Damage caused, loss assessment and emergence pattern of Acanthoscelides obtectus (Say) on the beans, Phaseolus vulgaris L. in Gaborone

Abstract

The damage caused, loss assessment and emergence pattern of Acanthoscelides obtectus Say was studied under laboratory condition (temperature range 27.5-30.0 °C and relative humidity 62-74%), on the beans Phaseolus vulgaris L. The mean percentage weight loss caused by A, obtectus on P. vulgaris during 2 months of storage was 13.7%. The percentage seed infestation was 81.5± 3.30 during 2 months of storage period. There was peak emergence of A. obtectus on the fourth day, thereafter the number of emerged adults decreased daily until the 17th day when there was no emergence. The number of adult emergence holes on P. vulgaris ranged from one to ten holes per seed. The results show that multiple infestations of P. vulgaris by A. obtectus can occur. In most cases one larva of A. obtectus infest one seed even though multiple infestations may occur in some cases.