Canadian Forest Service Publications
Primary cortex thickness influences the location of ovarian maturation feeding and oviposition of Pissodes strobi (Coleoptera: curculionidae) within a tree. 2002. Manville, J.F.; Sahota, T.S.; Hollmann, J.; Ibaraki, A.I. Environmental Entomology 31(2): 198-207.
Issued by: Pacific Forestry Centre
Catalog ID: 19703
The white pine weevil’s [Pissodes strobi (Peck)] choice of bark tissue for ovarian maturation feeding was determined. In addition,the thicknesses of primary cortex tissue were determined to ascertain if primary cortex thickness was positively correlated with the selection of oviposition sites.White pine weevils engaged in ovarian-maturation feeding and oviposition, referred to in this article as reproductively active female weevils, preferentially feed on primary cortex tissues of Sitka spruce, Picea sitchensis (Bongard) Carriere, and interior spruce (a complex of white spruce [Picea glauca (Moench)Voss ] and Englemann spruce [P. englemannii Parry]) leaders. On these leaders they feed mostly and oviposit almost exclusively in sterigmata ridges where the thickest primary cortex occurs. Branches of open-grown trees have insufficient primary cortex thickness; they are not normally used for oviposition and are used poorly by caged reproductively active female weevils. Reproductively active female weevils do not normally oviposit on the main stem below the leader where the primary cortex is thinner, but will do so when they do not have access to the leader or when caged on lower inter-nodes. This weevil attacked branches and the main stem below the leader in Picea chihuaiana (Martinez) and P. mexicana [P. engelmannii Parry variety mexicana (Martinez)] trees in locations where the thickness of the primary cortex is greater than in other species studied. Only primary cortex thickness increases with tree height in Sitka and interior spruces. The female white pine weevil’s preferential feeding upon this tissue in the spring can account for their movement from ground level to tree tops.