Adoption of Exotic Plants by an Endemic Australian Weevil, Orthorhinus cylindrirostris (Coleoptera: Curculionidae)

The elephant weevil Orthorhinus cylindrirostris (F.) (Coleoptera: Curculionidae) is endemic to Australia and has colonized several exotic crops including citrus, blueberries, and grapevines. We compared the life history of this pest on two native and two exotic host plants: hickory wattle Acacia falcata Willdenow, rough-barked apple Angophora floribunda (Smith) Sweet, lemon Citrus limon (L.) Burman, and blueberry Vaccinium corymbosum (L.). Blueberry was attacked more often (22 of the 24 plants) than lemon, rough-barked apple, and hickory wattle (6-8 plants of each species attacked of the 24). Adult emergence followed a similar pattern across hosts but emergence was low overall (58 adults from 176 eggs). Only blueberry had more than one weevil emerge from a single plant. Development from oviposition to adult emergence can take up to 2 yr, particularly on blueberry. Adult life span and weight varied between individuals although no effect of host plant was detected. Similar plant chemistry is unlikely to have triggered host range expansion by this species because the exotic host plants are from different families (Rutaceae, Vitaceae, and Ericaceae) to the native host plants (Myrtaceae, Mimosaceae, and Fabaceae). O. cylindrirostris colonized citrus trees over a century ago, yet it appears to have no preference for lemon over native host plants. In contrast, O. cylindrirostris has developed a preference for blueberry, the higher quality host plant, only a few decades after colonization.