|A. D. Banjo
|Journal of Entomology
Some aspects of the bioecology and behaviour of Gasteroclisus rhomboidalis Boh. at the Olabisi Onabanjo University were studied from March to September 2003. A survey of the speciation of the curculionid pest on Amaranthus plot of the University was carried out. The result revealed that three species occurred at study sites. The relative abundance of the pest, Gasteroclisus rhomboidalis earlier thought as a major pest of Amaranthus and Celosia is infact a minor one and that it does not occur abundantly. Infestation was all the year round on wild Amaranthus (Amaranthus spinosus) at the University site and possibly Amaranthus is the primary alternate host of this pest. The life history of G. rhomboidalis was studied using A. cruentus and result showed that there are three instar larval stages and take between 32 to 42 days ([overhead single bar]x 36[plus or minus]4 days) to complete its life cycle. The mating behaviour, oviposition, larval development and emergence of G. rhomboidalis on Amaranthus were studied. It was found that the male initiated mating and this last up to 12 h [overhead single bar]x 8.55[plus or minus]2.37 hours while oviposition commence immediately after copulation. Larval development takes place in the tunnels made by the larval instars and all development stages takes place inside the host (Amaranthus) stem. Adult emerges through a hole (emergence hole).