Seasonal Occurrence of Pine Root Collar Weevil, \u3ci\u3eHylobius Radicis\u3c/i\u3e (Coleoptera: Curculionidae), in Red Pine Stands Undergoing Decline

A trapping scheme was devised for sampling the pine root collar weevil, Hylobius radicis, in mature red pine plantations in Wisconsin. Adult weevils were trapped throughout the 1986 field season, and the method appears sensitive enough to discern temporal and spatial trends. The number of weevils caught was higher in stands symptomatic of the general condition currently labelled Red Pine Decline and Mortality. In some stands there was a strong tendency for trap catches to be particularly high near certain trees. Seasonal trends and sex ratios were compared with published reports of H. radicis activity in Michigan

Use of a Monitoring System to Evaluate Pesticide Efficacy and Residual Activity Against Two Pine Root Weevils, \u3ci\u3eHylobius Pales\u3c/i\u3e and \u3ci\u3ePachylobius Picivorus\u3c/i\u3e (Coleoptera: Curculionidae), in Christmas Tree Farms

Hylobius pales, the pales weevil, and Pachylobius picivorus, the pitch-eating weevil, comprise part of a weevil complex which affects plantation pine production in the Lake States. Common control practices on Christmas tree farms include calendar applications of persistent insecticides. The resulting environmental risks could be minimized by repeating applications only when needed. A sampling method using ethanol-and turpentine-baited pitfall traps was used here to assess the efficacy and monitor persistence of chemical sprays. Trap catch in lindane-treated field plots and untreated controls were compared over two years. Unsprayed controls had significantly higher weevil populations than treated plots. Spray efficacy continued for three years following tion. Weevil population growth in relation to insecticide efficacy and degradation is discussed

Effects of Hybrid Poplar (Salicaceae) Clone and Phenology on Gypsy Moth (Lepidoptera: Lymantriidae) Performance in Wisconsin

Gypsy moth (Lymantria dispar) developmental interactions with two hybrid Populus species clones were studied in laboratory trials. Significant differences in larval performance were found between clones and within the same clone at different phenological states. No larvae were able to complete development on clone NM6. All gypsy moth larvae feeding on clone NC5271 survived when leafflush was synchronized with gypsy moth eclosion in early May. However, neonates feeding on NC5271 foliage in July experienced in- creased mortality. Weights of surviving gypsy moth larvae feeding on NC5271 foliage in May versus July were not significantly different

\u3ci\u3eMicroctonus Pachylobii\u3c/i\u3e (Hymenoptera: Braconidae): New Host Record From \u3ci\u3eHylobius Radicis\u3c/i\u3e (Coleoptera: Curculionidae), and Additional Notes on Its Biology

The endoparasite Microctonus pachylobii was discovered parasitizing a new weevil host, Hylobius radicis. Thirteen of the 154 H. radicis adults collected were parasitized (8.5%). The median numbers of parasites per weevil were 26 (x =22.5) during the period April through June, and 4 (x =9.4) during August and September. The median male:female sex ratio was 0.91 (x =0.65). Males emerged approximately 1 day earlier than females. Median parasite mortality while in the cocoon was 10.2% per parasitized weevil (x = 11.8%). Microctonus pachylobii was not found parasitizing two previously recorded weevil hosts from field samples, Hylobius rhizophagus and H. pales, and a laboratory study suggests that the parasite may have difficulty parasitizing the latter species

New Host Records and Developmental Notes on the Pear Slug \u3ci\u3eCaliroa Cerasi\u3c/i\u3e (Hymenoptera: Tenthredinidae), Feeding on \u3ci\u3eCotoneaster\u3c/i\u3e and \u3ci\u3eChaenomeles\u3c/i\u3e Species.

The pear slug. Caliroa cerasi was collected and reared to adulthood on flowering quince and three species of Cotoneaster. This is the first record of C. cerasi attacking any member of the genus Chaenomeles and the first confirmation of feeding on Cotoneaster in North America. Adult emergence, oviposition, and larval development were evaluated under both laboratory and field conditions. Females lay an average of 48 eggs, with about two-thirds of the oviposition occurring during their first 24 hours. A method for monitoring adult emergence in the field was developed

Tolerance of Plant Monoterpenes and Diterpene Acids by Four Species of Lymantriidae (Lepidoptera) Exhibiting a Range of Feeding Specificities

