芦笋茎基部施药对芦笋木蠹蛾幼虫的防治试验

芦笋木蠹蛾Isoceras sibirica(Alpheraky)为芦笋(Asparagus officinalis(L.))上的一种蛀茎性害虫。试验结果表明,采用50%辛硫磷乳油300倍液在芦笋茎基部给药(5月中旬至6月中旬)为该虫的最佳化学防治方法,相对防治效果为92.5%,在所有处理中其加权Borda值最高(2.9)。调整芦笋播期,可使定植当年最易受害的笋苗免于虫害。     

Ploidy distribution in the explant tissue and the calluses induced during the initial stage of internode segment culture of Asparagus officinalis L.

Summary To pursue the causal factors of ploidy variation in tissue culture of asparagus (Asparagus officinalis L.), ploidy status of stem explants and the calluses induced from these explants were examined using flow cytometry (FCM). The frequency of higher ploidy (>8C) cells in the stem explants increased with increasing distance from the shoot apex. Calluses derived from sections far from the apex also showed higher ploidy distributions, and also higher ploidy (16C) in general than was observed in the explant tissue. Detailed studies using FCM and charge-coupled device (CCD)-equipped fluorescence microscopy showed that 16C cells appeared in the explant tissues within 1 wk of culture, possibly induced by the plant growth regulators (PGRs), especially 1-naphthaleneacetic acid (NAA), in the culture medium.     

Evaluating the Potential for Harmonized Prediction and Comparison of Disposal‐Stage Greenhouse Gas Emissions for Biomaterial Products

The carbon footprint (CF) of biofuels and biomaterials is a barrier to their acceptance, yet the greenhouse gas emissions associated with disposing of biomaterials are frequently omitted from analyses. This article investigates whether harmonization is appropriate for calculating the importance of biomaterials’ disposal. This research shows that disposal stages could double a biomaterial's CF, or reduce it to the point that it could claim to be zero carbon. Incineration with combined heat and power coupled with on‐site energy production in the biorefinery are identified as prerequisites to being zero carbon. The article assesses the current UK waste infrastructure's ability to support a low‐carbon bio‐based future economy, and finds that presently it only achieves marginal net reductions when compared to landfill and so cannot be said to support low‐carbon biomaterials, though the article challenges the polluter pays principle where low‐carbon disposal infrastructure are not available. Reuse and recycling are shown to have the potential to offset all the emissions caused by landfill of biomaterials. However, the savings are not so great as to offset the biomaterial's upstream emissions. The study explores the ability to overcome the barriers to incorporating disposal into life cycle assessment while identifying limitations of using harmonization as an assessment method. Specifically, data availability and industry consensus are flagged as major barriers. The study also uses sensitivity analysis to investigate the influence of methodological choices, such as allowing additional reuse and recycling stages, classifying biomaterials into different types, and choosing between opposing allocation methods.     

Molecular characterization and expression of a cDNA encoding fructan:fructan 6G-fructosyltransferase from asparagus (Asparagus officinalis)

* Fructan:fructan 6G-fructosyltransferase (6G-FFT) catalyses a transfructosylation from fructooligosaccharides to C6 of the glucose residue of sucrose or fructooligosacchrides. In asparagus (Asparagus officinalis), 6G-FFT is important for the synthesis of inulin neoseries fructan. Here, we report the isolation and functional analysis of the gene encoding asparagus 6G-FFT. * A cDNA clone was isolated from asparagus cDNA library. Recombinant protein was produced by expression system of Pichia pastoris. To measure enzymatic activity, recombinant protein was incubated with sucrose, 1-kestose, 1-kestose and sucrose, or neokestose. The reaction products were detected by high performance anion-exchange chromatography. * The deduced amino acid sequence of isolated cDNA was similar to that of fructosyltransferases and vacuolar type invertases from plants. Recombinant protein mainly produced inulin neoseries fructan, such as 1F, 6G-di-beta-D-fructofuranosylsucrose and neokestose. * Recombinant protein demonstrates 6G-FFT activity, and slight fructan:fructan 1-fructosyltransferase (1-FFT) activity. The ratio of 6G-FFT activity to 1-FFT activity was calculated to be 13. The characteristics of the recombinant protein closely resemble those of the 6G-FFT from asparagus roots, except for a difference in accompanying 1-FFT activity.     

