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We studied the adult ambulatory response of the predator, Laricobius nigrinus Fender (Coleoptera: Derodontidae), to odors from its prey, Adelges tsugae Annand, the hemlock woolly adelgid, and foliage of hemlock woolly adelgid, host hemlocks (Tsuga spp.), and other conifers. Both the predator and hemlock woolly adelgid are apparently native to western North America, but the predator is being released in the eastern United States, which has different hemlock species, for biological control of a lineage of hemlock woolly adelgid inadvertently introduced from Japan. L. nigrinus responded to odors from hemlock woolly adelgid host trees, but not to odors from hemlock woolly adelgid. L. nigrinus collected from hemlock woolly adelgid-infested western hemlock were more strongly attracted to odors from western hemlock [Tsuga heterophylla (Rafinesque) Sargent] than eastern hemlock [Tsuga canadensis (L.) Carrière] in most trials. Odors from western white pine (Pinus monticola Douglas ex D. Don) and white spruce [Picea glauca (Moench) Voss] were as attractive as western hemlock odors whereas odors from Douglas-fir [Pseudotsuga menziesii variety menziesii (Mirbel)] and ponderosa pine (Pinus ponderosa Douglas ex Lawson) were avoided. L. nigrinus reared on hemlock woolly adelgid-infested eastern hemlock in the laboratory were lethargic and were not attracted to either eastern or western hemlock odors. Predators collected in the field and tested monthly from December to March responded similarly each month, except February, when they flew rather than walked in the olfactometer, suggesting a period of dispersal or mate finding at that time of year. The implications of these results for programs to release L. nigrinus in the eastern United States for control of hemlock woolly adelgid are discussed. [ABSTRACT FROM AUTHOR]

1 Pole-sized, live western larch Larix occidentalis Nutt. were mass-inoculated with Ophiostoma pseudotsugae (Romb.) von Arx or Leptographium abietinum (Peck) Wingf., two blue-stain fungi associated with the Douglas fir beetle Dendroctonus pseudotsugae Hopkins, to assess their pathogenicity. 2 Inoculation with O. pseudotsugae resulted in significantly greater percentages of necrotic phloem compared with L. abietinum inoculations. 3 The percentage of occluded sapwood was significantly greater after L. abietinum inoculations compared with O. pseudotsugae inoculations. 4 Within the inoculation band, all trees had more than 60% functional sapwood 4 months after treatment. 5 The results suggest that western larch can successfully limit colonization by O. pseudotsugae and L. abietinum.. 6 The inability of the fungi to thrive in live western larch may be a factor in the consistent failure of Douglas fir beetle broods in this host tree species. [ABSTRACT FROM AUTHOR]

The article focuses on the risk rating systems used in the study of Douglas-Fir Beetle in the Interior Western United States. These rating systems were being enhanced for four U.S. Department of Agriculture Forest Service ranger districts in the northern part of Idaho for the Douglas-fir beetle or Dendroctonus pseudotsugae. The systems were being formulated using a geographic information systems, Forest Service aerial detection survey maps and nearest neighbor distances (NND). Infestations were measured and percentiles of NND were employed to calculate distances of which infestation took place at 50, 75 or 90 percent.

Pole-size Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) were inoculated with two fungi (Ophiostoma pseudotsugae (Rumb.) von Arx and Leptographium abietinum (Peck) Wingf) associated with the Douglas-firbeetle (Dendroctonus pseudotsugae Hopkins) to evaluate their pathogenicity. Pruning the lowermost 30% of the live crown had no effect on host tree defenses. Inoculation with O. pseudotsugae produced significantly longer lesions in the phloem and resulted in a significantly greater percentage of necrotic phloem than inoculation with L. abietinum. The percentage of occluded sapwood was also greater following O. pseudotsugae inoculations, but the difference was not statistically significant. Individual lesion lengths declined significantly with increasing inoculation density, but the total percentage of necrotic phloem increased significantly. Both fungi appeared to be better adaptedto grow in sapwood than in phloem. None of the inoculated trees weredead after 5 months, but some were chlorotic with less than 30% functional sapwood within the inoculation band. The results suggest that these fungi may assist the Douglas-fir beetle in overcoming the defenses of live trees. [ABSTRACT FROM AUTHOR]

