Abstract
A total of 2,548 second-year cones were collected from 10 ponderosa pine, Pinus ponderosa Doug!. ex Laws., trees at each of five representative stands in northern Arizona in fall 1984. Five insect species were responsible for cone mortality and seed destruction. Dioryctria auranticella Grote (Lepidoptera: Pyralidae) caused the most mortality, killing all of the cones on some individual trees. On a plot average basis, this species was responsible for 38.7-81.0% of the cone mortality. Less (but still substantial) cone mortality was caused by Conophthorus ponderosae Hopkins (Coleoptera: Scolytidae) and Conotrache- Ius neomexicana Fall (Coleoptera: Curculionidae). Cydia piperana (Kearfott) (Lepidoptera: Olethreutidae) destroyed 1.3–7.6 seeds per cone in the cones that survived. Radiographic examination of apparently normal seeds from surviving cones showed that 46.0–70.0% were destroyed by Megastigmus albifrons Walker (Hymenoptera: Torymidae). In combination, these five insect species dramatically reduced the production of ponderosa pine seeds at the locations studied.
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