Instar-specific defense ofColeomegilla maculata lengi (Col.: Coccinellidae): Influence on attack success of the intraguild predatorChrysoperla rufilabris (Neur.: Chrysopidae)

We conducted a laboratory study of the behavioural interactions between larval stages of the lady beetleColeomegilla maculata lengi Timberlake and an intraguild predator, the lacewingChrysoperla rufilabris Burmeister. Ladybird susceptibility to predation by third instarC. rufilabris is age-specific and influenced by larval defensive strategies. First and second instars ofC. maculata were captured more consistently by chrysopid larvae than third and fourth instars. Young coccinellids generally exhibit escape reactions (dropping, fleeing, retreating) but, do not survive after being caught by lacewings. In addition to escape reactions, older larvae may actively defend themselves by wriggling or biting, even after being pierced. The proportion of physical interactions that resulted in coccinellid death was significantly lower for older instars (<2%) than for first (35%) and second (19%) instars. Capture efficiency byC. rufilabris was related to the coccinellid-chrysopid size ratio. Dropping off the leaves, the most common defensive behaviour displayed by coccinellid larvae, contributed to reduce overall mortality of first instars to a level similar to the one observed for older stages. However, lacewings were able to prevent coccinellid dropping by impaling and holding their prey in the air, or by falling with the ladybirds to the ground where they continued their attack.     

Identification of tissues showing the lowest tolerance to freezing in larvae of the rice stem borer, Chilo suppressalis

Abstract.  Even though overwintering larvae of the rice stem borer, Chilo suppressalis , are freeze-tolerant, they cannot survive below −30 °C. Furthermore, nondiapausing larvae cannot survive freezing. However, the cause of death due to freezing is unclear. To identify the cause of death by freezing in larvae, those tissues most injured by low temperatures are identified using the vital stain trypan blue. In overwintering larvae, the midgut of dead larvae stains blue, and remarkable colour density differences between dead and surviving larvae are observed in the midgut. In nondiapausing larvae incubated at −10 °C for several hours, the fat body of dead larvae is strongly stained. Furthermore, increases in mortality with treatment time correspond with increases in the area of the fat body stained. Sterile nondiapausing larvae with lower supercooling points, below −20 °C, do not freeze at −10 °C and survive the treatment. However, all the larvae die when subjected to inoculative freezing at −10 °C, and the fat body stains blue. These results suggest that the midgut in overwintering larvae and the fat body in nondiapausing larvae have the lowest tolerance to freezing.     

Bacillus thuringiensis Cry3Aa toxin increases the susceptibility of Crioceris quatuordecimpunctata to Beauveria bassiana infection

The spotted asparagus beetle, Crioceris quatuordecimpunctata (Coleoptera: Chrysomelidae), is one of the most devastating pests of asparagus in China. Sprayed synthetic pesticides have been used to control C. quatuordecimpunctata damage, but they pose problems because of residues and harm to natural enemies. Neither the microbial coleopteran-specific toxin from Bacillus thuringiensistenebrionis, Cry3Aa, nor the fungal pathogen Beauveria bassiana have sufficient activity to effectively control C. quatuordecimpunctata damage to asparagus. However, second instar C. quatuordecimpunctata larvae exposed to a sublethal dose of Cry3Aa toxin demonstrated significantly higher larval mortality when exposed to B. bassiana. Our results suggest that a combination of Cry3Aa and B. bassiana may be effective in reducing damage by C. quatuordecimpunctata larvae to asparagus.     

