Richard H. A. Baker

The role of climatic mapping in predicting the potential geographical distribution of non-indigenous pests under current and future climates

Abstract Climatic mapping, which predicts the potential distribution of organisms in new areas and under future climates based on their responses to climate in their home range, has recently been criticised for ignoring dispersal and interactions between species, such as competition, predation and parasitism. In order to determine whether these criticisms are justified, the different procedures employed in climatic mapping were reviewed, with examples taken from studies of the Mediterranean fruit fly ( Ceratitis capitata ), Karnal bunt of wheat ( Tilletia indica ) and the Colorado potato beetle ( Leptinotarsa decemlineata ). All these studies stressed the key role played by non-climatic factors in determining distribution but it was shown that these factors, e.g., the availability of food and synchrony with the host plant, together with the difficulties of downscaling and upscaling data, were different to those highlighted in the criticisms. The extent to which laboratory studies on Drosophila populations, on which the criticisms are based, can be extrapolated to general predictions of species distributions was also explored. The Drosophila experiments were found to illustrate the importance of climate but could not accurately determine potential species distributions because only adult and not breeding population densities were estimated. The experimental design overestimated species interactions and ignored other factors, such as the availability of food. It was concluded that while there are limitations, climatic mapping procedures continue to play a vital role in determining what G.E. Hutchinson defined as the “fundamental niche” in studies of potential distribution. This applies especially for pest species, where natural dispersal is generally less important than transport by man, and species interactions are limited by the impoverished species diversity in agroecosystems. Due to the lack of data, climatic mapping is often the only approach which can be adopted. Nevertheless, to ensure that non-climatic factors are not neglected in such studies, a standard framework should be employed. Such frameworks have already been developed for pest risk analyses and are suitable for general use in studies of potential distribution because, in order to justify the phytosanitary regulation of international trade, they must also consider the potential for pests to invade new areas and the impacts of such invasions.

An analysis of pest risk from an Asian longhorn beetle (Anoplophora glabripennis) to hardwood trees in the European community

The risk posed by the wood-boring pest, Anoplophora glabripennis, to hardwood tree species in the EC was assessed using an internationally developed pest risk assessment scheme. The assessment reviewed information concerning the current distribution, biology and economic impact of A. glabripennis in Asia and North America together with recent European interceptions. Hosts grow across much of Europe and, using the computer program CLIMEX, southern regions of Europe were highlighted as areas where climate is most suitable for the pests establishment. There is a significant risk that A. glabripennis could enter, establish and cause damage to several important forest, fruit, and amenity tree species in the EC. This risk analysis contributed to the decision to add A. glabripennis to the list of quarantine pests whose introduction and spread within all EC Member States is banned.

Recent non-native invertebrate plant pest establishments in Great Britain: origins, pathways, and trends

1u2002An appraisal of non‐native invertebrate plant pest establishments in Great Britain, between 1970 and 2004, was carried out to improve our understanding of current invasion processes by non‐native plant pests, and to assist national strategies in managing the risks they pose.

The impact of interpolated daily temperature data on landscape-wide predictions of invertebrate pest phenology

Insect phenology depends upon temperature, and data from scattered synoptic weather stations are the principle inputs for phenology models used in decision support systems. The paper assesses the spatial dynamics of the penalty, as measured through errors in the timing of predicted insect development stages, that results when entomologists use daily maximum and minimum temperature data from the nearest station to a location, in comparison with an interpolated temperature equivalent, to drive their models. Jack-knife cross-validated estimates of temperature were propagated through an example phenology model, in this case for codling moth (Cydia pomonella). The intention was to contrast the effect of two interpolation methods on phenological results through time at different geographical locations. Use of weather data from the nearest UK meteorological data station (174 points) for phenological modelling doubled the error in predicted development dates for first generation development when compared with the use of landscape-wide interpolated daily temperature data. The results are based on a partial thin plate spline interpolation methodology: the figures are spatial and temporal averages for mainland England and Wales. Overall, spline interpolations provide phenology results that either exceed or are as good as nearest neighbour techniques for 75% of locations over England and Wales, taking first and second generation developmental stages into account. In a minority (21%) of cases nearest neighbour strategies (Voronoi methods) performed better, with an average 18-day improvement in the predictions of development date over the spline method on those occasions. Where splines performed best, their performance exceeded that of the Voronoi method by an average of 25 days. Nearest neighbour techniques did not necessarily perform well in lowland areas, indicating findings of potential significance to those considering input data requirements when modelling insect ecology.