Photoperiod modifies thermal reaction norms for growth and development in the red poplar leaf beetle Chrysomela populi (Coleoptera: Chrysomelidae)

Regression lines of development rate on temperature appeared significantly different between long (22 h) and short (12 h) day conditions and intersected each other at 23.8 °С. Thus, the rate of growth and development was higher at temperatures below the intersection point under short-day but above the intersection point it was higher under long day. Ecological relevance of this effect seems as follows: in autumn, as nights become longer and average daily temperature decreases, larvae have to speed up their development because it is only imago that overwinters. Conversely, midsummer offers long days and usually higher temperature, so again it is advantageous to develop as fast as possible in order to have at least one more generation per year. These results are compared with other studies showing interactions between photoperiod and temperature, and some possible general patterns are outlined. The lower thermal threshold for larval development depended on photoperiodic conditions; therefore rate isomorphy must be violated in this species. Development at higher temperatures generally resulted in smaller adults, as is usual with ectotherms according to the “temperature-size rule”, but body weight depended significantly on temperature only under short day. Our estimates of the lower temperature thresholds for growth and development in both cases did conform to the generalization made previously by Walters and Hassall (2006) in spite of another formula used by us. We briefly discuss this phenomenon and argue that relative position of these thresholds can be explained mathematically and per se may lack any biological sense.     

Cold tolerance of the montane Sierra leaf beetle,Chrysomela aeneicollis

Small ectothermic animals living at high altitude in temperate latitudes are vulnerable to lethal cold throughout the year. Here we investigated the cold tolerance of the leaf beetle Chrysomela aeneicollis living at high elevation in California’s Sierra Nevada mountains. These insects spend over half their life cycle overwintering, and may therefore be vulnerable to winter cold, and prior studies have demonstrated that survival is reduced by exposure to summertime cold. We identify overwintering microhabitat of this insect, describe cold tolerance strategies in all life stages, and use microclimate data to determine the importance of snow cover and microhabitat buffering for overwinter survival. Cold tolerance varies among life history stages and is typically correlated with microhabitat temperature: cold hardiness is lowest in chill-susceptible larvae, and highest in freeze-tolerant adults. Hemolymph osmolality is higher in quiescent (overwintering) than summer adults, primarily, but not exclusively, due to elevated hemolymph glycerol. In nature, adult beetles overwinter primarily in leaf litter and suffer high mortality if early, unseasonable cold prevents them from entering this refuge. These data suggest that cold tolerance is tightly linked to life stage. Thus, population persistence of montane insects may become problematic as climate becomes more unpredictable and climate change uncouples the phenology of cold tolerance and development from the timing of extreme cold events.     

Genetics of resistance to transgenic Bacillus thuringiensis poplars in Chrysomela tremulae (Coleoptera: Chrysomelidae)

The area under genetically engineered plants producing Bacillus thuringiensis (Bt) toxins is steadily increasing. This increase has magnified the risk of alleles conferring resistance to these toxins being selected in natural populations of target insect pests. The speed at which this selection is likely to occur depends on the genetic characteristics of Bt resistance. We selected a strain of the beetle Chrysomela tremulae Fabricius on a transgenic Bt poplar clone Populus tremula L. x Populus tremuloides Michx producing high levels of B. thuringiensis Cry3Aa toxin. This strain was derived from an isofemale line that generated some F2 offspring that actively fed on this Bt poplar clone. The resistance ratio of the strain was >6400. Susceptibility had decreased to such an extent that the mortality of beetles of the strain fed Bt poplar leaves was similar to that of beetles fed nontransgenic poplar leaves. Genetic crosses between susceptible, resistant, and F1 hybrids showed that resistance to the Cry3Aa toxin was almost completely recessive (D(LC) = 0.07) and conferred by a single autosomal gene. The concentration of Cry3Aa produced in the transgenic Bt poplar used in this study was 6.34 times higher than the LC99 of the F1 hybrids, accounting for the complete recessivity (D(ML) = 0) of survival on Bt poplar leaves. Overall, the genetic characteristics of the resistance of C. tremulae to the Cry3Aa toxin are consistent with the assumptions underlying the high-dose refuge strategy, which aims to decrease the selection of Bt resistance alleles in natural target pest populations.     

