Types of parasitism by larvae of water mites (Acari: Hydrachnellae)

The larvae of Hydrachnellae can be divided into three types, based on the habits of the parasitic (larval) stage in the life cycle. (1) The larvae do not leave the water. Parasitizing aquatic insects, they are permanently submerged and wet. Only some species of the family Hydrachnidae belong to this type. (2) The larvae leave the water. The parasitic phase occurs either on insects living on the water surface, or in the air stores of aquatic insects. In both cases the larvae are not in direct contact with water during the parasitic phase. The Limnocharidae, Eylaidae and some species of the Hydrachnidae belong to this type. (3) The larvae parasitize insects which live in the air and which can leave the direct proximity to water; therefore it may be difficult for the mite larva to return to water. Except for the Hydrachnidae, Limnocharidae and Eylaidae, all families of the Hydrachnellae belong to this type.     

The first record of the shore fly Paracoenia fumosalis (Diptera, Ephydridae) in the Palaearctic region

Paracoenia fumosalis Cresson previously known only from the USA and Canada is recorded in the Palaearctic Region for the first time. The adults were collected near a thermal hydrosulfuric spring in the Geiser Valley in Kamchatka. A key to species of the genus Paracoenia occurring in Russia is given.     

Sustainability and cyanobacteria (blue-green algae): facts and challenges

Cyanobacteria (blue-green algae) are widely distributed Gram-negative oxygenic photosynthetic prokaryotes with a long evolutionary history. They have potential applications such as nutrition (food supplements and fine chemicals), in agriculture (as biofertilizer and in reclamation of saline USAR soils) and in wastewater treatment (production of exopolysaccharides and flocculants). In addition, they also produce wide variety of chemicals not needed for their normal growth (secondary metabolites) which show powerful biological activities such as strong antiviral, antibacterial, antifungal, antimalarial, antitumoral and anti-inflammatory activities useful for therapeutic purposes. In recent years, cyanobacteria have gained interest for producing biofuels (both biomass and H₂ production). Because of their simple growth needs, it is potentially cost-effective to exploit cyanobacteria for the production of recombinant compounds of medicinal and commercial value. Recent advances in culture, screening and genetic engineering techniques have opened new ways to exploit the potential of cyanobacteria. This review analyses the sustainability of cyanobacteria to solve global problems such as food, energy and environmental degradation. It emphasizes the need to adopt multidisciplinary approaches and a multi-product production (biorefinery) strategy to harness the maximum benefit of cyanobacteria.     

Structure and biosynthesis of toxins from blue-green algae (cyanobacteria)

Microcystis andNodularia species produce cyclic hepta- and pentapeptides, microcystins and nodularin, respectively, both containing the same unusual C₂₀ amino acid, abbreviated Adda. Biosynthesis of nodularin fromNodularia and especially of Adda employs a pathway similar to that employed byMicrocystis for producting microcystins. Nearly 30 new microcystins have been isolated in our laboratory from cyanobacteria species and their structures assigned, largely employing tandem FAB mass spectrometry (FABMS/CID/MS). Acyclic peptides, some of them presumed precursors of nodularin and microcystins, have now been isolated and characterized. The numerous analogs identified or synthesized allow the identification of important parameters in a structure-activity relationship study.     

Survival and reproduction of some blue-green and green algae as affected by sewage water,fertilizer factory effluent,brassica oil,phenol, toluene and benzene

Fourteen blue-green and green algae survived for widely different time periods ranging between 22–102 d in control culture medium. Irrespective of their long or short survival period in control cultures, their pro- or eukaryotic nature, their different morphological types or natural habitats, they all survived for a short time period ranging between 3–8 d in sewage water, 5–10 d in fertilizer factory effluent, ¼-2 d in brassica oil, ½-2 d in phenol, 1–3 d in toluene, and 1–4 d in benzene (showing the relative toxicity of different chemicals to different algae, and the antialgal nature of brassica oil). Dilution decreased the toxicity of these agents very little, indicating that they all were very toxic to algae. None of the agent induced the formation of any reproductive or dormant cells. Sewage water, fertilizer factory effluent, brassica oil and/or benzene favored the formation of necridia cells in Phormidium bohneri, P. foveolarum, Microcoleus chthonoplastes, Lyngbya birgei, and L. major filaments. Scenedesmus quadricauda shed off all spines earlier, Hormidium flaccidum fragmented less or not at all, Scytonema millei formed no false branch and heterocyst, Aphanothece pallida and Gloeocapsa atrata cells did not divide, Cosmarium granatum cells did not form any zygospore and Oedogonium sp. not any oogonia-like cells under all or most of treatments with 25–100 % sewage water, 1–100 % fertilizer factory effluent, 1–100 % brassica oil, 25–100 % phenol, toluene and benzene.     

