Effect of Mango weevil (Coleoptera: Curculionidae) damage on Mango seed viability in Tanzania

Abstract

Studies were conducted at the horticulture unit of Sokoine University of Agriculture, Morogoro, Tanzania, to assess the incidence and effect of mango weevil, Cryptorhynchus mangiferae (F.) (Coleoptera: Curculionidae), infestation on mango, Mangifera indica L., seed viability. Three polyembryo mango cultivars (ÔSindano nyeusiÕ, ÔSindano nyeupeÕ, and ÔDodoÕ) as well as three monoembryo mango cultivars (ÔEx-horticultureÕ, ÔTangoÕ, and ÔBongwaÕ) were collected and examined for the presence ofC. mangiferae. The effect of seed damage on viability was assessed for both naturally and artiÞcially damaged seeds. However, for artiÞcially damaged seeds, the viability was assessed by cutting away 0, 25, 50, or 75% of the cotyledon before planting. In this experiment, only monoembryo mango cultivars were used. All the examined cultivars were infested by C. mangiferae, although at varying levels. Polyembryo mango cultivars were relatively more infested than monoembryo cultivars. Bongwa and Tango were least infested, whereas Sindano nyeusi recorded the highest C. mangiferae incidence. Germination rates of damaged seeds of polyembryonic cultivars differed signiÞcantly from the uninfested control, except for Sindano nyeusi. There were no signiÞcant differencesin germination percentage among the three monoembryo cultivars, and all the cultivars differed signiÞcantly from the uninfested control. The germination rates of seeds with 25% of their cotyledons removed did not differ signiÞcantly from the undamaged seeds, indicating that monoembryo cultivar seeds can withstand up to 25% damage and germinate successfully.