High tolerance against Chrysomela tremulae of transgenic poplar plants expressing a synthetic cry3Aa gene from Bacillus thuringiensis ssp tenebrionis

Hybrid poplars (Populus tremula ×Populus tremuloides) have been genetically engineered viaAgrobacterium tumefaciens, to express a syntheticcry3Aa gene derived from the native Bacillusthuringiensis subsp. tenebrionis cry3Aa gene.The presence and the expression of the transgene have been verified in fourtransgenic poplar lines, using Southern, northern and western analyses. Thetransgenic poplar's toxicity towards the phytophagous beetleChrysomela tremulae (Coleoptera, Chrysomelidae) has beenassessed on six month-old greenhouse-grown selected plants in laboratoryconditions. Laboratory experiments consisted of feeding tests of fresh detachedleaves on C. tremulae at all developmental stages. Ourresults indicate that the transgenic poplar leaves, expressing a Cry3Aa proteinamount in a range of 0.05–0.0025% of total soluble protein, weredefinitely deleterious for C. tremulae, regardless of thedevelopmental stage.     

Initial frequency of alleles conferring resistance to Bacillus thuringiensis poplar in a field population of Chrysomela tremulae

Globally, the estimated total area planted with transgenic plants producing Bacillus thuringiensis (Bt) toxins was 12 million hectares in 2001. The risk of target pests becoming resistant to these toxins has led to the implementation of resistance-management strategies. The efficiency and sustainability of these strategies, including the high-dose plus refuge strategy currently recommended for North American maize, depend on the initial frequency of resistance alleles. In this study, we estimated the initial frequencies of alleles conferring resistance to transgenic Bt poplars producing Cry3A in a natural population of the poplar pest Chrysomela tremulae (Coleoptera: Chrysomelidae). We used the F(2) screen method developed for detecting resistance alleles in natural pest populations. At least three parents of the 270 lines tested were heterozygous for a major Bt resistance allele. We estimated mean resistance-allele frequency for the period 1999-2001 at 0.0037 (95% confidence interval = 0.00045-0.0080) with a detection probability of 90%. These results demonstrate that (i) the F(2) screen method can be used to detect major alleles conferring resistance to Bt-producing plants in insects and (ii) the initial frequency of alleles conferring resistance to Bt toxin can be close to the highest theoretical values that are expected prior to the use of Bt plants if considering fitness costs and typical mutation rates.     

Frequency and fitness cost of resistance to Bacillus thuringiensis in Chrysomela tremulae (Coleoptera: Chrysomelidae)

The "high dose-refuge" (HDR) strategy is commonly recommended and currently used for delaying or preventing pest adaptation to transgenic plants producing Bacillus thuringiensis (Bt) toxins. The efficiency of this strategy depends, among other factors, on the initial frequency of Bt resistance alleles and on the fitness costs associated with these alleles. Two years ago, an allele conferring resistance to Bt poplar was detected in a French population of the poplar pest Chrysomela tremulae F. Although this pest had never been subjected to Bt selection pressure due to human activities, the frequency of this allele was estimated at 0.0037, with a 95% credible (CI) interval of 0.00045-0.0080. We investigated the frequency of this allele in a second sample of C. tremulae collected more than 500 km from the site of the initial population. The estimated frequency in this sample was 0.0113 (95% CI 0.0031-0.0247), reinforcing the conclusion that resistance to Bt plants may be present at detectable frequencies in pest populations before selection resulting from pest management by humans. The frequency of the Bt resistance allele over the two samples was 0.0049 (95% CI 0.0020-0.0091). We also followed five laboratory lines in which the frequency of this allele was initially fixed at 0.500. After five generations maintained on non-Bt poplar leaves, the frequency of this allele decreased in all lines, whereas allelic frequencies at a neutral locus were unaffected. Thus, the Bt resistance allele detected in French populations of C. tremulae is probably associated with a fitness cost.     

