The Migratory Locust, Tocusta migratoria L. (Orthoptera : Acrididae), in Japan I. Experiment on Crowding Effects

Abstract

Experiments were caarried out to elucidate crowding effects on Locusta migratoria in Kyoto. Hatchlings were obtained from eggs that had been laid by females caught in the field. The hoppers were subjected to three different densities (1, 2 and 5 per cage). Clear crowding effects were found in some of the 24 characteristics examined, such as hopper coloration, sexual dimorphism, (elytron length)/(posterior femur length) ratio, (posterior femur length)/(maximum width of head) ratio, yellowing of male, adult longevity, number of egg pods per female, number of eggs per pod, viability of eggs, percentage of eggs entering diapause, hatchling weight of the progeny, etc. Although Locusta migratoria has not shown any outbreaks in Kyoto at least in the last hundred years, it has not lost its ability to respond to crowding. The effect of age of the female on her eggs was also examined.