Abstract:
Some aspects of the bioecology and behaviour of Gasteroclisusrhomboidalis 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,
Gasteroclisusrhomboidalis 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 (
36±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 8.55±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).
A.D. Banjo , 2007. Bio-Ecology and Life History of Gasteroclisus rhomboidalis Boh.(Coleoptera: Curculionidae) a Pest of Amaranthus cruentus (L.) Sauer. Journal of Entomology, 4: 308-316.
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36±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 