Host-plant effects on larval survival of a salicin-using leaf beetle Chrysomela aeneicollis Schaeffer (Coleoptera: Chrysomelidae)

Several species of willow leaf beetles use hostplant salicin to produce a defensive secretion that consists of salicylaldehyde. Generalist arthropod predators such as ants, ladybird beetles, and spiders are repelled by this secretion. The beetle larvae produce very little secretion when they feed on willows that lack salicylates, and salicin-using beetles prefer salicylate-rich willows over salicylate-poor ones. This preference may exist because the larvae are better defended against natural enemies on salicylate-rich willows. If this is true, the larvae should survive longer on those willows in nature. However, this prediction has not been tested. I determined the larval growth and survival of Chrysomela aeneicollis (Coleoptera: Chrysomelidae) on five willow species (Salix boothi, S. drummondiana, S. geyeriana, S. lutea, and S. orestera). These species differed in their salicylate chemistries and in leaf toughness but not in water content. The water content varied among the individual plants. Larval growth of C. aeneicollis did not differ among the five species in the laboratory, but it varied among the individual plants and it was related to the water content. In the field, C. aeneicollis larvae developed equally rapidly on the salicylate-poor S. lutea and on the salicylate-rich S. orestera. Larval survival was greater on S. orestera than on S. lutea in one year (1986), but there was no difference between them during three succeeding years. In another survivorship experiment, larval survival was low on the medium-salicylate S. geyeriana, but high on the salicylate-poor S. boothi and on S. orestera. Larval survival in the field was related to the larval growth and water content that had been previously measured in the laboratory. These results showed that the predicted relationship between the host plant chemistry and larval survival did not usually exist for C. aeneicollis. One possible reason for this was that the most important natural enemies were specialist predators that were unaffected by the host-derived defensive secretion. One specialist predator, Symmorphus cristatus (Hymenoptera: Eumenidae), probably caused much of the mortality observed in this study. I discuss the importance of other specialist predators to salicin-using leaf beetles.     

Gene diversity at allozyme loci in the cottonwood leaf beetle,Chrysomela scripta

Gene diversity was studied in beetles collected from a poplar plantation at Ames, Iowa. The beetles are widely distributed throughout North America wherever poplars (Populus spp) occur. Of 38 loci interpretable by simple Mendelian criteria, 22 were polymorphic (58%). Nei's mean heterozygosity per locus was 20.1±4.0%. A mean 2.29±1.35 alleles per locus was detected. The foregoing levels of diversity are typical of Coleoptera. There were significant deviations from Hardy-Weinberg expectations at six loci, and of these loci, four deviations were judged to have been caused by technical problems in resolving heterozygotes. Twelve polymorphic loci are considered suitable to carry out studies on the breeding structure of this important pest.     

Colour polymorphism in relation to population dynamics of the leaf beetle, Chrysomela lapponica

We studied colour morph diversity and frequencies of light and dark morphs in non-fluctuating and fluctuating populations of willow feeding leaf beetle Chrysomela lapponica in the Kola Peninsula, NW Russia. Population-specific Shannon–Weaver diversity index positively correlated with dark morph frequencies, indicating that the larger part of colour polymorphism is related with numbers and diversity of dark morphs. Among-population variation in studied characters was not explained by pollution load or predation rates, but depended on the type of the population and the stage of density change in the fluctuating populations: both colour morph diversity and frequency of dark morphs were low in declining post-outbreak populations but equally high in non-fluctuating populations and in fluctuating populations at peak densities. In time-series, both diversity index and frequency of dark morphs decreased with post-outbreak density decline in the fluctuating population, but did not change in the non-fluctuating population. In the experiment, when adults received low quality food (plants from post-outbreak site), mortality of dark morphs during the hibernation was almost doubled relative to the mortality of light morphs, whereas on high quality food the colour morphs demonstrated similar mortality. This may indicate, that decrease in colour polymorphism extent and dark morph frequencies in the declining populations is due to selective mortality of dark morphs imposed by density dependent (induced by heavy herbivore damage during an outbreak) decrease in host-plant quality (delayed inducible resistance, DIR). DIR is known as one of the factors driving herbivore populations, but our result is the first evidence that DIR may act as a factor of natural selection. Dark morphs are not only susceptible to low food quality, but also have smaller size compared to light morphs, and therefore the dark females are presumably less fecund. Thus, decrease in frequency of low-fitness (dark) individuals in post-outbreak populations and accumulation of low-fitness phenotypes at the popu-lation peak may create feedbacks contributing to regulation of density fluctuations in Ch. lapponica.     

Host-plant effects on Parasyrphus melanderi (Diptera: Syrphidae) feeding on a willow leaf beetle Chrysomela aeneicollis (Coleoptera: Chrysomelidae)

Abstract.

