Factors affecting spider prey selection by Sceliphron mud-dauber wasps (Hymenoptera: Sphecidae) in northern Italy

2007 ◽  
Vol 57 (1) ◽  
pp. 11-28 ◽  
Author(s):  
Matteo Federici ◽  
Carlo Polidori ◽  
Carlo Pesarini ◽  
Francesco Andrietti
Keyword(s):  
Prey Availability ◽  
Prey Selection ◽  
Northern Italy ◽  
Generalist Predators ◽  
Factors Affecting ◽  
The Family ◽  
Orb Web ◽  
Males And Females ◽  
Orb Web Spiders ◽  
Wasp Nests

AbstractPredatory habits of apoid wasps are well documented for many species, revealing a choice of prey ranging from generalist to specialised, but few studies tested the degree of specialisation when compared with the availability of prey in the environment. In a study carried out in northern Italy, nests of the mud-dauber wasps Sceliphron spirifex L. and S. caementarium Drury were collected to obtain the spider prey of the wasps, and a survey of the nesting area was performed to ascertain frequency of the available spider prey species in the environment. Wasps preyed preferably upon spiders of the family Araneidae. Adult preferred spider prey size ranged from 4 to 6 mm in length. The factor which most affected prey selection was the ecology of the spiders, with orb-web spiders being the preferred prey despite the fact that terricolous, non-web groups were the most abundant in the locality. Sex (female, male or juvenile) of prey was also important in prey selection: juvenile spiders were the most preferred even though males and females were equally and most abundant (respectively). Sceliphron spp. seem almost to be specialised rather than generalist predators. These results suggest that the terms 'generalist' or 'specialised' should not be applied to predators solely on the basis of prey collected from wasp nests, but should also be related to local prey availability.

The dynamics of prey selection by the trap-building predator Gasteracantha hasselti

2020 ◽  
Vol 36 (3) ◽  
pp. 87-93
Author(s):  
Radek Michalko ◽  
Ondřej Košulič ◽  
Venus Saksongmuang ◽  
Prasit Wongprom ◽  
Prapinya Siripaiboon ◽  
...  
Keyword(s):  
Prey Availability ◽  
Prey Selection ◽  
Prey Type ◽  
Generalist Predators ◽  
Dynamic Component ◽  
Tropical Lowland ◽  
North Eastern ◽  
Lowland Forests ◽  
Dynamic Components ◽  
Relative Selectivity

AbstractPrey selection by generalist predators can be highly dynamic depending on the prey community structure. However, the dynamics of prey selection at the stage of prey entrapping are rarely investigated in trap-building predators, probably because their traps have been previously considered to intercept mobile prey proportionally to its availability in environment. Here we investigated the dynamics of prey selection by the orb-weaving spider Gasteracantha hasselti (Araneidae) depending on the composition of the available prey in tropical lowland forests located in north-eastern Thailand. We found that Gasteracantha captured a wide variety of prey but selected, on average, mostly Coleoptera and Diptera. The selectivity of Gasteracantha’s webs for Coleoptera was constant across the changes in overall prey availability and prey composition. The web selectivity for Hemiptera decreased rapidly with increasing relative densities of Hemiptera in the environment. The selectivity for Diptera and Hymenoptera increased and decreased, respectively, with their absolute densities in the environment. The relative selectivity of Gasteracantha’s traps for a particular prey type was driven by the presence and density of the highly selected prey rather than overall prey density. The results show that the selectivity of Gasteracantha’s traps for prey had both fixed and dynamic components and the dynamic component was determined by the relative as well as absolute densities of the particular prey types in the environment.

