THE SUSCEPTIBILITY STATUS OF MAIZE VARIETIES TO WEEVIL (SITOPHILUS SPP.) AND THE EFFECT OF STORAGE TYPE ON WEEVIL INFESTATION IN KOSHE AREA, SOUTHCENTRAL ETHIOPIA

Abstract

Maize weevils are cosmopolitan pests of stored grains and cause considerable economic losses to smallholder farmers. The infestation by maize weevils often start in the field, but serious damage is during storage. In this study, five maize varieties namely BH543, Jabi, Shala, Shone, and Abaraya were purchased from Mareko Woreda agricultural farmer training center and evaluated against maize weevils. The effect of different storage practices on maize weevil infestation was also evaluated in the five maize varieties. 200 gm of each of the maize variety was placed in six 750 ml jars to assess the infestation rate of maize weevils. The grain was sieved to remove dirt, and broken maize grain particles were removed, and then the normal grains were disinfested by keeping it in a deep freezer at -4 o c for two weeks. Four replicates were deliberately infested by 10 adult maize weevils (Sitophilus spp.) harvested from local farmer‟s stores. Two replicates were used as control. The grains were followed for 120 days. The percentage of germination and weight loss in control and infested maize grains was assessed. The five maize varieties were stored in three storage methods (with cobs, without cobs and in grain forms) to assess the effect of storage type on weevils infestation. The mean percentage germination in damaged seeds was 67.8%, while it was 85% in undamaged seeds. Among the damaged maize grains, the highest percent germination (76%) was recorded in BH543, while hybrid Shone preformed the least percentage of germination (52%). Mean live Sitophilus occurrence varied significantly in different storage forms (P = 0.001). Maize stored in grains form was most vulnerable to weevils with 5.73 weevils/100 gm mean number of weevils; it was 3.11weevils/100 gm in maize stored without cobs and only 0.65/100 gm maize stored with cobs. Shala allowed more weevils to be emerged across all types of storage forms, while Abaraya supported the lowest number of weevils in all storage types. Storage of maize varieties with cobs had provided a substantial protection from weevil infestation in the field. The storage of maize with cobs should be promoted to reduce damage and hence to improve food security in smallholder farmers. The use of maize varieties with thick husk covers may improve grain protection during storage.