• 1 Generalist predators are repelled by chrysomelid (Chrysomela spp., Phratora vitellinue L.) larval defensive secretions that are obtained from salicin in their host plants. But little is known about the effect of these secretions on specialist predators.
• 2 In this study, we describe the feeding behaviour of a fly, Parasyrphus melanderi Curran (Diptera: Syrphidae), which feeds on Chrysomela aeneicollis Schaeffer (Coleoptera: Chrysomelidae). Parasyrphus melanderi lays its eggs on C.aeneicollis egg clutches, and its larvae consume C.aeneicollis eggs and larvae.
• 3 Chrysomela aeneicollis hatching rates were significantly lower (20%) on clutches with fly eggs than on clutches without them (40%). Half of the clutches with one fly egg had survival rates below 5%, and when two fly eggs were present (four clutches), the entire clutch was consumed.
• 4 In nature, P.melanderi eggs were 3 times more abundant on a salicylaterich willow species S.orestera Schneider, than on the medium-salicylate S.geyeriana Anderss. (1.8 v 0.6 eggs per clutch). On 18% of the S.orestera clones, all the beetle clutches contained fly eggs. In laboratory-choice tests, P.melanderi larvae fed equally rapidly on C.aeneicollis larvae that were chemically defended (feeding on S.orestera) as on larvae that produced no secretion (feeding on the salicylate-poor S.lutea Nutt.). This predator does not appear to be deterred by C.aeneicollis's defensive secretion. We discuss the implications of specialist predators on determining host suitability to herbivorous insects.

     

Drivers of host plant shifts in the leaf beetle Chrysomela lapponica: natural enemies or competition?

1. The leaf beetle, Chrysomela lapponica, originally uses the salicyl glucosides (SGs) of its host plants to sequester salicylaldehyde, which serves as a defence against generalist enemies but attracts specialist enemies. However, some populations of C. lapponica have shifted to SG‐poor hosts, and their secretions do not contain salicylaldehyde. 2. In was suggested that beetles shift to SG‐poor hosts to escape from specialist enemies. To test this hypothesis, we compared field mortality between two populations of C. lapponica that were associated with SG‐rich willow, Salix myrsinifolia (Kola Peninsula and Finland) and two populations that fed on SG‐poor willows, S. glauca (Ural) and S. caprea (Belarus). 3. Mortality from generalist enemies was significantly higher in Belarus than in three other populations, whereas mortality from specialists did not differ among populations. A specialist predator (syrphid fly larvae, Parasyrphus nigritarsis) and specialist parasitoids (phorid flies, Megaselia spp.) were attracted to the secretions of larvae reared on both SG‐rich and SG‐poor hosts. 4. Feeding on leaves of S. caprea and S. myrsinifolia both previously damaged by leaf puncturing and by the larvae of potentially competing species Chrysomela vigintipunctata, decreased the weight and prolonged the development of C. lapponica. 5. Thus, populations of C. lapponica that have shifted to SG‐poor willow species did not obtain enemy‐free space because specialist enemies have developed adaptations to herbivores that switched to a novel host plant. We suggest that in some populations host plant shift was favoured by interspecific competition with the early season SG‐using specialist, C. vigintipunctata.     

Fly parasitoid Megaselia opacicornis uses defensive secretions of the leaf beetle Chrysomela lapponica to locate its host

Larvae of the leaf beetle Chrysomela lapponica derive a defensive secretion from salicyl glucosides found in the host plant Salix borealis. This secretion protects beetle larvae from some natural enemies, but does not appear to repel parasitoids. We tested the hypothesis that the fly parasitoid Megaselia opacicornis (Diptera, Phoridae) uses the larval defensive secretion of Ch. lapponica in its search for prey. In the field, nearly 30 times more M. opacicornis individuals were caught on leaves coated with sticky resin next to a source of secretion than on control leaves. In the laboratory, M. opacicornis females laid six times more eggs next to a cotton ball soaked in secretion than next to one soaked in water. Fly females also lay more eggs on prey rich in larval secretion than on secretion-poor prey. In the field, removal of defensive secretion from beetle prepupae resulted in a 7.5-fold reduction of oviposition by fly females. Parasitoids were nearly twice as likely to lay eggs on prepupae, rich in secretion, as on pupae, which contain little secretion. Fly offspring reared from beetle prepupae reached a 21% larger body mass than those reared from pupae. Finally, M. opacicornis females avoided host prepupae already parasitized by the tachinid fly Cleonice nitidiuscula, which possess little secretion. These experiments indicate that host plant-derived defensive secretions are used by this parasitoid for host location. Adaptation of parasitoids to use defensive secretions of hosts may selectively favor an increase in diet breadth in specialist herbivores.     

