共查询到20条相似文献,搜索用时 187 毫秒
1.
Summary. The oviposition-stimulating activity of (E)-capsaicin identified in the fruits of red pepper, Capsicum annuum L. (Solanaceae), towards the oriental tobacco budworm, Helicoverpa assulta (Guenée), was examined in the laboratory by using choice and no-choice bioassays. Results were compared with those of the
commercially available capsanthin and dihydrocapsaicin, another known constituents of C. annuum fruit, and (Z)-capsaicin. In no-choice oviposition bioassays at 10.5 μg/cm2, (E)-capsaicin was the most active oviposition stimulant. Weak stimulatory activity was observed with capsanthin, (Z)-capsaicin
and dihydrocapsaicin. In choice oviposition bioassays at 2.6 μg/cm2, there were significant differences in oviposition-stimulating activity between (E)-capsaicin and each of the other three alkaloids. Structure-activity relationships indicate that the presence of double bond
and its trans configuration appeared to play a crucial role in the oviposition-stimulating activity. On the basis of our results, (E)-capsaicin acts as a contact oviposition stimulant of female H. assulta. 相似文献
2.
Olivier Maire Jean-Michel Amouroux Jean-Claude Duchêne Antoine Grémare 《Marine Biology》2007,152(6):1293-1307
The filtration activity of the Mediterranean mussel, Mytilus galloprovincialis, was assessed under different concentrations and compositions of seston by using a new automated image acquisition and analysis
system. This approach allowed for frequent and simultaneous measurements of valve gape and exhalant siphon area. Filtration
rates were measured through clearance measurements whereas pumping rates were measured using hot-film probes. The average
filtration rate (17.5 l g h−1 DW−1 for a 0.36 g DW mussel) recorded during the present study was higher than those available for Mytilus edulis when standardized to flesh dry weight but almost equivalent (17.5 l h−1 g DW−1 for a 53 mm shell length mussel) to those rates when standardized to shell length. Immediately after the addition of algal
cells (Isochrysis galbana; 4.5 μm in size), valve gape, exhalant siphon area and filtration rate increased quickly as mussels reached their maximum
filtration activity. These three parameters then gradually decreased until complete closure of the shell. The algal cell concentration
inducing this transition was close to 800 cells ml−1 and 0.5 μg Chl a l−1. When algal concentration was maintained above this threshold by successive algal additions, both valve gape and exhalant
siphon area remained maximal. Temporal changes in the exhalant siphon area were continuous as opposed to those of valve gape.
Therefore, despite the significant correlation between these two parameters, valves and siphon were sometimes dissociated
due to a reduction of the area or even a closure of the exhalant siphon while the valves remained open. The velocity of exhaled
water tended to be constant irrespective of exhalant siphon area and thus pumping rates were a linear function of exhalant
siphon area. Consequently, reductions in exhalant siphon area and pumping rate were almost similar in M. galloprovincialis. Our results thus clearly support the hypothesis that exhalant siphon area constitutes a better proxy of pumping rate than
valve gape as already suggested for Mytilus edulis. Finally, the high filtration rates measured during the present study together with the high concentrations of inorganic
matter (> 40 mg DW l−1) requested to alter those rates suggest that the studied mussels were well adapted to oligotrophic waters featuring strong
hydrodynamism and frequent sediment resuspension events. 相似文献
3.
Summary. Antennae of six sympatric bark and ambrosia beetles (Scolytidae), Dendroctonus valens LeConte, Gnathotrichus retusus (LeConte), Hylastes tenuis Eichhoff, Ips mexicanus (Hopkins), Ips plastographus maritimus Lanier, and Pseudohylesinus sericeus (Mannerheim), and two scolytid predators, Enoclerus sphegeus (F.) (Cleridae) and Lascontonus tuberculatus Kraus (Colydiidae), were analyzed by gas chromatographic-electroantennographic detection (GC-EAD) for their responses to
synthetic Ips spp. pheromone components, and host and nonhost volatiles.
