Insect Pests of Farm-stored Sorghum in the Bako Area

Abstract

A survey was conducted in 1996 and 1997 to assess the species of insects and the associated damage levels in farm-stored sorghum. Fifty and 75 farm-stores in 1996 and in 1997 respectively were visited in some parts of western Shewa, east and western Wellega zones. Seven species of beetles, three species of moths, several hymenopteran parasitioids, bugs and pseudoscropions were recorded from the samples. Weevils of Sitophilus species followed by the Angomois grain moth were found to be the major
insect pests of stored sorghum causing substantial losses. Sitophilus weevils were collected from all sites in large numbers. S. cerealella was also observed in most of the samples. The average grain damage and weight losses for the two years were 38.7% and 14.5%, respectively. Fifty eight percent and 55% of the farmers used gotera (gombissa and gota) type of storage structures in 1996 and 1997, respectively. Other storage facilities such as sacks, gumbi, clay pots and wooden boxes are also used in smaller proportions. Fifty percent of the respondents in 1996 and 28% in 1997 reported that they applied different types of chemicals to protect their sorghum in storage. Ten percent of the respondents in 1996 and 6.6% of them in 1997 used the nonrecommended
chemical DDT while 6% and 4% used pirimiphos-methyl in respective years. Some of the farmers responded that the treated grain is not used for consumption, but is sold in the market. They also practised periodical exposure and drying of grains in the sun, mixing sorghum with tef and finger millet and admixing of sorghum with partially ground hot pepper to protect their sorghum. Sorghum is also stored by putting in the middle of tef or finger millet either of the two being put at the top and bottom layers.