Behavioural and electrophysiological responses of the European corn borer Ostrinia nubilalis to host‐plant volatiles and related chemicals

The European corn borer Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae) is a worldwide pest of maize (Zea mays L.) and other crops. The semiochemicals released by maize plants and structurally‐related compounds can be used by adult female O. nubilalis for host‐plant location and oviposition. Headspace volatile compounds emitted by watered and water‐deprived maize plants are collected and identified by their retention indices and mass spectra. The most abundant compounds from watered plants are limonene, linalool, benzoic acid, indole, β‐caryophyllene and acetophenone, whereas, in water‐deprived plants, limonene, acetophenone, hexanoic acid, benzoic acid and indole are dominant. In addition, (E)‐4,8‐dimethyl‐1,3,7‐nonatriene, 6‐methyl‐5‐hepten‐2‐one, anisole and 1‐carvone are undetected in the water‐deprived plants. Some of the identified compounds show electrophysiological activity (electroantennogram) in the antennae of both sexes, with the responses elicited by tridecane, tetradecane, dodecane, nonanal, decanal and 2‐ethylhexanol on males being particularly noteworthy. In a dual‐choice olfactometer, adult females show a preference for 2‐hexanol, heptanal, methyl salicylate, hexyl acetate, nonanal, methyl dodecanoate, β‐pinene and (E)‐2‐hexenyl acetate over hexane controls. Tetradecane, linalool, methyl hexanoate, methyl nonanoate, (Z)‐3‐hexenyl benzoate, tridecane, 2‐cyclopentylcyclopentanone, 3‐methylbutyl acetate, β‐myrcene and (Z)‐3‐hexenyl butanoate result in fewer females in the test arm compared with the control arm. No single compound displays an activity similar to watered maize plants, supporting the hypothesis that blends of volatiles in specific ratios are more effective than single volatile chemicals. The results of the present study suggest that methyl salicylate, which elicits also one of the highest electrophysiological responses in female antennae, plays a role in host preference by O. nubilalis females.     

Molecular systematics and phylogeny of the ‘Marbled Whites' (Lepidoptera: Nymphalidae,Satyrinae, Melanargia Meigen)

Abstract. We investigated genetic divergence and phylogenetic relationships amongst all known species of Palaearctic butterflies of the genus Melanargia using sequence information from three genes [mitochondrial cox1 barcode region (658 bp), ribosomal 16S rRNA (c. 518 bp), and nuclear wg (404 bp)]. Results show a lack of DNA divergence among several poorly characterized taxa, as well as deep divergences within and between others. We corroborated the molecular information with morphological and genitalic characters as well as with geographic data. We revise the taxonomy of Melanargia, and propose a new systematic scheme for the group. We revive some previous synonymies (M. lucasi meadwaldoi stat. rev. , M. ines fathme stat. rev. , M. ines jahandiezi stat. rev. , M. meridionalis tapaishanensis stat. rev. ), revise the status of some subspecies into species (M. transcaspica stat. nov. , M. lucida stat. nov. , M. wiskotti stat. nov. ) and of several species into subspecies of other taxa (M. evartianae sadjadii stat. nov. , M. larissa hylata stat. nov. , M. larissa grumi stat. nov. , M. larissa syriaca stat. nov. , M. larissa titea stat. nov. , M. lugens montana stat. nov. , M. epimede ganymedes stat. nov. ), revise the status of subspecies and transfer them to other species (M. larissa lorestanensis stat. nov. , M. larissa iranica stat. nov. , M. larissa karabagi stat. rev. , M. larissa kocaki stat. nov. , M. transcaspica eberti stat. nov. ), and propose new synonymies (M. larissa titea = M. titea standfussi syn. nov. = M. titea titania syn. nov. , M. leda leda = M. leda yunnana syn. nov. , M. lugens lugens = M. lugens ahyoui syn. nov. , M. lugens hengshanensis = M. lugens hoenei syn. nov. , M. halimede halimede = M. halimede gratiani syn. nov. , M. asiatica asiatica = M. asiatica dejeani syn. nov. , = M. asiatica elisa syn. nov. , = M. asiatica sigberti syn. nov. ).     

Inferring ancient Agave cultivation practices from contemporary genetic patterns

Several Agave species have played an important ethnobotanical role since prehistory in Mesoamerica and semiarid areas to the north, including central Arizona. We examined genetic variation in relict Agave parryi populations northeast of the Mogollon Rim in Arizona, remnants from anthropogenic manipulation over 600 years ago. We used both allozymes and microsatellites to compare genetic variability and structure in anthropogenically manipulated populations with putative wild populations, to assess whether they were actively cultivated or the result of inadvertent manipulation, and to determine probable source locations for anthropogenic populations. Wild populations were more genetically diverse than anthropogenic populations, with greater expected heterozygosity, polymorphic loci, effective number of alleles and allelic richness. Anthropogenic populations exhibited many traits indicative of past active cultivation: fixed heterozygosity for several loci in all populations (nonexistent in wild populations); fewer multilocus genotypes, which differed by fewer alleles; and greater differentiation among populations than was characteristic of wild populations. Furthermore, manipulated populations date from a period when changes in the cultural context may have favoured active cultivation near dwellings. Patterns of genetic similarity among populations suggest a complex anthropogenic history. Anthropogenic populations were not simply derived from the closest wild A. parryi stock; instead they evidently came from more distant, often more diverse, wild populations, perhaps obtained through trade networks in existence at the time of cultivation.     

