RESUMO
Abstract This work provides the results of a survey of entomonematodes parasites of grasshoppers in grasslands of the Pampean Region, Argentina. Nymphs of Staurorhectus longicornis Giglio-Tos, Laplatacris dispar Rhen, 1939, Dichroplus elongatus Giglio-Tos, 1894 and Metaleptea brevicornis (L.) (Orthoptera: Acrididae) were collected. Mermithidae was the only family registered with seven species: Agamermis decaudata Cobb, Steiner and Christie, 1923, Amphimermis bonaerensis Miralles and Camino, 1983, Amphimermis dichroplusi Camino and Lange, 1997, Amphimermis ronderosi Camino and Lange, 1997, Hexamermis coclhearius Stock and Camino, 1992, Hexamermis ovistriata Stock and Camino, 1992, and Longimermis acridophila Camino and Stock, 1989. The values of parasitism ranged between 1-12%, and intensity not overcome the number of 5.0 nematodes per larva. The nematodes observed showed specificity, not registering the same species of parasite in more than one host species. The Pampean region constituted an area with high diversity of mermithids where new species could be consider as bioregulator agents of this troublesome insect pests in agricultural areas of Argentina.
Resumo Este trabalho apresenta os resultados de uma pesquisa entomonematode parasitando gafanhotos em pastagens da região pampeana, Argentina. Ninfas de Staurorhectus longicornis Giglio-Tos, Laplatacris dispar Rhen de 1939, Dichroplus elongatus Giglio-Tos, 1894 e Metaleptea brevicornis (L.) (Orthoptera: Acrididae) foram coletados. Mermithidae era a única família registrado com sete espécies: Agamermis decaudata Cobb, Steiner and Christie, 1923, Amphimermis bonaerensis Miralles and Camino, 1983, Amphimermis dichroplusi Camino and Lange, 1997, Amphimermis ronderosi Camino and Lange, 1997, Hexamermis coclhearius Stock and Camino, 1992, Hexamermis ovistriata Stock and Camino, 1992, e Longimermis acridophila Camino and imagem, de 1989. Os valores de parasitismo variou entre 1-12%, e intensidade não superar o número de 5,0 nematóides por larva. Os nemátodos observados demonstraram especificidade, não registar as mesmas espécies de parasita em mais do que uma espécie de hospedeiro. A região pampeana constituída uma área com alta diversidade de mermithids onde novas espécies poderiam ser consideradas como agentes bio-reguladores deste incômodos insetos pragas em áreas agrícolas da Argentina.
Assuntos
Animais , Gafanhotos/parasitologia , Mermithoidea/isolamento & purificação , Argentina , Larva , Ninfa/parasitologiaRESUMO
Orthoptera assemblages associated with macrophytes of floodplain lakes of the Paraná River. The Orthoptera assemblage composition varies considerably, depending on habitat type. This study examines the spatiotemporal relationship between plant diversity, hydrometric level, environmental variables and the Orthoptera richness and abundance in floodplain lakes connected permanently or temporarily with the main channel of the Paraná River. The grasshoppers were collected fortnightly (April 2006May 2007). A total of 17 species were recorded and classified according to their frequency of occurrence in constant (7), accessory (4), or accidental (6) species. In the two lakes, the greater species richness and abundance was recorded in summer, thereby coinciding with the highest water level of the Paraná River. The most significant correlation between the orthopteran richness and abundance was with the water level. The aquatic plant richness was significantly different between the lakes, but the vegetation was dominated by Eichhornia crassipes (Mart.) Solms. (Liliales, Pontederiaceae). The lake, which was connected permanently, presented the highest values of diversity and abundance, proving to be a more diverse assemblage. The beta diversity was higher in the temporary connected lake than in the permanently connected one. The orthopterans assemblages were different between the lakes, Cornops aquaticum and Tucayaca gracilis were the species that contributed more to the level of dissimilarity. C. aquaticum was more representative in the lake temporarily connected, while T. gracilis in the permanent connected one. The water level of the Paraná River and the connectivity of the floodplain lakes play an important role to explain the abundance and richness of their orthopteran assemblages.
RESUMO
The effects of temperature and photoperiod on the nymphal development of the semi-aquatic grasshopper Stenacris fissicauda fissicaudafrom a Central Amazonian floodplain (várzea) near Manaus were studied. Newly hatched nymphs were collected in the field from the aquatic macrophyte Paspalum repens(Gramineae-Poaceae), and raised under controlled conditions in environmental chambers (8, 12 and 24 hours of light, 27°C and 27/21°C of temperature) and under natural conditions. This species has 5 nymphal instars in males and six in females under longday conditions in the laboratory, as well as during the period with lower precipitation ("dry season") under natural conditions. However, an extra instar for males (6th) and females (7th) was observed under short-day conditions in the laboratory. This instar occurred during the period with higher precipitation (rainy season) under natural conditions. Temperature and photoperiod were found to interact in the nymphal development under controlled conditions: 1) The number of instars (especially in females) was principally influenced by the photoperiod; 2) The developmental time of instars (in both sexes) was mainly influenced by temperature. The results are discussed under the aspect that light can act as a controlling factor (ecofactor) on the number of nymphal instars during the development of insects in tropical ecosystems, even when located near the equator, due to seasonal changes in insolation and/or light intensity during the year.
