Sweetpotato Weevil – Cylas formicarius

Sweetpotato Weevil (Cylas Formicarius) Common Name: Sweetpotato Weevil Latin Name: Cylas formicarius Appearance:

• The egg is round in form and cream-colored. It measures around 0.7 mm in length and 0.5 mm in breadth. The female deposits eggs in little holes formed by her mouthparts in the sweet potato root or stem. The female lays one egg at a time and seals it within the oviposition cavity with a fecal plug. The egg stage lasts from five to six days in the summer to 11 to 12 days in colder temperatures.
• The larva has no legs, is white, and has three instars. The larva normally burrows right into the plant’s tuber or stem when the egg hatches. The typical head capsule widths for instars 1 to 3 are 0.29 to 0.32 mm, 0.43 to 0.49 mm, and 0.75 to 0.78 mm, respectively. Each instar lasts 8 to 16, 12 to 21, and 35 to 56 days. Temperature is the most important element influencing the larval growth rate.
• The pupa resembles the adult in appearance, except that the head and elytra are twisted ventrally. The pupa is around 6.5 mm long. The adult larva forms a tiny pupal chamber in the tuber or stem. Initially white, the pupa develops grey coloration with darker eyes and legs during development.
• The adult emerges from the pupation site by biting a hole in the plant tissue. However, it sometimes feeds inside the tuber. The form and color are stunning. Long, slender body, legs, and head resemble an ant. Blackhead, orange-to-reddish brown antennae, thorax, and legs; metallic blue abdomen and elytra. The antennae are linked to the snout around midway. Close inspection reveals the beetle’s short hair.

Host plant: The Convolvulaceae plant family is a favorite food of this weevil. It has been associated with numerous species; however, Ipomoea plants are its major hosts. The sweet potato weevil relies heavily on native plants as food sources. Yet, only sweet potato is an appropriate host among vegetable crops. Territory: It is found in Africa, Australia, the Caribbean, Europe, Northern Asia (except China), Central America, North America, Oceania, South America, Southern Asia, the Pacific Ocean, and temperate Asia. Damages caused by Sweetpotato Weevil: Sweetpotato weevil is often regarded as the most harmful pest of sweet potato, with reported losses as high as 97% in places where the weevil is present. Vine damage or weevil density is correlated with ruined tubers. Despite this non-linear and sometimes insignificant link between vine damage and yield, the plants showed some compensating potential. Life history and habits: A whole life cycle can take anywhere from one to two months, with the average being between 35 and 40 days during the summer months. It isn’t easy to distinguish between the generations, and it is predicted that five generations will occur in Texas each year while at least eight will occur in Louisiana. Adults do not go through a period of dormancy known as diapause during the winter months; rather, they seek refuge and stay inactive until the weather improves. If sufficient host material is accessible throughout the year, all phases of the insect can be found.