No abstract

with contributions from Piotr Cerynger and Ivo Kovár. 1996. XVI + 464 pp., 133 tables, 95 figures, 11 plates. Kluwer Academic Publishers, Dordrecht, The Netherlands. ISBN 0-7023-4177-5. NLG 325.00; US $211.00; £143.00. Preparing a well-balanced review of the literature on Coccinellidae was a challenge, as limited space forced the authors to select the most important works of all related publications, the number of which has increased rapidly during the last decades. The authors have solved this problem successfully. This volume is not simply an extended edition of the previous book by I. Hodek (Biology of Coccinellidae, Academic, Prague and W. Junk, The Hague, 1973), rather, the two volumes partially complement each other, as the chapter on larval identification of Palaearctic Coc-cinellidae has been omitted. The title is somewhat misleading: the reader finds a considerably broader range of information than suggested by the title. The first chapter deals with the adult beetles' most important morphological and anatomical characteristics as related to feeding habits. The second chapter proposes a new phylogenetic tree of the higher coc-cinellid taxa based on adult morphology and anatomy. The third chapter surveys the heredity of colour patterns , their seasonal and geographic variability as well as the much discussed problem of Müllerian mimicry in these beetles. Chapter 4 treats the main factors affecting pre-adult and adult development, mating, flight, fecundity, longevity as well as energy conversion and allocation in both larvae and adults. The fifth chapter reviews the factors influencing distribution and abundance of coccinellid populations. The authors "use the term 'community' in its broadest sense as a set of coccinellid individuals present in a given habitat at a particular time" (p. 95). The term 'assemblage' would have been more appropriate. The description of several methods for the estimation of coccinellid numbers is followed by discussing the effect of geographic and local factors on the number and distribution of coccinellids. Data are presented on dominance, diversity and niche differentiation as related to the composition of coccinellid assemblages. Many examples of coccinellid assemblages reported from various habitats are surveyed, with special emphasis on their economic importance. The large sixth chapter is devoted to food relationships. The literature data on food range are extremely variable, mostly due to superficial observations. The authors present the main methods for ascertaining the natural food range of coccinellids appropriately. The data about the amount of food consumed by coccinellid larvae and adults also vary extremely due to the great variability of observational and experimental methods used. Concerning food related behaviour the authors in extenso deal with the searching behaviour of adults and larvae. The voluminous seventh chapter, amounting to one fourth of the text, surveys the literature on dormancy. This includes the adaptive function of dormancy as well as the anato...

This paper (i) reviews temperature/development rate relationships in plants and poikilothermic invertebrates, (ii) argues that the relationship is often linear over much of the range up to the thermal optimum (T o ) and provides a possible mechanism, (iii) provides evidence of a trade-off between the base temperature (T b ) and the thermal constant (DD) that enables each species to adapt to its thermal environment, and (iv) indicates some of the practical and ecological implications. Where a linear relationship has been characterised it is possible to estimate the base temperature for development (T b , expressed in °C) and the thermal constant for development (DD, the reciprocal of the temperature coefficient (a), expressed in degree [°C] days accumulated above T b ). A possible basis for the linear relationship between rate and temperature is proposed based on the Arrhenius and Sharpe-Schoolfield equations involving activation enthalpy and progressive inactivation of the reactant molecules at both low and high temperatures. Knowledge of T b and DD enables rates of development of organisms/ processes to be calculated and compared at any given temperature between T b and T o . An analysis of published results for differentiation processes (differentiation = a change of state) in species of insects, Collembola, spiders, nematodes and plants showed that T b tended to vary with the temperature of the niche to which the organism is adapted, and that there was a trade-off between T b and DD. Tropical species had higher values of T b than temperate and DD decreased as T b increased (and vice versa). This conferred a competitive advantage on each species in the thermal environment to which it was adapted. The decrease in DD tended to be relatively greater than the increase in T b, further favouring a high T b in tropical species. A mechanism for the trade-off is suggested whereby DD and T b were shown to be correlated (P < 0.01) with the activation enthalpy (H A ) of an assumed, rate-limiting enzyme. Thermal time can also be applied to processes involving growth (= an increase in dry weight) when the DD requirement for development to maturity is the sum of the requirements for differentiation and growth. Rates of both differentiation and growth can vary greatly between species, depending upon the niche they inhabit, and the implications of such differences for resource requirements are considered. In insects and nematodes, but not in annual plants, development is usually coupled to growth. Consequently, when resources are inadequate, mature size in these animals varies less than in plants. Thermal time is shown to provide insight into the life strategies of species within their communities and to have practical implications.

