Phenology and migration of tef Epilachna, Chnootriba similis Thunberg; (Coleoptera: Coccinellidae) in Ethiopia.

摘要

Studies were conducted on the phenology of tef Epilachna, Chnootriba similis Thunburg, formerly known as Epilachna similis, from 2003 to 2005 along two selected rivers and from 2004 to 2005 in two agricultural fields. Abundance of the insect was observed in barley fields every week and fortnightly along the rivers using 0.25 m2 quadrates and insect sweep nets, respectively. It survives along rivers during the dry period as adult in diapause, which terminates around mid-January, with increased feeding and initiation of mating. The adults then migrate to agricultural fields between March and April. This may be delayed because of the reduced cumulative rainfall in January and February. Termination of diapause and adult migration is influenced by rainfall. It is a bivoltine insect. The adults from the second generation migrate to rivers between September and October as they require moisture to overwinter during the dry period of the year, while the majority of the first generation adults remain in the agricultural fields. The ovipositional, larval and pupal periods of both generations was investigated and the duration of the developmental stages of the first generation were longer than in the second. This insect is mainly a pest of seedlings.