The systematics of the genus Zabrus Clairville, 1806 is currently based on morphological characters that show a high degree of parallelism. The aim of this study is to find new characters in the female genitalia, which give a better understanding of the phylogeny of the genus and result in a new classification based on monophyletic taxa (subgenera and species groups). For this purpose slides of the whole female reproductive tract were studied under light microscopy and the gonocoxa IX under scanning microscopy. The study of species belonging to eight subgenera of Zabrus, and of twelve subgenera of its sister taxon Amara, shows that Zabrus is characterised by the lack of a spermatheca. This apomorphy is reported for the first time in carabids, and corroborates the monophyly of the genus in comparison to Amara. A villous canal that is intimately joined to the distal bursa copulatrix was found in both genera and in species of related tribes. This feature could be an apomorphy of the Harpalidae sensu Deuve (1988). However, only in Zabrus does the villous canal end in a long falciform head, which is probably another autapomorphy of the genus. It is postulated that the primitive bursa copulatrix of the genus was made up of a moderately inflated basal half and an elongated and simple distal half. This pattern is found in species of the subgenus Zabrus, which are widely distributed, and the subgenera Euryzabrus, Platyzabrus, and Epomidozabrus, which are endemic to the Iberian Peninsula. Extra lobules arising in the region where the two parts of the bursa meet, and cup-like infoldings of the distal bursa are possible apomorphic states that characterise the subgenera Pelor and Iberozabrus. Gonocoxite 2 does not have the strong and short spines found in species of related taxa. Differences in size and shape of both gonocoxites, distribution of setation and microtrichia, and presence of furrow "pegs" are characters of potential phylogenetic interest, which should be thoroughly investigated in other subgenera.
Paussus favieri Fairmaire is one of only two species of the myrmecophilous carabid tribe Paussini known from Europe.
Larvae are known from only 10 of the 580 paussine species. As in many beetles with considerably modified later instar larvae, the
first instars represent a valuable source of informative characters for taxonomy and phylogenetic analyses (primary chaetotaxy, eggbursters, etc.). Therefore, the discovery of the first instar larva of P. favieri is particularly important, as it represents only the second
species for which this larval stage is known. In this paper we describe the behavior and morphology of the larval first instar of P.
favieri (subtribe Paussina of Paussini) and compare it with that of Arthropterus sp. (subtribe Cerapterina), which is the only other 1st
instar described in the Paussini. Most surprisingly, we found that the 1st instar of P. favieri lacks a prostheca, which was previously
thought to be a synapomorphy of Paussina + Platyrhopalina. Rather, P. favieri has a unique mandibular structure that seems to be
functionally analogous to the protheca. It is a long, broadly lanceolate, distinctly flattened structure apparently homologous to the
medial mandibular seta (MN2*), which arises from an area behind the cutting edge of mandible. We predict that the function of the
protheca and this similar structure in P. favieri are involved in a specialized feeding strategy that may include soliciting trophallaxis
from their host ants. We also report some observations of the first instar hatching from the egg, feeding on liquid and a behaviour we
interpret as a “calling behavior,” all of which were videotaped and posted on the Tree of Life Web Project.
Exposed Riverine Sediments (ERS) are often characterised by a high diversity of microhabitats due to strong lateral gradients in temperature, humidity, inundation frequency and availability of aquatic food resources and to variations in the degree of vegetation cover, sediment size and sorting. This variation, potentially in combination with interspecific competitive interactions, is thought to drive the microspatial distribution of ERS invertebrates. This research investigated the microspatial distribution of six ERS specialist beetles across three discreet patches of ERS. In particular it examined the temporal stability of species distributions, and their spatial association with environmental variability and other species. The research used a grid of 204 modified dry pitfall traps over six sampling periods in which weather conditions and water levels were stable, and used the Spatial Analysis by Distance IndicEs (SADIE) method to test the significance of spatial distributions and associations. Strong and significant microspatial zonation was observed for all species, and with few exceptions these distributions were remarkably stable across the study period. This zonation was mainly associated with elevation and proximity to the water, and several species were consistently spatially associated or disassociated with one another. This suggests that laterally more extensive patches of ERS support more species. Operations that reduce the size of ERS patches, such as channelisation, aggregate extraction and regulation are therefore likely to reduce ERS invertebrate diversity.
