Spiders of the families Theridiidae, Tetragnathidae and Araneidae (Arachnida: Araneae) from Aldabra atoll

A total of 36 spider species of the families Theridiidae, Tetragnathidae and Araneidae are recorded from Aldabra atoll. Of these, 26 are described as new, together with one new subspecies. The taxonomy of the new species is discussed and, for comparative purposes, five other species not from Aldabra are illustrated. One new synonymy is established. Records for each species are given with, in some cases, notes on biology. The possible biological significance of the egg sac strings found in some species is considered. Finally, the biogeographical affinities of the Aldabra species are briefly discussed.     

Predation activity of two winter-active spiders (Araneae: Anyphaenidae,Philodromidae)

Anyphaena accentuata and Philodromus spp. are cold adapted and winter-active spider species. Their predation activity was investigated at constant temperatures between –4 and 30 °C. The lower temperature threshold for Anyphaena was –3.7 °C, while that of Philodromus was –1.2 °C. At 1 °C the latency to capture and prey consumption was significantly shorter in Anyphaena than in Philodromus. The capture rate increased with temperature and was maximal at 15 °C in Anyphaena and at 30 °C in Philodromus. At 30 °C, the latency to the capture was significantly shorter in Philodromus than in Anyphaena whose mortality significantly increased.     

How glyphosate altered the behaviour of agrobiont spiders (Araneae: Lycosidae) and beetles (Coleoptera: Carabidae)

Cultivation of herbicide-tolerant strain of GM corn involves applications of a non-selective herbicide. Mortality of arthropod natural enemies resulting from the application of herbicides is negligible. But nothing is known how herbicides affect the behaviour of natural enemies and thus alter their pest control efficacy. Aim of the study was to assess the effect of the Roundup residues on the predatory, defensive, locomotory and reproductive behaviour of epigeic spiders and carabid beetles. Specimens of Pardosa agricola (Araneae: Lycosidae) and Poecilus cupreus (Coleoptera: Carabidae) were exposed for 2 h to the fresh and 1-day old residues of Roundup Biaktiv (Monsanto, IPA 480 g/l). Predation rate was similar for all treatments in both spiders and beetles. Spiders did not avoid surface treated with herbicide residues more than the control surface, but beetles slightly avoided surface with fresh residues. The speed of locomotion of spiders was not altered by herbicide residues, but beetles exposed to residues crawled at significantly lower speed than the control group. Herbicide residues did not affect the escape efficacy of spiders from a predator. Residues had no detrimental effect on the courtship, mating frequency and duration in spiders. Roundup Bioaktiv thus appears to be harmless to lycosid spiders and only slightly harmful to carabid beetles. The biological control potential of both predators should not be reduced by the application of Roundup Bioaktiv.     

中国转刺蛛属的修订(蜘蛛目:园蛛科)

对中国转刺蛛属Eriophora进行了修订,共记述8种,其中含3个新组合：宝天曼转刺蛛Eriophora baotianmanensis（Hu,Wang＆Wang,1991）和喜马拉稚转刺蛛Ehimalayaensis（Tikader,1975）从园蛛属Araneus移人,杂斑转刺蛛E．poecila（Zhu＆Wang,1994）从扇蛛属历肛n移人;3个新异名：王氏转刺蛛E.wangi Zhu et Song,1994和陕西转刺蛛E.shaanxiensis Zhu et Wang,1994均为宝天曼转刺蛛Ebaotianmanensis（Hu．Wang＆Wang,1991）的异名,松林园蛛A．pineus Yin et a1．,1990为萨哈林转刺蛛E.sachalinensis（Saito．1934）的异名。     

山西痣蛛属1新记录种(蜘蛛目:园蛛科)

报道了产自山西南部痣蛛属1新记录种,即八木氏痣蛛Araniella yaginumai Tanikawa,1995 .     

