Seasonal aspects of life cycles in Calathus melanocephalus and C. micropterus (Coleoptera, Carabidae) in the northern taiga

The seasonal dynamics of the activity and the demographic structure of Calathus melanocephalus and C. micropterus populations were studied in the northern taiga of Arkhangelsk Province. The period of adult activity lasts from early June to mid-or late September with the maximum surface activity observed in the middle of summer. In C. melanocephalus, mature individuals are recorded from early June to early September, and in C. micropterus, during the entire season. The data on seasonal changes of the demographic structure of the population demonstrate that in the northern taiga, these species probably possess a biennial life cycle with summer reproduction. The geographical variability of the demographic structure of populations and of life cycles of two species of the genus Calathus was demonstrated. Northwards from the south, the period of activity decreases and the period of reproduction increases and shifts from autumn to the middle of summer. A hypothesis was formulated, according to which in the species studied the annual life cycle in the central part of the range is replaced by the biennial cycle in the north.     

Seasonal patterns of life cycle of ground beetle <Emphasis Type="Italic">Carabus nitens</Emphasis> (Coleoptera,Carabidae) in southern tundra

Seasonal dynamics of activity and demographic structure of Carabus nietens in the forest-tundra and southern tundra of the Kanin Peninsula was studied. In the northernmost range, the species has a one-year life cycle with reproduction in the early season and summer larvae. C. nitens demonstrated elongated period of development from egg to imago compared to the temperate zone in the polar region. At the same time, overwintered beetles rapidly matured and the reproduction period was reduced to three decades. This synchronizes larval development and the young generation emergence. The northern populations have increased life span of imago, which leads to repeated postwinter reproduction during several seasons. As a result, the abundance of the northern C. nitens populations remains high.     

Temperature reconstruction in the Ob River valley based on ring widths of three coniferous tree species

Tree core samples of larch (Larix sibirica Ledeb.), spruce (Picea obovata Ledeb.) and pine (Pinus sibirica Du-Tour.) from the northern taiga of West Siberia were collected to assess their potential for summer temperature reconstructions in the Ob River region. Bootstrapped response functions showed that annual growth was mainly influenced by May to June temperatures in pine and by June to July temperatures in spruce and larch. Spruce and pine chronologies showed high positive correlations with previous October temperature. June–July temperatures were reconstructed based on spruce (1795–1996) and larch (1615–1999) tree ring chronologies. The pine chronology could not be used for a reliable temperature reconstruction, due to low values of explained May–June temperature variance (11–15%) but the species has a high potential to help clarify the May–June and October climatic influence on ring width observed in all three species. We explained the effect of the early vegetation period (May–July) and the differences in the temperature signals between spruce and larch tree ring chronologies with the influence of previous September and October temperature on tree growth with the warming effect of the Ob River and differences of the species’ photosynthetic possibilities and the activity of chloroplasts and bud meristem tissues.     

Cold tolerance and invasive potential of the redbay ambrosia beetle (<Emphasis Type="Italic">Xyleborus glabratus</Emphasis>) in the eastern United States

Native Lauraceae (e.g. sassafras, redbay) in the southeastern USA are being severely impacted by laurel wilt disease, which is caused by the pathogen Raffaelea lauricola T. C. Harr., Fraedrich and Aghayeva, and its symbiotic vector, the redbay ambrosia beetle (Xyleborus glabratus Eichhoff). Cold temperatures are currently the only viable limitation to the establishment of X. glabratus in northern populations of sassafras. The observed lower lethal temperature of X. glabratus (? 10.0 °C) is warmer than its supercooling point (? 22.0 °C), indicating the beetle is a freeze intolerant and chill susceptible species. Empirically derived X. glabratus lower lethal temperature thresholds were combined with host distribution and microhabitat-corrected climate data to produce species distribution models for X. glabratus in the eastern USA. Macroclimate data (30-year mean annual minimum temperature) were corrected (? 1.2 °C) to account for thermal buffering afforded to X. glabratus while living inside sassafras trees. Only 0.1% of the current US sassafras spatial extent experiences sufficiently harsh winters (locales where mean annual minimum winter temperatures ≤ ? 6.2 °C for ≥ 12 h) to exclude X. glabratus establishment in our species distribution model. Minimum winter temperatures will likely cause some X. glabratus mortality in ~ 52% of the current spatial extent of sassafras, although current data do not allow a quantification of X. glabratus mortality in this zone. Conversely, ~ 48% of the current spatial extent of sassafras is unlikely to experience sufficiently cold winter temperatures to cause any significant impediment to X. glabratus spread or establishment. A modest climate change scenario (RCP4.5) of + 1.4 °C would result in 91% of the current spatial extent of sassafras in the eastern USA occurring where winter minimum temperatures are unlikely to cause any mortality to X. glabratus.     

