Kleptoparasitic Species Research Articles

Social but not solitary bee abundance tracks pollen protein accumulation in forest canopy gaps

Abstract Forest restoration projects that create canopy gaps can promote floral diversity and may provide reservoirs for bee–flower interactions. However, periods of bee activity must match availability of floral nutrition for bees to benefit from these effects. We model variation in canopy gap size, floral density, pollen protein and bee and floral traits to test the hypothesis that patterns of floral visitation in bee–flower interactions are predicted by patch structure, variation in bee life histories and floral phenotypes. Canopy gap size did not predict overlap of foraging bee abundances and floral protein, but bee life‐history traits did. Foraging activity of large ground‐nesting bees matched accumulation of protein density, whereas activity of small cavity‐nesting bees and kleptoparasitic species preceded peak protein density. Floral visual traits predicted visitation rates, with more interactions for taller species with large floral displays. Both native and invasive species have high nutritional value for bees in canopy gaps and can support frequent and rich interactions. Landscapes with both weedy and native floral species may have higher phenological diversity and provide more foraging opportunities for early‐season bees. We conclude that canopy gap creation is likely to have similar impacts on bee–flower interactions regardless of gap size, but activity periods of larger bees are more aligned with pollen protein density than activity of small bees, and floral visual displays are decoupled from pollen protein content.

Bloodstained flowers and bloodthirsty flies.

This article is a Commentary on Heiduk et al. (2023), 239:1490–1504.

Phylogenomics illuminates the evolution of orb webs, respiratory systems and the biogeographic history of the world’s smallest orb-weaving spiders (Araneae, Araneoidea, Symphytognathoids)

The miniature orb weaving spiders (symphytognathoids) are a group of small spiders (<2 mm), including the smallest adult spider Patu digua (0.37 mm in body length), that have been classified into five families. The species of one of its constituent lineages, the family Anapidae, build a remarkable diversity of webs (ranging from orbs to sheet webs and irregular tangles) and even include a webless kleptoparasitic species. Anapids are also exceptional because of the extraordinary diversity of their respiratory systems. The phylogenetic relationships of symphytognathoid families have been recalcitrant with different classes of data, such as, monophyletic with morphology and its concatenation with Sanger-based six markers, paraphyletic (including a paraphyletic Anapidae) with solely Sanger-based six markers, and polyphyletic with transcriptomes. In this study, we capitalized on a large taxonomic sampling of symphytognathoids, focusing on Anapidae, and using de novo sequenced ultraconserved elements (UCEs) combined with UCEs recovered from available transcriptomes and genomes. We evaluated the conflicting relationships using a variety of support metrics and topology tests. We found support for the phylogenetic hypothesis proposed using morphology to obtain the “symphytognathoids'' clade, Anterior Tracheal System (ANTS) Clade and monophyly of the family Anapidae. Anapidae can be divided into three major lineages, the Vichitra Clade (including Teutoniella, Holarchaea, Sofanapis and Acrobleps), the subfamily Micropholcommatinae and the Orb-weaving anapids (Owa) Clade. Biogeographic analyses reconstructed a hypothesis of multiple long-distance transoceanic dispersal events, potentially influenced by the Antarctic Circumpolar Current and West Wind Drift. In symphytognathoids, the ancestral anterior tracheal system transformed to book lungs four times and reduced book lungs five times. The posterior tracheal system was lost six times. The orb web structure was lost four times independently and transformed into sheet web once.

Inter-species stimulus enhancement: herring gulls (Larus argentatus) mimic human food choice during foraging.

