Phytogeography of stem borer species of Zea mays L. and sorghum bicolor l. and their refugia graminae

Abstract

This study aimed at determining the phytogeography of stem borer species of Zea mays L. and Sorghum bicolor L. and refugia graminae. It involved two growing gramineous crops: maize Zea mays L. and Sorghum bicolor L. and three gramineous forages: Napier grass Pennisetum purpureum Schumach, Sudan grass and giant Setaria grass. These were planted both in pure and mixed stands and sampling for the borer infestation done throughout the phenology of crops . Three stem borers were recorded: Busseola fusca (Fuller), Chilo partellus (swinhoe) and Sasemia calamistis (Hampson).The B.fusca was more abundant in highlands (15 borers/10 plants with 1.5 + 0.6 larvae/plant) at 9 weeks after emergence (WAE). The C. partellus predominantly featured in lowlands with (22 borers /plant and 2.2 + 0.8 larvae/ plant) at 7 WAE. This was punctuated with the S. calamistis in the later habitat. However, on the overall, B. fusca was the most prevalent with a mean of 11.20 while S. calamistis had the least prevalence with a mean of 2.000.B.fusca was the most prevalent species in the highlands while C.partellus was the most abundant species in the lowlands and S.calamistis was scanty. More research should be conducted to determine the strains of B.fusca,C.partellus and S.calamistis as initially,these species had distinct ecological zones.However,they are currently found in various ecozones.Molecular techniques can be employed in characterize them for identity. Keywords: Phytogeography, stem borer,Zea mays L.,Sorghum bicolor,refugia and graminae