Varietal role in the management of the larger grain borer, Prostephanus truncatus (horn) in stored maize

Abstract

The study determined the amount of haemolymph vitellogenin (Vg) of the Larger Grain Borer (LGB), Prostephanus truncatus (Horn) vitellogenic females reared on different maize varieties. The varieties were ZM 521, ZM 421, ECAVL1-DLN, WEEVIL A, LOCAL 1 and LOCAL 2. Sodium Dodecyl Sulphate-Polyacrylamide Gel Electrophoresis (SDS - PAGE) was conducted on the insect haemolymph. F1 LGB adults from each variety were used to determine Indices of Susceptibility (IS) of the varieties to the insect pest attack. Percentages of Vg from female insects and IS were in the order ZM 521>ZM 421> ECAVL1-DLN>WEEVIL A >LOCAL 1>LOCAL 2. Weight losses of the varieties after F1 emergence were recorded. Findings showed that the IS and the weight losses were highest in ZM 521 and lowest in LOCAL 2. ANOVA indicated significant differences in the IS, weight loses and Vg levels of insects among the varieties. IS and Vg were positively correlated. Varying Vg levels reflect reproductive capacity of P. truncatus and therefore used to identify resistant maize grains. It is concluded that resistant varieties play a great role in stored maize pest management by reducing LGB populations below economic injury levels (EIL).

Tanzania Journal of Science Vol. 32 (2) 2006: pp. 13-22