Herring gulls (Larus argentatus) are one of few species that thrive in anthropogenic landscapes, and their familiarity with people makes them an excellent target for studies of inter-species social cognition. Urban gulls pay attention to human behaviour in food-related contexts and, thus, we set out to investigate whether such cues can influence a gull's attention to and choice of potential food items in their environment. Herring gulls were given free choice of two differently coloured anthropogenic food items in the presence of a demonstrator, who was either sitting still or eating food from an item that matched one of the presented ones. We found that a demonstrator eating significantly increased the likelihood of a gull pecking one of the presented items. Furthermore, 95% of pecks were directed toward the presented food item that colour-matched the demonstrator's food item. The results showed gulls were able to use human cues for stimulus enhancement and foraging decisions. Given the relatively recent history of urbanization in herring gulls, this cross-species social information transfer could be a by-product of the cognitive flexibility inherent in kleptoparasitic species.

Nestmate recognition in the Amazonian stingless bee Melipona paraensis.

Meliponine bees use chemical-based nestmate discrimination to protect their colonies from unrelated intruders. However, species from the Amazon basin are relatively poorly known from this perspective. Here, we investigated Melipona paraensis nestmate discrimination in different contexts (nests vs. neutral arenas), testing aggression in bees facing other bees varying in age and origin (same/different colony or a different kleptoparasitic meliponine species) or experimentally treated with odors from unrelated colonies. As expected, M. paraensis did not discriminate against callow non-nestmate workers with weak/undifferentiated chemical signatures. Workers specialized in nest defense aggressed intruders more often than non-specialized workers, but were less aggressive in neutral arenas than in the nest. Our study provides novel behavioral information relevant for social insect research and meliponiculture.

Chemoreceptor Diversity in Apoid Wasps and Its Reduction during the Evolution of the Pollen-Collecting Lifestyle of Bees (Hymenoptera: Apoidea)

Chemoreceptors help insects to interact with their environment, to detect and assess food sources and oviposition sites, and to aid in intra- and interspecific communication. In Hymenoptera, species of eusocial lineages possess large chemoreceptor gene repertoires compared with solitary species, possibly because of their additional need to recognize nest-mates and caste. However, a critical piece of information missing so far has been the size of chemoreceptor gene repertoires of solitary apoid wasps. Apoid wasps are a paraphyletic group of almost exclusively solitary Hymenoptera phylogenetically positioned between ant and bee, both of which include eusocial species. We report the chemosensory-related gene repertoire sizes of three apoid wasps: Ampulex compressa, Cerceris arenaria, and Psenulus fuscipennis. We annotated genes encoding odorant (ORs), gustatory, and ionotropic receptors and chemosensory soluble proteins and odorant-binding proteins in transcriptomes of chemosensory tissues of the above three species and in early draft genomes of two species, A. compressa and C. arenaria. Our analyses revealed that apoid wasps possess larger OR repertoires than any bee lineage, that the last common ancestor of Apoidea possessed a considerably larger OR repertoire (∼160) than previously estimated (73), and that the expansion of OR genes in eusocial bees was less extensive than previously assumed. Intriguingly, the evolution of pollen-collecting behavior in the stem lineage of bees was associated with a notable loss of OR gene diversity. Thus, our results support the view that herbivorous Hymenoptera tend to possess smaller OR repertoires than carnivorous, parasitoid, or kleptoparasitic species.

Analysis of RNA-Seq, DNA Target Enrichment, and Sanger Nucleotide Sequence Data Resolves Deep Splits in the Phylogeny of Cuckoo Wasps (Hymenoptera: Chrysididae)

AbstractThe wasp family Chrysididae (cuckoo wasps, gold wasps) comprises exclusively parasitoid and kleptoparasitic species, many of which feature a stunning iridescent coloration and phenotypic adaptations to their parasitic life style. Previous attempts to infer phylogenetic relationships among the family’s major lineages (subfamilies, tribes, genera) based on Sanger sequence data were insufficient to statistically resolve the monophyly and the phylogenetic position of the subfamily Amiseginae and the phylogenetic relationships among the tribes Allocoeliini, Chrysidini, Elampini, and Parnopini (Chrysidinae). Here, we present a phylogeny inferred from nucleotide sequence data of 492 nuclear single-copy genes (230,915 aligned amino acid sites) from 94 species of Chrysidoidea (representing Bethylidae, Chrysididae, Dryinidae, Plumariidae) and 45 outgroup species by combining RNA-seq and DNA target enrichment data. We find support for Amiseginae being more closely related to Cleptinae than to Chrysidinae. Furthermore, we find strong support for Allocoeliini being the sister lineage of all remaining Chrysidinae, whereas Elampini represent the sister lineage of Chrysidini and Parnopini. Our study corroborates results from a recent phylogenomic investigation, which revealed Chrysidoidea as likely paraphyletic.

