VARIATIONS IN THE LIFE CYCLE OF THE LODGEPOLE TERMINAL WEEVIL, PISSODES TERMINALIS HOPPING (COLEOPTERA: CURCULIONIDAE), IN CALIFORNIA,

Abstract

AbstractThe lodgepole terminal weevil, Pissodes terminalis Hopping (Coleoptera: Curculionidae), is widely distributed in western North America on three races of lodgepole pine (Pinus contorta Dougl.), as well as jack pine (P. banksiana Lamb.), Bishop pine (P. muricata D. Don.), and Monterey pine (P. radiata D. Don.).Three types of life cycle, one with three subtypes, are identified. In the univoltine type 1 cycle, adults emerge from attacked leaders in the fall, overwinter probably in the ground, and re-emerge in the spring to lay eggs in elongating leaders. Larval and pupal development is completed by early fall. The univoltine type 2 life cycle is similar, except that overwintering takes place in leaders; fourth-instar larvae overwinter in type 2A, pupae in type 2B, and adults in type 2C. The type 3 life cycle takes 2 years to complete, with the first winter being passed as a third-instar larva in the leader and the second as an adult, probably in the ground. The type 1 life cycle is most common at altitudes < 2000 m and the type 3 life cycle at altitudes over ca. 2500 m; all types may be found at altitudes of 2000–2500 m.