Summer diapause in <i>Chrysolina hyperici</i> and <i>C. quadrigemina</i> (Coleoptera: Chrysomelidae) in relation to biological control of St John's wort, <i>Hypericum perforatum</i> (Clusiaceae)

AbstractThe success of the chrysomelid beetles, Chrysolina hyperici (Forster) and C. quadrigemina (Suffrian), used widely for biological control of St John's wort (Hypericum perforatum) seems to depend on the synchronization of their phenologies with climate. The factors governing the termination of diapause in the field and laboratory were assessed in New Zealand. Before summer diapause, C. hyperici made up more than 70% of adult beetles in the field. Both species entered summer diapause at the beginning of January, but C. quadrigemina terminated diapause 3–4 weeks earlier (early March) than C. hyperici. Both male and female C. quadrigemina and male C. hyperici adults became sexually mature during summer diapause but C. hyperici females still had immature ovaries. Females of C. quadrigemina began laying eggs immediately after summer diapause but females of C. hyperici did not oviposit until more than 2 weeks after they terminated diapause in late March. In the laboratory summer diapause was terminated in both species by short day length, not by simulated rainfall, contradicting previous assumptions that autumn rainfall is the critical factor. The demonstrated differences in phenology are reflected in different overwintering strategies for the two species. Because C. hyperici overwinters in the egg stage, this species will be a more successful biological control agent of St John's wort in countries with cold winters than C. quadrigemina, which overwinters in the more vulnerable larval stage. However, in countries with mild winters C. quadrigemina is more successful in controlling St John's wort than C. hyperici, since it has a developmental lead with its larvae feeding and growing during the winter.</jats:p

The effects of forest edges on dung beetle communities in a tropical montane forest

Land use has been implicated as the largest global driver of biodiversity loss, largely due to associated habitat loss and fragmentation. The resulting production of habitated ges have pervasive impacts on the distribution and persistence of invertebrates. Land use change is of particular concern in African tropical montane forests as populations are increasing dramatically throughout these areas. Therefore, this study focuses on the impacts of livestock and fire on forest edges around a unique Afromontane forest in Nigeria

Assessing the future global impacts of ozone on vegetation.

Ozone is a major secondary air pollutant, the current concentrations of which have been shown to have significant adverse effects on crop yields, forest growth and species composition. In North America and Europe, emissions of ozone precursors are decreasing but in other regions of the world, especially Asia, where much less is known about its impacts, they are increasing rapidly. There is also evidence of an increase in global background ozone concentrations, which will lead to significant changes in global ozone exposure over this century, during which direct and indirect effects of other changes in the global atmosphere will also modify plant responses to ozone. This paper considers how far our current understanding of the mechanisms of ozone impacts, and the tools currently used for ozone risk assessment, are capable of evaluating the consequences of these changing global patterns of exposure to ozone. Risk assessment based on relationships between external concentration and plant response is inadequate for these new challenges. New models linking stomatal flux, and detoxification and repair processes, to carbon assimilation and allocation provide a more mechanistic basis for future risk assessments. However, there are a range of more complex secondary effects of ozone that are not considered in current risk assessment, and there is an urgent need to develop more holistic approaches linking the effects of ozone, climate, and nutrient and water availability, on individual plants, species interactions and ecosystem function