Pre-Harvest Assessment of Sitophilus Zeamais Motshulsky and Sitotroga Cerealella (Olivier) in Major Maize Producing Areas: Evidence from Southern Ethiopia

Abstract

An assessment of the levels of field infestation of maize to major primary maize stored pests, namely Sitophilus zeamais Motshulsky and Sitotroga cerealella (Olivier) was carried out in major maize growing district of  ‘Sidama Zone’, Southern Ethiopia in 2002 cropping season. During survey time questionnaries were parepared to know farmers’ peception about these two pests and to get information on whether infestation starts at field or at storage and there exist alternative host for S. zeamais and S. cerealella. At the same time the distance of maize field from farmer’s house and/or storage structure was measured to know the impact of nearness of house and/or storage structure on field infestation. Moreover, cropping pattern together with the history of the field was recorded to know their impact on field infestation of maize by these insect pests. Both S. zeamais Motschulsky and S. cerealella (Olivier) were recorded from standing maize in the field. Field population of both pests was not significantly different among Peasant Associations (PAs). However, population of the pests varied among farmers’ fields within PAs and plots within farmers’ fields. More number of S. zeamais adults than S. cerealella were recorded both at sampling time and after keeping the sampled cobs in the laboratory for four weeks. Field population of the pests was governed by characteristics of the sheath cover of the cobs. Bare tipped cobs appear to attract more S. zeamais than S. cerealella. The higher the initial infestation the higher the subsequent damage in the store was observed. This indicates that to reduce damage to the grain in the store management practices shouldn’t concentrate only in the store, but should start from the field.The distance of maize field from farmer’s residence was negetively coorelated, which indicates that the higher the maize field from the residence of the farmer the lower the pests population. Almost all farmers in the surveyed area considered S. zeamais and S. cerealela as one species and all know that infestation starts in the field.

Keywords: Sitophilus zeamais, Sitotroga cerealella, field infestation, distance of maize