The beetles emerged from cut logs of pitch canker-infected Monterey pine trees, Pinus radiata D. Don. There were significant disparities in EAD response patterns to the hemiterpene and monoterpene alcohol pheromone
components that are typically produced by Ips spp. Antennae of I. p. maritimus responded strongly to ( ± )-ipsdienol, ( ± )-ipsenol, amitinol, and lanierone; antennae of I. mexicanus responded strongly to (1S,2S)-(–)-cis-verbenol, with weaker responses to ( ± )-ipsdienol, ( ± )-ipsenol, and amitinol; antennae of H. tenuis responded to (1S, 2R)-(–)-trans-ver-benol, with less pronounced responses to (–)-cis-verbenol and 2-methyl-3-buten-2-ol; and antennae of D. valens, G. retusus, and P. sericeus generally responded to all Ips spp. pheromone components except 2-methyl-3-buten-2-ol (D. valens and G. retusus) and E-myrcenol (G. retusus and P. sericeus). Ips mexicanus
responded only to the (–)-enantiomers of ipsenol and ipsdienol, whereas I. p. maritimus responded to (–)-ipsenol, but to both the (+)- and (–)-enantiomers of ipsdienol. The antennae of the two predaceous insects
(E. sphegeus and L. tuberculatus) responded to a range of the Ips spp. pheromone components. Host monoterpenes elicited no antennal responses from E. sphegeus, G. retusus, H. tenuis, and I. mexicanus, but several monoterpenes elicited various levels of responses from D. valens and I. p. maritimus antennae. Interestingly, antennae of female D. valens responded to (–), but not (+)-limonene. α- and β-Pinene elicited weak responses from L. tuberculatus antennae. EAD responses to selected nonhost volatiles were almost identical among the six scolytid species, with trans-conophthorin eliciting the strongest response in most cases, followed by three C6- alcohols and two C8-alcohols. The antennal responses by most of these species to linalool or geranylacetone were very weak; (E)-2-hexenal, (Z)-3-hexenyl acetate, and benzyl alcohol elicited almost no response. The response pattern of P. sericeus to nonhost volatiles differed slightly from the rest of the scolytids: a strong response to linalool, weaker response to
the C8-alcohols. The two predaceous Coleoptera generally had weak, but detectable, responses to nonhost volatiles, except for a
relatively strong response to trans-conophthorin by L. tuberculatus. No notable differences in EAD responses were observed between males and females of the two Ips spp. Our results provide an electrophysiological baseline for future efforts to identify attractive and repellent semiochemicals
(aggregation pheromones, host kairomones, or nonhost interruptants) for this guild of scolytids and their key predators that
are associated with moribund and pitch canker- infected P. radiata. 相似文献
4.
M. I. Silva H. D. Burrows S. J. Formosinho L. Alves A. Godinho M. J. Antunes D. Ferreira 《Environmental Chemistry Letters》2007,5(3):143-149
Advanced oxidation processes, such as photocatalysed oxidation, provide an important route for degradation of wastes. In this
study, the lowest excited state (3MLCT) of Ru(bpy)32+ is used to break down chlorophenol pollutant molecules to harmless products. This has the advantage of using visible light
and a short-lived catalytically active species. Photolysis of deaerated aqueous solutions of a variety of mono- and poly-substituted
chlorophenols has been followed in the presence of Ru(bpy)32+/S2O82− with near visible light (λ > 350 nm) by UV/visible absorption spectroscopy, luminescence, potentiometry, NMR and HPLC techniques.
Upon irradiation, a decrease is observed in the chlorophenol concentration, accompanied by the formation of Cl−, H+ and SO42− ions as the main inorganic products. Benzoquinone, phenol, dihydroxybenzenes and chlorinated compounds were the dominant
organic products. As the ruthenium(II) complex is regenerated in the reaction, the scheme corresponds to an overall catalytic
process. The kinetics of the rapid chlorophenol photodechlorination has been studied, and are described quite well by pseudo-first
order behaviour. Further studies on this were made by following Cl− release with respect to the initial Ru(bpy)32+ and S2O82− concentrations. A comparison is presented of the photodechlorination reactivity of the mono and polychlorophenols studied
at acidic and alkaline pH. 相似文献
5.