Differential efficacy of toxic pederin in deterring potential arthropod predators of Paederus (Coleoptera: Staphylinidae) offspring

This study investigates the effects of pederin, a hemolymph toxin that is accumulated in the eggs of most Paederus females, on potential arthropod predators of the offspring of P. fuscipes and P. riparius. Insects generally do not respond to pederin present in the prey. Paederus larvae are sufficiently agile to escape from these predators by running away, and the eggs are hidden by the females. Unlike insects, (wolf) spiders are deterred by prey with pederin. They turn away from larvae they have already captured and exhibit cleansing behavior. Larvae containing pederin survive the attacks of spiders without damage, whereas larvae descended from females that do not transfer pederin into their eggs are often killed and eaten. In the case of sudden attacks by spiders, the larvae have no chance of escape. Their survival thus depends on chemical defense. These investigations show for the first time why pederin might be of considerable importance for Paederus in the field.     

The potential of Thelypteris palustris and Asparagus sprengeri in phytoremediation of arsenic contamination

The potential of two plants, Thelypteris palustris (marsh fern) and Asparagus sprengeri (asparagus fern), for phytoremediation of arsenic contamination was evaluated. The plants were chosen for this study because of the discovery of the arsenic hyperaccumulating fern, Pteris vittata (Ma et al., 2001) and previous research indicating asparagus fern's ability to tolerate > 1200 ppm soil arsenic. Objectives were (1) to assess if selected plants are arsenic hyperaccumulators; and (2) to assess changes in the species of arsenic upon accumulation in selected plants. Greenhouse hydroponic experiments arsenic treatment levels were established by adding potassium arsenate to solution. All plants were placed into the hydroponic experiments while still potted in their growth media. Marsh fern and Asparagus fern can both accumulate arsenic. Marsh fern bioaccumulation factors (> 10) are in the range of known hyperaccumulator, Pteris vittata Therefore, Thelypteris palustris is may be a good candidate for remediation of arsenic soil contamination levels of < or = 500 microg/L arsenic. Total oxidation of As (III) to As (V) does not occur in asparagus fern. The asparagus fern is arsenic tolerant (bioaccumulation factors < 10), but is not considered a good potential phytoremediation candidate.     

Genomic organization of the AODEF gene in Asparagus officinalis L

The perianths of Liliaceae plants, such as lily and tulip, have two whorls of almost identical petaloid organs, which are called tepals. According to the modified ABC model proposed in tulip, the class B genes are expressed in whorl 1 as well as whorls 2 and 3, so that the organs of whorls 1 and 2 have the same petaloid structure. The floral structure of asparagus (Asparagus officinalis L.) is similar to that of Liliaceae plants, however, the expression of B-class genes (AODEF, AOGLOA, AOGLOB) was not found in whorl 1, but was confined to whorls 2 and 3. This result does not support the modified ABC model in asparagus. In order to gain a better understanding of asparagus flower development, we have characterized a genomic clone of the AODEF gene. We compared the genomic organization and promoter sequence of AODEF with three well-studied DEF-like genes, DEFICIENS (Antirrhinum), APETALA3 (Arabidopsis), and OSMADS16 (rice). Exon-intron structures of these genes are well-conserved except for the large fifth intron in the AODEF gene and the OSMADS16 gene. Putative cis-elements including CArG-boxes were found in the promoter region and forty-two microsatellites were found in the AODEF genomic sequence.     

Two GLOBOSA-like genes are expressed in second and third whorls of homochlamydeous flowers in Asparagus officinalis L

Garden asparagus (Asparagus officinalis L.) has homochlamydeous flowers. Like Liliaceae plants such as lily and tulip, the perianths of asparagus have two whorls of almost identical petaloid organs, called tepals. Floral structures of these homochlamydeous flowers could be explained by a modified ABC model, in which the expression of the class B genes has expanded to whorl 1, so that the organs of whorls 1 and 2 have the same petaloid structure. In this study, we isolated and characterized two GLOBOSA-like genes (AOGLOA and AOGLOB), one of class B gene, from asparagus. Southern blot showed that AOGLOA and AOGLOB genes are single copy genes. Northern blot analysis indicated that these genes were specifically expressed in male and female flowers. In situ hybridization showed that the expression of AOGLOA and AOGLOB genes is confined to whorls 2 and 3 (inner tepal and stamen) and not detected in whorl 1 (outer tepal). The other asparagus class B gene, AODEF, was also not expressed in outer tepal [Park et al. (2003) Plant Mol Biol. 51: 867]. These results indicate that the class B genes are not involved in the outer tepal development in asparagus, not supporting the modified ABC model in asparagus.     