Developmental times and life tables for shore flies, Scatella tenuicosta (Diptera: Ephydridae), at three temperatures

Development times and survivorship of immature shore flies and longevity and reproduction of adult shore flies, Scatella tenuicosta Collin, reared on algae-infested filter paper, were studied at three temperatures (constant 20, 26, and 28.5 degrees C) through life table analysis. The development time for each individual life stage and the total time from egg to adult decreased with increasing temperature. Duration of the third (ultimate) larval instar ranged from 3.3 +/- 0.09 d at 20 degrees C to 1.4 +/- 0.04 d at 28.5 degrees C and was 1.7-1.9 times longer than the approximately equal first and second instars. Development of male and female shore flies from egg to adult needed an average of 14.5 +/- 0.13, 8.2 +/- 0.05, and 7.0 +/- 0.04 d at 20, 26, and 28.5 degrees C, respectively, and needed an estimated 154.4 +/- 1.2 thermal units (degree days). At these respective temperatures, adult females lived 21.8 +/- 2.2, 19.9 +/- 2.4, and 15.0 +/- 1.4 d and produced 379 +/- 62, 710 +/- 119, and 477 +/- 83 eggs during oviposition periods of 14.3 +/- 2.1, 15.0 +/- 2.2, and 10.8 +/- 1.4 d; daily lifetime egg production averaged 16.3 +/- 2.3, 33.5 +/- 3.8, and 29.7 +/- 3.5. Developmental stage-specific mortality was relatively low for all life stages at all temperatures, with maximum percent mortalities of 5.7% occurring in both the egg stage and in the third instar. The highest net reproductive rate (R(o)) was obtained for insects reared at 26 degrees C and was 329.6. The intrinsic rate of natural increase (r(m)) was highest at 28.5 degrees C and was 0.430. Generation time and doubling time of the population were shortest at 28.5 degrees C and were 12.4 and 1.6 d, respectively. Results suggested that 26 degrees C was near optimum for reproduction.     

Phycochromes b and d: their occurrence in some phycoerythrocyanin-containing blue-green algae (cyanobacteria)

Abstract
Phycochromes b and d, two types of photoreversibly photochromic pigments previously extracted from the blue-green alga Tolypothrix distorta , which contains phycoerythrocyanin, have now been found in three Anabaena strains also containing phycoerythrocyanin. Tests for the presence of phycochromes b and d in a number of blue-green algae lacking phycoerythrocyanin have been negative. The possibility that phycochrome b-type absorbance changes are due to changes in the α-subunit of phycoerythrocyanin is discussed.     

Composition of cyclic peptide toxins among strains ofMicrocystis aeruginosa (blue-green algae,cyanobacteria)

The distribution of the cyclic heptapeptide toxin, microcystin, was studied among 31 strains of Microcystis aeruginosa. Microcystins-RR, -YR and -LR were detected in fifteen strains and microcystin-LR was in two strains, but no toxin was found in fourteen strains. All three toxins were detected in all 12 strains belonging to the large cell-size group recognized by cell size and allozyme genotype. This pattern of toxin composition is compatible with that of M. viridis. The small cell-size group showed variation in the toxin composition as in the case of allozyme genotype.     

Growth interactions among blue-green (Anabaena Oscillarioides,Microcystis aeruginosa) and green (Chlorella sp.) algae

The growth interactions amongst the blue-green algal species Anabaena oscillarioides, Microcystis aeruginosa and the green alga, Chlorella sp. were studied both in mixed cultures and in filter cultures separated by a membrane filter in the two arms of an interaction U-tube. The role of nutrients especially phosphate upon the interaction has also been studied. Anabaena and Microcystis both inhibited the growth of Chlorella while Microcystis also inhibited the growth of Anabaena. The inhibitory effect of Microcystis was found to be dependent on high concentrations of the initial algal inocula and independent of the initial concentration of nutrients such as inorganic phosphate, indicating that the nature of the inhibition is probably due to the production of inhibitory extracellular products by Microcystis. On the other hand, the inhibitory effect of Anabaena on Chlorella is the consequence of nutrient competition with Anabaena competing more effectively for the available phosphate.     