The parsnip webworm, Depressaria pastinacella, specializes on wild parsnip, Pastinaca sativa, and several species of Heracleum, hostplants rich in toxic furanocoumarins. Rates of furanocoumarin metabolism in this species are among the highest known
for any insect. Within its native range in Europe, webworms are heavily parasitized by the polyembryonic parasitoid wasp Copidosoma sosares. In this study, we determined whether these parasitoids are exposed to furanocoumarins in host hemolymph, whether they can
metabolize furanocoumarins, and whether parasitism influences the ability of webworms to detoxify furanocoumarins. Hemolymph
of webworms fed artificial diet containing 0.3 % fresh weight xanthotoxin, a furanocoumarin prevalent in wild parsnip hosts,
contained trace amounts of this toxin; as well, hemolymph of webworms consuming P. sativa flowers and fruits contained trace amounts of six of seven furanocoumarins present in the hostplant. Thus, parasitoids likely
encounter furanocoumarins in host hemolymph. Assays of xanthotoxin metabolism in C. sosares failed to show any ability to metabolize this compound. Parasitized webworms, collected from populations of Heracleum sphondylium in the Netherlands in 2004, were on average 55 % larger by weight than unparasitized individuals. This weight is inclusive
of host and parasitoid masses. Absolute rates of detoxification (nmoles min−1) of five different furanocoumarins were indistinguishable between parasitized and unparasitized ultimate instars, suggesting
that the intrinsic rates of metabolism are fixed. Thus, although parasitized larvae are larger, detoxification rates are not
commensurate with size; rates in parasitized larvae expressed per gram of larval mass were 25 % lower than in unparasitized
larvae. 相似文献
6.
为揭示重金属镉对脊尾白虾的毒性效应,采用急性毒性实验方法,研究了不同浓度镉(Cd~(2+))对脊尾白虾(Exopalaemon carinicauda)血清氧化应激相关生理指标的活性以及肌肉组织中腺苷酸转移酶基因(ANT)和热激蛋白70基因(HSC70)表达水平的影响。共设置4个Cd2+浓度胁迫(0、0.0002、0.001、0.005 mmol·L~(-1)),分别在0、3、6、9、12、24、36、48、72和96 h共10个时间点对相关指标进行测定。结果显示:不同浓度镉胁迫下,脊尾白虾血清中H_2O_2含量、MDA含量和GSH含量均表现为先升高后降低的趋势,H2O2含量在胁迫3 h时即出现明显的升高,而MDA和GSH则均在9 h时出现升高趋势,表现为一定的滞后性。H2O2含量在0.005 mmol·L~(-1)胁迫3 h时出现峰值,MDA含量在0.005 mmol·L~(-1)胁迫9 h时出现峰值,GSH含量在0.001mmol·L~(-1)胁迫48 h时出现峰值,且均与对照组存在显著性差异(P0.05)。HSC70基因的表达量在不同浓度胁迫下均表现为先升高后降低的趋势,且均在24 h时达到峰值,具体表达量水平的顺序为:0.0002 mmol·L~(-1)0.001 mmol·L~(-1)0.005 mmol·L~(-1)。ANT基因的表达量在不同浓度下则均表现为明显的下调趋势。由此可见,急性Cd~(2+)胁迫不仅影响脊尾白虾的氧化应激相关生理指标,还影响机体内组成型HSC70及与能量传递有关的ANT基因的表达水平。 相似文献
7.
Summary. Male satin moths, Leucoma (Stilpnotia) salicis L. (Lepidoptera, Lymantriidae) were attracted only to (3Z,6R,7S,9R,10S)-isomer out of the four (3Z)-cis-6,7-cis-9,10-diepoxy-3-henicosenes (leucomalure). This was demonstrated by field trapping test with a bivoltine population in a mixed poplar-willow forest along the flood area of the river Danube at Adony, Hungary. 相似文献
8.