Native bee diversity and abundance in an urban green space in Bengaluru, India

Aim: The aim of the present study was to estimate the diversity and abundance of native bee fauna in an urban green space in Bengaluru, India. Methodology: Native bees were sampled from ten observational plots randomly selected from a 20 ha urban green space. Bee diversity and abundance were recorded at 15-day interval and estimated using diversity indices. Results: Nineteen species and thirteen genera under Apidae, Halictidae, and Megachilidae family were recorded. Bee species under Apidae were the most abundant, with four social, five solitary, and one kleptoparasitic species, followed by Halictidae and Megachilidae, with five and four solitary bee species, respectively. Trigona iridipennis was the dominant species followed by Apis dorsata among the social bees, and Lasioglossum sp. and Hriades sp. were dominant among the solitary bees. The number of cavity-nesting species was more that of tree-nesting or ground-nesting species. Shannon’s and Simpson’s diversity indices confirmed the species richness, species abundance, and uniform distribution of native bee species in the urban green space. Interpretation: Green patches within urban areas can support a diverse population of bees. The study area consisted of both social and solitary bees. Cavity-nesting and oligolectic generalist bees were more predominant in the urban area, thus confirming the role of urban spaces in adding to bee diversity. Green pockets within urban areas support a diverse population of bees, and urban green spaces and green corridors can help to conserve bee biodiversity and, in turn, the urban ecosystem.

Megadiverse Ecuador: a review of Mysmenopsis (Araneae, Mysmenidae) of Ecuador, with the description of twenty-one new kleptoparasitic spider species.

The spider family Mysmenidae includes two genera in which kleptoparasitic species are known to occur, Isela and Mysmenopsis. Mysmenopsis is the most speciose with 31 species described so far. Herein, we describe twenty-one new species from Ecuador: M. alvaroi n. sp., M. amazonica n. sp., M. angamarca n. sp., M. awa n. sp., M. baerti n. sp., M. bartolozzii n. sp., M. choco n. sp., M. cube n. sp., M. corazon n. sp., M. guanza n. sp., M. guayaca n. sp., M. hunachi n. sp., M. junin n. sp., M. lasrocas n. sp., M. lloa n. sp., M. otokiki n. sp., M. pululahua n. sp., M. salazarae n. sp., M. shushufindi n. sp., M. tepuy n. sp. and M. tungurahua n. sp. We report for the first time the presence of four species of Mysmenopsis in the web of a Lycosidae, namely M. salazarae n. sp., M. shushufindi n. sp., M. bartolozzii n. sp. and M. amazonica n. sp. All new species described here were collected in spider webs either from the family Dipluridae (Linothele) or Lycosidae (Aglaoctenus) and therefore are assumed to be kleptoparasitic. New locality records are presented for M. otonga, M. fernandoi, M. atahualpa and M. penai, the female of M. penai is described for the first time. Maps of all Ecuadorian species are presented, kleptoparasitism, morphological characters and distribution of Mysmenopsis species are discussed.

La diversité des abeilles parisiennes

The diversity of Parisian bees. - Despite the forever increasing urbanization, cities often shelter a significant biodiversity. As many other taxa, wild bees may find refuge in urban areas because of relative favorable conditions compared to intensive agricultural environments. In this study, we compiled our joint work to extend the list of Parisian bees. Over 4 years of monitoring (2011, 2014, 2015, 2016), we recorded 87 bee species in intra-muros Paris. In 2016 we added net captures to our sampling procedures with colored pan traps, which provided 11 additional species. The assemblage now represents 8.8 % of the French fauna of Apoïdae. However, this assemblage is mostly dominated by Halictidae and includes only few kleptoparasitic species highlighting an impoverished community.

