Relationship between cortical resin acids and resistance of Sitka spruce to the white pine weevil

1996 ◽  
Vol 74 (4) ◽  
pp. 599-606 ◽  
Author(s):  
Elizabeth S. Tomlin ◽  
John H. Borden ◽  
Harold D. Pierce Jr.

Cortical resin acids were analyzed both quantitatively and qualitatively among 10 provenances and 11 genotypes of Sitka spruce, Picea sitchensis Bong (Carr.), putatively resistant to the white pine weevil, Pissodes strobi (Peck), and compared with susceptible trees. Trees in 5 of the 11 resistant genotypes had significantly greater amounts of cortical resin acid than susceptible trees. Of seven individual acids analyzed, pimaric, isopimaric, levopimaric, dehydroabietic, abietic, and neoabietic acid, but not palustric acid, were found in significantly greater amounts in trees from resistant than susceptible provenances. Eighteen percent of the variation in resin acid content could be accounted for by variation in the capacity of cortical resin ducts, indicating that the other 82% of variation is a result of differences in resin acid concentration in the resin. Trees with very high resin acid levels may have a greater capacity for resinosis than susceptible trees, may deter feeding, or may produce resin that is toxic to eggs and larvae. Canonical discriminant analysis revealed that several resistant clones, particularly two from the Kitwanga provenance, could be distinguished from others on the basis of their resin acid profiles. Because it separated trees on the basis of genotype, but not according to degree of resistance, canonical discriminant analysis may be more useful in "chemotyping" trees than in screening for resistance. Keywords: Picea, cortex, resin acids, Pissodes strobi, resistance.

1980 ◽  
Vol 112 (12) ◽  
pp. 1259-1270 ◽  
Author(s):  
R. I. Alfaro ◽  
J. H. Borden

AbstractThe predatory behavior of Lonchaea corticis Taylor on the white pine weevil, Pissodes strobi Peck, in Sitka spruce, Picea sitchensis (Bong.) Carr., was studied by temporal sampling and dissection of terminal leaders, and by laboratory experiments. L. corticis oviposition occurred when mining P. strobi larvae were consolidating the feeding ring, an event that segregates the weevil larvae into healthy front-feeders and weak, starving "followers." The number of L. corticis within a Sitka spruce terminal was highly correlated with the number of weak and dying P. strobi larvae, but not with healthy larvae.L. corticis larvae experimentally deprived of dead P. strobi larvae, behaved as an effective predator, consuming both weak P. strobi larvae and healthy pupae, but apparently not healthy larvae. The transition of L. corticis from second to third instar appeared to occur only after sufficient weevils had been consumed. When an excess of prey was present, L. corticis larvae consumed a mean of 2.9 P. strobi pupae over their entire life cycle. In choice experiments, L. corticis larvae searched for and located mining P. strobi larvae, and fed preferentially on P. strobi pupae rather than granary weevil pupae, Sitophilus granarius L. Under certain circumstances, L. corticis could be an important regulatory agent of P. strobi populations.


1993 ◽  
Vol 69 (5) ◽  
pp. 600-603 ◽  
Author(s):  
R. G. Fraser ◽  
D. G. Heppner

Young Sitka spruce, Picea sitchensis (Bong.) Carr., trees in three stands were treated with either Gelcaps® containing oxydemeton-methyl or Acecaps® containing acephate to test their effectiveness in protecting trees from white pine weevil, Pissodes strobi (Peck) attack. All treatments were applied in late March 1989. Weevil attack was recorded in early September 1989, 1990 and 1991. Attack was significantly reduced (P < 0.01) in all but one stand/treatment combination in 1989. Gelcaps provided significant protection (P < 0.01) in two of three stands after two years. Stem implants containing systemic insecticide can protect young Sitka spruce from weevil attack. Alternative delivery systems, such as the Ezect® lance, should be evaluated as they may improve the speed and lower the cost of operational treatments. Keywords: acephate, oxydemeton-methyl, stem implants, systemic insecticides, white pine weevil


1984 ◽  
Vol 116 (1) ◽  
pp. 41-44 ◽  
Author(s):  
R. I. Alfaro ◽  
J. H. Borden ◽  
L. J. Harris ◽  
W. W. Nijholt ◽  
L. H. McMullen

AbstractPine oil effectively reduced feeding by the white pine weevil, Pissodes strobi Peck, in a laboratory feeding bioassay utilizing agar discs containing dry, powdered bark of its host Sitka spruce, Picea sitchensis (Bong.) Carr. Possible utilization of pine oil under field conditions is discussed.


