Host range, development, survival and population dynamics of cotton stainers (dysdercus spp) in Kilosa district, Tanzania

Abstract

A field survey was conducted in cultivated and uncultivated fields in cotton growing areas in Kilosa District to determine the host range of different species of cotton stainers (Dysdercus spp). Five species of cotton stainers were identified, namely Dysdecus fasciatus Sign; D. intermediosus Dist; D. nigrofasciatus Stål; D. cardinalis Gerst and D. superstitiosus (F). Most of the host plants identified to harbour cotton stainers belonged in the order Malvales. Dysdercus fasciatus; D. intermediosus and D. nigrofasciatus were found to have wider host ranges than D. cardinalis and D. superstitiosus. Some few plants that were potentially found to host cotton stainers belonged to the families of Asteraceae, Moraceae, Myrtaceae, Caricaceae, Musaceae, Anacadiaceae, Bromeliaceae and Poaceae. In the population dynamics study, fluctuation patterns of the individual species varied greatly. Dysdercus fasciatus was dominant on Gossypium hirsutum throughout the year except for the two months that D. intermediosus was dominant on the same plant species. Dysdercus fasciatus was dominant on G. barbadense, Ceiba pentandra and Adansonia digitata. In this study, it has been revealed that both D. fasciatus and D. intermediosus are currently the major cotton stainer species in Kilosa district. Among the alternative host plants studied, G. barbadense, Ceiba pentandra and Adansonia digitata have been regarded as the most dangerous plant species for cotton industry due to their tendency of harbouring large populations of the major cotton stainer species. In the laboratory experiment to determine survival and development of Dysdercus fasciatus when fed on various cultivated and wild host plant species, Gossypium barbadense, G. hirsutum, were better-than-adequate host plants for D. fasciatus. Ceiba pentandra, Adansonia digitata were adequate, Hibiscus micranthus was relatively poor and Abelmoschus esculentus was very poor as a host plant. Results of the studies can be used in the formulation of integrated cotton stainer management strategies.