Abstract:Summary1. The population density and age structure of two species of heather psyllid Strophingia ericae and Strophingia cinereae, feeding on Calluna vulgaris and Erica cinerea, respectively, were sampled using standardized methods at locations throughout Britain. Locations were chosen to represent the full latitudinal and altitudinal range of the host plants. 2. The paper explains how spatial variation in thermal environment, insect life-history characteristics and physiology, and plant distribution, interact … Show more
“…The prediction of the responses of insects to thermal changes is largely based on studies of phytophagous species (i.e. Strathdee & Bale, 1995;Williams & Liebhold, 1995;Hodkinson & Bird, 1998;Hodkinson et al, 1999). Nevertheless, there is no information on the reproductive biology of C. florentinus, a potential pest of Quercus species, which are the main component of the Mediterranean mixed forests.…”
Abstract. Environmental degradation caused by climate change greatly affects the forest ecosystems of the Mediterranean region, in particular the sclerophyllous Quercus forests typical of central and southern Spain. An important pest that damages oak trees in this area is Coraebus florentinus (Herbst), a heliophilous and thermophilous insect whose survival could be favoured by the temperature increase associated with climate change. The main objective of this paper was to determine the effect of temperature on the duration and percentage survival of the preimaginal stage of C. florentinus and provide data for determining more precisely when to control for this pest by applying silvicultural techniques. The experiment included six treatments, with 25 branches infested with C. florentinus in each of the treatments, which were kept at different temperatures over the range 15-28°C. The results clearly support the hypothesis that higher temperatures affect the post-larval development of C. florentinus by increasing the percentage survival and shortening the developmental time. In fact, partial correlations confirm that the highest percentages of emergence and survival were recorded when the developmental times were shortest, which occurred at the highest temperatures used. Despite the clear influence of temperature on the development of the preimaginal stage of C. florentinus, additional trials are required to accurately determine future trends in C. florentinus populations. Accordingly, it is necessary to develop monitoring programs in zones affected by C. florentinus and to apply scheduled management techniques that ensure the control of this species.
“…The prediction of the responses of insects to thermal changes is largely based on studies of phytophagous species (i.e. Strathdee & Bale, 1995;Williams & Liebhold, 1995;Hodkinson & Bird, 1998;Hodkinson et al, 1999). Nevertheless, there is no information on the reproductive biology of C. florentinus, a potential pest of Quercus species, which are the main component of the Mediterranean mixed forests.…”
Abstract. Environmental degradation caused by climate change greatly affects the forest ecosystems of the Mediterranean region, in particular the sclerophyllous Quercus forests typical of central and southern Spain. An important pest that damages oak trees in this area is Coraebus florentinus (Herbst), a heliophilous and thermophilous insect whose survival could be favoured by the temperature increase associated with climate change. The main objective of this paper was to determine the effect of temperature on the duration and percentage survival of the preimaginal stage of C. florentinus and provide data for determining more precisely when to control for this pest by applying silvicultural techniques. The experiment included six treatments, with 25 branches infested with C. florentinus in each of the treatments, which were kept at different temperatures over the range 15-28°C. The results clearly support the hypothesis that higher temperatures affect the post-larval development of C. florentinus by increasing the percentage survival and shortening the developmental time. In fact, partial correlations confirm that the highest percentages of emergence and survival were recorded when the developmental times were shortest, which occurred at the highest temperatures used. Despite the clear influence of temperature on the development of the preimaginal stage of C. florentinus, additional trials are required to accurately determine future trends in C. florentinus populations. Accordingly, it is necessary to develop monitoring programs in zones affected by C. florentinus and to apply scheduled management techniques that ensure the control of this species.