Effect of VA Mycorrhizal Inoculation on Growth of Asparagus Seedlings

Experiments on asparagus (Asparagus of)icinalis L.) inoculated with VA mycorrhizal fungi were conducted under two fluvo-aquatic phosphorus deficient soils. This study was to examine the growth response of VA mycorrhizae and fertilizer effects on the growth of mycorrhizal and non-mycorrhizal asparagus seedlings in pots and under field conditions. Inoculation with VA mycorrhizal fungi significantly increased mycorrhizal infection and enhanced seedling growth. In treatments of fertilization by different batches of NPK or by different amount of application it was shown that phosphorus was most favourable to VAM activity. Both the prevalance of mycorrhizal infection and the dry weight of seedlings in treatment with NPK in 1:0:1 was similar to that in 1:1:1 and 1:2:1 after inoculation. Further more the prevalance of infection, plant growth and P content in the treatment of 1/2 an amount of NPK in 1:1:1 were even higer than those in full amount of NPK and in non-fertilization. It is indicated that phosphorus uptake and plant growth benefit greatly by mycorrhizal inoculation. Mycorrhizal plant requires only about half as much phosphorus to achieve maximum growth as the uninoculated plants.     

Fusarium asiaticum: an Emerging Pathogen Jeopardizing Postharvest Asparagus Spears

Asparagus spears are usually vulnerable to pathogenic micro‐organisms. In this study, 217 pathogens were isolated from symptomatic asparagus, and one highly virulent fungus (designated EXAP‐08) isolated from the rotted asparagus spears in cold storage was characterized in detail. Koch's postulates were checked through pathogenicity tests, indicating that EXAP‐08 infection could cause reproducible rot symptoms similar to those observed on naturally infected asparagus spears, and the pathogenicity of EXAP‐08 was also relatively higher than other Fusarium pathogens, especially at 4°C. Through morphological and molecular identification, EXAP‐08 was characterized as Fusarium asiaticum. This identification was further confirmed by phylogenetic analysis with the Histone gene H3 of EXAP‐08 and other Fusarium species. EXAP‐08 also belongs to 3A‐DON (3‐acetyl‐4‐deoxynivalenol) chemo‐type, and the mycotoxin was detected during the infection of plant, implying the potential risks of mycotoxin contamination in fresh crops infected by this pathogen. Thus, this emerging pathogen threatening edible safety of asparagus spears should deserve particular quarantine inspection in the future.     

Analysis of Transposable Elements in the Genome of Asparagus officinalis from High Coverage Sequence Data

Asparagus officinalis is an economically and nutritionally important vegetable crop that is widely cultivated and is used as a model dioecious species to study plant sex determination and sex chromosome evolution. To improve our understanding of its genome composition, especially with respect to transposable elements (TEs), which make up the majority of the genome, we performed Illumina HiSeq2000 sequencing of both male and female asparagus genomes followed by bioinformatics analysis. We generated 17 Gb of sequence (12×coverage) and assembled them into 163,406 scaffolds with a total cumulated length of 400 Mbp, which represent about 30% of asparagus genome. Overall, TEs masked about 53% of the A. officinalis assembly. Majority of the identified TEs belonged to LTR retrotransposons, which constitute about 28% of genomic DNA, with Ty1/copia elements being more diverse and accumulated to higher copy numbers than Ty3/gypsy. Compared with LTR retrotransposons, non-LTR retrotransposons and DNA transposons were relatively rare. In addition, comparison of the abundance of the TE groups between male and female genomes showed that the overall TE composition was highly similar, with only slight differences in the abundance of several TE groups, which is consistent with the relatively recent origin of asparagus sex chromosomes. This study greatly improves our knowledge of the repetitive sequence construction of asparagus, which facilitates the identification of TEs responsible for the early evolution of plant sex chromosomes and is helpful for further studies on this dioecious plant.     

