Genetic Control of Diapause and Other Developmental Traits in Japanese Strains of the Migratory Locust, Locusta migratoria L. : Univoltine vs. Bivoltine

Two Japanese strains of the migratory locust, Locusta migratoria L., and their reciprocal hybrids were reared under different photoperiodic conditions, and their developmental traits and diapause response were compared to determine the genetic control of these traits. Nymphal development was shorter in a univoltine strain from Hokkaido (43°N) than in a bivoltine strain from Ibaraki (36°N). No consistent correlation was found between nymphal development and body weight at adult emergence. In either trait, no significant difference was observed between the reciprocal crosses, suggesting that the gene(s) regulating these traints are autosomal. The Hokkaido strain laid diapause eggs at any photoperiod while the Ibaraki strain did so in response to short days, and the eggs tended to avert diapause at a high temperature. Adults of F_1 hybrids produced eggs with an intermediate incidence of diapause between the two parent strains. It is likely that the diapause in this species is under polygenic control and such genes are located on autosomes.