There is much current discussion about the factors that control the distribution and abundance of animal species, particularly at the edges of their range. The significance of temperature for survival and development is compared in two closely related psyllid species (Craspedolepta nebulosa and C. subpunctata) living on the same host plant (Chamerion angustifolium) (Onagraceae) but displaying different distributions along latitudinal and altitudinal gradients. The following measurements were made at critical periods during the life cycle (a) winter supercooling points (SCPs), (b) tolerance of short (1 min) and long term (1-25) days exposure to sub-zero temperatures above the SCP, (c) tolerance of short term exposure to high spring/summer temperatures and (d) comparative field development rates among species and sites during the early critical part of the growing season. Successful completion of the life cycle is related to heat availability during the growing season. This appears to limit the distribution of the Craspedolepta species, rather than their survival response to thermal extremes. No significant differences were found between the two species in the supercooling point or in their long and short term survival responses at low or high temperatures., Jeremy M. Bird, Ian D. Hodkinson, and Lit
Ant assemblages were studied in Warsaw in the context of the effects of urban pressure. Four types of urban greenery were selected: (1) green areas bordering streets, (2) in housing estates, and (3) in parks, and (4) patches of urban woodland. In total, there were 27 species of ants. In terms of the total ant activity density, Lasius niger predominated in all the the lawn biotopes (1–3) and Myrmica rubra in the wooded areas. Ant species diversity was highest in parks and wooded areas and lowest in green areas bordering streets. In contrast, activity density was highest in green areas bordering streets and lowest in wooded areas. Some species are found only in a few habitats. Stenamma debile, Lasius brunneus, L. fuliginosus and Temnothorax crassispinus almost exclusively occurred in wooded areas, whereas L. niger was most often found in lawn biotopes. Myrmica rugulosa and Tetramorium caespitum were most abundant in green areas bordering streets, while in parks Lasius flavus, Formica cunicularia and Solenopsis fugax were most abundant. In general, the ant assemblages recorded showed a significantly nested pattern, with biotope type being a significant determinant of nestedness. The assemblages found in green areas in housing estates and bordering streets constituted a subsample of the assemblages in parks and wooded areas. Ant species were non-randomly distributed in this urbanized landscape and the species recorded in the most transformed biotopes constitute subsamples of those inhabiting less transformed biotopes. This finding emphasizes the importance of wooded areas for the maintenance of biodiversity in urban areas., Piotr Slipinski, Michal Zmihorski, Vojciech Czechowski., and Obsahuje seznam literatury
In some species of insects, individuals with fully developed wings and capable of flying coexist with flightless individuals that lack functional wings. Their diets may differ if long-winged individuals are more mobile and therefore likely to be better at finding and utilizing high quality food resources, or if they have different food preferences or physiological requirements. Despite its potential importance, differences in the diet of dispersal phenotypes have not been unequivocally demonstrated under natural conditions. To test for dietary divergence, we compared natural abundances of carbon and nitrogen stable isotope ratios (d13C and d15N) in long- and short-winged free ranging Tetrix subulata pygmy grasshoppers collected as adults from two natural populations. Overall, this comparison of stable isotopes indicated long-term differences in the diet of the two wing morphs in both populations, but not between males and females of the same morph. We conclude that it is likely that the dietary niches of the long winged and flightless individuals differ under natural conditions. This may reduce intra-specific competition, offset the expected trade-off between flight capacity and reproduction and promote ecological speciation. Address, Einat Karpestam, Anders Forsman., and Obsahuje seznam literatury
The effects of 5 pmols of adipokinetic hormone (Lom-AKH-I) on both the locomotion and mobilization of lipids were studied in 10-day-old diapausing adult females of the short-winged (brachypterous) morph of Pyrrhocoris apterus (L.). The results revealed that AKH stimulation of locomotion in this bug is wing-morph independent. The stimulatory effect of AKH on locomotion was shown to be positively correlated with its effect on lipid mobilization., Radomír Socha, Dalibor Kodrík, Rostislav Zemek, and Lit
