Aspects of the Life Cycle and Behaviour Of Cosmopoutes Sordid Us Germar (Coleoptera: Curculionidae).

Abstract

The life cycle of the banana weevil borer.Cosmopolites sordidus Germar (Coleoptera: Curculionidae) was evaluated under laboratory and screen house conditions. Choice chamber tests were also conducted to assess the comparative responses of weevils to banana tissues and extracts and light and moisture conditions. Developmental period ofthe weevil averaged 56.4 days (range 53 - 63) in thelaboratory and 67.1 days (range 63 - 72) in the screen house. Larval duration was significantly (PSG.05) longer than previously recorded, being 40.5 and 50.5 days in the laboratory and in the screen house respectively. The big difference in larval duration indicated the possibility of the occurrence of a distinct biotype of the weevil in this region. Higher temperatures in the laboratory also prolonged egg and larval development and caused higher mortality of all stages. Four times more weevils were attracted by rhizome pieces compared to pseudostem tissues and inclusion of rhizome extracts enhanced attraction to pseudostem pieces. Negative phototaxis was the most important behavioural response of C. sordidus and over-rode attraction to rhizome tissue or moisture. When pseudostem traps set in the morning were covered with black polythene sheets or trash almost as many weevil adults were trapped during the day as at night This result suggested that in heavily mulched or poorly pnmed banana crops. C. sordidus was active during the day and so caused greater damage.