Evidences of habitat displacement between two common soft-bottom SW Atlantic intertidal crabs

The intertidal burrowing crab Chasmagnathus granulatus Dana is the dominant species in soft sediments and vegetated intertidal areas along the SW Atlantic estuaries (southern Brazil 28°S to the northern Argentinean Patagonia 41°S) where it produces dense and extensive burrowing beds. The mud crab Cyrtograpsus angulatus Dana coexists with Ch. granulatus in this area, but it also inhabits areas to the south (northern and central Argentinean Patagonia). A survey covering both areas showed that C. angulatus rarely live in burrows when coexisting with Ch. granulatus, but form large burrowing beds when not coexisting with Ch. granulatus. When both species coexisted, burrowing beds of C. angulatus are restricted to sandy-muddy areas. Only rarely are burrows of C. angulatus found within Ch. granulatus beds. However, when Ch. granulatus were experimentally excluded within their burrowing beds, new settlers of C. angulatus made burrows and maintained them until they reached large size. Paired (inside and outside Ch. granulatus burrowing bed) sampling during high tide using beach nets showed that C. angulatus rarely venture inside the Ch. granulatus crab beds. Other field experiments showed that adults Ch. granulatus always displace C. angulatus from burrows. Furthermore, in several sites located south of the limit of distribution of Ch. granulatus at the Patagonian coast, soft bare intertidals are dominated by burrowing beds of C. angulatus mixed with the congener C. altimanus Dana. Together, these evidences suggest that the mud crab C. angulatus is displaced from soft bottom areas by the burrowing crab Ch. granulatus. It is an example of competitive exclusion through aggressive interference in soft-bottom habitats when the shared resource is the access to sediment surface, a two-dimensional well-defined resource.     

Mites (Acari) phoretic on ground beetles (Coleoptera,Carabidae) in a southern taiga forest in the environs of Vologda

Ground beetles were captured in a mixed southern taiga forest near the city of Vologda, Russia, from March to September 2014 using different collection techniques. Of the 250 specimens of ground beetles belonging to 22 species, 109 beetles representing 11 species yielded 326 specimens of mites of the cohorts Gamasina (4 species), Astigmatina (5), and Heterostigmatina (1). Two mite species, Antennoseius pseudospinosus Eidelberg, 1990, a common species in the steppes of southeastern Europe, and Halodarcia incideta Karg, 1969, a polyzonal European hydrophile, are recorded in the taiga zone for the first time. Dorsipes dorsipes Regenfuss, 1968, a specialized parasite of beetles of the genus Carabus Linnaeus, 1758, is new to the fauna of Eastern Europe. An adult mite of the genus Stylochirus G. Canestrini et R. Canestrini, 1882 was found for the first time in a natural hibernating chamber in close contact with an overwintering ground beetle, in particular, a male of S. fimetarius (Müller, 1859) on Carabus granulatus Linnaeus, 1785. The most common mite to occur on ground beetles was Antennoseius bullitus Karg, 1969, which was found on 7 carabid species with the mean occurrence of 41% and comprised 68% of the total mite sample. Joint phoresy of 2–3 mite species was recorded on 12 specimens of ground beetles; in 5 cases the co-occurring mites were Antennoseius bullitus and Stylochirus fimetarius. Three dominant mite species (85% of the total mite sample) were mainly collected off three dominant carabid species (70% of the beetle sample), but individual mite species preferred different hosts.     

