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.