Molecular phylogeny of Miltogramminae (Diptera: Sarcophagidae): Implications for classification, systematics and evolution of larval feeding strategies

Miltogramminae is one of the phylogenetically most poorly studied taxa of the species-rich family Sarcophagidae (Diptera). Most species are kleptoparasites in nests of solitary aculeate wasps and bees, although parasitoids and saprophagous species are also known, and the ancestral miltogrammine life habit remains unsettled. Here, we present for the first time a comprehensive phylogenetic tree consisting of 58 representatives of Miltogramminae, reconstructed using sequence data from three mitochondrial (COI, cytB, ND4) and one nuclear (Ef-1α) genes. Our phylogenetic hypothesis suggests that: (1) Miltogramminae are sister to Paramacronychiinae, (2) Miltogramminae can be divided into the “lower miltogrammines” containing two clades of mainly saprophages and a clade of “higher miltogrammines” with mainly kleptoparasitic species, (3) only three genera turn out to be non-monophyletic: Miltogramma, Senotainia and Pterella and (4) the genus Sarcotachina, which traditionally has been considered as belonging to the Paramacronychiinae, is placed in one of the clades of “lower miltogrammines”. Ancestral state reconstruction of larval feeding strategy and five larval characters reveals that the ancestor of Miltogramminae was likely a saprophage retaining plesiomorphic oral ridges and a cephaloskeleton with sclerotized dorsal bridge. Synapomorphies like large pseudocephalic sensory organs and well-developed cuticular sculpture suggest that the ancestral first instar larva actively searched for a buried food supply.

A Kleptoparasitic Chase by Brown Pelicans on a Western Gull

interspecific kleptoparasitism, or the stealing of food from other species, is fairly widespread among birds, most frequently reported for seabirds, especially among the Charadriiformes (Brockman and Barnard 1979, Furness 1987, iyengar 2008). Though most kleptoparasitic species engage in this behavior facultatively, some (especially within the Charadriiformes) may be obligate kleptoparasites during a particular season and potentially throughout the year (iyengar 2008). Within the family Pelecanidae it has been infrequently reported in the literature. The ecology and behavior of seabirds meet many of the ecological factors proposed for the evolution of kleptoparasitism, including open habitat, feeding in mixed-species groups, scavenging, and the host’s habits being predictable (Brockman and Barnard 1979, Paulson 1985, iyengar 2008). Though kleptoparasitism often involves a larger species stealing food from a smaller species, the Brown Pelican (Pelecanus occidentalis) is perhaps better known as the victim of kleptoparasitism by smaller gulls than vice versa, with several species of gulls and terns reported to steal from it (Shields 2014). The Brown Pelican was the first species of pelican reported to kleptoparasitize (Sefton 1950, Brockmann and Barnard 1979), and this behavior has since been reported in the americas by the closely related Peruvian Pelican (P. thagus) (Duffy 1980) and the american White Pelican (P. erythrorhynchos) (O’malley and evans 1983, anderson 1991). reports of kleptoparasitic attacks by the Brown Pelican have appeared to be isolated incidents. in the Peruvian Pelican, however, Duffy (1983) reported that 18% of attempts to obtain prey involved piracy. most reported kleptoparasitic attacks by the Brown Pelican and closely related Peruvian Pelican have been in mixed feeding flocks where the pelican is sitting on the water and grabs with its bill or otherwise attacks a nearby species, getting it to drop its food (Sefton 1950, Duffy 1980, lanciani 2000). This is especially common in situations where the birds are feeding on offal being thrown by people, though it occurs regularly in “wild” situations as well (D. anderson pers. comm.). The Brown Pelican’s target species have included the Double-crested Cormorant (Phalacrocorax auritus) and unidentified gulls (Larus spp.), as well as other Brown Pelicans (D. anderson pers. comm.). Brown Pelicans have also been observed landing on Great Blue Herons (Ardea herodias) in order to get them to drop food (Bildstein 1980). O’malley and evans (1983) observed aerial chases by american White Pelicans in pursuit of food, but i am aware of no such observations involving the Brown Pelican. at ~16:30 on 19 October 2013, during an organized whale watch out of long Beach, California, in the vicinity of Platform ellen (Orange County), i noted a subadult (second-cycle) Western Gull (L. occidentalis) chasing an adult Western Gull, followed by two adult Brown Pelicans. The four birds were first seen flying parallel to the boat, about a kilometer away and only a few meters above the water. The second-cycle Western Gull was close behind the adult Western Gull with the two pelicans following about three meters behind the gulls. The adult gull banked up at roughly a 45° angle to a height of about 5 meters above the water before gliding back down in an attempt to escape. The second-cycle gull followed closely, and the pelicans also followed, banking up behind the gulls. The lead gull reversed course and quickly made a sharp ascent; through labored flight the pelicans were able to follow. While the second-cycle gull was able to stay on the tail of the lead gull, the pelicans fell back to about 10 meters behind both gulls. However, when the lead gull reversed course again, flying low over the water, both pelicans were able to shorten the gap and eventually overtake the second-cycle gull, placing nOTeS

