Tephritid pests controlled through the sterile insect technique (SIT) are mass-reared and subsequently released in affected areas. Several quality parameters are currently used to test adults, but none take into account interactions with a predator. When sterile males are released in the field, they will need to avoid predators until they reach sexual maturity and survive long enough to mate with wild females. Spiders are one of the most common predators that flies may encounter in release sites. In this study, we evaluated the antipredator behavior of a mass-reared sterile unisexual strain (‘Tapachula-7’) of the Mexican fruit fly Anastrepha ludens (Diptera: Tephritidae) against their spider predators. We sampled spiders in citrus trees to determine which families could be more common. We established the baseline activity rates of sterile Tapachula-7 (Tap-7) flies in comparison with wild flies. We also tested the behavior of the fertile and sterile bisexual strain and wild flies against hunting spiders (Family Salticidae) and orb building spiders (Family Tetragnathidae). We recorded 18 spider families, with Salticidae being the most dominant. Tap-7 flies diminished their activity in comparison with wild males at 1800 h but showed similar activity levels earlier in the day. When exposed to orb-web spiders (Leucauge venusta), Tap-7, fertile and sterile males from the bisexual strain had similar rates of survival, but Tap-7 males showed lower survival than wild males. Against hunting spiders (Phidippus audax), wild males had higher probability of defensive wing displays, but there was no difference in spider attack rates. In general, sterile Tap -7 males performed as well as males from the bisexual strain, although they had lower survival than wild males. This could be due to either mass-rearing and/or irradiation effects. We recommend the use of the defensive wing display behavior as a quality parameter and propose a rapid and effective method to evaluate fly activity. The efficiency of SIT will be improved if released sterile males have the same antipredator repertoire as their wild counterparts.

Let $G$ be a simple algebraic group. Labelled trivalent graphs called webs can be used to produce invariants in tensor products of minuscule representations. For each web, we construct a configuration space of points in the affine Grassmannian. Via the geometric Satake correspondence, we relate these configuration spaces to the invariant vectors coming from webs. In the case of $G= \mathrm{SL} (3)$, non-elliptic webs yield a basis for the invariant spaces. The non-elliptic condition, which is equivalent to the condition that the dual diskoid of the web is $\mathrm{CAT} (0)$, is explained by the fact that affine buildings are $\mathrm{CAT} (0)$.

Activity of 12 beneficial invertebrate groups was assessed in 2005 and 2006 on a farm in northern England split into conventional and organic management halves, using pitfall and pan traps set in both crops and field boundaries. Management, crop and boundary structure influences on invertebrate activity were assessed, as was the relationship between crop and boundary type. Classification of crop and boundary assemblages produced three and two groups, respectively, in both years. Organic arable crops had well-defined assemblages in both years; and, while grass and grass/clover fields were separated from conventional arable fields in 2005, there was mixing in 2006. One boundary group, in both years, was dominated by conventional arable fields with tall herbaceous boundary vegetation. The other group had more organic arable and grassy fields with shorter boundary vegetation. Redundancy analyses showed that a number of groups (Cantharidae, Coccinellidae, Syrphidae, Ichneumonidae, Braconidae, Proctotrupoidea, Lycosidae) were more active in organic arable fields with more Staphylinidae in conventional arable crops and no obvious trend with Carabidae, Hemiptera, Neuroptera and Linyphiidae. Activity of some groups, especially Coccinellidae, Syrphidae and parasitic wasps, was strongly related to weed cover. Staphylinidae were most active in tall herbaceous boundaries by conventional arable crops with more of a number of groups (Cantharidae, Coccinellidae, parasitic wasps) in short herbaceous boundaries by organic arable crops. Organic management produced most differences in aerially-dispersed invertebrates, and management had a profound effect on activity in field boundaries. Possible management prescriptions to increase invertebrate activity include changing sowing times, weed cover manipulation and field boundary and margin management.

Spiders from 10 rainforest tree canopies in Borneo were sampled by knockdown insecticide fogging. Spider density ranged from 2.0 to 10.1 m−2 on different trees, and species numbers ranged from 16 to 62; species diversity, as measured by William's α, ranged from 26 to 92. Similarity of the spider assemblages on individual trees was low, whether measured by the number of shared species or the Morisita-Horn index of similarity.

The contribution of five descriptor variables of tree taxonomy and structure to the similarity of the spider assemblages on different trees was assessed using stepwise multiple regression. No variable made a significant contribution to the variation in similarity indices for the spider assemblages and it was concluded that either other factors were important in determining similarity or that the measurement of these variables was too imprecise. In particular, there was no evidence that taxonomic similarity between tree species influenced the similarity of spider assemblages.