Summary. Summary. Oilseed rape, Brassica napus L. (cv Express),
plants were grown under three different sulphur regimes:
sulphur-free (S0), normal sulphur (Sn, normal field concentration)
and a sulphur-rich (S+, 2 × concentration of Sn). We
performed dual choice oviposition assays with the diamondback
moth, Plutella xylostella, using real plants and,
for the first time with this insect, artificial leaves sprayed
with methanolic leaf-surface extracts. The results mirrored
those of a separate study of preferences for whole plants.
Females laid more eggs on surrogate leaves that were
treated with Sn extracts than on S0 plants, while only a
slight, not significant, difference was observed between
extracts of normal and sulphur-rich plants. This shows
that chemical compounds on the leaf surface mediate the
oviposition preference and that the female insect can
perceive the quality of the host-plants in terms of their
fertilisation status.Since leaf volatiles are known to be oviposition stimulants,
we investigated the effects of leaf-surface extracts on
insect olfactory responses using electroantennograms
(EAGs). In agreement with the behavioural data, we found
that extracts of sulphur-treated plants yielded higher EAG
amplitudes than the S0 extracts. Since the leaf content of the
volatiles isothiocyanates is influenced by sulphur nutrition,
we analysed the extracts for these compounds. Above the
detection threshold of our GC-MS system, no isothiocyanates
were found. Thus, other compounds present in the
surface extracts must be perceived by the antenna.However, the HPLC analysis revealed 11 different
glucosinolates. Progoitrin (2-Hydroxy-3-butenyl) and
gluconapoleiferin (2-Hydroxy-4-pentenyl), which belong to
the hydroxy-alkene class of glucosinolates, were the most
abundant compounds. The total glucosinolate content
sharply increased from S0 to Sn plants, whereas it was slightly
lower in n versus S+ plants. Since it is known that glucosinolates
can stimulate oviposition, it seems likely that the
increased content we observed was influencing the insect
preference in this study too. 相似文献
9.
Thomas J. SmithIII Ginger Tiling Pamela S. Leasure 《Journal of Coastal Conservation》2007,11(1):67-74
The wetlands surrounding Tampa Bay, Florida were extensively ditched for mosquito control in the 1950s. Spoil from ditch construction
was placed adjacent to the wetlands ditches creating mound-like features (spoil-mounds). These mounds represent a loss of
14% of the wetland area in Tampa Bay. Spoil mounds interfere with tidal flow and are locations for non-native plants to colonize
(e.g., Schinus terebinthifolius). Removal of the spoil mounds to eliminate exotic plants, restore native vegetation, and re-establish natural hydrology is
a restoration priority for environmental managers. Hydro-leveling, a new technique, was tested in a mangrove forest restoration
project in 2004. Hydro-leveling uses a high pressure stream of water to wash sediment from the spoil mound into the adjacent
wetland and ditch. To assess the effectiveness of this technique, we conducted vegetation surveys in areas that were hydro-leveled
and in non-hydro-leveled areas 3 years post-project. Adult Schinus were reduced but not eliminated from hydro-leveled mounds. Schinus seedlings however were absent from hydro-leveled sites. Colonization by native species was sparse. Mangrove seedlings were
essentially absent (≈2 m−2) from the centers of hydro-leveled mounds and were in low density on their edges (17 m−2) in comparison to surrounding mangrove forests (105 m−2). Hydro-leveling resulted in mortality of mangroves adjacent to the mounds being leveled. This was probably caused by burial
of pneumatophores during the hydro-leveling process. For hydro-leveling to be a useful and successful restoration technique
several requirements must be met. Spoil mounds must be lowered to the level of the surrounding wetlands. Spoil must be distributed
further into the adjacent wetland to prevent burial of nearby native vegetation. Finally, native species may need to be planted
on hydro-leveled areas to speed up the re-vegetation process. 相似文献
10.
