VARIABILITY IN WING FORM OF CRICKETS

Loss of functional hindwings is observed in most subfamilies of Japane se crickets. Habitat, behaviour, body size and phylogenetic factors mi ght be involved, but interactions among them may obscure the general t rend. Wing dimorphism is common among the relatively small-sized membe rs of Gryllinae, and the two small-sized subfamilies, Nemobiinae and T rigonidiinae. Both environmental cues (e.g, photoperiod) and genetic f actors affect the wing form. In Dianemobius fascipes (Nemobiinae), the percentage macroptery was drastically changed by selection for macrop tery or microptery. Crossing experiments indicated polygenic control o f wing form as well as X-chromosomal and maternal effects. Neither the long-winged nor short-winged line bred true after 40 generations of s election. Full-sib families revealed a large genetic variation in freq uency of macropterous forms within a population. The genetic determina tion of the propensity for macropterism did not seem to be directly co upled to the mechanism performing the photoperiodic time-measurement.