Infestations of the western pine shoot borer, Eucosma sonomana Kearfott, in young stands of ponderosa pine, Pinus ponderosa Lawson, were surveyed on the Deschutes National Forest in central Oregon. Elevation, slope, aspect, tree height, tree diameter, number of shoots in theterminal whorl, stand density, stand age, and plant association for each stand were used in logistic regression analyses to predict the percentage of infested terminal shoots. The best model included numberof shoots in the terminal whorl and stand age. Values for these stand characteristics can be used with the appropriate equation to predict the percentage of terminal whorls damaged by shoot borer in a givenstand. A companion study conducted at 6 progeny test sites on the Ochoco National Forest in eastern Oregon found significant differences in shoot borer infestations among 29 ponderosa pine half-sib families. [ABSTRACT FROM AUTHOR]

Field observations of remnants from predation on Pandora moths, Coloradia Pandora Blake, suggested that eggs from gravid females were being rejected. Captive feeding trials with golden-mantled ground squirrels, Spennophilus lateralis Say, verified that this rodent is a natural enemy of C. pandora that rejects eggs while feeding on moths. Nutritional analyses indicated C. Pandora moths (both females and males)and eggs are of comparable food quality, so additional feeding trials were conducted to determine why eggs were unpalatable to the groundsquirrels. Chemical fractions of eggs did not inhibit consumption consistently enough to explain the rejection behavior; neither did the extracted residue of egg tissue. Whole eggs, whole shells, and groundshells did inhibit consumption by the same ground squirrels. A follow-up trial with a naive group of S. lateralis confirmed that whole eggs and whole shells inhibit consumption. Consumption of egg contents was equivalent to controls for both groups of S. lateralis. We conclude that C. Pandora eggs are protected physically, but not chemically,from consumption by S. lateralis. The foraging range of S. lateralis, a generalist predator in central Oregon, includes the lower canopy of pine (Pines spp.) forests where C. Pandora eggs are deposited. Therefore, the tough eggshell probably inhibits S. lateralis predation of C. Pandora eggs under natural conditions. [ABSTRACT FROM AUTHOR]

The hemlock woolly adelgid (Hemiptera: Adelgidae: Adelges tsugae Annand) is an invasive insect, introduced from Japan to eastern North America, where it causes decline and death of hemlock trees. There is a closely related lineage of A. tsugae native to western North America. To inform classical biological control of A. tsugae in the eastern USA, the density and phenology of three native western adelgid specialist predators, Leucopis argenticollis (Zetterstedt), Le. piniperda (Malloch) (Diptera: Chamaemyiidae), and Laricobius nigrinus Fender (Coleoptera: Derodontidae), were quantified in the Pacific Northwest. Infested branches were collected from western hemlock (Pinaceae: Tsuga heterophylla (Raf.) Sarg.) at four sites around the Puget Sound, Washington and three sites in Oregon. Immature Leucopis were identified to species using DNA barcodes. Leucopis argenticollis was roughly twice as abundant as Le. piniperda. Laricobius nigrinus larvae were more abundant than the two species of Leucopis during the egg stage of the first adelgid generation, but Leucopis were present as feeding larvae during the second adelgid generation when La. nigrinus was aestivating in the soil, resulting in Leucopis being more abundant than La. nigrinus across the entire sampling period. Adelges tsugae and La. nigrinus densities were not correlated, while A. tsugae and Leucopis spp. densities were positively correlated. Leucopis spp. and La. nigrinus densities were negatively correlated. These results support the complementary use of La. nigrinus and the two Leucopis species for biological control of A. tsugae in the eastern USA, and point to the need for further investigation of spatial and temporal niche partitioning among the three predator species.