (27.41%), Ephemeroptera (26.25%) y Coleoptera (28.96%). Formicidae fue dominante en todas las estaciones del año, en especial en la primavera, mientras, Trichoptera y Ephemeroptera fueron más consumidos en las demás estaciones del año. En la zona alta, predominaron Trichoptera y Ephemeroptera, mientras en las zonas baja e intermedia predominaron Formicidae y Belostomatidae. T. striatulus presenta potencial como muestreador de la entomofauna contribuyendo para el conocimiento de la biología y ecología de los insectos y la ecología trófica de los organismos acuáticos.