Artículo de publicación ISIThe harlequin ladybird, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), is native to Asia but has been intentionally introduced to many countries as a biological control agent of pest insects. In numerous countries, however, it has been introduced unintentionally. The dramatic spread of H. axyridis within many countries has been met with considerable trepidation. It is a generalist top predator, able to thrive in many habitats and across wide climatic conditions. It poses a threat to biodiversity, particularly aphidophagous insects, through competition and predation, and in many countries adverse effects have been reported on other species, particularly coccinellids. However, the patterns are not consistent around the world and seem to be affected by many factors including landscape and climate. Research on H. axyridis has provided detailed insights into invasion biology from broad patterns and processes to approaches in surveillance and monitoring. An impressive number of studies on this alien species have provided mechanistic evidence alongside models explaining large-scale patterns and processes. The involvement of citizens in monitoring this species in a number of countries around the world is inspiring and has provided data on scales that would be otherwise unachievable. Harmonia axyridis has successfully been used as a model invasive alien species and has been the inspiration for global collaborations at various scales. There is considerable scope to expand the research and associated collaborations, particularly to increase the breadth of parallel studies conducted in the native and invaded regions. Indeed a qualitative comparison of biological traits across the native and invaded range suggests that there are differences which ultimately could influence the population dynamics of this invader. Here we provide an overview of the invasion history and ecology of H. axyridis globally with consideration of future research perspectives. We reflect broadly on the contributions of such research to our understanding of invasion biology while also informing policy and people

Abstract. The consumption and preferences of polyphagous ground beetles (Coleoptera: Carabidae) for the seeds of herbaceous plants was determined. The seeds were stuck into plasticine in small tin trays and exposed to beetle predation on surface of the ground. In the laboratory the effect of carabid (species, satiation) and seed (species, size) on the intensity of seed predation was investigated. The consumption of the generally preferred Cirsium arvense seed by 23 species of common carabids increased with body size. Seed of Capsella bursa-pastoris was preferred by small carabids and their consumption rates were not related to their size. The average daily consumption of all the carabid species tested (0.33 mg seeds . mg body mass-1 . day-1) was essentially the same for both kinds of seed. Because of satiation the consumption of seed of C. arvense provided ad libitum to Pseudoophonus rufipes decreased over a period of 9 days to 1/3-1/4 of the initial consumption rate. Preferences of P. rufipes (body mass 29.6 mg) and Harpalus afifiinis (13.4 mg) for the seeds of 64 species of herbaceous plants were determined. The small H. afifiinis preferred smaller seed than the large P. rufipes. Predation of seed present on the ground in the field was studied in 1999-2000, at PrahaRuzyne (50°06' N 14°16'E). Seeds were placed in stands of different crops as in the laboratory experiments and vertebrate predation was excluded by wire mesh cages. Pitfall traps placed near the cages revealed that carabids were the only seed predators active in the area. Rates of removal of seed of 6 weed species varied with crop, season, seed and site. Average rate of removal in June-August was 2.5 seeds.day-1.tray-1 and was smaller before and after this period. The rates of removal increased with increasing activity den sity of the carabids and paucity of seed from naturally occurring weeds, which may have satiated the carabids. In stands of winter wheat, millet and soybeans there were significant differences in the rates of removal of the seed of 43 herbaceous species. The field preferences were correlated with those established in the laboratory. Predation of seed on the ground in arable fields can be as high as 1000 seeds.m-2.day-1 and may selectively influence the quantity of seed of particular herb species that enters the soil seed bank. Seed predation thus may be an effective component of weed control on arable land, particularly at low weed densities.

No abstract

Summary 1.The objective of this study was to test the theoretical prediction that the thermal tolerance range for development in insects should be about 20 ° C. 2. The data on the thermal requirements for development of 66 species from eight orders of insects was obtained from the literature. The temperatures at which the developmental rates are at their minimum and maximum was obtained for each population by defining the relationship between developmental rate (1/ D ) and temperature, using either Lactin et al. 's (1995) or Briére et al. 's (1999) model. 3. Thermal windows, i.e. the range in temperature between the minimum and maximum rate of development for individual species, and the relationship between the minimum and maximum temperatures, were examined. 4. The mean thermal window, 19·8 ° C with 95% confidence interval 19·1-20·5 and range 13·3 − 28·6, was influenced by species phylogeny, with the windows narrower for species having a true pupal stage, but not by ecological traits thought to affect species thermal requirements. The relationship between the minimum and maximum temperatures was highly significant and independent of species phylogeny. 5. Theory and this analysis of empirical data indicate that each species of insect can only develop over a limited range of temperatures independent of species traits. In addition, the relationship between the minimum and maximum developmental rates co-vary independent of species phylogeny. This may help identify the precise nature of the physiological mechanism underlying the seasonal development and distribution of insects, and possibly other ectotherms.

When the proportion of total developmental time spent in a particular developmental stage does not change with temperature, an organism shows "rate isomorphy." This is the case only if the lower developmental threshold is the same for all developmental stages. In this study, the incidence of rate isomorphy in seven species of mites and 342 species from 11 insect orders (some represented by several populations) was determined. Whether a species shows rate isomorphy or not was determined over a range of temperatures where the relationship between the rate of development and temperature is linear. Proportion of total developmental time spent in a particular stage was plotted against temperature and the existence of rate isomorphy inferred from a zero change in proportion. Rate isomorphy was detected in 243 (57%) of 426 populations. In the rest of the cases, rate isomorphy was violated by deviations in the proportion of time spent in a stage by an average of 0.2% (range 4.5E-06% to 2.8%) at the mean of the range of temperatures of all the data sets (11 degrees C). The violations occurred most frequently at the extremes of the linear phase, which is attributed to methodical biases, mortality at low temperatures, or too coarse an estimate of developmental time at high temperatures. Similarly, a meta-analysis also revealed an overall prevalence of rate isomorphy. Consequently, in insect and mite species, all the developmental stages appear to have the same population-specific lower developmental threshold. The existence of rate isomorphy could be of great practical importance, for example, in the timing of life-history events and in determining preadult thermal requirements. There are also indications that it may act as a phylogenetic constraint.