“…While several studies have examined the importance of climate, host plant phylogeny, and host plant traits in influencing insect assemblage structure (Hairston et al 1960;Hodkinson et al 1999;Novotny et al 2002;Speight et al 1999), the relative influences of two or more factors remain poorly understood. Here, using highly specialized herbivores (plant gallers and leaf miners) to assess the influences of these factors, we found that the factors that best explained leaf miner richness across the climatic gradient included specific leaf area (SLA), foliage thickness and mean annual rainfall, whereas C:N ratio was the most important factor that explained plant galler richness across the climatic gradient.…”
Diversity patterns of herbivores have been related to climate, host plant traits, host plant distribution and evolutionary relationships individually. However, few studies have assessed the relative contributions of a range of variables to explain these diversity patterns across large geographical and host plant species gradients. Here we assess the relative influence that climate and host plant traits have on endophagous species (leaf miners and plant gallers) diversity across a suite of host species from a genus that is widely distributed and morphologically variable. Forty-six species of Acacia were sampled to encapsulate the diversity of species across four taxonomic sections and a range of habitats along a 950 km climatic gradient: from subtropical forest habitats to semi-arid habitats. Plant traits, climatic variables, leaf miner and plant galler diversity were all quantified on each plant species. In total, 97 leaf mining species and 84 plant galling species were recorded from all host plants. Factors that best explained leaf miner richness across the climatic gradient (using AIC model selection) included specific leaf area (SLA), foliage thickness and mean annual rainfall. The factor that best explained plant galler richness across the climatic gradient was C:N ratio. In terms of the influence of plant and climatic traits on species composition, leaf miner assemblages were best explained by SLA, foliage thickness, mean minimum temperature and mean annual rainfall, whilst plant gall assemblages were explained by C:N ratio, %P, foliage thickness, mean minimum temperature and mean annual rainfall. This work is the first to assess diversity and structure across a broad environmental gradient and a wide range of potential key climatic and plant trait determinants simultaneously. Such methods provide key insights into endophage diversity and provide a solid basis for assessing their responses to a changing climate.
“…Given the diversity of invertebrate responses to climate change (e.g., ref. 44), it seems likely that the avian insectivores least affected by climate change will be those with the greatest diversity of suitable prey for egg laying and chick rearing.…”
Across North America, tree swallows have advanced their mean date of clutch initiation (lay date) by Ϸ9 days over the past 30 years, apparently in response to climate change. In a sample of 2,881 nest records collected by the lay public from 1959 to 1991, we examined whether clutch size has also responded to climate change. We found that clutch size is strongly related to lay date, both within and among years, and there has been no significant temporal variation in the slopes or intercepts of the clutch-size͞ lay-date regressions. As a consequence, we expected increases in clutch size with advancement in lay date; however, we detected no such trend over time. The distributions of egg-laying dates were more constricted in the warmest (and earliest) years, suggesting that changes in mean clutch size might be constrained by changes in the distribution of laying dates. If spring temperatures continue to increase, we predict further reductions of variance in laying dates and relatively small increases in clutch size. Such constraints on life-history variation probably are common and need to be considered when modeling the effects of climate change on reproduction in natural populations. Predicting the long-term effects of constraints and interpreting changes in life-history traits require a better understanding of both adaptive and demographic effects of climate change. O ver the past century, global surface temperature has increased by an average of 0.6°C (1). It is now widely accepted that air temperatures have been increasing as a result of increased anthropogenic carbon dioxide in the atmosphere. Air temperature could be one of the key environmental cues affecting the seasonal timing of egg laying in birds, and there is evidence that increases in mean temperatures have led to earlier lay dates in birds (2-6) and accelerated phenologies in many other taxa (7-9).One of the most general patterns in the life histories of birds is that females that lay later in a breeding season tend to lay smaller clutches (refs. 10 and 11, but see refs. 12 and 13 for exceptions in multiple-brooded species), raising the possibility that earlier breeding may be leading to larger clutches being laid. Clutch size is an important life-history trait, because it sets a hard upper limit on offspring production. It is also the easiest life-history trait to measure, and data on clutch size variation often are available when data on other life-history traits are not.There is considerable evidence that the correlation between lay date and clutch size may be the result of a strong biological coupling (7,14), yet the nature of this biological link is very poorly understood. In an early attempt to study this connection between lay date and clutch size, von Haartman (15) suggested a dichotomy in the way that birds adjust their clutch sizes to the timing of breeding. At a study site in Lemsjöholm, Finland, both pied flycatchers (Ficedula hypoleuca) and starlings (Sturnus vulgaris) laid smaller clutches as each breeding season progressed. However, wh...
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