Lymantriidae (Lepidoptera) is a family of leaf-feeding insects that includes some of the most damaging forest pests worldwide. Species within this family vary widely in feeding specificity. We evaluated the ability of four species, Douglas fir tussock moth (Orgyia pseudotsugata McDunnough), nun moth (Lymantria monacha L. ), rusty tussock moth (Orgyia antiqua (L.)), and white- marked tussock moth (Orgyia leucostigma (J. E. Smith)), to contend with one of the most ubiquitous and effective groups of plant defense compounds, terpenoids. We selected these species to provide a range of feeding specificities on conifer hosts, from obligate to occasional. We evaluated the effects of three monoterpenes (bornyl acetate, limonene, and myrcene) and two diterpene acids (isopimaric acid and neoabietic acid) on larval performance. Although these four species differ in their feeding ranges, utilization of conifers as hosts, and other life history processes, each shows a relatively high tolerance for conifer terpenes. The mean relative growth rates, relative consumption rates, and development times were not affected by these monoterpenes and diterpene acids when administered at concentrations present in the foliage of conifers in which they are most abundant. The most likely explanation seems to be metabolism, as a) no limonene or myrcene were recovered from frass or larvae, and b) borneol, an apparent metabolite of bornyl acetate, was recovered from frass of Douglas fir tussock moth, rusty tussock moth, and white-marked tussock moth, and from tissues of Douglas fir tussock moth and white-marked tussock moth

Use of Baited Pitfall Traps for Monitoring Pales Weevil, \u3ci\u3eHylobius Pales\u3c/i\u3e (Coleoptera: Curculionidae)

Pitfall traps baited with ethanol and turpentine serve as an effective tool for monitoring pales weevil (Hylobius pales) populations. Males and females are equally attracted to this bait. Neither component alone showed any attractiveness. The presence of a pine stem for weevil feeding does not affect the number or sex ratio of captured weevils. The potential of using attraction to baited traps as a sampling method for pales weevil is discussed

\u3ci\u3eDendroctonus Valens\u3c/i\u3e and \u3ci\u3eHylastes Porculus\u3c/i\u3e (Coleoptera: Scolytidae): Vectors of Pathogenic Fungi (Ophiostomatales) Associated With Red Pine Decline Disease.

A study was conducted to determine whether Dendroctonus valens and Hylastes porculus could vector their commonly associated fungi to red pine. Field collected adult D. valens transmitted Leptographium terebrantis, Leptographium procerum and Ophiostoma ips into 45%, 30%, and 5%, respectively of the wounded red pine roots onto which they were caged. Field collected H. porculus transmitted L. terebrantis, L. procerum and O. ips into 55%, 40%, and 5%, respectively, of the wounded red pine roots onto which beetles were caged. None of the control roots, which were mechanically wounded only, were found to contain O. ips, whereas only one control root contained L. terebrantis and only one control root contained L. procerum. This work demonstrates that D. valens and H. porculus can vector their associated Leptographium fungi to red pine trees and that these organisms are likely involved in red pine decline disease

Tolerance of Plant Monoterpenes and Diterpene Acids by Four Species of Lymantriidae (Lepidoptera) Exhibiting a Range of Feeding Specificities

Lymantriidae (Lepidoptera) is a family of leaf-feeding insects that includes some of the most damaging forest pests worldwide. Species within this family vary widely in feeding specificity. We evaluated the ability of four species, Douglas fir tussock moth (Orgyia pseudotsugata McDunnough), nun moth (Lymantria monacha L. ), rusty tussock moth (Orgyia antiqua (L.)), and white- marked tussock moth (Orgyia leucostigma (J. E. Smith)), to contend with one of the most ubiquitous and effective groups of plant defense compounds, terpenoids. We selected these species to provide a range of feeding specificities on conifer hosts, from obligate to occasional. We evaluated the effects of three monoterpenes (bornyl acetate, limonene, and myrcene) and two diterpene acids (isopimaric acid and neoabietic acid) on larval performance. Although these four species differ in their feeding ranges, utilization of conifers as hosts, and other life history processes, each shows a relatively high tolerance for conifer terpenes. The mean relative growth rates, relative consumption rates, and development times were not affected by these monoterpenes and diterpene acids when administered at concentrations present in the foliage of conifers in which they are most abundant. The most likely explanation seems to be metabolism, as a) no limonene or myrcene were recovered from frass or larvae, and b) borneol, an apparent metabolite of bornyl acetate, was recovered from frass of Douglas fir tussock moth, rusty tussock moth, and white-marked tussock moth, and from tissues of Douglas fir tussock moth and white-marked tussock moth

Effects of Feeding by Two Folivorous Arthropods on Susceptibility of Hybrid Poplar Clones to a Foliar Pathogen

We investigated variation in folivore-induced effects on subsequent plant suitability to a foliar pathogen. We used a leaf disk assay to expose three clones of hybrid poplar, NC11382, NE332 and NM6, to colonization by a leaf spot pathogen, Septoria musiva. Undamaged leaf disks of NE332 were the most resistant to S. musiva, followed by NM6 and NC11382, respectively. To test the effects of prior herbivory on subsequent susceptibility to this fungal pathogen, we inoculated S. musiva on leaf disks taken from leaves which had been exposed to feeding by Tetranychus mites or cottonwood leaf beetles. Prior activity by mites and cottonwood leaf beetle affected the subsequent susceptibility of clones NC 11382 and NE332 to S. musiva