Developmental trade-offs in Southern Ocean mollusc kleptoparasitic species

Connectivity is a key factor in determining the genetic structure of marine populations, and type and duration of the larval phase strongly affect dispersal abilities of species. In Antarctica, invertebrates show a higher proportion of species with limited pelagic dispersal, and any exception to this pattern is worthy of attention. Capulidae is a family of kleptoparasitic gastropods, with two larval strategies. Most species have a peculiar planktotrophic larva, the ‘echinospira’, which enables a long pelagic dispersal; a minority of species undergo lecithotrophic development. We provide the first molecular phylogenetic framework for the family and define the Antarctic species based on molecular data. Based on this information, and on larval shell morphology, we tested the hypothesis that capulid species with high dispersal capacities via planktotrophic larvae display high genetic connectivity over long distances. Our data showed that whilst larval planktotrophy is the predominant larval strategy of the family worldwide, the vast majority of Antarctic species exhibit non-planktotrophic development. The unique exception, Capulus subcompressus, showed high genetic connectivity between the Ross Sea and Weddell Sea-Antarctic Peninsula. In all other Antarctic species, environmental constraints selected towards intracapsular metamorphosis, despite the associated limits of dispersal and finding a host.

The effect of kleptoparasite and host numbers on the risk of food‐stealing in an avian assemblage

Kleptoparasitism involves the theft of resources such as food items from one individual by another. Such food‐stealing behaviour can have important consequences for birds, in terms of individual fitness and population sizes. In order to understand avian host–kleptoparasite interactions, studies are needed which identify the factors which modulate the risk of kleptoparasitism. In temperate European intertidal areas, Eurasian oystercatchers Haematopus ostralegus feed primarily on bivalve molluscs, which may be stolen by kleptoparasitic species such as carrion crows Corvus corone and herring gulls Larus argentatus. In this study we combined overwinter foraging observations of oystercatchers and their kleptoparasites on the Exe Estuary, UK, with statistical modelling to identify the factors that influence the likelihood of successful food stealing behaviour occurring. Across the winter, 16.4% of oystercatcher foraging attempts ended in successful kleptoparasitism; the risk of theft was lowest in February (10.8%) and highest in December (36.3%). Using an information theoretic approach to compare multiple logistic regression models we present evidence that the outcome of host foraging attempts varied with the number of kleptoparasites per host within the foraging patch for two out of five individual months, and for all months grouped. Successful, kleptoparasitism was more likely to occur when the total number of all kleptoparasites per host was greater. Across the entire winter study period, oystercatcher foraging attempts that resulted in kleptoparasitism were associated with a mean number of kleptoparasites per host that was more than double that for foraging attempts that ended in the oystercatcher successfully consuming the mussel. Conversely, the stage of the tidal cycle within the estuary did not affect the outcome of oystercatcher foraging attempts. Our study provides evidence that bird numbers influence the risk of kleptoparasitism within avian assemblages.