The Control of Dragline Spinning in the Garden Spider

1962 ◽  
Vol s3-103 (64) ◽  
pp. 557-571
Author(s):  
R. S. WILSON
Keyword(s):  
Control Valve ◽  
Experimental Results ◽  
Abdominal Pressure ◽  
Silk Thread ◽  
Smooth Control ◽  
Factors Affecting ◽  
Orb Web ◽  
Araneus Diadematus ◽  
Orb Web Spiders

A study of the tarsal claws, the spinning apparatus, and other factors affecting dragline spinning has been made using certain orb-web spiders, principally Araneus diadematus. The structure of the tarsal claws suggests that they are incapable of smoothly controlling the speed at which the silk thread is extracted, although they can grip and release the thread quickly. Evidence is presented that smooth control of spinning is achieved through the interaction of the intra-abdominal pressure and the control valve which lies in the silk duct. The intra-abdominal pressure is shown to be equivalent to from 3 to 4 cm of mercury, and to be responsible for moving the fluid silk out of the gland and up the duct. The experimental results also suggest that the control valve regulates the amount of fluid silk available for spinning as a thread and that it also acts as the functional spinning orifice, its aperture controlling the diameter of the thread spun.

The sensitivity of Australian animals to 1080 poison. I. Intraspecific variation and factors affecting acute toxicity

1981 ◽  
Vol 8 (2) ◽  
pp. 369 ◽  
Author(s):  
J. C. Mcilroy
Keyword(s):  
Acute Toxicity ◽  
Intraspecific Variation ◽  
Factors Affecting ◽  
Eastern Australia ◽  
Vertebrate Pests ◽  
Breeding Condition ◽  
Different Populations ◽  
Males And Females

The calculated sensitivity (LD50) of a species to 1080 poison (sodium fluoroacetate), used for control of vertebrate pests, is affected by the experimental procedures employed. Variation can be minimized if the most obvious sources are avoided, as described in this paper. Very young mammals and female waterfowl in breeding condition may be more sensitive to 1080 than other members of their populations. No other substantial differences in sensitivity were found between males and females, immatures and adults, or within and between different populations of six species of birds and mammals in eastern Australia.

scholarly journals Ecological preference of the diving bell spider Argyroneta aquatica in a resurgence of the Po plain (Northern Italy) (Araneae: Cybaeidae)

2016 ◽  
Vol 48 (1) ◽  
pp. 9 ◽  
Author(s):  
Stefano Mammola ◽  
Riccardo Cavalcante ◽  
Marco Isaia
Keyword(s):  
Ecological Study ◽  
Aquatic Vegetation ◽  
Linear Models ◽  
Prey Availability ◽  
Ecological Factors ◽  
Northern Italy ◽  
Aquatic Life ◽  
Po Plain ◽  
Ecological Importance ◽  
Positive Effect

The diving bell spider <em>Argyroneta aquatica</em> is the only known spider to conduct a wholly aquatic life. For this reason, it has been the object of an array of studies concerning different aspects of its peculiar biology such as reproductive behavior and sexual dimorphism, physiology, genetic and silk. On the other hand, besides some empirical observations, the autoecology of this spider is widely understudied. We conducted an ecological study in a resurgence located in the Po Plain (Northern Italy, Province of Vercelli) hosting a relatively rich population of <em>Argyroneta</em> <em>aquatica</em>, aiming at identifying the ecological factors driving its presence at the micro-habitat level. By means of a specific sampling methodology, we acquired distributional data of the spiders in the study area and monitored physical-chemical and habitat structure parameters at each plot. We analyzed the data through Bernoulli Generalized Linear Models (GLM). Results pointed out a significant positive effect of the presence of aquatic vegetation in the plot. In addition, the presence of <em>A. aquatica</em> was significantly associated with areas of the resurgence characterized at the same time by high prey availability and low density of predators. Considering the ecological importance and rarity of this species, we update and revise the data on the distribution of <em>A. aquatica</em> in Italy.