Conflicting mitochondrial and nuclear phylogeographic signals and evolution of host-plant shifts in the boreo-montane leaf beetle Chrysomela lapponica

We conducted a phylogeographic study on the cold-adapted leaf beetle Chrysomela lapponica, that feeds on willow or birch, by sampling several populations throughout most of the geographic distribution of the species, and by sequencing for each individual one mitochondrial and two nuclear DNA fragments. Patterns of DNA sequence variation from the mitochondrial and nuclear loci, as displayed in the median-joining networks, appear to display contradicting historical signal: a deep genealogical divergence is observed with the mitochondrial genome between the Alpine population and all other populations found in the Euro-Siberian distribution of the species, that is completely absent with both nuclear loci. We use coalescence simulations of DNA sequence evolution to test the hypothesis that this apparent conflict is compatible with a neutral model of sequence evolution (i.e., to check whether the stochastic nature of the coalescence process can explain these patterns). Because the simulations show that this is highly unlikely, we consider two alternative hypotheses: (1) introgression of the mitochondrial genome of another species and (2) the effect of natural selection. Although introgression is the most plausible explanation, we fail to identify the source species of the introgressed mitochondrial genome among all known species closely related to C. lapponica. We therefore suggest that the putative introgression event is ancient and the source species is either extinct or currently outside the geographic range of C. lapponica explored in this study. The observed DNA sequence variation also suggests that a host-plant shift from willow to birch has occurred recently and independently in each of the three birch-feeding populations. This emphasizes further the relative ease with which these beetles can escape their ancestral host-plant specialization on willow, but shows at the same time that host-plant shifts are highly constrained, as they only occur between willow and birch.     

Host plant preference based on salicylate chemistry in a willow leaf beetle (Chrysomela aeneicollis)

Summary Chrysomela aeneicollis (Coleoptera: Chrysomelidae) uses salicin from its host plant (Salix spp.) to produce a defensive secretion, salicylaldehyde. Because it requires salicin for this secretion, I predicted that C. aeneicollis should be attracted to willows which possess salicin and other salicylates. To test this prediction, I determined the host-plant preferences of C. aeneicollis among four potential hosts which occur in the Sierra Nevada range of eastern California. These species have very different salicylate chemistries but do not differ in nutritional quality for C. aeneicollis. In oviposition-preference tests, gravid females showed no preference between a salicylate-poor species, S. lutea, and a salicylate-rich species, S. orestera. However in feeding-choice tests, both larvae and adults preferred S. orestera over S. lutea. This preference was not affected by the species on which the larvae were reared. In other feeding tests, adults preferred S. orestera over two medium-salicylate species, S. boothi and S. geyeriana, regardless of which host species they had been feeding on in nature. In a final feeding test, adults were stimulated to feed by salicin itself. In nature, the relative abundances of C. aeneicollis adults and egg clutches among these species correspond to the adult feeding preference in the laboratory. Additionally, multiple regression analyses showed that adult abundance was not related to among-clone differences in leaf toughness or nutritional quality, but rather to salicin content and plant size. Thus for C. aeneicollis, both laboratory and field results demonstrate a preference for salicylate-rich willows which is partly responsible for the increased level of attack on them.     

Activity and heavy metal resistance of non-specific esterases in leaf beetle Chrysomela lapponica from polluted and unpolluted habitats

We compared the general activity and heavy metal resistance of non-specific esterases in two populations of the leaf beetle Chrysomela lapponica from habitats severely contaminated by heavy metals (mostly Ni and Cu) and two populations from unpolluted habitats. Concentrations of Ni and Cu in adult beetles from the most polluted site were 7.7 and 3.6 times higher that in beetles from unpolluted habitats. Larval esterases showed higher activity and lower susceptibility to heavy metals than esterases of adults. Larval esterase activity did not differ between populations from polluted and unpolluted sites, but adult beetles from polluted localities had lower esterase activity than beetles from unpolluted habitats. Both Cu and Ni sulfates in millimolar concentrations in vitro suppressed esterase activity of larvae from unpolluted habitats, but caused no negative effect on esterases of larvae from polluted sites. Similarly, inhibition of adult esterase activity by Ni was stronger in beetles from unpolluted localities than in beetles from polluted localities. This indicates that resistance of non-specific esterases to heavy metals is higher in leaf beetle populations from contaminated environment.     