Bioecology of the fiddler crab <Emphasis Type="Italic">Uca uruguayensis</Emphasis> and the burrowing crab <Emphasis Type="Italic">Chasmagnathus granulatus</Emphasis> (Decapoda,Brachyura) in the Refugio de Vida Silvestre Bahía Samborombón,Argentina

The aim of the present work conducted at the Refugio de Vida Silvestre Bahía Samborombón, Argentina, is to analyse the most relevant aspects of the life cycles of Chasmagnathus granulatus and Uca uruguayensis: their abundance, size distribution and sex ratio in order to be used for make management purposes. A total of 1200 individuals of U. uruguayensis (megalopae, juveniles and adults) and 957 individuals of C. granulatus (juveniles and adults) were collected from March 2001 to February 2003. U.␣uruguayensis had a maximun density of 42 ind./m² in February 2003, while the maximun density of C.␣granulatus was 52 ind./m² in June 2001. Minimun density was zero individual for both species in July 2002. Each environmental factor sampled (temperature of water, salinity and pH) was correlated with the abundance of each species by Pearson’s linear correlation analysis. Sex ratio did not significantly differ from the expected Mendelian ratio, except for U. uruguayensis in December 2002 (male-biassed) and C.␣granulatus in June and December 2001, April 2002 and February 2003 (female-biassed). Ovigerous females of U. uruguayensis and C. granulatus were found during the summer.     

The SW Atlantic burrowing crab Chasmagnathus granulatus Dana affects the distribution and survival of the fiddler crab Uca uruguayensis Nobili

In this paper, we address the question of whether the presence of the burrowing crab Chasmagnathus granulatus affects the habitat use of the fiddler crab Uca uruguayensis. Field samples showed that the species have a disjoint spatial distribution. Male fiddler crab density decreased in zones with C. granulatus, however, female density increased. Male fiddler crabs avoided feeding on sediment affected by C. granulatus and were more preyed. Predation was higher during the fiddler crab reproductive season and, probably due to predation risk, males showed lower reproductive display in shared zones. Field experiments shows that when C. granulatus were excluded, densities of U. uruguayensis increased mainly due to an increase in density of males. Habitat differentiation of these species may be because C. granulatus affects U. uruguayensis in several ways, including direct predation, disturbance and behavioural changes associated to predation risk. Males and females are affected differentially probably because of the extreme sexual dimorphism of this crab species. Coloration on enlarged claw and waving activities are all factors that increase predation risk for male and the presence of only one feeding claw may increase sediment-mediated effects.     

Augmentation of beneficial arthropods by strip-management

The effect of strip-management on surface activity, movements and activity density of abundant carabid beetles during two vegetation periods in a cereal field was investigated using mark-recapture techniques. Significantly higher recapture rates, indicating higher activity, were found in the strip-managed area than in the control area, especially in Poecilus cupreus and also in Carabus granulatus and Pterostichus melanarius. Several observations led to the conclusion that this higher activity is generally due to a prolongation of the reproductive period in the strip-managed area. Significantly higher activity densities were found for P. cupreus, Pterostichus anthracinus, C. granulatus and Pt. melanarius in the strip-managed area than in a bordering control area. P. cupreus is greatly attracted to the strips during its migrations, as can be deduced from the high percentage of movements that contact the strips. Also, significantly more marked individuals moved from the control to the strip-managed area than vice versa. Pt. melanarius and Pt. anthracinus show less preference for the strips in their movements than P. cupreus. However, significantly more individuals of Pt. melanarius also moved from the control to the strip-managed area. C. granulatus, on the other hand, kept mainly to the cereal areas. After harvest only Pterostichus niger and Harpalus rufipes distinctly preferred the strips. The generally marked degree of attraction exercised by strip-management on carabid beetles is discussed.     

Features of the life cycles of <Emphasis Type="Italic">Pterostichus montanus</Emphasis> (Motschulsky, 1844) and <Emphasis Type="Italic">Carabus loschnikovi</Emphasis> (Fischer-Waldheim, 1822) (Coleoptera,Carabidae) in conditions of the mountain taiga belt in the Eastern Sayan

We studied the seasonal dynamics and demographic structure of abundant ground beetle species from the mountain taiga belt in the Eastern Sayan. Data on the dynamics of the sexual and age structure of the populations as well as on the reproductive capacity of females in the biotopes on the slopes with different exposure and height were obtained. Life cycles with one-and two-year development were revealed for the ground beetles typical for the mountain taiga belt. As an example, data on the life cycles of Pterostichus montanus (Motschulsky, 1844) with one-year spring development and Carabus loschnikovi (Fischer-Waldheim, 1822) with two-year polyvariant multiseasonal development are given for the first time. Two strategies were revealed in the life cycles of ground beetles under alpine conditions: an accelerated population development in spring one-year species and a two-year development with pronounced polyvariance in two intrapopulation groups of ground beetles of the Carabus genus. The seasonal dynamics of the activity and reproduction periods proved to vary for these species on the slopes along the height gradient.Translated from Izvestiya Akademii Nauk, Seriya Biologicheskaya, No. 1, 2005, pp. 36–46.Original Russian Text Copyright © 2005 by Sharova, Khobrakova.     