Summary. In amphibians and fishes, evidence is increasing that chemical cues from injured conspecifics can play a role in the chemical
labelling and learned recognition of unfamiliar predators. In this laboratory study, we tested the prediction that prior chemical
exposure to a non-native predator feeding on conspecific tadpoles will subsequently allow tadpoles of the common toad (Bufo bufo) to recognize the chemical cues specifically released by this starved predator. Furthermore, we investigated the vulnerability
of this chemically-mediated process to herbicide contamination. With these aims in view, groups of tadpoles were kept either
unexposed or exposed for ten days to chemical cues from Turkish crayfish (Astacus leptodactylus) previously fed on tadpoles, both in uncontaminated water and in the presence of four sublethal concentrations of amitrole
(0.01, 0.1, 1 and 10 mg.l−1). We then assessed the effects of the six conditioning treatments on general activity and behavioural response to chemical
cues from starved crayfish. Larval treatments did not affect the general activity of the tadpoles. By contrast, the treatments
had significant effects on the behavioural response to the test solution prepared form starved crayfish. The only tadpoles
to show an antipredator behavioural response to the chemical stimulation from starved crayfish belonged to the groups derived
from chemical exposure to tadpole-fed crayfish in uncontaminated water and in contaminated water with the lowest concentration
of amitrole (0.01 mg.l−1). Conversely, this chemical stimulation produced no behavioural change in the control group or in the groups derived from
exposure to tadpole-fed crayfish in contaminated water containing 0.1, 1 and 10 mg.l−1 of amitrole. This study demonstrates that chemical cues released during the predator’s feeding activity can subsequently
be used by common toad tadpoles in the recognition of an unfamiliar predator. In addition, our results show that the presence
of sublethal amitrole concentrations can impair this recognition process. Such a pesticide effect might be especially detrimental
for amphibian populations threatened by invasive predators. 相似文献
11.
This work deals with the biodiversity and distribution of benthic macrophytes in the Ghar El Melh lagoon, a Mediterranean
coastal lagoon located in the North of Tunisia. An inventory was made of the benthic flora and submerged macrophyte communities
were mapped during two successive campaigns (the summer of 1999 and the winter of 2000). The following 24 macrophyte species
were identified: seven red algae, two brown algae, 11 green algae, and four marine angiosperms. The results were compared
with available data from the literature.
Ruppia cirrhosa is the most dominant species. It is found in all lagoon parts, except in the west sector.Ruppia beds are usually associated withCladophora forming heterogeneous communities. During summerRuppia cirrhosa shows a large distribution, covering an area of ca. 21.4 km2, with dense, extensive beds covering 80–100%. In winter, severalCladophora species have a very large distribution as well, covering nearly an area of 28.5 km2 with an average cover of 46%. The green algaeCaulerpa prolifera is confined to the eastern part of the lagoon which is mainly affected by seawater.
In comparison with previous situations, many transformations were observed in biodiversity and spatial distribution of the
dominant communities. Thus,Cymodocea nodosa andZostera beds, which dominated in the 1970s, were replaced byZostera andCaulerpa prolifera in the 1980s and are currently succeeded byRuppia cirrhosa andCladophora.
Restoration of the Ghar El Melh lagoon will enable an increase in the exchange with the open sea and the circulation of water,
in particular in the confined zones. This should considerably improve the water quality and would positively influence the
phytobenthic communities. 相似文献
12.
A test of elemental defence against slugs by Ni in hyperaccumulator and non-hyperaccumulator Streptanthus species 总被引:2,自引:0,他引:2
Summary. Tissues of most plant species contain < 10 μg Ni g−1 but Ni hyperaccumulators contain more than 1000 μg Ni g−1 . Hyperaccumulated Ni can defend plants from some herbivores but the defensive role of lesser Ni concentrations is little explored. We raised five species of Streptanthus (Brassicaceae) native to ultramafic soils, one of which (S. polygaloides) is a Ni hyperaccumulator whereas the others are simply Ni-tolerant, on Ni-amended and unamended green-house soils to create plants differing in Ni concentrations. On high-Ni soil, leaves of the hyperaccumulator contained 3800 μg Ni g−1 whereas leaves of non-hyperaccumulator species contained 41–64 μg Ni g−1. Plants of all species grown on low-Ni soils had < 14 μg Ni g−1. Slugs (Limax maximus) were fed plant material in no-choice tests over a 50-day period and survival and mass changes were recorded. All slugs fed high-Ni leaves of the hyperaccumulator species died within 21 d. Slugs fed high-Ni leaves of the other species did not differ significantly in survival or mass change from those fed low-Ni leaves. In choice tests, slugs (Lehmannia valentiana) offered both high- and low-Ni S. polygaloides leaves did little damage to high-Ni leaves. We conclude that hyperacumulated Ni can defend S. polygaloides from slug herbivory via both toxicity and deterrence, but these defensive effects do not extend to Streptanthus species containing < 70 μg Ni g−1. 相似文献
13.
