Effects of Density and Host Quality on Rate of Development, Survivorship, and Sex Ratio in the Carmine Spider Mite 1

Abstract

The effects of host quality and mite density on developmental rate, survivorship and sex ratio of Tetranychus cinnabarinus were investigated. Males developed faster than females and more females than males were produced. Female mites reared on good leaves tended to produce offspring with a slightly slower developmental rate and lower sex ratio and survivorship than females from poor quality leaves. The effects were shown to be indirect influences of density. Good leaf quality during oviposition and development of offspring resulted in relatively faster developmental rates and higher survivorship of offspring but had no effect on sex ratio. The density regimes used drastically affected the traits. At high density, the mites showed a marked reduction in developmental rate, survivorship, and sex ratio as compared with mites reared in the low density regime.