Cylas

Latreille, 1802

sweet potato weevils

Species Guides

Cylas formicarius(Sweet Potato Weevil)

Cylas is a of sweet potato weevils comprising over 20 described , classified in the monogeneric tribe Cyladini within the Brentinae. The genus contains major agricultural pests, particularly Cylas formicarius, which is considered the most serious pest of sweet potato worldwide. Several species including C. formicarius, C. brunneus, and C. puncticollis are known to infest sweet potato crops, causing substantial economic losses through damage to storage roots and vines.

Cylas formicarius by (c) Roman Gaidier, some rights reserved (CC BY), uploaded by Roman Gaidier. Used under a CC-BY license.

Cylas formicarius larva by Caroline Harding, MAF. Used under a CC BY 3.0 au license.

Sweet Potato Weevil. Cylas formicarius. Cyladinae, Brentidae. - Flickr - gailhampshire by gailhampshire from Cradley, Malvern, U.K. Used under a CC BY 2.0 license.

Pronunciation

How to pronounce Cylas: //ˈsaɪlæs//

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

within Cylas are distinguished by differences in their chemistry: C. formicarius produces (Z)-3-dodecenyl-(E)-2-butenoate, C. brunneus produces dodecyl-(E)-2-butenoate, and C. puncticollis produces decyl-(E)-2-butenoate. These are species-specific in laboratory assays, though cross-species responses can occur at elevated doses. The crotonate (trans-crotonic acid) moiety is essential for complete mating in C. formicarius and C. brunneus, while C. puncticollis males exhibit incomplete mating behavior when exposed to this compound alone.

Images

Habitat

Associated with cultivated sweet potato (Ipomoea batatas) in tropical and subtropical agricultural systems. Larval development occurs within sweet potato vines or tubers.

Distribution

Widespread across tropical and subtropical regions globally. C. formicarius occurs in Asia (including China, India, Indonesia, Philippines, Thailand, Vietnam), Africa (Cameroon, Ghana, Madagascar, Uganda, and others), Australasia and Pacific Islands (Australia, Fiji, Hawaii, Papua New Guinea, Solomon Islands), North America (Mexico, USA), Central America and West Indies, and South America (Guyana, Venezuela). C. brunneus is distributed in Africa (Burundi, Côte d'Ivoire, Ghana, Kenya, Nigeria, Rwanda, Sierra Leone, Togo, Uganda).

Diet

Larvae and feed on sweet potato (Ipomoea batatas). Larvae develop internally within vines or tubers, consuming plant tissue.

Host Associations

Ipomoea batatas - primary sweet potato; larval development and feeding occur on this

Life Cycle

Larval period is spent within sweet potato vines or tubers. are .

Behavior

are . Males exhibit elevation as initial mating when exposed to . Complete mating behavior sequence (antennae elevation through copulation) is triggered by -specific sex pheromones. Cross-species activity is possible at elevated doses. Dodecan-1-ol functions as an compound. The free alcohol precursor 3-Z-dodecen-1-ol causes sexual stimulation in heterospecific males. Trap color preference differs between indoor and outdoor conditions: green traps are most effective indoors, while red traps (particularly light red) are most effective in field conditions.

Human Relevance

Major agricultural pest of sweet potato, ranked as the seventh most important food crop globally. C. formicarius alone inflicts over $7 million in losses in the southern United States. Estimated losses of 60-100% occur in sub-Saharan Africa, primarily during dry spells. Management strategies include varieties (e.g., 'Covington', 'Bonita'), crop with non- crops, cover cropping, using bassiana and , and mass trapping with synthetic . Pheromone-based mass trapping has suppressed male but has not substantially reduced crop damage.

More Details

Pheromone Chemistry

Each Cylas produces a distinct ester : C. formicarius (Z)-3-dodecenyl-(E)-2-butenoate, C. brunneus dodecyl-(E)-2-butenoate, C. puncticollis decyl-(E)-2-butenoate. Natural extracts contain additional compounds that may act synergistically, as synthetic pheromones alone are less attractive than crude extracts.

Breeding Challenges

is considered one of the most promising protection strategies, but breeding for weevil- sweet potato cultivars has been slow due to the complex hexaploid of sweet potato, pollen sterility, cross incompatibility, and poor seed set and germination.