ISSN: 0041-3216 (Online), 0041-3216 (Print)
Volume 68 Number 2
Convolvulaceae and Cylas: a proposed hypothesis on the origins of this plant/ insect relationship*
Sweet potato weevils, assigned to Cylas formicarius (Fabricius), have been associated for certain with cultivated sweet potato (lpomoea batatas [L.] Lam.) only since the 19th century, although their early history is obscure and they probably have been associated for much longer. To date, the weevils have been reported on a total of 35 species of Convolvulaceae and are not restricted to the genus lpomoea. The weevils have been found on seven genera in six tribes within the family. Such a wide usage of the family members suggests that the insect is oligophagous. Data indicate that the weevils may originally have utilized several members of Convolvulaceae in the lpomoea section of Erpipomoea. It is hypothesized that the weevil is native to the Old World where it became associated with the introduced American sweet potato. From the point of contact, both were spread into areas where one or the other did not previously exist. A proposed phylogeny for the lpomoea sections is given as well as one for the tribes within the Convolvulaceae. A revised host plant list of C. lonnicarius weevils is provided according to current taxonomic disposition.
Keywords: Cylas Formicarius; Plant/insect relationships; Alternate host; lpomoea; Taxonomy