The Srilanka weevil or Asian gray weevil, Myllocerus undatus Marshall is native to southern India, Sri Lanka and Pakistan. The species has been reported in Florida on numerous oranamental plants and fruit crops. It causes damage to the foliage and possibly root systems (Thomas, 2000; O'Brien et al., 2006). Adults feeding is most noticeable when plants are producing new foliage. The species is particularly abundant in northern Miami-Dade and southern Broward Counties.
There are 336 species recongized as valid in this genus from Southeast Asia, the Indian subcontinent, Africa, Asia (including China and Japan), the Palearctic, Indonesia, Australia and the United States (Florida). There are 73 species recognized as valid for the Indian subcontinent and the excellent revision of the species by Ramamurthy and Ghai (1988) and by Marshall (1916) in the fauna of British India series, were used to identify our introduced species. Four subspecies of M. undecimpustulatus including muculosus Desbrochers des Loges, undecimpustulatus, marmoratus Faust and undatus Marshall are among the most serious pest weevils in India and Pakistan, where they attack more than 20 crops (O'Brien et al., 2006).
In Florida this species was confirmed feeding on more than 80 plant species. This includes, citrus, cotton, sweet potato, fig, loquat, plum, mango, mahogany, etc. etc.
Larvae feeds on the roots of plants, however, the exact level of damage they cause is unknown. Adults of this pest cause severe feeding damage to the foliage. Damage can range from notching on the leaf margins in an irregular pattern to much more extensive feeding along the leaf veins. Small plants and young trees usually need protection.
Biological and Ecological Notes
Adults feed on leaves potentially reducing the quality and quantity of ornamentals and fruit production. In southern India pest is active from April to November and passes winter in the adult stages under the debris (Atwal, 1976). Oviposition occurs in soil close to roots. A single female lays on an average of 360 eggs over a period of 24 days. Larvae feed on roots, however, extent of root damage is unknown. Pupation occurs in soil inside the earthen cells and take about one week . Life cycle is usually completed in 6-8 weeks (Atwal, 1976). Adults of this insect can be easily confused with a native weevil species known as little leaf notcher, Artipus floridanus Horn due to their general similarity. However, M. undatus has a dull, white and black, maculate, scale covering (often with yellowish scales on the rostrum and head). Also, it has the front and middle femora bidentate and hind femora distinctly tridentate.
Although, few references exist on this weevil pest, it can be considered a pest of quarantine significance.
Atwal, A.S. 1976. Agricultural Pests of India and Southeast Asia. Kalyanri Publishers, Delhi, India.
Marshall, G.A.K. 1916. Coleoptera, Rhynchophora: Curculionidae. Fauna of British India. Taylor and Francis, London. 367 pp.
O'Brien, C.W., M. Haseeb and M.C. Thomas. 2006. Myllocerus undecimpustulatus undatus Marshall (Coleoptera: Curculionidae), a recently discovered pest weevil from the Indian subcontinent. Fla. Dept. of Agri. Cons. Svs. Division of Plant Industry. Entomology Circular No. 412: 1-4.
Ramamurthy, V.V. and S. Ghai. 1988. A study on the genus Myllocerus (Coleoptera: Cuculionidae). Oriental Insects 22: 377-500.
Thomas, M.C. 2002. Myllocerus undatus Marshall, a weevil new to the Western Hemisphere. Pest Alert. Florida Department of Agriculture & Consumer Services, Division of Plant Industry [http://www.doacs.state.fl.us/pi/enpp/ento/weevil-pestalert.html]