ABSTRACT
Nymphs and adults of Paulinia acuminata accepted five aquatic macrophytes out of 20 plant species offered during 12 days: Pistia stratiotes, Salvinia auriculata, S. minima, Azolla sp. and Ludwigia natans. The low survival rates obtained on Azolla sp. for adults (26%) and on L. natans for nymphs (40%) and adults (30%) indicate that these two aquatic macrophytes may represent alternative food sources. Cage experiments with P. statiotes and S. auriculata in the field resulted in 51-64% increase of fresh plant weight without P. acuminata and in 40-45% decrease, both compared to the initial plant weight, when 20 grasshoppers (nymphs and adults) were present. All these data reinforce the potential of P. acuminata as biological control agent for specific aquatic macrophytes.
Ninfas e adultos do gafanhoto Paulinia acuminata aceitaram como alimento cinco (5) espécies de macrófitas aquáticas entre as 20 testadas, durante 12 dias: Pistia stratiotes, Salvinia auriculata, S. minima, Azolla sp. e Ludwigia natans. As baixas taxas de sobrevivência de adultos (26%) alimentados com Azolla sp. e de ninfas (40%) e adultos (30%) em L. natans indicam que estas plantas podem representar recursos alimentares alternativos. Experimentos com P. stratiotes e S. auriculata dentro de gaiolas flutuantes, no campo, sem P. acuminata, resultaram num aumento do peso fresco das plantas (51-64%). Com 20 gafanhotos (ninfas e adultos) houve decréscimo de peso (40-45%). Estes dados reforçam o potencial dc P. acuminata como agente de controle biológico de macrófitas aquáticas específicas.