Evolutionary variations on a theme: host plant specialization in five geographical populations of the leaf beetle Chrysomela lapponica

The ancestral host plants of Chrysomela lapponica are Salicaceae rich in salicylic glycosides (SGs), which serve as precursors for larval chemical defensive secretions. Nevertheless, some populations have shifted to plants poor in SGs or even lacking these compounds. To study whether this shift is accompanied by adaptations to novel SG-poor host plants, we reared C. lapponica larvae from five geographical populations on host plants with high (Salix myrsinifolia) or low (S. caprea) SG content. Individuals from two populations (Finland and Kola region in Russia) associated in nature with SG-rich S. myrsinifolia showed higher survival and shorter developmental time on native host species than on foreign SG-poor S. caprea, thus demonstrating local adaptations to their ancestral SG-rich host plant. Individuals from a Belarus population associated in nature with SG-poor S. caprea showed higher survival on this species than on foreign SG-rich S. myrsinifolia, thus demonstrating local adaptation to the novel SG-poor host. On the other hand, individuals from two other populations associated in nature with SG-poor plants (Baikal and Ural region) performed equally well on both SG-rich S. myrsinifolia and SG-poor S. caprea in our rearing experiments, thus showing no local adaptation to a specific SG-host type, but rather a wide feeding niche including several Salicaceae species of different SG-type. Our results suggest that diet breadth of C. lapponica is a local phenomenon, and that adaptation strategies to novel host plants may differ between populations of a single leaf beetle species.     

Endemism patterns in the Italian leaf beetle fauna (Coleoptera,Chrysomelidae)

In this contribution the results of a zoogeographical analysis, carried out on the 123 endemic leaf beetle species (Coleoptera: Chrysomelidae) occurring in Italy and its immediately adjacent regions, are reported. To assess the level of faunistic similarity among the different geographic regions studied, a cluster analysis was performed, based on the endemic component. This was done by calculating the Baroni Urbani & Buser’s similarity index (BUB). Finally, a parsimony analysis of endemicity (PAE) was used to identify the most important areas of endemism in Italy.     

Spatial distribution of the cereal leaf beetle (Coleoptera: Chrysomelidae) in wheat

A 2-yr study was conducted in wheat fields in South Carolina involving weekly sampling of cereal leaf beetle, Oulema melanopus (L.). In each of the six fields of this study, temporal patterns showed two distinct peaks in March and in May of adult O. melanopus. Populations decreased as wheat plants matured. In 2009, larval populations had one peak in April in between the two adult peaks. The χ(2) statistics for observed and Poisson predicted distributions of O. melanopus indicated nonrandom distribution for adults and larvae. In addition, the values of I(D) were >1 for adults and larvae in both years across sampling dates. These results indicate that the sampling distributions of both adult and larval populations of O. melanopus were aggregated. Slopes of Taylor power's law (b) and patchiness regressions (β) were significantly (P < 0.05) different than one in all cases, except for b in 2008 for adults. Across sampling dates, the distance from field border had a significant effect on adult O. melanopus in both years, but not on larval O. melanopus. Densities of adult O. melanopus were greatest at 0 m (the field edge), and decreased at 5-25 m from the field edge. The inverted distance weighted interpolation method showed considerable levels of spatial variability in densities within fields. High densities along the edge of wheat fields suggests that localized control methods in wheat may be effective in reducing migration of O. melanopus and damage in corn, Zea mays L.     

To the knowledge of the leaf beetle genus Cystocnemis (Coleoptera, Chrysomelidae)

Four subspecies of Cystocnemis discoidea are distinguished; two subspecies are described as new to science based on investigation of intraspecific variation in different parts of the species range, and ssp. gebleri was resurrected from synonymy. The ways of speciation in highland-hollow landscapes are discussed. The alpine subspecies C. discoidea oreas ssp. n. has an altibiome disjunction with the nominotypical subspecies. Similarity of the alpine subspecies of C. discoidea to the species from the subgenus Entomomela was found to be the reason of permanent confusion of representatives of these taxa. The subgenus Entomomela is transferred from the genus Oreomela to the genus Cystocnemis. A key to species and subspecies of the genus Cystocnemis is given.