Joseph D. Shorthouse

Influence of galls of Phanacis taraxaci on carbon partitioning within common dandelion, Taraxacum officinale

We examined how leaf galls, induced by the cynipid wasp Phanacis taraxaci, influence the partitioning of photoassimilates within the host, the common dandelion, Taraxacum officinale. Galled and ungalled plants were exposed to 14CO2 and the labelled photoassimilates accumulating within galls and other parts of the host were measured. During the growth phase of the gall they were physiological sinks for photoassimilates, accumulating 9% to 70% of total carbon produced by the host, depending upon the number of galls per plant. High levels of 14C assimilation in the leaves of galled plants compared to controls, suggest that galls actively redirect carbon resources from unattacked leaves of their host plant. This represents a significant drain on the carbon resources of the host, which increases with the number and size of galls per plant. Active assimilation of 14C by the gall is greatest in the growth phase and is several orders of magnitude lower in the maturation phase. This finding is consistent with physiological and anatomical changes that occur during the two phases of gall development and represents a key developmental strategy by cynipids to ensure adequate food resources before larval growth begins.

Mite (Acari) colonization of vegetated mine tailings near Sudbury, Ontario, Canada

INCO Ltd. near Sudbury, Ontario is rehabilitating nickel- and copper-mine tailings using vegetating techniques that have resulted in habitats of varying age and complexity. Mite (Acari) communities and soil quality characteristics were used to evaluate soil ecosystem development on four tailings sites, 0, 8, 20 and 40 years post rehabilitation in comparison with that on four control sites. Abundance, species richness, diversity (H′) and community structure of soil mites were sensitive indicators of tailings rehabilitation and soil formation. Mite density on older and botanically diverse tailings sites was comparable to that on control sites; however, species richness of oribatids and mesostigmatics was lower than on control sites. Mite species richness and diversity on tailings were lower at less botanically diverse sites regardless of age. Similarity of tailings-mite communities to control-site communities generally increased with age; however, similarities were all less than 60% (Sorensons quantitative index, CN). Mite assemblages on tailings were dominated by a few colonizing species, whereas control sites had a diverse assemblage of species. Soil pH and organic matter (SOM) of rehabilitated tailings improved with age and degree of botanical complexity. Mite density and diversity was positively related to SOM particularily for the Oribatida. SOM and mites were mainly restricted to the 0–5-cm horizon.

Accumulation of Cu and Ni in successive stages of Lymantria dispar L. (lymantriidae, lepidoptera) near ore smelters at Sudbury, Ontario, Canada

The accumulation of Cu and Ni in successive life stages of the gypsy moth (Lymantria dispar), feces, and foliage near an ore smelter at Sudbury, Ontario and a control site was investigated. Higher concentrations of Cu and Ni were found in all larval stages collected at Sudbury than in those from the control site indicating that elevated levels of these metals in the Sudbury environment is an important factor influencing body burdens. These differences were associated with higher metal concentrations in the foliage of host trees from this site. However, differences between sites became less significant for pupae and adult stages. At the Sudbury site, concentrations of Cu (microg g(-1) dry wt) decreased in successive instars and then increased in tissues of pupae and adults. In contrast, Cu content (microg/individual) increased during larval development and then decreased in pupae and adults. The pattern of Ni concentration and content in larvae from the Sudbury site was similar to that of Cu. Patterns of Cu and Ni concentration and content throughout the life stages are explained by changes in weight resulting in a dilution effect in early stages, and a concentrating effect in later stages. Differences in Cu and Ni concentration and content between Sudbury and control populations became less significant following the pupal stage suggesting metal elimination with the exuviae and meconium. This study also illustrates the importance of sampling all stages in an insects development when measuring accumulation of metals. Fecal and foliar concentrations of Cu and Ni from Sudbury were not significantly different suggesting that metal assimilation is low. Even though gypsy moths from Sudbury contain elevated levels of Cu and Ni, metal burdens in their tissues do not represent a significant route through the food chain. However, the conversion of foliage with high metal content to feces implies that other ecosystem consequences should be investigated.

Seasonal acquisition of mineral nutrients by a chalcid gall on lowbush blueberry

Seasonal accumulation of various mineral nutrients by galls of the chalcid Hemadas nubilipennis on lowbush blueberry were examined in various phases of gall development. Levels of copper, nickel, iron, and zinc were higher in tissues of galls in initiation phase compared to tips of ungalled shoots and in general were higher than galls in growth and maturation phases. Levels of manganese and magnesium in gall tissues decrease throughout the season compared to ungalled shoots. Levels of calcium are less in gall tissues in initiation phase compared to ungalled shoots, and elevated in maturation phase. Patterns of mineral concentration within galls at various phases of development are related to known physiological roles of minerals in plant nutrition; however, we conclude that patterns are variable and their significance in gall physiology requires further study.

Evaluation of municipal solid waste (MSW) compost as a soil amendment for acidic, metalliferous mine tailings

ABSTRACT Four 0·5 ha plots were established on freshly dried tailings of INCO Ltd. near Sudbury, Ontario, Canada and received the following treatments: 1) 125 t/ha Municipal Solid Waste (MSW) compost, 2) 250 t/ha MSW compost, 3) INCOs standard application of crushed limestone, fertilizer and hay mulch and 4) control - no application of compost. Application of compost at a rate of 250 t/ha yielded the same increase in tailings pH (from 2·80 to 4·65) as that achieved with the typical INCO application of 40 t lime/ha. The INCO treatment with lime and fertilizer resulted in no initial input of organic matter; whereas, a 250 t/ha application of compost increased organic content by 8·3%. Moisture retention in tailings at the two compost-treated plots was significantly higher (26%) than that of the INCO treated plots (<10%). Application of lime as part of the INCO treatment reduced levels of water soluble Cu and Ni from 22·8 pgCu/g to 0·4 pgCu/g and from 35·5 pgNi/g to 5·2 ngNi/g. Similar reductions in water soluble copper and nickel in tailings were achieved with the 250 t/ha application of compost. It was concluded that tailings amelioration with MSW compost is superior to the INCO treatment because it more rapidly increases pH, moisture content and organic content, and reduces concentrations of water soluble (plant available) Cu and Ni.

Potential Role of Lowbush Blueberry (Vaccinium angustifolium) in Colonizing Metal-Contaminated Ecosystems

The industrially damaged lands around the smelters of Sudbury are inhabited by several species of plants that can tolerate high levels of toxic metals (Hogan and Rauser 1978; Cox and Hutchinson 1980). One of these plants, the sweet lowbush blueberry (Vaccinium angustifolium), has colonized large areas of the smelter-affected area. It is particularly abundant within the birch transition forest described in the previous chapter (Chapter 18). This chapter reviews the attributes of V. angustifolium that made it successful in the Sudbury industrially damaged lands. There are actually two species of blueberry near Sudbury, V. angustifolium and V. myrtilloides, of which V. angustifolium is the more common of the two. Although they are similar (see descriptions of each in Vander Kloet [1988]) and grow in the same habitats, care was taken to restrict our studies to V. angustifolium.