Estudou-se a influência da temperatura e do fotoperíodo no desenvolvimento ninfal do gafanhoto semi-aquático Stenacris fissicauda fissicaudaproveniente de uma região de várzea, perto de Manaus. Ninfas recém-eclodidas foram coletadas no campo na macrófita aquática Paspalum repens (Gramineae-Poaceae)e criadas sob condições controladas em câmaras de criação (8, 12 e 24 horas de luz, 27°C e 27/21°C de temperatura) e sob condições naturais. Esta espécie apresenta 5 estádios ninfais para os machos e 6 para as fêmeas sob condições de dia longo no laboratório e durante o período com menos precipitação (estação "seca") sob condições naturais. No entanto, observou-se um estádio extra para machos (6o) e fêmeas (7o) sob condições de dia curto no laboratório. Este estádio ocorreu durante o período com mais precipitação (estação chuvosa) sob condições naturais. Constatou-se que a temperatura e o fotoperíodo interagiram no desenvolvimento ninfal sob condições controladas: 1) O número de estádios (especialmente em fêmeas) foi principalmente influenciado pelo fotoperíodo; 2) O tempo de desenvolvimento ninfal (em ambos os sexos) sobretudo foi influenciado pela temperatura. Os resultados estão sendo discutidos sob o ponto de que a luz pode atuar como fator de controle (ecofator) no número de estádios ninfais de insetos em ecossistemas tropicais, mesmo sendo situados perto do equador, devido à mudanças sazonais de insolação e/ou intensidade de luz durante o ano.
RESUMO
Average leaf consumption of the grasshopper species Stenacris f. fissicauda is determined. The results are expressed as grams of leaf biomass/gram dry weight grasshopper/ day. The material used in the experiments was collected on Ilha de Marchantaria (island of "várzea ' - Rio Solimões) near Manaus. The animals were grouped accoding to nymph stage (initial (l+ll), middle (III+IV), final (V+VI)), and sex (males, females, males+females). The plant used as food was Paspalum repens, an aquatic macrophytc of the Poaceae on which Stenacris f. fissicaudadevelops its life cycle. The initial stage nymphs consumed the most (0.7740 g/g of animal bio-mass/day), while the smallest consume of leaf biomass was done by adults (0.2622 g/g of animal biomass/day). The calculated average consumption was about 0.5 g (dry weight) of leaf biomass consumed per gram (dry weight) of animal biomass/day. Data are compared with leaf consumption of Cornops aquatietun (Acrididae) on Eichiiornia crassipes (Pontederiaceae) from the same area.
É feita a determinação da quantidade média (g) de biomassa foliar consumida por 1 g (peso seco) de gafanhoto/dia nesta espécie. O material para a realização dos experimentos foi coletado na ilha de Marchantaria (várzea - Rio Solimões) perto de Manaus. Os animais testados foram agrupados por estádio ninfal (ninfas iniciais (I+II), médias (111+lV) e finais (V+VI)) e os adultos pelo sexo (machos, fêmeas, machos+fêmeas). A planta utilizada como alimento foi Paspalwn repens, macrófita aquática das Poaceac, onde Stenacrisf. fissicaudadesenvolve o seu ciclo vital. Verificou-se que as ninfas de estádios iniciais realizam o maior consumo (0,7740 g/g de biomassa animal/dia), enquanto que o menor consumo de biomassa foliar, foi feito pelos adultos (0,2622 g/g de biomassa animal/dia). O consumo médio foi calculado em 0,5 g (peso seco) de biomassa foliar consumida por g (peso seco) de biomassa animal por dia. Estes dados estão sendo comparados com o consumo foliar de Cornops aquaticum (Acrididac) em Eichhornia crassipes (Pontederiaceae) da mesma área.
RESUMO
Digamacris, a new genus of the Dichroplini (Acrididae, Melanoplinae) is described for the species Pezotettix amoenus Stal, 1878 and Dichroplus fratemus Carl, 1916, both included at present in the genus Dichroplus. These species live in edges and clearings of the Atlantic Forest (Mata Atlantica) of Brazil. D. fratemus is found in the states of Minas Gerais, Espirito Santo and Rio de Janeiro east of the Bay of Guanabara. D. amoenus in the state of Rio de Janeiro W. of the Bay of Guanabara and in the coastal area of the state of São Paulo. The species are illustrated and redescribed. Both have two neatly different chromatic forms of females, while the males are uniform in coloration and closely correspond with one of the female forms.