Comparative development of cowpea bruchid, (Callosobruchus maculates (F.) (Coleoptera: bruchidae) on pods and seeds of some cowpea cultivars (Vigna unguiculata)

Abstract

The seeds of high-yielding and earlier-maturing cowpea cultivars, IT83E-761, TVNu-72, TVx3236 and Ife Brown were compared for their pods resistance to Callosobruchus maculates, a cosmopolitan field-to-store pest and principal post-harvest pest of cowpeas. Parameters used for comparison were mean number of eggs laid on each cultivar, mean percent egg hatched, mean percent larval mortalities, mean percent pupal mortalities, mean percent emerging adult mortalities, mean percent adult emergence, developmental periods and percent weight loss of seed. TVNu-72, Tvu 3236 and TVu 3000 demonstrated significant resistance to C. maculates compared to IT83E-716 and Ife brown with pods showing more resistance than seeds. These cultivars caused both larval mortalities and significant deterrence to oviposition. In comparison, C. maculates showed significant preference for Ife brown and IT83E-716 compared to others as significantly more eggs were laid on the former than the latter (cultivars). It is suggested that pod wall hairiness and thickness, seed coat oviposition deterrent factor(s) and cotyledonal antibiotic factor(s) are involved in conferring polygenic resistance on TVNu-72 and Tvx 3236 cultivars.

Keywords: Callosobruchus maculates, Vigna unguiculata, cultivar

Global Journal of Pure and Applied Sciences Vol. 12(1) 2006: 35-40