2011 ◽  
Vol 65 (6) ◽  
pp. 936-948 ◽  
Author(s):  
Dawn E. Hall ◽  
Jeanne A. Robert ◽  
Christopher I. Keeling ◽  
Dominik Domanski ◽  
Alfonso Lara Quesada ◽  
...  

1975 ◽  
Vol 107 (3) ◽  
pp. 251-256 ◽  
Author(s):  
D. L. Overhulser ◽  
R. I. Gara

AbstractObservations were made on the flight patterns, sex ratios, and ovipositional activity of Pissodes strobi in Sitka spruce. There is an aggregation of adults on spruce leaders early in the flight season during which sexual maturation and mating take place. Males are more active early in the flight season, while females are more numerous during the latter half of the flight season.


2013 ◽  
Vol 89 (02) ◽  
pp. 235-245 ◽  
Author(s):  
René I. Alfaro ◽  
John N. King ◽  
Lara vanAkker

The Sitka spruce (Picea sitchensis [Bong.] Carr) breeding program for resistance against the white pine weevil Pissodes strobi Peck (Coleoptera: Curculionidae) is arguably one of the most successful pest resistance breeding programs for plantation forest species in North America, with a substantial proportion of the planting stock in BC and Washington State currently coming from this breeding program. Using conventional selection and breeding, and by screening Sitka spruce populations using artificial weevil infestations, we identified sources of heritable and stable weevil resistance. We also used this program to investigate potential causes behind this resistance and identified several heritable resistance mechanisms, including anatomical characteristics, such as constitutive resin canals and sclereid cells in the bark, terpene defenses and variation in tree phenology. We concluded that resistance is conferred by a suite of traits whose composition varies among resistant sources. In addition, we evaluated the efficiency of screening for resistance using weevil population enhancement as a screening method. Our results culminated in the establishment of seed orchards, and the availability of resistant seed that is contributing to the return of Sitka spruce as a species of choice in coastal British Columbia.


1996 ◽  
Vol 128 (4) ◽  
pp. 539-549 ◽  
Author(s):  
Elizabeth S. Tomlin ◽  
John H. Borden

AbstractFeeding preferences of the white pine weevil, Pissodes strobi (Peck), for resistant or susceptible Sitka spruce, Picea sitchensis (Bong) Carr., were investigated using three types of laboratory bioassay. In paired-twig bioassays, fall weevils were significantly deterred from feeding up to 80% by resistant clones from four British Columbia provenances: Green Timbers, Cedarvale, Haney, and Big Qualicum. Females showed greater discrimination than males. Spring weevils were deterred from feeding by clones from the Green Timbers and Big Qualicum provenances by up to 60%. Fall males were more consistently deterred than spring males, suggesting that some host selection occurs in the fall. Females were significantly deterred from ovipositing on twigs from one clone from Big Qualicum, and stimulated by clones from Cedarvale when given a choice. Given no choice, however, they were significantly deterred from ovipositing, but not feeding by several resistant clones. In agar-disc bioassays, spring weevils were significantly deterred from feeding by bark from the provenances of Cedarvale and Big Qualicum by up to 86%. Trees from the provenances of Big Qualicum and Green Timbers caused the most consistent feeding or oviposition deterrency and may rely on this in part as a resistance mechanism. Because not all resistant clones and provenances were deterrent, we hypothesize that these trees may employ other resistance mechanisms which could be incorporated along with feeding and oviposition deterrency into breeding for resistance.


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