Laboratory Assessment of Predation by Lonchaea corticis (Diptera: Lonchaeidae) on Pissodes strobi (Coleoptera: Curculionidae)

Abstract

Larvae of Lonchaea corticis Taylor killed and consumed pupae and to a lesser extent prepupal larvae of Pissodes strobi (Peck) at temperatures ranging from 5 to l4°C during a 3-wk experiment in glass vials that were monitored weekly. Marginal predation of pupae but not prepupal larvae was observed at O°c. In simulated pupal cells of P. strobi stored outdoors in a Victoria, British Columbia, winter, L. corticis larvae killed and consumed pupae and prepupal larvae of P. strobi in a 3-wk experiment that left most cells devoid of obvious prey remains. Tests in glass vials in March with L. corticis larvae collected during March and during the previous August showed that L. corticis larvae remain predacious at the end of winter. When the insects were left in situ in severed leaders stored outdoors in a Victoria, British Columbia, winter, the proportion of pupal cells with live P. strobi decreased significantly and the proportion of pupal cells emptied without insect emergence increased significantly; the numbers of L. corticis larvae and total P. strobi pupal cells did not change significantly. These experiments show that P. strobi pupae and prepupal larvae can be vulnerable prey for L. corticis larvae and that predation may be common in the winter conditions of coastal British Columbia.