Laboratory evaluation of two native fishes from tropical North Queensland as biological control agents of subterranean Aedes aegypti

The ability of 2 freshwater fishes, eastern rainbow fish Melanotaenia splen dida splendida and fly-specked hardyhead Craterocephalus stercusmuscarum st ercusmuscarum. native to North Queensland to prey on immature Aedes aegypti was evaluated under laboratory conditions. The predation efficiency of the 2 species was compared to the exotic guppy, Poecilia reticulata, which is commonly used as a biological control agent of mosquito larvae. Of the 3 fi sh species tested, M. s. splendida was shown to be the most promising agent for the biological control of Ae. aegypti that breed in wells. Melanotaeni a s. splendida consumed significantly greater numbers of immature Ae. aegyp ti than P. reticulata, irrespective of developmental stage or light conditi ons. Unlike C. s. stercusmuscarum, M, s. splendida could be handled, transp orted, and kept in captivity for extended periods with negligible mortality . However, M. s. splendida was also an efficient predator of Litoria caerul ea tadpoles, a species of native frog found in wells during the dry season. This result may limit the usefulness of M. s. splendida as a biological co ntrol agent of well-breeding Ae. aegypti and suggests that predacious copep ods, Mesocyclops spp., are more suitable. However, the use of M. s. splendi da as a mosquito control agent in containers that are unlikely to support f rog populations (e.g., aquaculture tanks and drinking troughs) should be gi ven serious consideration.