Dispersal and upstream migration of an amphidromous neritid snail: implications for restoring migratory pathways in tropical streams

1. The amphidromous life cycle of several species of neritid snails, shrimp and gobies throughout the tropics includes juveniles that migrate from the ocean to breed in fresh water. In many Hawaiian streams, the decline of Neritina granosa, an endemic gastropod, has been associated with habitat degradation and water withdrawal, which are common factors affecting tropical rivers around the world. 2. We investigated the effects of water withdrawal and density on dispersal and upstream migration of N. granosa using three experimental treatments: (i) reduced flow (RF) owing to a stream diversion, (ii) natural flow (NF) and (iii) natural flow with artificially increased snail density. For each treatment, snails were differentially tagged and released in a stream without a natural, extant population of N. granosa. 3. Capture rates ranged from 17 to 65% over a 63‐day period following release. Captures on 2–6 days after release measured initial dispersal and migration, whereas longer‐term migration rates were calculated from snails captured 16–63 days after release. Snails under NF displayed positive rheotactic behaviour, with only 3–12% demonstrating initial downstream movement. Under RF, 22–77% of snails moved downstream or showed no bias either way. 4. Initial mean upstream migration rate (UMR) was 0.25, 0.66 and 1.16 m day^?1 under RF, NF and natural flow with increased snail density, respectively. Longer‐term migration rates did not differ significantly between treatments, and the overall mean was 0.62 m day^?1. 5. Principal component analysis and generalised linear models were used to identify habitat characteristics important to UMR, with habitat and reach‐scale hydraulics as the most important factors. The relationship between discharge and UMR suggested it would take 11–35 years for snails to migrate past the most upstream water diversion. However, rates from published studies of neritid snail species migrating en masse or in long lines under natural situations suggested that N. granosa could migrate above stream diversions within 72 days–2.5 years (when in an aggregation) and 29 days–1.1 years (when following in long lines of individuals). 6. An understanding of upstream neritid snail migration can be used for the management and conservation of this and other migratory species in tropical streams.     

Characterization and Localization of Acid Phosphatase Activity of Trypanosoma gambiense*

SYNOPSIS. Properties and cellular location of acid phosphatase in Trypanosoma gambiense were studied. Activity was found in both the sediment (32,000 ×g) and the supernatant of homogenates. Cenrifugation in 0.3 M sucrose showed activity principally in the lowspeed fraction (4,000 ×g). One min of sonication released most of this activity. Several phosphomonoesters were hydrolyzed at acid H's. Enzymatic activity was relatively specific for pyrophosphate and p-nitrophenylphosphate at pH 3.6. At pH 5.2, purine and pyimidine nucleotide 5′-triphosphates as well as adenosine di- and ono-5′-phosphates were hydrolyzed nonspecifically. Activity with yrophosphate at pH 3.6 had a temperature optimum of 60-70 C while that for adenosine 5′-triphosphate (pH 5.2) was 50 C. These ctivities of the sediment required no metal co-factors and were inibited by Fe⁺⁺, inhibition at the lower pH being greater. Glucose 6-phosphate was hydrolyzed by the supernatant with maximum activity between pH 6.0 and 7.2 and a temperature optimum of 50 C. This pH range showed a broad plateau with 2 or 3 minor peaks. The hydrolysis of p-nitrophenylphosphate showed a similar pH curve. In glucose 6-phosphate hydrolysis, Mg⁺⁺ was a required co-factor but could be replaced by Ni⁺⁺ or Co⁺⁺. Ammonium sulfate fractionation precipitated most of the supernatant activity between 50 and 75% saturation. A modified Gomori technic produced spherical deposits of PbS thruout the cytoplasm of the intact cell. With the electron microscope, Pb phosphate deposition was observed in membrane-bound vesicles (i.e., lysosomes) approximately 100-150 mμ in diameter. These organelles were common in the region of the reservoir at the base of the flagellum. Acid phosphatase activity specific for glucose 6-phosphate as substrate was localized within this basal pocket.     

The Role of Osmotic Pressure in the Germination of Nosema algerae Spores1

ABSTRACT. Both the lag period and the time required for the filament and sporoplasm to emerge from Nosema algerae spores were prolonged when germination occurred under hyperosmotic conditions. Polyethylene glycol (PEG) and sucrose inhibited germination, first by preventing eversion of the filament, and then at higher concentrations by preventing stimulation. The size of the spore cases decreased by about 21% following germination, indicating an elastic spore wall and turgor pressure in the dormant spores. Increased pressure during germination was indicated by less osmotically-induced shrinkage in stimulated than in dormant spores and by higher concentration of solutes in the homogenates of germinated than ungerminated spores. These results are consistent with the hypothesis of a pressure increase during germination that is caused by an endogenous increase in solute concentration.     

我国南方红壤矿区复垦土壤的微生物生态特征研究Ⅰ对土壤微生物活性的影响

通过对浙江哩浦铜矿废弃地土壤微生物、土壤酶活性及生化作用强度研究表明,与对照土壤相比,矿区土壤微生物总数下降68．43％～80．32％,细菌、放线菌数量减少,但真菌变化不明显,各主要生理类群硝化细菌、氨化细菌、固氮菌、纤维素分解菌数量均呈下降趋势,土壤基础呼吸速率下降;土壤脲酶、蔗糖酶、蛋白酶、酸性磷酸酶、过氧化氢酶、多酚氧化酶和脱氢酶酶活性均有不同程度减弱;土壤硝化作用、氨化作用、固氮作用和纤维素分解强度降低,抑制了矿区土壤C、N的周转速率和能量循环,土壤微生物活性减弱是矿区复垦土壤微生物生态的重要特征之一。