Factors Affecting Personal Space toward a Group

1977 ◽  
Vol 45 (3) ◽  
pp. 735-743 ◽  
Author(s):  
Darhl M. Pedersen
Keyword(s):  
Group Size ◽  
Significant Interaction ◽  
Personal Space ◽  
Target Person ◽  
Target Groups ◽  
Factors Affecting ◽  
Face To Face ◽  
Main Effect ◽  
Males And Females ◽  
Left Target

The personal space of 160 males and 160 females was measured relative to target groups whose characteristics varied in size (1, 2, 3, 4), type of person (men, women, boy, and girl), and direction of orientation (right, front, left). Two analyses of variance were completed: (a) sex of subject × type of target person × group size × direction of facing and (b) sex of subject × direction of facing of right target × direction of facing of left target person × man-woman composition. Personal space was smaller toward groups not containing a man than for those containing a man, for groups of children than adults when approaching face to face, for groups of females than males when approaching from behind, for groups facing away than for groups facing at right angles than for groups facing toward. Although group size was involved in a significant interaction with type of person and direction of facing, it did not produce a significant main effect. Sex of subject also was not significant, showing that males and females exhibited generic social schemas in personal spacing toward groups.

Web characteristics determine niche partitioning for orb-web spiders (Araneae, Tetragnathidae) in Malaysia

2017 ◽  
Vol 51 (3) ◽  
pp. 262-275 ◽  
Author(s):  
Dzulhelmi Muhammad Nasir ◽  
Thary Gazi Goh ◽  
Asraf Bakri ◽  
Faszly Rahim ◽  
Zulqarnain Mohamed ◽  
...  
Keyword(s):  
Niche Partitioning ◽  
Orb Web ◽  
Orb Web Spiders

scholarly journals First Report of Powdery Mildew Caused by Erysiphe aquilegiae var. aquilegiae on Aquilegia flabellata in Italy

Plant Disease ◽  
2004 ◽  
Vol 88 (6) ◽  
pp. 681-681
Author(s):  
A. Garibaldi ◽  
D. Bertetti ◽  
M. L. Gullino
Keyword(s):  
United States ◽  
Powdery Mildew ◽  
The United States ◽  
Northern Italy ◽  
American Phytopathological Society ◽  
First Report ◽  
Powdery Mildews ◽  
The Family ◽  
White Mycelium ◽  
The University

Aquilegia flabellata Sieb. and Zucc. (columbine) is a perennial garden species belonging to the family Ranunculaceae. During the summer of 2003, a severe outbreak of a previously unknown powdery mildew was observed in several gardens near Biella (northern Italy). Upper surfaces of leaves were covered with a white mycelium and conidia, and as the disease progressed infected leaves turned yellow and died. Foot cell was cylindric and appressorium lobed. Conidia were hyaline, ellipsoid, and measured 31.2 to 47.5 × 14.4 to 33 μm (average 38.6 × 21.6 μm). Fibrosin bodies were not present. Cleistothecia were globose, brown, had simple appendages, ranged from 82 to 127 (average 105) μm in diameter, and contained one to two asci. Ascocarp appendages measured five to eight times the ascocarp diameter. Asci were cylindrical (ovoidal) and measured 45.3 to 58.2 × 30.4 to 40.2 μm. Ascospores (three to four per ascus) were ellipsoid or cylindrical and measured 28.3 to 31.0 × 14.0 to 15.0 μ;m. On the basis of its morphology, the pathogen was identified as Erysiphe aquilegiae var. aquilegiae (1). Pathogenicity was confirmed by gently pressing diseased leaves onto leaves of five, healthy A. flabellata plants. Five noninoculated plants served as controls. Inoculated and noninoculated plants were maintained in a garden where temperatures ranged between 20 and 30°C. After 10 days, typical powdery mildew symptoms developed on inoculated plants. Noninoculated plants did not show symptoms. To our knowledge, this is the first report of the presence of powdery mildew on Aquilegia flabellata in Italy. E. communis (Wallr.) Link and E. polygoni DC. were reported on several species of Aquilegia in the United States (2), while E. aquilegiae var. aquilegiae was previously observed on A. flabellata in Japan and the former Union of Soviet Socialist Republics (3). Specimens of this disease are available at the DIVAPRA Collection at the University of Torino. References: (1) U. Braun. Nova Hedwigia, 89:700, 1987. (2) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St Paul, MN, 1989. (3) K. Hirata. Host Range and Geographical Distribution of the Powdery Mildews. Faculty of Agriculture, Niigata University, 1966.

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