A temperature-dependent growth model is presented for nauplii and copepodites of the estuarine calanoid copepod Acartia tonsa from southern Europe (Portugal). Development was followed from egg to adult in the laboratory at four temperatures (10, 15, 18 and 22°C) and under saturating food conditions (>1,000 μg C l−1). Development times versus incubation temperature were fitted to a Belehradek’s function, showing that development times decreased with increasing incubation temperature: at 10°C, A. tonsa need 40.3 days to reach adult stage, decreasing to 8.9 days when reared at 22°C. ANCOVA (homogeneity of slopes) showed that temperature (P<0.001) and growth phase (P<0.01) had a significant effect on the growth rate. Over the range of temperatures tested in this study, highest weight-specific growth rates were found during naupliar development (NI–NVI) and varied from 0.185 day−1 (10°C) to 0.880 day−1 (22°C) with a Q
10 equal to 3.66. During copepodite growth (CI–CV), the weight-specific growth rates ranged from 0.125 day−1 (10°C) to 0.488 day−1 (22°C) with a Q
10 equal to 3.12. The weight-specific growth rates (g) followed temperature (T) by a linear relationship and described as ln g=−2.962+0.130 T (r
2=0.99, P<0.001) for naupliar stages and ln g=−3.134+0.114T (r
2=0.97, P<0.001) for copepodite stages. By comparing in situ growth rates (juvenile growth and fecundity) for A. tonsa taken from the literature with the temperature-dependent growth model defined here we suggest that the adult females of A. tonsa are more frequently food limited than juveniles. 相似文献
14.
Carlos Rosas Gerard Cuzon Cristina Pascual Gabriela Gaxiola Darwin Chay Nelda López Teresita Maldonado Pedro M. Domingues 《Marine Biology》2007,152(2):371-381
The present study was designed to evaluate the effect of a natural prey (the crab Callinectes sp.) and an artificial diet (pellet with squid paste and offered as a paste) on the survival and assimilation efficiency
of subadult octopuses with 486 g of initial live weight. In order to reach this goal, the effects of the type of diet on energetic
balance were assessed by recording ingestion rate (C), respiratory rate (R = R routine, R
rout + R apparent heat increment, R
AHI), ammonia production rate (U = U routine, U
rout + U post-prandial, U
PP) and biomass production (P) of Octopus maya during its growing process. Energy lost from faeces (H) was calculated as H=C−(U+R+P) and assimilated energy (As) as R + P. Octopuses fed an artificial diet had almost five times higher ingestion rate compared to that observed in octopuses fed
crab. However, growth rate and production (P) were high in octopuses fed crab in comparison to octopuses fed artificial diet. An inverse relation between faeces (H) and type of food was observed, indicating that animals lost 77% of the ingested energy when fed artificial diet and only
5% when fed crab. A higher assimilation and production efficiency were obtained in octopuses fed crab (P/As: 61%) than in animals fed the artificial diet (P/As: −5%). The routine O : N ratio for animals in fasting was 9.1 and 2.3 for octopuses being fed crabs and the artificial
diet, respectively. The post-alimentary O : N ratio was 3.6 and 2.2 for animals fed crabs and the artificial diet, respectively.
This indicates that animals fed on both diets rely almost exclusively on protein. Based on energy balance data, a value of
472 kJ week−1 kg−1 of live octopus was estimated as the energy needed to obtain a growth rate near 9 g day−1 (2.8% BW day−1) for O. maya subadults. The total crab biomass needed to obtain 1 kg of fed O. maya biomass was calculated. A comparison with other different energy balance measurements made in other octopus species indicates
that O. maya and Enteroctopus megalocyathus (Pérez et al. 2006) tend to be more efficient by channelling more ingested energy to biomass production (P = 69.5% of C) than O. vulgaris (P = 23% of C; Petza et al. 2006) or Paraledone charcoti (P = 4% of C; Daly and Peck 2000). 相似文献
15.