The presence of adipokinetic activity in crude extracts of corpora cardiaca (CC) from the butterfly (Vanessa cardui L., Nymphalidae) was demonstrated by bioassay and Mas-AKH was revealed as the major adipokinetic hormone (AKH) by use of two different technologies of sequence elucidation: HPLC separation of the peptide followed by Edman degradation and Q-TOF mass spectrometry. In contrast to the time- and material-consuming conventional methods of peptide purification and sequencing, substantial structural data of the peptide were confirmed - post factum - from one pCC (pair of CC) by Q-TOF mass spectrometry. Only males of our laboratory colony showed a significant lipid increase in the haemolymph after injection of either crude CC extract (1 pCC equivalent) or 10 pmol of synthetic peptide., Gabriele Köllisch, Peter D. Verhaert, Matthias W. Lorenz, Roland Kellner, Gerd Gäde, Klaus H. Hoffmann, and Lit
1_Red wood ants are ecologically important members of woodland communities, and some species are of conservation concern. They occur commonly only in certain habitats in Britain, but there is limited knowledge of their numbers and distribution. This study provided baseline information at a key locality (Abernethy Forest, 37 km2) in the central Highlands of Scotland and trialed a new method of surveying red wood ant density and stand type associations: a distance sampling line transect survey of nests. This method is efficient because it allows an observer to quickly survey a large area either side of transect lines, without having to assume that all nests are detected. Instead, data collected on the distance of nests from the line are used to estimate probability of detection and the effective transect width, using the free software "Distance". Surveys took place in August and September 2003 along a total of 71.2 km of parallel, equally-spaced transects. One hundred and forty-four red wood ant nests were located, comprising 89 F. aquilonia (Yarrow, 1955) and 55 F. lugubris (Zetterstedt, 1838) nests. Estimated densities were 1.13 nests per hectare (95% CI 0.74–1.73) for F. aquilonia and 0.83 nests per hectare (95% CI 0.32–2.17) for F. lugubris. These translated to total estimated nest numbers of 4,200 (95% CI 2,700–6,400) and 3,100 (95% CI 1,200–8,100), respectively, for the whole forest. Indices of stand selection indicated that F. aquilonia had some positive association with old-growth and F. lugubris with younger stands (stem exclusion stage). No nests were found in areas that had been clear-felled, and ploughed and planted in the 1970s–1990s. The pattern of stand type association and hence distribution of F. aquilonia and F. lugubris may be due to the differing ability to disperse (F. lugubris is the faster disperser) and compete (F. aquilonia is competitively superior)., 2_We recommend using line transect sampling for extensive surveys of ants that construct nest mounds to estimate abundance and stand type association., Kerry M. Borkin, Ron W. Summers, Len Thomas., and Obsahuje seznam literatury
Developmental characteristics of the predatory bug Orius similis fed on Tetranychus cinnabarinus were investigated at three constant temperatures (25, 28, and 31°C) under laboratory conditions (75±5% relative humidity and a 14L : 10D photoperiod). The survival of nymphs was highest at 28°C (75.57%) and at this temperature female adults O. similis had the longest oviposition period (21.1 d), the greatest fecundity (40.3 eggs) and the highest potential intrinsic rate of increase (rm: 0.108 d–1). These results suggest that O. similis can maintain greater population densities at 28°C than at the other temperatures tested. In addition, the functional response indicates that the attack rate of O. similis (1.04) and the maximum prey capacity (30.7 spider mites per bug in 24h) are greatest at 28°C. The results of this study provide useful information on the biology and time when to release O. similis in order to reduce the abundance of T. cinnabarinus in cotton fields., Shi-Chang Zhang ... [et al.]., and Obsahuje seznam literatury
Field and laboratory experiments were conducted to assess the time ground beetles (Coleoptera: Carabidae) survive during actual and simulated flood conditions. The effects of three variants of potential flood conditions were tested: (1) beetles trapped on the surface of flood water; (2) beetles trapped in air pockets; (3) submersion of beetles in flood water without access to air. Ground beetles trapped on the surface of water survived more than two weeks (Carabus granulatus – up to 16 days; Oxypselaphus obscurus – up to 22 days). Carabus granulatus in simulated hibernation chambers that had air-pockets also survived for 15 days. The time for which ground beetles submerged without access to air survived differed significantly among species and was affected by season. They survived longest in mid-spring and late-autumn when water temperature is low. In mid-spring, survival times for C. granulatus and Platynus assimilis were 12 days and 9 days, respectively. During late summer and early autumn all species survived for a shorter period of time. In August, at least half of the individuals tested were dead after three days of immersion (water temperature 16–18°C). Removal of both of the elytra of adult of C. granulatus resulted in them surviving immersion for a shorter period, which indicates that air stored in the sub-elytral cavity is used to prolong the period they can survive immersion. The results of these experiments broaden the knowledge of how adult beetles survive seasonal flooding and are able to persist in floodplain habitats., Felix N. Kolesnikov, Arevik N. Karamyan, W. Wyatt Hoback., and Obsahuje seznam literatury