Results were compared with similar data from tropical and sub-tropical rainforests in Sulawesi and Australia. Species densities in Borneo and Sulawesi were similar but lower than in Australia. Species richness and diversity were markedly higher in the Bornean rainforest than in Sulawesi or Australia.

Spiders were sampled by knockdown insecticide fogging from the canopies of tropical rainforest sites in Dumoga-Bone National Park, Sulawesi, at altitudes of 210 m, 300 m, 400 m and 1150 m. The density of spiders in the canopies increased with altitude from 0.97 m−2 at 210 m to 14.6 at 1150 m−2. Species numbers increased five-fold between 210 m and 1150 m but species diversity (α of the log series) was greatest at 210 m and least at 1150 m, partially due to dominance of the fauna by few species at the highest altitude. Similarity between the spiders' communities (as measured by the Morisita-Horn index) was greatest between canopies at 300 m and 400 m and least at 400 m and 1150 m.

Theridiidae were abundant in forests at all altitudes, Pholcidae and Salticidae in the lowland forests between 210 m and 400 m and Clubionidae, Linyphiidae and Oonopidae in the montane forest at 1150 m. Theridiidae was the most species-rich family at all altitudes (22−30% of all species). Other species-rich families included Araneidae (7−19%) and Salticidae (8−17%) in lowland forests and Clubionidae (12%), Oonopidae (10%) and Salticidae (12%) in the montane forest.

Published information on density, proportion and diversity of spiders in canopies of both tropical and temperate trees is reviewed and the results discussed in relation to those from the present study.

Although the effects of nutrient enhancement on aquatic systems are well documented, the consequences of nutritional supplements on soil food webs are poorly understood, and results of past research examining bottom-up effects are often conflicting. In addition, many studies have failed to separate the effects of nutrient enrichment and the physical effects of adding organic matter. In this field study, we hypothesised that the addition of nitrogen to soil would result in a trophic cascade, through detritivores (Collembola) to predators (spiders), increasing invertebrate numbers and diversity.

Nitrogen and lime were added to plots in an upland grassland in a randomised block design. Populations of Collembola and spiders were sampled by means of pitfall traps and identified to species.

Seventeen species of Collembola were identified from the nitrogen plus lime (N+L) and control plots. Species assemblage, diversity, richness, evenness and total number were not affected by nutrient additions. However, there was an increase in the number of Isotomidae juveniles and Parisotoma anglicana trapped in the N+L plots.

Of the 44 spider species identified, over 80% were Linyphiidae. An effect on species assemblage from the addition of N+L to the plots was observed on two of the four sampling dates (July 2002 and June 2003). The linyphiid, Oedothorax retusus, was the only species significantly affected by the treatments and was more likely to be trapped in the control plots.

The increased number of juvenile Collembola, and change in community composition of spiders, were consequences of the bottom-up effect caused by nutrient inputs. However, despite efforts to eliminate the indirect effects of nutrient inputs, a reduction in soil moisture in the N+L plots cannot be eliminated as a cause of the invertebrate population changes observed. Even so, this experiment was not confounded by the physical effects of habitat structure reported in most previous studies. It provides evidence of moderate bottom-up influences of epigeic soil invertebrate food webs and distinguishes between nutrient addition and plant physical structure effects. It also emphasises the importance of understanding the effects of soil management practices on soil biodiversity, which is under increasing pressure from land development and food production.

We consider an ecosystem in whichspiders may be transported by the wind from vineyards into thesurrounding woods and vice versa. The model takes into accountthis tranport phenomenon without building space explicitly intothe governing equations. The equilibria of the dynamical systemare analyzed together with their stability, showing thatbifurcations may occur. Then the effects of indiscriminatedspraying to keep pests under control is also investigated viasuitable simulations.

To monitor the biodiversity quality of rainforest fragments in the eastern region of the Ivory Coast, the density of at least one important invertebrate group needs to be determined. This has been possible for nocturnal hunting spiders from the family Ctenidae using a novel combination of sampling and census techniques. The reflective characteristics of the eyes of these spiders meant that individuals were readily located using headlamps. Collections were made along transects (total length 5.5 km), adopting a distance sampling protocol. Density was estimated using distance sampling models. More than 2600 ctenids (15 species) were captured and identified. Seven of these species were present in sufficient numbers for density assessment. The combined density of these seven most common species in degraded forest fragments (0.124 m−2) was only half that in less disturbed forest (0.240 m−2). Ctenidae are a promising candidate for future monitoring of invertebrate groups in the rainforest.