Chattonella marina, a raphidophycean flagellate, is a highly toxic red tide phytoplankton which causes severe damage to fish farming. Recent
studies demonstrated that Chattonella spp. continuously release superoxide anions (O2
−) while they are living. Heterosigma akashiwo, another raphidophycean flagellate, also produces O2
−. In the present study, we found that lectins such as concanavalin A (Con A), wheat germ agglutinin (WGA), and castor bean
hemagglutinin (CBH) stimulated C. marina and H. akashiwo to generate enhanced amounts of O2
− in a concentration-dependent manner. The lectin-specific sugars potently inhibited the lectin-induced increase of O2
− production, suggesting that the effects of lectins are mediated mainly through the interaction of these lectins with carbohydrate
moiety present on the flagellate cell surface. In contrast to the potent ability of native Con A (tetravalent), succinylated
Con A (divalent) showed only a slight stimulative effect on these flagellates. O2
− production was totally inhibited by treatment with proteinase K for 30 min, without affecting the viabilities of flagellates.
These results suggest that cell-surface redox enzymes may be involved in O2
− production, and such enzymes are responsible for the lectin-stimulation.
Received: 21 August 1997 / Accepted: 8 January 1998 相似文献
16.
为评价杀菌剂戊唑醇对水生生态系统的影响,以斑马鱼(Brachydanio rerio)为试验生物,采用半静态法分别研究了戊唑醇原药和其6种不同剂型对斑马鱼的急性毒性以及戊唑醇原药对斑马鱼的生物富集效应。结果表明:97.4%戊唑醇原药、25%戊唑醇水乳剂、430 g·L-1戊唑醇悬浮剂、25%戊唑醇可湿性粉剂、80 g·L-1戊唑醇悬浮种衣剂、250 g·L-1戊唑醇乳油、80%戊唑醇水分散粒剂对斑马鱼96 h-LC50分别为8.73、3.35、6.44、9.68、4.60、0.892和6.81 mg·L-1;选择97.4%戊唑醇原药进行斑马鱼生物富集试验,在9.00×10-2和0.900 mg·L-12个处理浓度下连续暴露8 d,相应的富集系数(BCF8 d)分别为27.7和25.4。根据《化学农药环境安全评价试验准则》毒性划分标准,除250 g·L-1戊唑醇乳油对斑马鱼急性毒性属于高毒,其他剂型均为中毒,且戊唑醇属于中等富集性农药。该研究为戊唑醇田间安全使用提供理论依据。 相似文献
17.
Summary. Polyphagous caterpillars of the giant geometer
Biston robustum resemble the twigs of their respective food
sources in color and shape. Common predatory ants, including
Lasius and
Formica, were often observed to freely prowl directly on caterpillars bodies, even after antennal contact.
This suggests that the cuticular chemicals of the caterpillars
resemble those of the twigs of the foodplants, so we analyzed
both by GC and GC-MS. The chemical compositions
differed among caterpillars fed on a cherry, Prunus yedoensis,
a chinquapin Castanopsis cuspidata, and a camellia Camellia japonica. The cuticular chemicals of the caterpillars
resembled those of their corresponding food sources.
When the caterpillar diets were switched from the cherry to
camellia or chinquapin at the 4th instars, the caterpillars
cuticular chemicals changed after molting to resemble those
of their respective foods. Caterpillars also changed their
cuticular chemicals when they perched on cherry twigs and
fed on camellia or chinquapin leaves, but not when they
perched on camellia or chinquapin twigs and fed on cherry
leaves. The chemical similarities between the caterpillars
and the twigs were due to the digestion of host leaves, which
indicates that this is a diet-induced adaptation. 相似文献
18.
