A Field Study of Diapause in Coccinella novemnotata (Coleoptera: Coccinellidae),

Abstract

There are two generations of Coccinella novemnotata Herbst per year in central California. The adults of the spring generation aestivate and those of the fall generation hibernate. A field study of the physical and biological factors possibly influencing induction of diapause in the adult was conducted. All stages of the spring generation arc subject to a regime of long, increasing photoperiods and increasing mean temperatures, while all stages of the fall generation are subject to a regime of short, decreasing photoperiods and decreasing mean temperatures. In non-irrigated areas with native vegetation the reproductive cycle of this species is synchronized with the availability of prey species. In irrigated agricultural areas prey species are relatively abundant throughout the summer but the adults of the spring generation still aestivate. It is hypothesized that diapause is induced in the adult by both short and long photoperiods and that intermediate photoperiods are required for reproduction.The biology of C. novemnotata is described briefly with emphasis on the aggregational behavior of the adult.