HOST SPECIFICITY IN PISSODES STROBI (COLEOPTERA: CURCULIONIDAE): ROLES OF GEOGRAPHY, GENETICS, AND BEHAVIOR

2000 ◽  
Vol 132 (6) ◽  
pp. 811-823 ◽  
Author(s):  
Thomas W. Phillips ◽  
Gerald N. Lanier

AbstractHost specificity of Pissodes strobi (Peck) from different geographic regions and genetic divergence of local host-associated weevil populations were studied in a series of experiments. Pacific coast P. strobi reared from Sitka spruce, Picea sitchensis (Bong.) Carr (Pinaceae), were unable to successfully colonize either eastern white pine, Pinus strobus L. (Pinaceae), or western white pine, Pinus monticola Dougl. ex D. Don., in a forced-infestation study on interplanted trees in New York. Reproductively mature field-collected P. strobi from British Columbia did not oviposit on eastern white pine in New York, but field-collected New York weevils successfully reproduced in Sitka spruce leaders in British Columbia. Unacceptability of eastern white pine for western P. strobi was shown to be under genetic control, rather than influenced by prior host experience on Sitka spruce. Pissodes strobi originating from Sitka spruce but reared one generation in the laboratory on the exotic Norway spruce, Picea abies (L.) Karst., were also unable to utilize eastern white pine as a host in a forced-infestation experiment in the field. Population genetic studies using allozyme electrophoresis found that P. strobi populations occurring on different host species within 2 km of each other had significant differences in allele frequencies in three out of four cases. These results suggest that P. strobi can exist as small breeding populations that can facilitate host specialization. Applied research on host resistance against P. strobi could target mechanisms that prevent western P. strobi from utilizing nonhosts such as eastern and western white pines.

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


1987 ◽  
Vol 65 (6) ◽  
pp. 1249-1252 ◽  
Author(s):  
J. E. Brooks ◽  
J. H. Borden ◽  
H. D. Pierce Jr. ◽  
G. R. Lister

As part of a study on the relationship between the monoterpene composition of Sitka spruce, Picea sitchensis (Bong.) Carr., and resistance to the white pine weevil, Pissodes strobi Peck, seasonal differences in the relative monoterpene content of developing buds and 1-year-old foliage were followed. In 2nd-year foliage of four trees from the University of British Columbia Research Forest, Maple Ridge, B.C., α-pinene and camphene levels increased in May and returned to their original levels by September. Myrcene, isopentenyl isovalerate, and camphor levels decreased in May. Isopentenyl isovalerate and camphor levels increased over the summer, but myrcene continued to decline, offsetting rising levels of 3-carene and β-pinene. To obtain representative monoterpene distributions, foliar samples should be taken after September 30, when trees are dormant for the winter. There was significant developmental variation in buds from 20 trees from Say ward, B.C. α-Pinene and β-pinene were prominent initially and then declined, while myrcene increased to become the major volatile component of the elongating buds. β-Phellandrene levels declined and then increased as the season progressed. There was no significant difference in percent monoterpene composition between buds from resistant and susceptible trees.


1997 ◽  
Vol 129 (6) ◽  
pp. 1105-1120 ◽  
Author(s):  
Hugh J. Barclay

AbstractAn evolutionary model was constructed for the white pine weevil (Pissodes strobi Peck). This weevil attacks Sitka spruce [Picea sitchensis (Bongard) Carriere], and Sitka spruce trees have two forms, one being susceptible to the insect attacks and the other being resistant to attack. There is a fear that insects may develop tolerance to the resistant trees. The strategy of interplanting susceptible and resistant trees to minimize the likelihood of the insects developing tolerance mechanisms to circumvent the resistance is examined. It is found that if only one gene locus is involved, the development of tolerance occurs more quickly than if resistance is governed by two independent loci. The rate of evolution of tolerance to tree resistance is retarded by increased adult survivorship, the degree of recessiveness of the gene, preferential attack of susceptible trees, redistribution of intolerant insects from resistant to susceptible trees, and the immigration of wild-type insects.


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.


2001 ◽  
Vol 31 (9) ◽  
pp. 1561-1568 ◽  
Author(s):  
J R Nault ◽  
Rene I Alfaro

Terpene levels were measured in bark and wood samples of Sitka spruce (Picea sitchensis (Bong.) Carrière) trees. The trees that had been selected as early or late flushing were subjected to artificial wounding to simulate attack by the white pine weevil, Pissodes strobi (Peck). Samples were taken at four times during the growing season: before wounding, shortly after wounding, and two times later in the season. Terpenes were extracted with hexane and quantified by capillary gas chromatography. There were no significant differences in total bark terpenes between early- and late-flushing trees or between control and wounded trees over all sampling times. There were no significant differences in total wood terpenes between early- and late-flushing trees or among sampling times, but a statistically significant difference was found between control and wounded trees. Eleven individual terpenes accounted for the majority of the terpenes in the extracts. Four bark terpenes showed significant differences with sampling time, two with flushing class, and none with treatment. Five wood terpenes showed significant differences with sampling time, two with flushing class, and nine with treatment. We concluded that flushing had only a minor effect on bark and wood terpene profiles and that wounding significantly increased terpene concentration in wood shortly after injury.


1990 ◽  
Vol 122 (4) ◽  
pp. 607-615 ◽  
Author(s):  
Rene I. Alfaro ◽  
Cheng C. Ying

AbstractVariation in tree height, number of attacks by the Sitka spruce weevil (= white pine weevil) (Pissodes strobi [Peck]), tree form, and stem defect were studied in a 15-year-old Sitka spruce (Picea sitchensis [Bong.] Carr.) provenance test near Sayward, on Vancouver Island, B.C. An aggregated spatial distribution of the attacks was found in the plantation. Average number of attacks, tree form, and total tree height varied significantly among provenances and among families within provenances in both light and severe infestation patches. The number of unattacked trees varied by provenance from 5 to 51%, but in patches of severe infestation it varied from 0 to 64%. The number of attacks per tree had a significant negative effect on tree height. However, at the same level of attack, some provenances grew significantly taller than others. Thirty, 19, and 51% of all trees were classified as having a good, medium, or poor form, respectively. Among provenances located in severe infestation patches, the percentages of trees having good form varied from 4 to 64%. The type of defect that formed after an attack (minor crook, major crook, or fork) varied by provenance. Aggregated weevil attack and genetic differences among provenances may have accounted for this variation.


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.


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