Study on the Population of Chafer Grub

Abstract

A trial was carried out in 1998 and 1999 at Tikur Inchini in Western Shewa, where barley is predominantly grown, to determine the population of the Chafer grub, Coptognathus curtipennis. Population counts were made after the crops (barley, tef and linseed) were
harvested and on the fields left fallow for at least one year. Diggings were carried every 15 days in five quadrats per each crop or fallow land to about 20 cm depth. The larval, pupal and adult populations of the chafer grub were low in previously tef grown plots followed by barley and linseed grown plots and in plots left fallow for at least one year. The farmers at Tikur Inchini could follow cropping sequence: Fallow —» Tef —» Barley/Wheat —> Linseed/Tef —> Barley/Wheat -> Linseed -> Fallow. The low population of chafer grub in tef grown fields may be due to the intensive cultural practice in land preparation which usually include repeated
plowings and trampling that exposed the different insect developmental stages to the adverse environmental conditions.