Origin of tetraploid cultivated asparagus landraces inferred from nuclear ribosomal DNA internal transcribed spacers’ polymorphisms

The genus Asparagus includes a group of wild species that are closely related to the cultivated Asparagus officinalis (2n = 2× = 20). The narrow genetic background present in the asparagus cultivars shows the importance of asparagus landraces and the wild related species. The study of both genetic resources becomes necessary to facilitate their effective use in the breeding programmes. ‘Morado de Huetor’ (MH) and ‘Violetto d’Albenga’ (VA) are tetraploid asparagus landraces (2n = 4× = 40) cultivated in Spain and Italy, respectively, and whose origin remains unknown. To discover the origin of these landraces, a phylogenetic study was conducted based on restriction fragment length polymorphism (RFLP) of nuclear ribosomal DNA (nrDNA). The sequence of the two internal transcribed spacers (ITS) flanking the nrDNA5.8S gene (ITS1‐5.8S‐ITS2) were analysed for RFLP in 11 populations including both landraces (MH and VA), A. officinalis (wild and cultivated) and a group of closely related wild species (Asparagus maritimus, Asparagus prostratus, Asparagus pseudoscaber and Asparagus tenuifolius) with a European distribution. Restriction fragment patterns of both cultivated asparagus (2×) and two populations of A. maritimus (6×) from the Adriatic Sea area were present in the MH landrace. However, VA showed a similar pattern to A. officinalis. This study revealed that MH seems to be a hybrid between A. officinalis and A. maritimus that may have occurred in the Adriatic Sea region where hybridisations between cultivated diploid and wild species may have taken place. The origin of another tetraploid landrace (VA) might have had a similar origin but followed a different evolutionary path. Therefore, these landraces constitute a valuable genetic resource that could be used to enlarge the genetic background of modern cultivars. The ploidy levels of the populations employed in this study were analysed and levels not described previously were detected: A. maritimus (12×), A. tenuifolius (6×) and A. pseudoscaber (2×).     

Notes on the life-history of the rabbit flea Caenopsylla laptevi ibera Beaucournu & Marquez, 1987 (Siphonaptera: Ceratophyllidae) in eastern Spain

The rabbit flea Caenopsylla laptevi ibera occurs in arid environments of central and eastern Spain. Although the fleas breed during the coolest, most humid part of the year, the larvae survive and grow in sand at only 50-60% relative humidity. At 22 degrees C and 80% relative humidity eggs hatch in six days and the cocoon stage is reached 10-11 days after hatching. Female fleas emerge from pupation at about 17 days after cocoon spinning; males emerge a little later at a mean of 20 days. Adult fleas are mainly found on the host Oryctolagus cuniculus. Measurements of burrow microclimate confirmed that in south-eastern Spain burrow humidity was adequate for the development of C. I. ibera larvae over most of the year. However, breeding may be restricted for at least part of the year, as the larvae of C. I. ibera apparently cannot complete development at 25 degrees C or above. In the laboratory, fleas can enter a prolonged quiescent period while in the cocoon. This is possibly a facultative, pre-pupal diapause and the likely mechanism that accounts for the disappearance of adult fleas from the field by spring and their reappearance each autumn.     

Resistance to Diaphania hyalinata (Lepidoptera: Crambidae) in Cucumis species.