The renaissance of interest in sexual selection during the last decades has fuelled an extraordinary increase of scientific papers on the subject in spiders. Research has focused both on the process of sexual selection itself, for example on the signals and various modalities involved, and on the patterns, that is the outcome of mate choice and competition depending on certain parameters. Sexual selection has most clearly been demonstrated in cases involving visual and acoustical signals but most spiders are myopic and mute, relying rather on vibrations, chemical and tactile stimuli. This review argues that research has been biased towards modalities that are relatively easily accessible to the human observer. Circumstantial and comparative evidence indicates that sexual selection working via substrate-borne vibrations and tactile as well as chemical stimuli may be common and widespread in spiders. Pattern-oriented research has focused on several phenomena for which spiders offer excellent model objects, like sexual size dimorphism, nuptial feeding, sexual cannibalism, and sperm competition. The accumulating evidence argues for a highly complex set of explanations for seemingly uniform patterns like size dimorphism and sexual cannibalism. Sexual selection appears involved as well as natural selection and mechanisms that are adaptive in other contexts only. Sperm competition has resulted in a plethora of morphological and behavioural adaptations, and simplistic models like those linking reproductive morphology with behaviour and sperm priority patterns in a straightforward way are being replaced by complex models involving an array of parameters. Male mating costs are increasingly being documented in spiders, and sexual selection by male mate choice is discussed as a potential result. Research on sexual selection in spiders has come a long way since Darwin, whose spider examples are reanalysed in the context of contemporary knowledge, but the same biases and methodological constraints have persisted almost unchanged through the current boom of research.

Many orb-web building spiders add conspicuous, white silk decorations termed stabilimenta onto the central portion of the webs. Stabilimenta are known to vary greatly in form and quantity from species to species, and also within a species. In the present study, stabilimentum variations in form and quantity are described, and the factors influencing stabilimentum variations in Argiope versicolor from Singapore, in both the field and the laboratory, are examined. Our results from field survey and laboratory experiments show that: (1) the form and occurrence of stabilimenta varied with developmental stage of spiders: A. versicolor juveniles (body length: < 0.6 cm) built disc-like (discoid) stabilimenta while adults spun cross-like (cruciform) stabilimenta; (2) the quantity of stabilimenta (percentage of stabilimentum area covering the web to the web area) decreased with increasing web size and spider size; (3) light intensity affected the density and percentage cover of stabilimentum on the web: A. versicolor tend to build more and denser stabilimenta in dim conditions than in bright surroundings; (4) well-fed A. versicolor adults added more stabilimenta than starved spiders. These findings suggest that A. versicolor may adjust the frequency and quantity of stabilimenta to suit multiple functions, specifying the circumstances under which to use each function (conditional stabilimentum-building strategies).

The arthropod fauna inhabiting 90 individuals of three different species of epiphyte was investigated in the moist lowland forest of the Barro Colorado National Monument in Panama. In total, 3694 arthropods belonging to 89 morphospecies and 19 orders were collected. While arthropod abundance was primarily a function of host plant biomass irrespective of epiphyte species, there were pronounced differences in species richness, species composition and guild structure of the arthropod faunas of the three epiphyte species. Although all study plants were growing in close proximity on the same host tree species, there was remarkably little overlap in the species assemblages across epiphyte taxa. The inhabitant species also differed dramatically in their ecological functions, as feeding guild and hunting guild analyses indicated. The influence of plant size, structure and impounded leaf litter on arthropod diversity is discussed. We conclude that epiphytes are microhabitats for a diverse and numerous fauna, and that different species of epiphytes foster both taxonomically and ecologically very distinct arthropod assemblages.

Portia fimbriata from Queensland, Australia, is an araneophagic jumping spider (Salticidae) that includes in its predatory strategy a tactic (cryptic stalking) enabling it to prey effectively on common sympatric salticids from other genera. Using standardized tests in which only optical cues were available (prey enclosed in small glass vial within large cage), the reactions of P. fimbriata to 114 salticid species were investigated. Except for Myrmarachne spp. (ant mimics), all salticids tested triggered cryptic stalking by P. fimbriata. This included not only sympatric, but also allopatric, salticids. The salticid on which P. fimbriata most commonly preys in nature is Jacksonoides queenslandicus, but cryptic stalking was triggered by salticid species with considerably different appearances, including beetle mimics, species with unusual body shapes and species with a wide variety of camouflaging markings. Portia fimbriata was also tested with lycosid, clubionid, theridiid and desid spiders and with flies and ants, but none of these arthropods triggered cryptic stalking. Optical cues used by P. fimbriata for discrimination between salticid and non-salticid prey are discussed.