Low-molecular-weight factors from colonial hydroids affect pattern formation

Summary Two morphogenetic factors have been isolated from tissue of colonial hydroids. Both exert strong effects on pattern formation during metamorphosis, regeneration and colony development. Polyp-inhibiting factor (PIF) is a bivalent inhibitor which strongly affects head and bud formation but acts weakly on stolon branching. Proportion-altering factor (PAF) is a distalizing factor. It counteracts the formation of stolon and promotes the formation of head structures during metamorphosis and regeneration. PIF and PAF antagonistically influence the spatial arrangement of polyps within a colony. They are capable of dislocating structures and thus appear to interfere with or are even part of the pattern-controlling mechanism. Both factors are of low molecular size (about 500 daltons), hydrophilic and probably not peptides.     

Compared chemical properties of dermonecrotic and lethal toxins from spiders of the genusLoxosceles (Araneae)

Loxosceles spider venom usually causes a typical dermonecrotic lesion in bitten patients, but it may also cause systemic effects that may be lethal. Gel filtration on Sephadex G-100 ofLoxosceles gaucho, L. laeta, orL. intermedia spider venoms resulted in three fractions (A, containing higher molecular mass components, B containing intermediate molecular mass components, and C with lower molecular mass components). The dermonecrotic and lethal activities were detected exclusively in fraction A of all three species. Analysis by SDS-PAGE showed that the major protein contained in fraction A has molecular weight approximately 35 kDa inL. gaucho andL. intermedia, but 32 kDa inL. laeta venom. These toxins were isolated from venoms ofL. gaucho, L. laeta, andL. intermedia by SDS-PAGE followed by blotting to PVDF membrane and sequencing. A database search showed a high level of identity between each toxin and a fragment of theL. reclusa (North American spider) toxin. A multiple sequence alignment of theLoxosceles toxins showed many common identical residues in their N-terminal sequences. Identities ranged from 50.0% (L. gaucho andL. reclusa) to 61.1% (L. intermedia andL. reclusa). The purified toxins were also submitted to capillary electrophoresis peptide mapping afterin situ partial hydrolysis of the blotted samples. The results obtained suggest thatL. intermedia protein is more similar toL. laeta toxin thanL. gaucho toxin and revealed a smaller homology betweenL. intermedia andL gaucho. Altogether these findings suggest that the toxins responsible for most important activities of venoms ofLoxosceles species have a molecular mass of 32–35 kDa and are probably homologous proteins.     

Thirteen new species and two new combinations of Stevia (Asteraceae: Eupatorieae) from Mexico

Thirteen new species of the genusStevia are described and illustrated from Mexico:S. chilapensis, S. coahuilensis, S. crassifolia, S. ecatepecana, S. filodecaballoana, S. mascotensis, S. mexicana, S. oaxacana, S. oligophylla, S. potosina, S. rotundifolia, S. scabrelloides, andS. viejoana. In addition, two varieties,Stevia aschenborniana Sch. Bip. ex Klotzsch var.occidentalis Grashoff andS. palmeri A. Gray var.constricta Grashoff are herein redefined as being distinct species,S. occidentalis andS. constricta stat. nov.Stevia mexicana resemblesStevia trifida Lagasca but differs in the habit.     

Three new species of ferns (Woodsiaceae and Polypodiaceae) from Mexico

Three new species of ferns are described from Mexico:Athyrium tripinnatum, Cystopteris millefolia, andPolypodium praetermissum.     

Three new species of mygalomorph and filistatid spiders from Iran (Araneae,Cyrtaucheniidae, Nemesiidae and Filistatidae)

Three new spider species are described from Iran: Anemesia koponeni sp. n. (♂, Cyrtaucheniidae); Raveniola mazandaranica sp. n. (♂, Nemesiidae) and Sahastata sinuspersica sp. n. (♀, Filistatidae). Cyrtaucheniidae and Sahastata Benoit, 1968 are reported from Iran for the fisrt time.     