Geographic variability of the life cycle in Pterostichus melanarius (Coleoptera, Carabidae)

In Pterostichus melanarius, the seasonal dynamics of activity is characterized by two peaks (in mid-June-early July and in late July-mid-August). In southwestern Moldova, these peaks were registered twenty days later than in Moscow Province. In both regions, larvae and adults hibernate. Both hibernated immature adults and adults that had already bred before wintering start reproduction simultaneously. In hibernated immature individuals, the average number of eggs per female constituted 1.5 times that in the postgenerative females. In the steppe zone, the total number of eggs laid by immature females was closed to that laid by previously bred females, while in the southern taiga zone, hibernated immature females laid a greater number of eggs. In the steppe zone, females of a new generation lay a somewhat lower number of eggs in comparison with hibernated immature females, whereas the total number of laid eggs is significantly higher. In the southern taiga zone, both the average number of laid eggs and their total number are equal in females of a new generation and hibernated immature females. In Moldova, the majority of individuals of a new generation breed in the current season, whereas in Moscow Prov., about half the individuals hibernate without breeding. Over the largest part of the range, the life cycle of P. melanarius combines the one-year development with hibernating larvae with two-year development with the hibernating immature and postgenerative adults. The two subpopulation groups, wintering at different phases of the ontogenesis, are totally isolated at the northern border of the range. Within each subpopulation., individuals are characterized by the biennial life cycle; as a result, the polyvariant character of the life cycle turns into the monovariant one. We suggest that such a life cycle should be designated as the compensatory monovariant cycle, and populations, in which it is realized, as byside populations (from the English “side by side”).     

Changes in the ranges of pasture ixodid ticks of the genus Ixodes Latr., 1795 (Parasitiformes, Ixodidae) in West Siberia

The distribution pattern of two tick species, Ixodes persulcatus and Ixodes pavlovskyi, in the plain part of West Siberia is analyzed. The exact northern range boundary of I. persulcatus in the Khanty-Mansi Autonomous Area is determined based on long-term data on the population density of adult and immature ticks (1960–2011). The shift of the southern boundary of the species range in West Siberia as related to anthropogenic transformation (reforestation measures, reduced or stopped sanitary forest cutting, road construction, etc.) is demonstrated. The specific traits of distribution of the taiga tick I. persulcatus in some localities of Southwest Siberia are analyzed. The modern state of the tick population in the areas co-inhabited by the two species is characterized. The possible reasons of changes in the structure of tick communities toward complete prevalence of I. pavlovskyi in recreational zones of Novosibirsk and Tomsk are discussed. The most significant changes in the distribution pattern of these two tick species in West Siberia seem to have occurred after 1990. During this period, the local stable populations of the taiga tick to the south of its main range in West Siberia (within Omsk and Novosibirsk provinces) were formed, the pattern of its distribution on the right bank of the Ob River (Novosibirsk Province) and in the Tom River valley (Tomsk Province) changed, whereas I. pavlovskyi became the dominant species.     

Interspecific and intraspecific variation of the duration and thermal requirements for egg development in carabid beetles (Coleoptera,Carabidae) in the North-West of Russia

The thermal norms of egg development were studied in the ground beetles Amara communis, A. nitida, Carabus granulatus, Platynus assimilis, Poecilus versicolor, Pterostichus oblongopunctatus (spring breeding species), P. melanarius, and P. niger (autumn breeding species). The adults were collected in soil traps near Arkhangelsk, St. Petersburg, Moscow, and Bryansk in May–June. Females and males were kept in pairs at 20°C and 22 h light per day. The eggs laid by females were kept at constant temperatures (12, 14, 16, 18, 20, and 22 ± 0.1°C). The development time for each egg was determined accurate to 0.5 day. From the values of the individual development rate (a reciprocal of development time) at all the temperatures, the thermal constants for development were calculated: the coefficient of linear regression (CLR) of the development rate on temperature, the sum of degree-days, and the thermal threshold for development (TTD). The egg development time was found to vary significantly between the species, except for A. communis, A. nitida, and C. granulatus. The values of CLR (i.e., the slopes of the regression lines) and TTD varied rather distinctly between the species and populations that revealed differences in the thermal requirements for egg development. In the spring breeding species the mean egg development time was significantly shorter, and the CLR and TTD values were on average higher than those of the autumn breeding species. Intraspecific latitudinal variation of the development time and the thermal requirements for egg development was revealed. The eggs laid by beetles from the Arkhangelsk population developed faster than those of the same species from the southern populations at all experimental temperatures. These differences were not great but statistically significant. At the same time, the differences between the CLR and TTD values for the northern and southern populations of the same species were non-significant in most cases. Thus, the main ecophysiological adaptation of carabid beetles during their northward expansion was the shortening of development time within the entire range of favorable temperatures, while the CLR and TTD values only insignificantly changed.     

