CONSUMO DE ALIMENTO POR UM GAFANHOTO NEOTROPICAL, Stenacris fissicauda fissicauda (BRUNER, 1908) (ORTHOPTERA:ACRIDIDAE) DA VÁRZEA AMAZÔNICA

Abstract

1RESUMO -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. fissicauda desenvolve 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.Palavras-chave: Orthoptera, Acrididac, Consumo de Alimento, Macrófitas Aquáticas, Várzea. (Bruner, 1908) (Orthoptera: Acrididae) from the Amazonian "Várzea". Food consumption of a Neotropical grasshopper, Stenacris fissicauda fissicaudaABSTRACT -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. fissicauda develops its life cycle. The initial stage nymphs consumed the most (0.7740 g/g of animal biomass/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.

The role of the host-specific grasshopper Cornops aquaticum (Orthoptera: Acrididae) as consumer of native Eichhornia crassipes (Pontederiaceae) floating meadows

“…The CI of C. aquaticum found in our study is higher than the consumption found for other semiaquatic grasshoppers (Thomas 1974, Amorim & Adis 1994. Based on the amount of consumption reported by Amorim & Adis (1994) for Stenacris fissicauda fissicauda (Leptysminae), we estimated the CI for the different specific age classes of this Amazonian grasshopper (nymphs A: 0.774, nymphs B: 0.473-0.502 and adults: 0.262). Because the mean individual dry weights of both Leptysminae species are similar, thus, we postulate that C. aquaticum has a greater consumption capacity than S. fissicauda fissicauda.…”

“…According to the longevity of each specific age class of the C. aquaticum population (Franceschini 2008), individual cumulative consumption of a specific age class (C cum ) was calculated using the criteria of Amorim & Adis (1994):…”

“…Higher daily consumption by individual females is related to a highest mean dry weight and increase in dry weight per individual found in this specific age class of the population. Highest individual consumption in females is also found in semiaquatic (Amorim & Adis 1994) and grassland grasshoppers (Gangwere 1959, Sánchez & De Wysiecki 1990.…”

“…Quantitative data on the feeding impact and the amount consumed by semiaquatic grasshoppers in their natural habitat are practically non-existent. The only information available is for populations of C. aquaticum (Adis & Junk 2003) and Stenacris fissicauda fissicauda (Amorim & Adis 1994) in the Amazon floodplain. In contrast, many studies on consumption, preference and feeding impact have been carried out on terrestrial generalist grasshoppers, due to the economic importance of losses of natural grasslands and crops (Haniffa & Periasamy 1981, Ronderos et al 1981, Sánchez & De Wysiecki 1990, De Wysiecki & Sánchez 1992, Pereyra et al 1996, Cigliano & Lange 1998, Abdel-Rahman 2001, Torrusio et al 2005, Franzke et al 2010.…”

Congruence between fish and plant assemblages in drifting macrophyte rafts in Central Amazonia

“…Macrophyte species may also harbor different invertebrate assemblages(Amorim & Adis, 1994;Vieira & Adis, 2000;Adis & Victoria, 2001), which are prey for fish, resulting in an indirect relationship between plant and fish species in the stands along the banks. Stands with different macrophyte compositions have different habitat complexity and macroinvertebrate and periphyton assemblages…”