Impact of predation by spiders on a territorial damselfly (Odonata: Calopterygidae)

Summary Predation by orb-weaving spiders and crab spiders on the damselfly Calopteryx haemorrhoidalis was studied at a small stream in Southern France. One species of orb-weaving spider, Larinioides folium, caught 76% of the damselflies which fell prey to spiders. Displacement experiments on spiders on sections of bank and the positioning of webs in male territories show that the density and distribution of damselflies is not influenced by orbweb density or by the position of webs. Predation rates corresponded to orb-web density, but neither for sex nor for stage was there a relationship with damselfly density. Mean daily predation rates ranged between 0.9% for females and 4.1% for adult males. Predation risk to adult damselflies by orb-weaving spiders was male biased, whereas among tenerals there was no bias. Males were captured more frequently at territories near the water. Captures show a maximum at noon when territorial disputes of adult males were most frequent. After orbwebs were placed within territories predation rate of males was strongly increased. Predation risk to adult females in the direct vicinity of the stream was less than in the bank vegetation where they perch close to orbwebs. The risk of predation by crab spiders, which catch damselflies at their perching sites, was not sex-biased.     

Olfactory response of three parasitoid species (Hymenoptera: Braconidae) to volatiles of guavas infested or not with fruit fly larvae (Diptera: Tephritidae)

The olfactory responses of the native parasitoids Doryctobracon areolatus (Szépligeti) and Asobara anastrephae (Muesebeck) and of the exotic parasitoid Diachasmimorpha longicaudata (Ashmead) to guava (Psidium guajava L.) infested or not with fruit fly larvae were evaluated. D. areolatus and D. longicaudata females responded to the odors of uninfested rotting guavas, although D. areolatus was also attracted to fruits at the initial maturation (turning) stage. The females of these species recognized the volatiles of guavas containing Ceratitis capitata (Wied.) larvae. However, in bioassays involving fruits with larvae of different instars, D. longicaudata females were not able to separate between fruits containing C. capitata larvae at the initial instars and larvae at the third instar. In the evaluations of volatiles released by guavas containing C. capitata and Anastrepha fraterculus (Wied.) larvae, the D. longicaudata females were oriented toward the volatiles of fruits containing both host species, but differed significantly from volatiles of guavas containing C. capitata larvae. The D. areolatus females also showed responses to both species, although with a preference for volatiles of fruits containing A. fraterculus larvae. The A. anastrephae females were oriented toward the odors of fruits infested with both fruit fly species. In the shade house, D. longicaudata females were oriented to volatiles of rotting fruits containing larvae or not, but could not significantly differentiate between hosts. D. areolatus females were not attracted toward fruits on the ground in the shade house, regardless of host, suggesting that this parasitoid does not forage on fallen fruits.     

An organic coating keeps orb‐weaving spiders (Araneae,Araneoidea, Araneidae) from sticking to their own capture threads

More than 95% of orb‐weaving spider species ensure prey capture success by producing viscous threads equipped with gluey droplets. However, this trap may bear serious risks for the web‐inhabiting spider as well. The obvious question, how a spider avoids getting stuck in its own capture spiral, has gained little scientific attention up till now. In 1905, the French naturalist Jean‐Henry Fabre concluded from anecdotal observation that orb‐weaving spiders protect themselves by a fatty surface coating. Here, we test this hypothesis by indirectly measuring the force necessary to detach an autotomized spider’s leg from the capture spiral of its own web (here called ‘index of adhesion’, IOA). Three groups of legs, each of the species Araneus diadematus Clerck, 1757 and Larinioides sclopetarius (Clerck, 1757), were tested. One was left untreated, one was washed with distilled water (H₂O), and one was washed with the organic solvent carbon disulphide (CS₂). In both species, we found a weak IOA between the spider leg and the gluey capture spiral in untreated and water‐washed legs without significant differences between the two. The IOA approximately doubled, when spider legs had been washed with carbon disulphide prior to measurement, that is, the CS₂‐washed legs stuck significantly more strongly than the untreated and water‐washed legs. These results provide indirect evidence for a protective anti‐adhesive organic coating on the spider’s body surface and so support Fabre’s hypothesis.     