Pitfall trap construction affects the efficacy of ground beetle counts

Ground beetles were sampled in a broadleaved deciduous forest in Kaluga Province in April–October 1995 using 90 traps grouped in 18 experimental plots. Three types of pitfall traps were used: glass jars, white plastic cups, and cylindrical containers made of transparent plastic bottles. Two types of cover put above the traps were tested: transparent and black. Altogether, 72 carabid species were found, of which only 10 species were shared by all the experimental plots: Leistus terminatus, Carabus hortensis, C. glabratus, Cychrus caraboides, Pterostichus niger, P. oblongopunctatus, P. strenuus, P. melanarius, Calathus micropterus, and Badister lacertosus. The Jaccard binary similarity index between the experimental plots amounted to 37–68% while the Bray-Curtis similarity index was 66–89%. Both the trap type and the cover color significantly affected the similarity of the species structure and species composition of the samples. Plastic cups provided the highest catches of beetles, but this was due to the most abundant species, P. oblongopunctatus. Containers provided the highest catches of C. glabratus. The total abundance was higher for the traps with transparent covers than for those with black covers. Traps with transparent covers provided significantly higher catches of L. terminatus, P. oblongopunctatus, Asaphidion flavipes, and Harpalus rufipes. An adequate assessment of the species composition of a particular habitat requires at least 30 pitfall traps.     

Population structure of the South American Estuarine crab, Chasmagnathus granulatus (Brachyura: Varunidae) near the southern limit of its geographical distribution: comparison with northern populations

Crabs are among the most conspicuous and ecologically important invertebrates of the large intertidal zones that characterize estuarine and protected coastal areas in temperate regions. The habitat, population structure and breeding cycle of Chasmagnathus granulatus (Brachyura: Varunidae), a semiterrestrial burrowing crab endemic to the warm temperate coasts of the Southwestern Atlantic, were studied in San Antonio Bay (Argentina), near the southern limit of its range. San Antonio Bay has no freshwater input, winter is relatively colder, and summer warmer, than northern habitats of this species. Crabs lived both in vegetated and unvegetated zones, but density and sex ratio varied among dates and zones. The maximum observed density was 136 crabs/m² , the maximum carapace width (CW) was 32 mm (males) and 29.8 mm (females), ovigerous females were found only in November and January, and the smallest ovigerous female measured 17 mm CW. The population structure, spatial distribution, and recruitment pattern of C. granulatusdid not differ between San Antonio Bay and northern habitats. The higher density, smaller maximum size and shorter reproductive cycle observed in San Antonio cannot be atributed to changes associated with a latitudinal cline and other factors, such as thermal amplitude and food availability, need to be studied.     

New records of the Egyptian Fruit Bat,Rousettus aegyptiacus,in Turkey

Spermatogenesis in the Caspian Bent-toed Gecko, Cyrtopodion caspium, was studied in Mazandaran Province, northern Iran. Sampling took place periodically every 15 days during the activity period of this species at night, from 5 April to 20 October 2011. In total, 70 adult males were captured by hand. Testes were removed and processed for histological and morphometric studies. The results show that spermatogenesis begins in early April, reaches its peak in late May and early June, and ends in early to mid August. The maximum level of sperm production occurred in early June. The minimum diameter, weight and volume of testes were observed in early August. Three phases were observed during the activity period for spermatogenesis in C. caspium: active, transitional and inactive phases. Spermatogenesis of C. caspium in Iran is seasonal and alternate.     

