The total number of eggs laid by Callosobruchus rhodesianus (Pic.) and Callosobruchus maculatus (F.) females in the presence of single and mixed species populations of males at different densities were counted. Increasing male density significantly reduced the realised fecundity of C. maculatus but not C. rhodesianus females. In the presence of C. maculatus males, however, the number of eggs laid by C. rhodesianus was greatly reduced. The reduction in egg laying and observations on mating behaviour indicates direct physical interference between weevils and competition for mates. An adequate number of beans were provided so competition for oviposition sites by females was unlikely. The ability of C. maculatus to inhibit oviposition of C. rhodesianus is suggested as one reason for its superiority over the latter when the two species compete for limited resources.Resume-Le nombre d'oeufs pondus par Callosobruchus rhodesianus (Pic.) et Callosobruchus maculatus (F.) en presence de differentes densities de males d'especes unique ou mixtes hlrent compte. L'augmentation des densities de males ont reduit de fagon significative la fecondite realisee de C. maculatus mais non celle de C. rhodesianus. Par contre en presence de males de l'espece C. maculatus, le nombre d'oeufs pondus par C. rhodesianus fut grandement reduit. La reduction d'oeufs pondus inique une interference physique directe entre les charancpns ainsi qu'une competition pour l'accouplement. Une qualite suffissante de feves fut fournie afin que la competition entre les femelles pour les sites d'oviposition soit improbable. La capacite d'inhiber l'oviposition de C. rhodesianus par C. maculatus est suggeree comme une raison pour sa superiorite sur C. rhodesianus lorsque les deux especes competitione pour des ressources limitees.
The fecundity and duration of oviposition in three strains ofCallosobruchus rhodesianus from the highveld, middleveld and lowveld regions of Zimbabwe and a laboratory strain were recorded on cowpea and greengram. Within-legume variability for both parameters was high among the four strains. The lowveld strain was the least fecund and had the longest duration of oviposition. The middleveld strain showed the highest fecundity on cowpea, but did not differ significantly from the other three strains on greengram.
Resume 1 -La fecondite' et la duree de la ponte chez trois biotypes de Callosobruchus rhodesianus des regions du haut veld, du moyen veld et du bas veld du Zimbabwe ont €U rapportees sur le nie'be' et le haricot dor£ (golden gram/greengram/mung bean: Vigna radiata/Phaseolus aureus).La variability intra-legume des deux parametres etait elevee parmi les quatre biotypes. La biotype du bas veld etait le moins fecond et sa ponte durait le plus longtemps. La biotype du moyen veld presenta la plus haute fecondite' sur le nieb6 mais qui n'&ait pas significativement differente de la ponte des trois autres biotypes sur le haricot dore'.Mots Clis: Callosobruchus rhodesianus, biotypes ge'ographiques, ponte, p6riode de ponte, Zimbabwe
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