Variation in foraging investment during the intermolt interval and before egg-laying in the spiderNephila clavipes (Araneae: Araneidae)

Repeated observations were made of marked, freeliving females in three disjunct populations of the orb-weaving spider Nephila clavipes,recording orb size and structure and barrier web complexity. These longitudinal studies revealed regular patterns of variation in orb size associated with the molting cycle and cycle of egg maturation. Juveniles maintained in an insectary under a controlled feeding regime exhibited similar variation in orb size. All spiders ceased orb renewal prior to molting and the majority replaced the viscid orb with a nonviscid platform prior to molting. Differences among the populations in molting web structure are discussed in light of differences in the physical and biological environments. Cessation of orb renewal corresponded temporally with reported physiological changes associated with the molt cycle and possibly reflect changes in resource partitioning between growth and foraging during the molt cycle.     

Previous experience and site tenacity in the orb spider Nephila (Araneae,Araneidae)

Summary The tenacity of the orb spider Nephila clavipes to a web site was studied in the laboratory. No differences were found between the giving-up-times and the site tenacity of spiders reared in the laboratory or those caught in the field, nor between spiders raised under a poor or a richt diet. The animals left sites at random and seemed to ignore experiences gained at previous sites.     

The protective function of the compact silk nest of social Stegodyphus spiders (Araneae,Eresidae)

Summary This study investigates the suggested protective function of the compact silken nest of two species of social Stegodyphus spiders (S. dumicola and S. mimosarum), as a possible ultimate factor for their sociogenesis. Being inhabitants of African dry thornbush country, these spiders are endangered by overheating and desiccation. In the laboratory, both species were found to avoid temperatures >40° C. In the field, temperature in the nest between 7:00 and 21:00 h tends to be higher than air-temperature outside, and between 13:00 and 15:00 h even tends to exceed 40° C. The nest thus is of no value in temperature regulation. Nor is it effective in protecting the spiders from desiccation: Both species have a body water content of 65.2±3.8% and are extremely desiccation resistant; they survived 9 days at 37°C in an exciccator with P₂O₅, with a daily average % liveweight reduction of 4.94(±1.1). In the field, relative humidity inside the nest between 11:00 and 19:00 h tends to be lower than that of the air outside. Inspection of burnt areas showed that the nest does not protect the spiders from bushfire. The nest does protect from wind, hail, and direct sun-radiation; but available natural retreats, or a simple silken shield, or the funnel-shaped silk tube inhabited by solitary Stegodyphus, have the same effect.     

四种园蛛同工酶的比较研究

本文采用聚丙烯酰胺凝胶电泳的方法,对叶斑园蛛、角类肥蛛(黑、白2种体色)、大腹园蛛、黑斑园蛛4种园蛛科蜘蛛的酯酶(EST)同工酶、乳酸脱氢酶(LDH)同工酶、超氧化物歧化酶(SOD)同工酶进行了比较研究。结果表明,4种园蛛的EST、LDH具有明显的种族特异性,而SOD在种间基本没有差别。不同种蜘蛛都有各自的EST、LDH同工酶谱型,可以用它们作为识别物种的附加指标。     

A 3-year field-scale monitoring of foliage-dwelling spiders (Araneae) in transgenic Bt maize fields and adjacent field margins

Concerns have been raised that genetically modified Bt maize may harm non-target organisms, and there is a general call and need for a risk assessment of Bt maize. Spiders are important pest predators in agroecosystems and in maize, and can be exposed to the Bt toxin by herbivorous or pollen-collecting prey, by active Bt maize pollen feeding, and by ingesting their pollen-dusted webs. The foliage-dwelling spider fauna of Bt maize fields and adjacent margins was monitored and compared to non-transgenic maize fields. The study took place during the vegetation seasons of 2001–2003 in Bavaria, South Germany. Maize fields and adjacent nettle field margins were colonized by a typical spider assemblage, dominated by space-web spiders (Theridiidae and Linyphiidae). Abundance and species richness of spiders was higher in nettle margins than in maize fields. The proportion of hunting spiders tended to be higher in nettle margins, whereas space-web spiders tended to be more frequent in maize fields. Bt maize showed no consistent effect on individual numbers, species richness and guild structure of spiders in maize fields and adjacent nettle field margin strips. The spider abundance was higher in Bt treatments in 2003, whereas in 2001 and 2002 no significant differences were found. The results provide an important contribution for the implementation of case-specific and general surveillance of transgenic plants to be employed due to the regulations of the European Community.