Both intensity and type of habitat management in grasslands and heathlands affect spider communities. With high intensity management, spider communities often lack diversity and are dominated by a few r-selected species affiliated with bare ground. Low intensity management produces more complex communities introducing more niches for aerial web spinners and climbing spiders. The preferred management will be site-dependent and may not be appropriate for all spiders in all situations, particularly for some rare or threatened species. Providing natural cover is recommended when using extreme forms of management or intensive grazing (particularly by sheep). In extreme cases, or where trampling is heavy, the litter layer should be conserved. We advocate research and survey before and after major management implementation. Habitat management for spiders should not be considered alone, but integrated into a holistic plan. Management for spiders may conflict with rare plant conservation and small reserves should examine the viability of providing two contrasting regimes.

Pitfall-trap sampling was used to determine the activity (numbers collected as determined by locomotor activity and density) of epigaeic (soil-surface dwelling) arthropods in rice cultivated at various toposequence sites on the slope of an inland valley in Bouaké, Côte d'Ivoire, West Africa in 1994–1996. The major arthropod groups collected were ants, spiders, crickets, carabids and grasshoppers. Ants and spiders were the most active. Arthropod activity changed in response to crop growth stage with activity generally increasing towards harvest. Ant activity differed significantly between toposequence sites and was highest in the upper portion of the slope. The pattern for spider activity in relation to toposequence site varied among years. Agronomic practices that would enhance the populations of ground-dwelling predaceous arthropods are an important consideration when developing cultural practices for rice production on hillsides of inland valleys in West Africa.

A 2-year study was conducted to determine the abundance of rice arthropods as affected by weeding regimes and toposequence sites, from upland to lowland, in an inland valley in Côte d'Ivoire, West Africa. Toposequence site had an effect on insect populations. Most insects were found in the moist, lower portion of the slope (hydromorphic or phreatic zone) and in the valley bottom (irrigated lowland). Among these were the white leafhoppers Cofana spectra and C. unimaciilata (Hemiptera: Cicadellidae), the green leafhoppers Nephotettix spp. (Hemiptera: Cicadellidae), and the diopsids Diopsis longicornis and D. apicalis (Diptera: Diopsidae). Stemborer damage was generally most severe in the lowland ecology. Weed dry weights and weed species composition were affected by toposequence site. Cyperns difformis L. was most abundant in the lowland and Digitarla horizontalis Willd. in the upland sites. Weeding regime had an effect on the abundance of insect pests and natural enemies (spiders and damselflies) and on the extent of stemborer damage, the effect varying with toposequence site. Implications of the results for the integrated management of weeds and insects are discussed.

Argyrodes flavipes illustrates a novel form of highly social behaviour in spiders. Although A. flavipes lives in groups, forages communally, and has parental care, it is also highly aggressive towards conspecifics. These observations, plus the relatively small group sizes, suggest that sociality in these animals may be more akin to that in social mammalian carnivores than in social insects. Most highly social spiders are thought to have developed sociality via the sub-social route because of their high level of parental care. Although A. flavipes also exhibits high levels of parental care, its phylogenetic background and the fact that it needs to defend its young from conspecifics, suggest that both sub-social and para-social factors may have influenced its social development.

A total of 17 species of Hemiptera were collected from sorghum with compact panicles during the 1982 and 1983 cropping seasons at Samaru and Kano, Nigeria. The most important species based on time of appearance and abundance were Eurystyhis rufocunealis, Campylomma angustior and C. subflava. Paramixia suturalisand Taylorilygus vosseleri occurred in high numbers only at Samaru in 1982. Significantly more Orius spp. were collected at Kano. These species represented 95 % of all hemipterans collected.

The number of spiders per panicle were significantly lower at Samaru, up to three per panicle, than at Kano, up to 10 per panicle, in 1983. There was no relationship between the number of spiders and the number of hemipterans at Samaru, but at Kano a significant positive relationship was observed between the number of spiders and the number of immature hemipterans. The spider families Dysderidae, Thomisidae and Salticidae represented 80% of the spiders collected.