Desirable Host Plant Qualities in Wild Rice \u3ci\u3e(Zizania Palustris)\u3c/i\u3e for Infestation by the Rice Worm \u3ci\u3eApamea Apamiformis\u3c/i\u3e (Lepidoptera: Noctuidae)

The rate at which an insect infests hosts by ovipositioning and/or subsequent growth of larvae often depends on specific desirable host plant qualities. In this study, we measured the infestation rate of wild rice, Zizania palustris, by the wild rice worm, Apamea apamiformis, D. F. Hardwick (Lepidoptera: Noctuidae) and compared it to sediment nitrogen availability, plant biomass, plant density, litter accumulation, and seed carbohydrate and nitrogen concentration. Plant density and litter accumulation had no effect on infestation rates. Infestation rate increased with plant biomass and sediment nitrogen availability. The correlation between infestation rate and sediment nitrogen availability seems to reflect the fact that high nitrogen availability produces larger plants rather than more nutritious seeds as the infestation rate was not correlated with seed glucose content and surprisingly decreased with concentration of nitrogen in seeds. Infestation rate was not related to any other measured quantities. Therefore, Apamea appear to infest larger, rapidly growing host plants which are made possible by high sediment nitrogen availability

Simulating antler growth and energy, nitrogen, calcium and phosphorus metabolism in caribou

We added antler growth and mineral metabolism modules to a previously developed energetics model for ruminants to simulate energy and mineral balance of male and female caribou throughout an annual cycle. Body watet, fat, protein, and ash are monitored on a daily time step, and energy costs associated with reproduction and body mass changes are simulated. In order to simulate antler growth, we had to predict calcium and phosphorus metabolism as it is affected by antler growth, gestation, and lactation. We used data on dietary digestibility, protein, calcium and phosphorus content, and seasonal patterns in body mass to predict the energy, nitrogen, calcium, and phosphorus balances of a "generic" male and female caribou. Antler growth in males increased energy requirements during antler growth by 8 to 16%, depending on the efficiency with which energy was used for antler growth. Female energy requirements for antler growth were proportionately much smaller because of the smaller size of female antlers. Protein requirements for antler growth in both males and females were met by forage intake. Calcium and phosphorus must be resorbed from bone during peak antler growth in males, when > 25 g/day of calcium and > 12 g/day of phosphorus are being deposited in antlers. Females are capable of meeting calcium needs during antler growth without bone resorption, but phosphorus was resorbed from bone during the final stages of antler mineralization. After energy, phosphorus was most likely to limit growth of antlers for both males and females in our simulations. Input parameters can be easily changed to represent caribou from specific geographic regions in which dietary nutrient content or body mass patterns differ from those in our "generic" caribou. The model can be used to quantitatively analyze the evolutionary basis for development of antlers in female caribou, and the relationship between body mass and antler size in the Cervidae

Desirable Host Plant Qualities in Wild Rice \u3ci\u3e(Zizania Palustris)\u3c/i\u3e for Infestation by the Rice Worm \u3ci\u3eApamea Apamiformis\u3c/i\u3e (Lepidoptera: Noctuidae)

The rate at which an insect infests hosts by ovipositioning and/or subsequent growth of larvae often depends on specific desirable host plant qualities. In this study, we measured the infestation rate of wild rice, Zizania palustris, by the wild rice worm, Apamea apamiformis, D. F. Hardwick (Lepidoptera: Noctuidae) and compared it to sediment nitrogen availability, plant biomass, plant density, litter accumulation, and seed carbohydrate and nitrogen concentration. Plant density and litter accumulation had no effect on infestation rates. Infestation rate increased with plant biomass and sediment nitrogen availability. The correlation between infestation rate and sediment nitrogen availability seems to reflect the fact that high nitrogen availability produces larger plants rather than more nutritious seeds as the infestation rate was not correlated with seed glucose content and surprisingly decreased with concentration of nitrogen in seeds. Infestation rate was not related to any other measured quantities. Therefore, Apamea appear to infest larger, rapidly growing host plants which are made possible by high sediment nitrogen availability