Description, molecular phylogeny, and natural history of a new kleptoparasitic species of gelechiid moth (Lepidoptera) associated with Melastomataceae galls in Brazil

The male, female, pupa and larva of a new species of Gelechiidae (Lepidoptera), Locharcha opportuna Moreira and Becker, are described and illustrated with the aid of optical and scanning electron microscopy. A preliminary analysis of mitochondrial DNA sequences including members of related lineages is also provided. The immature stages are associated with galls induced by a species of Palaeomystella Fletcher (Lepidoptera: Momphidae) on Tibouchina sellowiana (Cham.) Cogn. (Melastomataceae), endemic to the Atlantic Rainforest. Larvae are kleptoparasitic, usurping the gall internal space and thereafter feeding on the internal tissues. By determining the variation in population density of both species and following gall development individually throughout ontogeny under field conditions, we demonstrated that the kleptoparasite completes its life cycle inside galls induced by Palaeomystella, where pupation occurs. The variation in seasonal abundance of the kleptoparasite is tied to that of the cecidogenous species, with their corresponding peaks in density occurring sequentially.http://zoobank.org/urn:lsid:zoobank.org:pub:525F6D52-8CE1-47D1-A0D9-78B564DF5565

Evolution of nesting behaviour and kleptoparasitism in a selected group of osmiine bees (Hymenoptera: Megachilidae)

The construction of nests to rear offspring is restricted to vertebrates and few insect taxa, such as termites, wasps, and bees. Among bees, species of the family Megachilidae are characterized by a particularly high diversity in nest construction behaviour. Many megachilid bees nest in excavated burrows in the ground, others place their brood cells in a variety of above-ground cavities or attach them to the surface of a substrate, and yet others have adopted a kleptoparasitic habit. Evolutionary transitions between the different nesting sites and between conventional nesting and kleptoparasitism in bees are poorly understood. In the present study, we traced the evolution of nesting site selection and kleptoparasitism in the Annosmia–Hoplitis group (Osmiini), which displays an exceptionally high diversity in nesting behaviour. We found that the evolution of nesting behaviour proceeded unidirectionally from nesting in excavated burrows in the ground to nesting in rock depressions and cavities, followed by the colonization of snail shells and insect borings in dead wood or hollow stems. Kleptoparasitism evolved once and the kleptoparasitic species have derived from the same lineage as their hosts.

Intraspecific kleptoparasitism and counter-tactics in the archerfish (Toxotes chatareus)

The mechanics of the archerfish’s remarkable ability to spit down aerial prey is well studied. Relatively unknown, however, are the social consequences of this hunting method. To explore how physical factors and behavioural choices affect the use and success of intraspecific kleptoparasitism in socially foraging archerfish, 10 tagged, juvenile archerfish (Toxotes chatareus) were presented in groups of 3, 5, and 7 with single crickets of 3 sizes overhanging the water by either 15 or 30 cm. Video review revealed all spits, jumps, attempted thefts, and consumptions. Kleptoparasitism attempts were common, resulting in a 43.6% loss rate to the fish that successfully brought down the prey. Group size affected the probability of kleptoparasitism asymptotically: loss rate increased as group size increased from 3 to 5 members, but with no further increase at 7 members. As observed with other kleptoparasitic species, the rate and success of kleptoparasitism increased with both prey size and prey height (analogous to handling time). Several counter-kleptoparasitism behaviours were observed, including jumping to grab prey directly, aggression, spitting technique, and positioning.

Competition for mangrove leaf litter between two East African crabs, Neosarmatium meinerti (Sesarmidae) and Cardisoma carnifex (Gecarcinidae): a case of kleptoparasitism?