Identification of one X‐linked and five autosomal microsatellite loci in Carabus violaceus (Coleoptera,Carabidae) and their applicability to related taxa

We characterize six microsatellite loci from the ground beetle Carabus violaceus. The polymorphism of the loci was assessed in 46 individuals from one population. The number of alleles ranges between three and eight, and the observed heterozygosities between 0.46 and 0.76. All males are homozygous for locus CVI08106CMPG, whereas most females are heterozygous. This suggests that this locus is situated on the X chromosome. Tests in eight different species of ground beetles showed that four loci could be amplified in C. coriaceus and one each in C. glabratus, C. nemoralis, C. problematicus and Abax parallelepipedus.     

Annual dynamics and production of rotifers in an eutrophication gradient in the Baltic Sea

Spatial and temporal fluctuations in rotifer abundance have been monitored along a trophic gradient in the northern Baltic. The most common rotifer was Synchaeta spp., which had one abundance peak in June and one in September–October. Only during the latter period was the abundance significantly higher in the eutrophic basin compared to the reference area. The annual production of Synchaeta spp. was about double in the eutrophic basin. A positive correlation between Synchaeta spp. biomass and phytoplankton biomass was obtained during the autumn, but not during the early summer peak, although the phytoplankton community was dominated by the same species. Keratella quadrata, K. cochlearis and K. cruciformis were most abundant in August–September, and all three species had increased abundance in the eutrophic basin.     

Does Dispersal Limit Beetle Re‐colonization of Restored Fenland? A Case Study Using Direct Measurements of Dispersal and Genetic Analysis

Dispersal ability is known to limit the colonization by many fenland species onto restored habitat but factors determining colonization by wetland invertebrates onto restored fenland have not been previously examined. We used mark‐release‐recapture and harmonic radar tracking coupled with genetic analysis (ISSR‐PCR, inter‐simple sequence repeat—polymerase chain reaction) to assess the population structure and colonization of a brachypterous wetland carabid (Carabus granulatus) onto restored fenland. The first two methods were used to determine the dispersal rate of C. granulatus in the absence of barriers, while the genetic analysis was used to examine whether populations were separated by either distance or the water channels and drainage ditches that intersect fenland landscapes. Mark‐release‐recapture and harmonic radar tracking indicated that the most active 6% of individuals could travel over 25 m in a day and individuals found to be traveling these distances remained atypically active throughout the season. Thus, C. granulatus can disperse at a rate great enough to colonize all areas of restored fenland in the study site within 1 year in the absence of barriers. We found no evidence of genetically distinct sub‐populations of C. granulatus showing that distance and water barriers did not limit the movement of individuals from potential source populations to the restored habitat. This research indicates that where fenland is created with nearby established fenland, colonization opportunities should not be considered a limiting factor to colonization by wetland carabids, even where waterways divide sites.     

Alkaline phosphatase activities in muscle of the euryhaline crab Chasmagnathus granulatus: Response to environmental salinity

The occurrence, characteristics and response to environmental salinity of alkaline phosphatase (AP) activity were studied in chela muscle of the euryhaline crab Chasmagnathus granulatus from Mar Chiquita coastal lagoon (Buenos Aires Province, Argentina). Chela muscle exhibited a levamisole-insensitive and a levamisole-sensitive AP activities with distinct characteristics. Levamisole-insensitive activity appeared to be maximal at pH 7.7, whereas levamisole-sensitive AP activity was similar with the range of pH 7.4 to 8.0. Both activities at pH 7.7 exhibited a Michaelis-Menten kinetics (K_m = 0.789 and 1.416 mM, respectively). I₅₀ for levamisole-sensitive AP activity was about 12 mM. Levamisole-insensitive and levamisole-sensitive AP activities were differentially affected by temperature. Levamisole-sensitive AP activity was quite sensitive to temperature, exhibiting a peak at 37 °C but being low at 5 to 30 °C and 45 to 60 °C. Both activities were inhibited by Cu²⁺. At 1.0 mM Cu²⁺, levamisole-insensitive AP activity was inhibited about 82% whereas levamisole-sensitive AP activity was almost completely inhibited. Levamisole-insensitive AP activity appeared to be sensitive to environmental salinity. In crabs acclimated to low salinity (10‰) this activity was lower than in 35‰ salinity. The response to environmental salinity suggests that levamisole-insensitive AP activity could be a component of muscle regulatory mechanisms at the biochemical level secondary to hyperregulation of C. granulatus. The possible physiological roles and functional relationship of AP activity with Na⁺/K⁺ ATPase in muscle are discussed.