Slugs are important pests of many agricultural crops, especially oilseed rape. The carabid beetles Pterostichus melanarius Illiger and Poecilus cupreus L. are among the most abundant large carabid beetles of European arable land and were therefore explored as potential slug antagonists. Damage to oilseed rape caused by the slugs Deroceras reticulatum Müller and D. laeve Müller in the presence or absence of P. melanarius and P. cupreus was observed in the laboratory. Whereas P. cupreus failed to reduce damage to oilseed rape by D. reticulatum, P. melanarius significantly reduced slug damage. However, P. melanarius was unable to protect oilseed rape from damage by D. laeve. This can be explained by the fact that D. laeve caused damage to oilseed rape below ground, where P. melanarius did not encounter the slugs. According to our laboratory experiments P. melanarius has the potential to reduce slug damage to oilseed rape by D. reticulatum.
In 1995-1997, we studied the factors which may influence the ground "activity density" of Carabidae using pitfall traps placed in winter wheat, winter rape and pea stands (1995 only) grown within a 1 km2 area with uniform physical conditions. The traps were placed in plots of bare ground established within the crops and under surrounding intact plant stands. The communities were similar between crops within years (Pearson's correlation coefficient r = 0.60 - 0.81), and between years within crops (r = 0.89 - 0.91), except for the poor winter rape stand in 1997. Factors influencing carabid "activity density" were: (i) Density of crop stand. The carabids preferred crop-shaded ground as long as crop density was low or medium but moved to bare ground plots when crop density became high. Under moderate crop density the preference differed between beetle species, most of which preferred crop-shaded ground while a few ones preferred bare ground. Carabid preferences were probably determined by microclimatic differences caused by presence and density of crop cover. (ii) Presence of seeds dropped on the ground. In rape stands, presence of crop and weed seeds increased the "activity density" of seed predators (species of genera Amara, Harpalus, Ophonus and Pseudoophonus). Scattering of rape seeds significantly increased local activity density of Harpalus affinis and H. distinguendus in the wheat stand. (iii) Presence of aphids. Activity density of Bembidion lampros and Trechus quadristriatus and between-year variation in pooled abundance of the five species recognised as aphid predators was associated with variation in aphid abundance.
This review considers factors affecting the flight capacity of carabid beetles and the implications of flight for carabids. Studies from the Dutch polders in particular show that young populations of carabids consist predominantly of macropterous species and macropterous individuals of wing-dimorphic species. Also populations of wing-dimorphic carabid species at the periphery of their geographical range contain high proportions of macropterous individuals. However, studies from Baltic archipelagos show that older populations of even highly isolated island habitats contain considerable proportions of brachypterous species and individuals. This suggests that macroptery is primarily an adaptation for dispersal and that there exists a mechanism for subsequently reducing the ratio of macropterous to brachypterous species under stable conditions, due to the competitive advantage of brachyptery. Populations in isolated habitats, such as islands and mountains, have high proportions of brachypterous species. Many macropterous species do not possess functional flight muscles. Species of unstable habitats, such as tree canopies and wet habitats, are mostly macropterous. Brachypterous species tend to disappear from disturbed habitats. There is uncertainty regarding the extent to which carabid dispersal is directed and how much passive. Both Den Boer and Lindroth recognized that mostly macropterous individuals of macropterous and wing-dimorphic species disperse and found new populations, after which brachyptery tends to rapidly appear and proliferate in the newly founded population. It is most likely that the allele for brachyptery would arrive via the dispersal of gravid females which had mated with brachypterous males prior to emigration. Whilst many studies consider wing morphology traits of carabid beetles to be species-specific and permanent, a number of studies have shown that the oogenesis flight syndrome, whereby females undertake migration and subsequently lose their flight muscles by histolysis before eventually regenerating them after reproducing, has been reported for a growing number of carabid species. Wing morphology of carabid beetles clearly offers strong potential for the study of population dynamics. This field of study flourished during the 1940's to the late 1980's. Whilst a considerable amount of valuable research has been performed and published, the topic clearly holds considerable potential for future study., Stephen Venn., and Obsahuje bibliografii