SPECIES COMPOSITION, BIOLOGY AND MANAGEMENT OF SWEET POTATO WEEVILS (CYLAS SPECIES) IN SOUTHERN GHANA.

ABSTRACT

Species composition of sweet potato weevils (Cylas spp) on two sweet potato varieties was determined in the southern parts of the country. One species, Cylas puncticollis Boh. was found to be present in the southern part of Ghana. Studies on the biology of Cylas puncticollis were evaluated on two varieties, red and white varieties, under laboratory conditions at 27.0°C and 70% RK The incubation period of the eggs were 4 days on the red variety and 5 days on the white variety. Larval stages ranged from 10-11 days on the red and 10-12 days on the white. The pupal stage lasted 6-8 days on the red and 7-8 days on the white. Three larval instars were identified. Total developmental period from the egg stage to the adult stage ranged from 19-23 days on the red variety and 19-25 days on the white variety. Limited copulation significantly (P0.05) from each other and from the control. However, furadan moderately reduced tuber infestation (damage) during the two planting seasons.