Treesearch

With administrative and financial support from its State and Private Forestry division, the USDA Forest Service has directed much effort toward developing viral pesticides that kill forest insect pests. Most environmentally benign viral pesticides are narrow host-range products (Groner 1986) that are most useful in situations where environmental concerns are paramount and application of either broad-spectrum chemical or other biological pesticides (biopesticides) are undesirable, if not illegal.

A family of highly repetitive elements, named LDT1, has been identified in the gypsy moth, Lymantria dispar. The complete element is 5.4 kb in length and lacks long-terminal repeats, The element contains two open reading frames with a significant amino acid sequence similarity to several non-LTR retrotransposons. The first open reading frame contains a region that potentially encodes a polypeptide similar to DNA-binding GAG-like proteins. The second encodes a polypeptide resembling both endonuclease and reverse transcriptase sequences. All members of the LDT1 element family sequenced thus...

The genome of the Lymantria dispar multinucleocapsid nucleopolyhedrovirus (LdMNPV) was sequenced and analyzed. It is composed of 161,046 bases with a G + C content of 57.5% and contains 163 putative open reading frames (ORFs) of ≥150 nucleotides. Homologs were found to 95 of the 155 genes predicted for the Autographa californica MNPV (AcMNPV) genome. More than 9% of the LdMNPV genome was occupied by 16 repeated genes related to AcMNPV ORF2. Readily identifiable homologs of several genes that have been reported to play important roles in the AcMNPV life cycle are not present; these include...

The Lymantria dispar multicapsid nucleopolyhedrovirus (LdMNPV) is used on a limited basis as a gypsy moth (L. dispar) control agent. In an effort to improve the efficacy (i.e., killing speed) of the LdMNPV, we generated a recombinant viral strain (vEGT-) that does not produce the enzyme ecdysteroid UDP-glucosyltransferase (EGT). We compared the potency and efficacy of vEGT- to wild-type virus (A21-MPV) and the impact of vEGT- and A21-MPV on larval weight gain. Bioassay of L. dispar 1st, 4th, and 5th instars showed no significant difference in the LC50 values in larvae infected with vEGT-...

The Lymantria dispar multicapsid nucleopolyhedrovirus (LdMNPV) is an effective biological control agent of the gypsy moth, L. dispar, but is not in general use because the high cost of production limits availability. In an effort to generate a more cost efficient LdMNPV biopesticide, two recombinant baculoviruses were generated to evaluate the impact of deleting the polyhedral envelope protein (PEP) gene on viral potency. One of these baculoviruses had the PEP gene inactivated by insertional mutagenesis with the green fluorescent protein (GFP) gene from Aequorea victoria (vGFP: PEP-); and...

Sugar maple (Acer saccharum Marsh.) height-diameter and age-diameter relationships are explored in a balanced uneven-aged northern hardwood stand in central New York. Results show that although both height and age vary considerably with diameter, these relationships can be described by statistically valid equations. The age-diameter relationship compares favorably to one reported by Tubbs (1977) for sugar maple in unmanaged (virgin) northern hardwoods, suggesting that periodic cuttings improved growing conditions in our stand. Deliberate attempts to control size-class distribution and tree...

Tsuga canadensis (L.) Carr. (eastern hemlock) is a common species throughout the Acadian forest. Studies of leaf area and growth efficiency in this forest type have been limited by the lack of equations to predict leaf area of this species. We found that sapwood area was an effective leaf area surrogate in T. canadensis, though adding crown length to the sapwood equations improved model performance. Prediction bias was observed at the upper end of our data for the best sapwood equation. Sapwood area at crown base did not predict leaf area as well as sapwood area at breast height. Equations...

The Kaskaskia Woods (Lat. 37.5 N, Long. 88.3 W), an old-growth hardwood forest in southern Illinois, has one of the oldest and best documented set of permanent plots with individual tree measurements in the Central Hardwood Region. In 1935, eight 0.101-ha plots were installed in a 7.4 ha upland area consisting of xeric oak-hickory and mesic mixed hardwoods communities. The soils are cherty silt loams of the Alford and Baxter soil series in which productivity depends largely on moisture availability. The Kaskaskia Woods has never been cleared; however, increment coring in 1965 revealed a...

Leaves from twenty-three deciduous tree species and five conifer species were collected within a limited geographic range (1 km radius) and evaluated for possible application of scanning electron microscopy and X-ray microanalysis techniques of individual particle analysis (IPA). The goal was to identify tree species with leaves suitable for the automated characterization of aerosol particles deposited on their adaxial surfaces. Evaluations considered morphology of the leaf surface, ability of the preparations to withstand the high vacuum environment of the IPA equipment and potential for...

Research has demonstrated that even-aged regeneration harvests, especially clearcutting, can have a major and long-lasting detrimental effect on forest amphibians, but the effects of less intensive silvicultural treatments have not been well documented. Additionally, the chronic overabundance of white-tailed deer (Odocoileus virginianus) has become a problem in many parts of North America, with associated effects on vegetation composition and structure and on other wildlife. I assessed the effects of crown thinning and deer overabundance on the relative abundance of forest-floor salamanders...