1. Sweet Potato weevil ~ Cyclas Puncticollis
The potato weevil is the most severe and destructive pest affecting the growth and production of sweet potatoes. It is usually elongated, small in size and black or blue. Sweet potatoes weevils resemble an ant, has an antenna which is usually differentiated by the gender of the weevil, the females have club-shaped antennae while the males are straight.
The females lay eggs on the leaves or chew their way into the vines and lay eggs there, they lay oval-shaped eggs which are usually yellowish-white in colour. After a few days the larva develops and is regarded to as grub is white, they mainly feed on the leaves at the base of the plant the grub then grows into a pupa which usually feeds by tunneling into the veins and leaves.
Sweet potatoes weevils resemble an ant, has an antenna which is usually differentiated by the gender of the weevil, the females have club-shaped antennae while the males are straight.
The females can survive for a duration of up to 4 months, these pests usually feed on the leaves, tubers and the vines. They normally puncture numerous holes into the tubers thus lowering the quality and quantity of the produce, this causes wilting and yellowing of the leaves while turning the tubers spongy and brownish-blackish in appearance and even causing some of them to rot.
Some cultural methods of controlling these pests include practicing crop rotation, use of clean planting materials as they usually tend to lay eggs on some parts of the vines; planting materials should be taken from healthy-looking plants for good productivity also early land cultivation and plowing should be practiced before planting; as this helps to kill the grub in the soil and minimize pest spread.
The farmer can also introduce natural enemies i.e. Ants and Spiders which will help to curb their population and spread, these Cylas Spp can be controlled by practicing mulching this helps to prevent the soil from cracking and reduce weevil infestation at the same time retaining the soil moisture content. The farmer is urged to flood the field 48 hours after harvesting this will help to drown the weevils thus killing them also practice proper field sanitation after harvest.