Diaphania hyalinata (L.), the melonworm, causes economic damage in cucurbit species in the Caribbean region. To control larvae feeding on leaves, frequent pesticide applications are needed, but this favors outbreaks of other pests. We looked for plant resistance to D. hyalinata in Cucumis melo L. and two wild Cucumis, C. metuliferus Meyer and C. pustulatus Naudin. Fifteen genotypes were observed using a 1-81 damage scale during 8 wk in two field trials in Guadeloupe, French West Indies. Among the C. melo genotypes, we observed different levels of damage (scores of 32-74 at the maximum damage date) ranging from partially resistant to susceptible genotypes. Both wild species scored <20 at the maximum damage date, and were more resistant in the field tests than the tested genotypes of C. melo. Five C melo genotypes and one C. pustulatus genotype were tested using a detached leaf test. Under controlled conditions, newly hatched larvae were fed with leaves from plants that were 5-9 wk old. Duration and mortality of immature stages were highly correlated. Strong antibiosis (long development and high mortality) was expressed by PI 140471 and Concombre Chien (two C. melo genotypes). For both genotypes, mortality was at least 87.9 versus 34% for Védrantais, a susceptible genotype. Because antibiosis and field resistance were not correlated, we hypothesize that some genotypes expressed antixenosis in the field trials. In addition, possibilities of breeding for C. melo resistance to D. hyalinata is discussed.     

The effect of stem diameter on European corn borer behavior and survival: potential consequences for IRM in Bt-corn

The ability of non‐crop plants to support complete development of insect pests is an important factor for determining the impact of those plants on resistance management programs for transgenic crops. We assessed the effect of one physical factor, plant stem diameter, on the ability of plants to support full development of the European corn borer (ECB), Ostrinia nubilalis Hübner (Lepidoptera: Crambidae), the target pest of transgenic Bt‐corn. In the field, European corn borer larvae were significantly more likely to tunnel and survive in plants with larger stem diameters. Larvae were 40× more likely to survive on corn, the largest plant tested, compared to many of the smaller plants. In the laboratory, larvae were more likely to survive in and less likely to abandon the largest diet‐filled artificial stems that varied only in stem diameter. In conditions simulating those that an ECB larvae would encounter upon abandoning a host, larvae survived up to three weeks and were able to locate corn as a new host with a significantly higher frequency than would be expected if they were foraging randomly. These results indicate that the probability of ECB larval survival to maturity on a plant other than corn is relatively low and thus these smaller stemmed non‐corn plants may not make a substantial contribution to the pool of susceptible adults. Conversely, since more mature larvae are not as susceptible as neonates, any larvae that partially develop on non‐corn plants and subsequently colonize Bt‐corn may not be exposed to a lethal dose of the toxin. Since some proportion of the individuals that survive could be partially resistant heterozygotes the presence of non‐corn host plants could facilitate the development of resistant ECB populations.     

The effect of stem diameter on European corn borer behavior and survival: potential consequences for IRM in Bt-corn

The ability of non-crop plants to support complete development of insect pests is an important factor for determining the impact of those plants on resistance management programs for transgenic crops. We assessed the effect of one physical factor, plant stem diameter, on the ability of plants to support full development of the European corn borer (ECB), Ostrinia nubilalis Hübner (Lepidoptera: Crambidae), the target pest of transgenic Bt-corn. In the field, European corn borer larvae were significantly more likely to tunnel and survive in plants with larger stem diameters. Larvae were 40× more likely to survive on corn, the largest plant tested, compared to many of the smaller plants. In the laboratory, larvae were more likely to survive in and less likely to abandon the largest diet-filled artificial stems that varied only in stem diameter. In conditions simulating those that an ECB larvae would encounter upon abandoning a host, larvae survived up to three weeks and were able to locate corn as a new host with a significantly higher frequency than would be expected if they were foraging randomly. These results indicate that the probability of ECB larval survival to maturity on a plant other than corn is relatively low and thus these smaller stemmed non-corn plants may not make a substantial contribution to the pool of susceptible adults. Conversely, since more mature larvae are not as susceptible as neonates, any larvae that partially develop on non-corn plants and subsequently colonize Bt-corn may not be exposed to a lethal dose of the toxin. Since some proportion of the individuals that survive could be partially resistant heterozygotes the presence of non-corn host plants could facilitate the development of resistant ECB populations.