Rewetting of drought-resistant blue-green algae: Time course of water uptake and reappearance of respiration,photosynthesis, and nitrogen fixation

Summary The response of the terrestrial blue-green algae Nostoc flagelliforme, Nostoc commune, and Nostoc spec. to water uptake has been investigated after a drought period of approximately 2 years. Rapid half-times of rewetting (0.6, 3.3, and 15.5 min, respectively) are found. The surfaceto-mass ratio of the three species is inversely correlated to the speed of water uptake and loss. The ecological relevance of these different time courses is discussed.Respiration starts immediately after a 30-min rewetting period, whereas photosynthetic oxygen evolution reaches its maximum activity after 6 and 8 h with N. commune and N. flagelliforme, respectively. In the dark, recovery of oxygen uptake by N. commune is somewhat impaired, while slightly stimulated with N. flagelliforme. With both species, recovery of photosynthesis is inhibited by darkness.Using colonies kept dry for two years, nitrogenase activity of N. commune attains its maximum 120 to 150 h after rewetting, while only 50 h were needed with algal mats kept dry for two days.Thus, after a 2-year drought period, the physiological sequence of reactivation is respiration—photosynthesis—nitrogen fixation. Respiration and photosynthesis precede growth and are exhibited by existing vegetative cells, whereas recovery of nitrogen fixation is dependent on newly differentiated heterocysts.     

Mating and spermatophore morphology of water mites (Acari: Parasitengona)

In this paper I synthesize original and published studies of sperm transfer behaviour of 23 genera of water mites from 15 families. The morphology of spermatophores from 16 genera (12 families) is described. Behaviour and/or spermatophores are described for the first time for the following species: Hydrachna magniscutata Marshall, Hydrachna hesperia Lundblad, Hydrachna sp. nr. leegei Koenike, Limnochares americana Lundblad, Limnesia undulata (Müller), Neumania distincta Marshall, Unionicola (three species in the U. crassipes-complex), Thyas slolli Koenike, Lebertia annae Habeeb, Lebertia sp., Piona sp. nr. debilis (Wolcott), Tiphys vernalis (Habeeb), Arrenurus dentipetiolatus Marshall, Arrenurus marshalli Piersig and Arrenurus birgei Marshall. On the basis of proximity of male and female during sperm transfer, I divide water mites into four groups: complete dissociation, involving no physical or chemical contact between the sexes (nine genera); incomplete dissociation, requiring distance-or contact-chemoreception but not involving pairing behaviour (five genera); pairing with indirect transfer, involving pairing behaviour with females controlling sperm uptake (three genera); pairing with direct transfer (=copulation), involving pairing behaviour and male placement of sperm in the receiving structure of the female (12 genera). Four genera have representative species in more than one category of sperm transfer. Factors possibly leading to the diversity of water mite mating behaviour include an evolutionarily flexible mode of sperm transfer in the ancestral water mite, and the development of planktonic and endoparasitic habits in many mites. Morphological features of spermatophores that improve physical stability, probability of females taking up sperm and resistance against osmotic stress are discussed. Finally, I present implications of mating behaviour and spermatophore morphology for phylogenetic relationships within water mites and between this group and terrestrial Acari.     

Sulfide inhibition of photosystem II in cyanobacteria (blue-green algae) and tobacco chloroplasts.

The present study shows that in the presence of 600 nm light, sulfide acts as a specific inhibitor of photosynthetic electron transport between water and Photosystem II in the cyanobacteria Aphanothece halophytica and Synechococcus 6311 as well as in tobacco chloroplasts. In the presence of 600 nm light sulfied affects the fast fluorescence transients as does a low concentration (10 mM) of hydroxylamine; the fluorescence yield decreases in the presence of either chemical and can be restored by the addition of 3-(3,4-dichlorophenyl)-1,1-dimethylurea. In chloroplasts, however, NH2OH, an electron donor at high concentrations (40 mM), relieves the sulfide effect. In the dark, sulfide affects the cyanobacterial fluorescence transients through decrease of oxygen tension. The fluorescence yield increases in a similar pattern to that observed under nitrogen flushing. Upon omission of sulfide in A. halophytica, the characteristic aerobic fluorescence transients return, consistent with the ease of alternation between oxygenic and sulfide-dependent anoxygenic photosynthesis in many cyanobacteria.     

感染丝状蓝藻的噬藻体的裂解周期和释放量的测定

近年来,随着浮游病毒的认识的深入,人们认识到浮游病毒对水体中初级生产力的影响是巨大的[1],其主要证据就是发现噬藻体在海洋蓝藻的种群控制上发挥着重要作用[2]. 噬藻体的释放量和裂解周期是衡量噬藻体感染力的重要指标,很多重要的生态指标如病毒在生态系统中对宿主的致死率、病毒种群得以维持的阈浓度等都需要使用病毒的释放量和裂解周期来加以推算[3,4], 因此准确地测定这两个基本参数是十分重要的.在自然界,很多丝状蓝藻,如颤藻、鱼腥藻、螺旋藻、席藻等是能够形成水华的,其中有些还具有产毒的功能[5].丝状蓝藻的形态特征有别于单细胞蓝藻, 在被噬藻体感染时,丝状蓝藻的感染周期和光合生理也与单细胞蓝藻有较大的差异[6],因此研究裂解丝状蓝藻的噬藻体的方法可能不同于感染单细胞的噬藻体.本次试验以一种感染丝状宿主的噬藻体为材料,探讨了确定其裂解周期和释放量的研究方法.     