Progress towards the experimental reintroduction of woodland caribou to Minnesota and adjacent Ontario

Woodland caribou (Rangifer tarandus caribou) are native to Minnesota but started to decline in the mid 1800s and disappeared from the state by 1940. Their demise had been attributed to extensive timber harvest and ovethunting; but more recently mortality from the meningeal worm, Parelaphostrongylus tenuis, carried by white-tailed deer (Odocoileus virginianus), and increased prédation by timber wolves (Canis lupus) and black bears (Ursus americanus) have been suggested as additional causes. We describe a current initiative to explore feasibility of restoring caribou to the boundary waters region of Minnesota and Ontario. Feasibility studies have been conducted under the guidance of the North Central Catibou Corporation (NCCC), a non-governmental organization with representation from relevant state, federal, Native American, and Canadian agencies. Results indicate a) Within Minnesota the most suitable site for woodland caribou lies within the eastern sector of the Boundary Waters Canoe Area Wilderness (BWCAW), and this is contiguous with a similarly suitable sector of Ontario's Quetico Provincial Park: Together these comprise the recommended 1300-km2 Boundary Waters Caribou Region (BWCR); b) Vegetation in the BWCR has changed little since the 1920s when caribou were last present other than effects of fire suppression; c) Level of white-tailed deer, hence the meningeal worm, is so low in the BWCR that this factor is unlikely to impede survival of re-introduced caribou; d) While wolf numbers within the wider region are relatively high, their impacts may be minimized if caribou are released in small, widely scattered groups; in addition, an abundance of lakes with islands affords good summer-time prédation security; e) Threat to calves from black bears, probably more numerous than in earlier times, appears lessened by the security of lakeshores and islands; and f) A simulation model, combining knowledge from elsewhere with the BWCR assessment, suggests that released animals have a 0.2 to 0.8 chance of increasing in numbers during the first 20 years post-release. Strategies for maximizing success are identified. NCCC has concluded that the only practical approach that remains for determining restoration feasibility is through experimental releases or caribou. While promise of eventual success appears only moderate, the NCCC feels that costs and uncertainties associated with the experiment are justified by the environmental benefits from a success. Even if the effort fails, valuable knowledge would accrue for conservation biologists in general. An action plan is outlined, and progress and problems in selling the caribou initiative are discussed

Ariel - Volume 12 Number 1

Executive Editors David G. Polin Larry H. Pastor Business Manager Alex Macones Jean Lien Editorial Page Editor Sam Markind Photography Editors Ken Yonemura Lois Leach Sports Editor Todd Hoove

Methane production and consumption in grassland and boreal ecosystems

The objectives of the this project were to develop a mechanistic understanding of methane production and oxidation suitable for incorporation into spatially explicit models for spatial extrapolation. Field studies were undertaken in Minnesota, Canada, and Colorado to explore the process controls over the two microbial mediated methane transformations in a range of environments. Field measurements were done in conjunction with ongoing studies in Canada (the Canadian Northern Wetlands Projects: NOWES) and in Colorado (The Shortgrass Steppe Long Term Ecological Research Project: LTER). One of the central hypotheses of the proposal was that methane production should be substrate limited, as well as being controlled by physical variables influencing microbial activity (temperature, oxidation status, and pH). Laboratory studies of peats from Canada and Minnesota (Northern and Southern Boreal) were conducted with amendments of a methanogenic substrate at multiple temperatures and at multiple pHs (the latter by titrating samples). The studies showed control by substrate, pH, and temperature in order in anaerobic samples. Field and laboratory manipulations of natural plant litter, rather than an acetogenic substrate, showed similarly large effects. The studies concluded that substrate is an important control over methanogenesis, that substrate availability in the field is closely coupled to the chemistry of the dominant vegetation influencing its decomposition rate, that most methane is produced from recent plant litter, and that landscape changes in pH are an important control, highly correlated with vegetation