Many Indo-Pacific mangrove macroinvertebrates are herbivorous and heavily dependent on leaf litter. As a consequence, fallen leaves become a limiting factor and competition occurs among conspecifics and heterospecifics. Neosarmatium meinerti and Cardisoma carnifex are two of the most common herbivorous crabs of the landward mangrove belt in East Africa, often sharing an area and time of activity. This study used a series of field experiments to investigate their feeding habits when co-existing. The high density reached by both species led to overlapping of the individual feeding ranges: during the feeding excursions each crab inevitably encountered, and actively interacted with, other conspecifics and heterospecifics. Competition for food was high: N. meinerti lost approximately 50% of its leaves to theft by C. carnifex. Thus, approximately half of the leaves obtained by C. carnifex were stolen from a foraging N. meinerti. Considering the frequency of such thefts, C. carnifex may be regarded as a facultative kleptoparasitic species. This is the first time that a such strategy has been recorded for a crab species and for a vegetable resource.

Kleptoparasites: a twofold cost of group living for the colonial spider, Metepeira incrassata (Araneae, Araneidae)

Several species of kleptoparasitic and araneophagic spiders (Araneae: Family Theridiidae, Subfamily Argyrodinae) are found in colonial webs of the orb-weaving spider Metepeira incrassata (Araneae, Araneidae) from Mexico, where they steal food and/or prey upon their spider hosts. Census data from natural M. incrassata colonies reveal that the incidence of these species increases with colony size. This pattern may reflect the presence of several other orb-weaving spiders, each with their own kleptoparasitic species, invading larger M. incrassata colonies. As the number of these associated spiders increases, so does the density and number of Argyrodinae species in M. incrassata colonies, suggesting that associated spiders might reduce their own kleptoparasite load by building their webs within M. incrassata colonies. This represents a twofold cost to M. incrassata, as a field enclosure experiment revealed that a primarily kleptoparasitic species (Argyrodes elevatus) may reduce prey available to their hosts, but a kleptoparasitic/araneophagic species (Neospintharus concisus) inflicts high mortality upon M. incrassata. However, the cost of kleptoparasitism and predation by these species may be offset in part for M. incrassata individuals in large colonies by certain defensive mechanisms inherent in groups, i.e., “attack-abatement” and “selfish herd” effects. We conclude that increased occurrence of kleptoparasitic and/or predatory Argyrodinae spiders is a consequence of colonial web building and is an important potential cost of group living for colonial web-building spiders.

WEB ORIENTATION, STABILIMENTUM STRUCTURE AND PREDATORY BEHAVIOR OF ARGIOPE FLORIDA CHAMBERLIN &amp; IVIE 1944 (ARANEAE, ARANEIDAE, ARGIOPINAE)

This study was undertaken to describe the web orientation, stabilimentum structure and predatory behavior of Argiope florida Chamberlin & Ivie 1944 (Araneae, Araneidae, Argiopinae), a vir- tually unstudied orb-web spider of the southeastern United States. Adult female Argiope florida were sampled from five sandy ridge areas of Florida. Compass orientation of the spider's dorsum, incline of the web from vertical and hub height were measured. The presence of male A. florida, barrier webs, kleptoparasitic species of Argyrodes Simon 1864 (Araneae, Theridiidae), wrapped prey and large areas of web damage were noted. Predatory behavior was elicited by touching a radius with a 100 Hz tuning fork. The number of stabilimentum arms was measured, along with their arrangement, length and number of silk bands. On average, webs faced 100 8 E of N, were inclined 198 from vertical and were 1 m from the ground at the hub. Responses to the tuning fork, which closely resembled the responses to actual prey, were more vigorous when Argyrodes spp. were present on the web, but were not different when wrapped prey were present on the web. Most webs had stabilimenta and most stabilimenta had four arms in a cruciate pattern. The upper arms tended to be smaller and spaced further apart than the lower arms. Spider size was related to the angle between the lower arms of the stabilimentum, but not to other measures of the stabilimentum.