Parasitism of the backswimmer Buenoa scimitra (Hemiptera: Notonectidae) by the water mite Hydrachna virella (Acari: Hydrachnellae)

SUMMARY. The life cycle of Hydrachna virella , a water mite parasitic on the notonectid backswimmer Buenoa scimitra , is described. The mite parasitizes immature instars 2–5 as well as adult males and females of the notonectid. Parasitized immature backswimmers spent longer periods of time between moults than unparasitized immature backswimmers. Initially attaching mites appeared to be generally distributed over the host body surface but previously attached mites that reattached after host ecdysis were found primarily on the dorsum of the thorax. The observed frequency distribution of mite larvae on the host was similar to that predicted by the negative binomial distribution.     

感染丝状蓝藻的噬藻体的裂解周期和释放量的测定

近年来 ,随着浮游病毒的认识的深入 ,人们认识到浮游病毒对水体中初级生产力的影响是巨大的[1] ,其主要证据就是发现噬藻体在海洋蓝藻的种群控制上发挥着重要作用[2 ] 。噬藻体的释放量和裂解周期是衡量噬藻体感染力的重要指标 ,很多重要的生态指标如病毒在生态系统中对宿主的致死率、病毒种群得以维持的阈浓度等都需要使用病毒的释放量和裂解周期来加以推算[3,4 ] ,因此准确地测定这两个基本参数是十分重要的。在自然界 ,很多丝状蓝藻 ,如颤藻、鱼腥藻、螺旋藻、席藻等是能够形成水华的 ,其中有些还具有产毒的功能[5] 。丝状蓝藻的形态特征…     

水螨群总科阶元系统发育的支序分析 (蜱螨亚纲：水螨群)

对水螨群9总科进行了系统发育分析,支序分析选用了23个形态学特征和3个生物学特征。据分析结果所揭示的9总科间的系统发育关系和姐妹群关系,将水螨群9总科划分为5类：拟水螨类,含冥绒螨总科;始水螨类,含溪螨总科;真水螨类,含古水螨类和新水螨类;古水螨类,含水螨总科、盾水螨总科和皱喙螨总科;新水螨类,含刺触螨总科、腺水螨总科、湿螨总科和雄尾螨总科。类间姐妹群关系为：拟水螨类与始水螨类+真水螨类为姐妹群,始水螨类与真水螨类(古水螨类+新水螨类)为姐妹群,古水螨类与新水螨类为姐妹群。该文还就所提出的水螨群5类9总科的阶元排列建议与已有的观点进行了比较。     

Biodiversity and distribution of water mites (Acari, Hydrachnidia) in spring habitats

1. The distribution, species richness and ecology of spring‐dwelling water mites in Italy were investigated with the aim to better elucidate the role of spring habitats to sustain high levels of biodiversity and their contribution to freshwater biodiversity at a local and regional scale. 2. More than 300 springs in different geographic areas (Alps, Central and Southern Apennines, Sicily and Sardinia), were examined with a total of 163 water mite species recorded. 3. Species richness in each area ranged from 33 species on Sardinia to 77 on Sicily. The highest diversity was found in the Gran Sasso (Central Apennines). The proportion of crenobionts (species strictly bound to this type of habitat) exceeded 50% in almost all the areas investigated. 4. A diverse (up to 20 species per spring) and highly specialised mite fauna was observed in undisturbed rheocrenes and in natural springs of intermediate typology (rheohelocrenes and rheopsammocrenes). In springs subjected to human impacts (pasture, deforestation, alteration and transformation of spring sources) species richness declined and crenobionts were replaced by unspecialised crenoxenes. 5. The zoogeographic importance of spring habitats is confirmed by the presence of 18 endemic species and by members of genera with an interesting disjunct and relict distribution. 6. A comparison with other geographic areas suggests that springs contain a significant fraction of the total number of species found in freshwater habitats and may contribute almost one third of regional freshwater biodiversity. The presence of endemic crenobionts and rare taxa highlights the importance of these habitats in maintaining high levels of biodiversity as well as their contribution to a better understanding of biodiversity patterns in freshwaters.     

Effects of stable flies (Diptera: Muscidae) on weight gains of grazing yearling cattle.

Differences in weight gains caused by stable flies, Stomoxys calcitrans (L.), on grazing yearling steer/calves averaged 0.2 kg per steer in a 3-yr study on canyon range pastures in West Central Nebraska, Stable fly numbers averaged 0.85 per front leg on treated calves and 3.64 per front leg on control calves. In 2 of the 3 yr after the grazing trials were completed, the calves were placed in a feedlot and fed a finishing ration. Compensatory gain did not occur in the feedlot after the stable fly stress was removed.