Influence of cadmium accumulation and dietary status on fatty acid composition in two colour forms of shore crabs, Carcinus maenas 总被引:2,自引:0,他引:2
The effects of cadmium exposure and dietary status on cadmium accumulation, fatty acid (FA) content and profiles were investigated
in two colour forms of the shore crab Carcinus maenas. Groups of shore crabs were either starved or fed with blue mussels, Mytilus edulis, during a 40 d exposure period to 2 or 6 μM Cd2+ (as CdCl2). Starved green individuals accumulated more cadmium in haemolymph and hepatopancreas than did red crabs and green crabs
fed during the experiments. In the red colour form, no difference in cadmium accumulation was observed between starved and
fed individuals. In both colour forms, hepatopancreas contained more FA than gills and muscle. The FAs often present in the
largest amounts in the tissues were 16:0, 16:1ω7, 18:1ω7, 18:1ω9, 20:4ω6, 20:5ω3 and 22:6ω3. However, saturated (SAFA) and
mono-unsaturated fatty acids (MUFAs) were dominant in hepatopancreas, whereas poly-unsaturated fatty acids (PUFAs) were dominant
in gills and muscles. At the beginning of the experiment, the total FA content in the hepatopancreas was 111.6 mg g−1 (dry weight) for red crabs and 78.4 mg g−1 for green shore crabs. During the experiment, however, the FA content decreased in red crabs. This decrease was more pronounced
for starved individuals than for fed individuals. Also, the decrease in FA content was more pronounced in crabs exposed to
6 μM cadmium compared to crabs exposed to 2 μM or crabs not exposed to cadmium. No change in FA content was observed in green shore crabs, irrespective of diet and cadmium
exposure. For both colour forms, no change in FA content was observed for gills and muscle. In red crabs, a decrease was observed
for all FAs in the hepatopancreas. This decrease, however, was more pronounced for SAFAs and MUFAs than for PUFAs, indicating
that the metabolism of FAs during starvation and cadmium exposure is selective. The experiments indicate that green colour
forms of shore crabs are more tolerant of natural stress such as starvation and anthropogenic stress, e.g. cadmium exposure,
than are red colour forms of shore crabs.
Received: 23 September 1999 / Accepted: 29 April 2000 相似文献
19.
Jim Hardie Stephen F. Nottingham Glenn W. Dawson Richard Harrington John A. Pickett Lester J. Wadhams 《Chemoecology》1992,3(3-4):113-117
Summary Transparent plastic water traps, baited with the synthetic aphid sex pheromone components (4aS,7S,7aR)-nepetalactone and (1R,4aS,7S,7aR)-nepetalactol or control lures, were placed in four semi-sheltered field sites at a height of 1.1 m. Although males of twenty-one aphid species were collected from the water traps, onlySitobion fragariae (Walker) was abundant. In total, 8 pheromone traps produced 102 males compared with only 10 males in 8 control traps. The sex pheromone released by sexual femaleS. fragariae was identified as the nepetalactone used in the lures. Aphid sex pheromones may be more species-specific than previously thought and the presence of a host plant is not essential for males to locate sexual females. 相似文献
20.
Thomas Eisner Daniel Aneshansley Marta L. del Campo Maria Eisner J. Howard Frank Mark Deyrup 《Chemoecology》2006,16(4):185-189
Summary. Data are presented on the repellency of the spray of a bombardier beetle (Pheropsophus aequinoctialis) to a lycosid spider (Lycosa ceratiola). The secretion is shown to cause the spider to desist from its assault on the beetle within, on average, 58 ms of onset
of the beetle’s secretory emission, a reaction time that is at a par with latencies previously reported for startle, escape,
and avoidance reactions of cockroaches, flies, and moths. Spray ejections by the beetle, are shorter in duration (43 ms, on
average) than the response time of the spider, an indication that the beetle does indeed pack a formidable “punch” into its
ejection. After being hit by a beetle’s spray, L. ceratiola were found occasionally to autotomize one or two of their legs. It is argued, but not proven, that this unusually severe
effect from exposure to an arthropodan defensive secretion may be caused by the high temperature of the bombardier beetle
spray. 相似文献