Studies on the degeneration of the flight muscles of alate aphids—I: A comparative study of the occurrence of muscle breakdown in relation to reproduction in several species

Abstract

When alate aphids of several species were allowed to settle down on their host plants, their flight muscles began to break down within a few days. The onset of muscle degeneration could be delayed by preventing the aphids from settling down, either by denying them their host altogether or by leaving them on a poor host in darkness for several days. The reproductive capacity of alatae before they lost the ability to fly varied for different species. Embryo development was arrested in alatae of all the species that were studied after the end of the teneral condition following the final ecdysis, and was resumed when they settled down on a new host. Some species of aphids contained a number of fully formed embryos at the time embryo development was arrested, and these plus a few additional embryos whose development had been completed after the aphids settled down were born before the ability to fly was lost. In other species the young alatae contained only rudimentary embryos that required several days to develop to the stage at which they were normally born; in these species no larvae were born until the muscles had begun to degenerate and the ability to fly was lost. Other species fell between these two groups and in one species, Macrosiphum euphorbiae (Thomas), whether or not the aphids reproduced at all before losing the ability to fly depended upon their size. The ability of alatae of Aphis fabae Scop. to engage in long flights of 1 hr or more was retained for as long as the aphids retained the ability to fly.