Prey analysis of four species of tropical orb-weaving spiders (Araneae: Araneidae) and a comparison with araneids of the temperate zone

Summary The actual prey in the orb webs of four araneid spiders (Nephila clavipes, Eriophora fuliginea, Argiope argentata, and A. savignyi) and the relative abundance of their potential prey (pitfall traps, yellow traps, and sweep-netting) was investigated over 1 year at different locations in Panama. The relative abundance of insects and spiders depends on seasonal fluctuations (Fig. 2) which are reflected by corresponding variations in the effectiveness of the webs. The main prey groups are Nematocera (50%–68%), winged Formicoidea (6%–15%) and Hymenoptera, Coleoptera, and Brachycera (4%–10% each) (Fig. 4-6). The remaining 10%–17% of the prey comes from up to 26 other groups (Table 2). Differences in prey size and prey composition between the spider species are small (Fig. 7). Most prey items are 1–2 mm long: only a few insects exceed 30 mm body length (Figs. 9–12). Relative to the available prey, some groups (e.g. Nematocera, Aphidoidea, Psocoptera) are caught selectively, while other groups (e.g. Heteroptera, Coleoptera, Brachycera, Orthoptera) are underrepresented in the prey spectrum and obviously avoid orb webs (Table 7). The differences in prey composition between araneids of the tropics and of the temperate zone are discussed (Table 8) and compared to those recorded in other studies (Table 9, 10). Most of these report large numbers of big prey items (Odonata, Lepidoptera, wasps/bees). It is pointed out that those studies do not take into account the total available prey in a spider's web but only that part which the spider selects from the web (mainly according to size). The importance of small prey items even for large spiders is explained and an obvious lack of niche partitioning among coexisting araneids is discussed (Table 11).     

Dietary composition and echolocation call design of three sympatric insectivorous bat species from China

Studying the diet of echolocating, insectivorous bats can provide important insights into their foraging behaviors and ecological constraints they are facing. By examining an extensive data set covering a period of 2 years, the present study identifies the dietary composition of three sympatric insectivorous bat species in rural areas of Beijing municipality. Each species clearly has different preferences for particular food items. Greater horseshoe bats, Rhinolophus ferrumequinum, preferred to catch nocturnal, actively flying insects, mostly moths (Lepidoptera), and to a lesser percentage flies (Diptera), beetles (Coleoptera), and flying ants and termites (Hymenoptera). Other nocturnal insects which do not exhibit any perceptible wing movements, such as true bugs (Homoptera), or strictly diurnal insects that hardly ever fly in the dark, such as grasshoppers (Orthoptera) and dragon- and damselflies (Odonata), were never found in droppings of horseshoe bats. Large mouse-eared bats, Myotis chinensis, preferentially glean relatively large terrestrial prey of the order Coleoptera (mostly carabid beetles) and Orthoptera, whereas greater tube-nosed bats, Murina leucogaster, consume predominantly smaller, diurnal Coleoptera (mostly soldier beetles, Cantharidae, and ladybugs, Coccinellidae). Our findings also indicate previously not described, significant spectro-temporal differences in the echolocation signals of M. chinensis and M. leucogaster. The results suggest that in our study area the dramatic differences in the dietary composition of these three bat species are mainly based upon differences in their foraging behaviors, including differences in their echolocation signal structure. The dietary data provide important background information for conservational efforts, such as habitat protection.     

The meaning of predatory specialization as illustrated by Aelurillus m-nigrum, an ant-eating jumping spider (Araneae: Salticidae) from Azerbaijan

The distinctions between a predator's diet, its prey-choice behaviour and its preference are illustrated in a study of Aelurillus m-nigrum Kulczyn'ski, a salticid spider from Azerbaijan. The natural diet of A. m-nigrum was determined from records of individuals feeding in the field (N=58). Ten arthropod orders were represented. Nine were from the class Insecta (Coleoptera, Collembola, Diptera, Heteroptera, Homoptera, Hymenoptera, Lepidoptera, Orthoptera, Psocoptera) and one from the class Arachnida (Araneae). Of 50 insects among the prey, 21 (42%) were Hymenoptera, with ants (family Formicidae) alone accounting for 31% of all prey records. Although the majority (69%) of the natural prey were not ants, results from prey-choice testing in the laboratory implied that A. m-nigrum preferred ants as prey. However, this preference was evident only when the testing environment included sand and a small stone. Our findings illustrate the importance of not conflating the concept of a predator's preference with the concept of a predator's natural diet and illustrate that physical features of a predator's habitat may be an important factor in influencing how strongly preference is expressed.     

Food habits of the barbastelle bat Barbastella barbastellus

The diet of Barbastella barbastellus was investigated through analysis of droppings collected from three maternity roosts in Germany and Switzerland The results showed a high dominance of moths (Lepidoptera). which accounted for 73-94% of the recovered items by volume Flies (Diptera). ranging in size from blow flies (Calliphoridae) and large crane flies (Tipulidae) to small Nematocera, were the second most important prey items (4-17%) Prey types recovered also included small numbers of Trichoptera, Neuroptera, Homoptera. Hymenoptera. Coleoptera and spiders (Araneae) The diet of the barbastelie differs from that of most other bats in Europe m the predominance of moths and the corresponding virtual absence of dung beetles (Coleoptera, Searabaeidae) and midges (Diptera. Chironomidae) Conservation measures for barbastelles should therefore consider facilitation of the diversity and abundance of moths     

昆明滇蛙的取食策略

目前国内研究两栖类食性选择或偏好多未考虑蛙胃内不同食物的丰盈程度与栖境不同食物资源是否存在相关性.在分析了采自昆明白龙寺和昆明石林西街口的494只滇蛙(Rana pleuraden)的食性的同时,分析了采自对应栖境中的食物资源组成.结果表明,滇蛙的食物成份与食物资源相具有稳定性,主要类群均为直翅目、同翅目、半翅目、鞘翅目、双翅目、鳞翅目、膜翅目和蛛形纲等8类.但又存在变异性,不同产地、不同年份和不同月份之间的蛙标本胃内的食物成分各类群的比例均不相同.主要食物成份与食物资源相的差异显著性分析、相关性分析和选择性分析等方面的结果均支持或证明:滇蛙对食物具有选择性或取食偏好.栖境的食物资源相与蛙胃内的食物成分不存在相关性(白龙寺:r=0.077,P=0.575;西街口:r=-0.086,P=0.500).直翅目(Ei＜-0.35)和同翅目(Ei＜-0.37)昆虫是滇蛙取食时回避的食物,而对鞘翅目、鳞翅目、膜翅目和蛛形纲等4个类群(Ei＞0.45)具有明显偏好.     

Feeding ecology of the tropical spitting spider Scytodes longipes (Araneae,Scytodidae)

Summary Feeding experiments and prey collections in Panama have shown the tropical spitting spider Scytodes longipes to be a specialized feeder on soft-chitinized arthropods (Diptera, Lepidoptera, Hemiptera, Orthopteroidea, and Araneae); hard-chitinized insects (Hymenoptera, Coleoptera, and Heteroptera) are refused. There is a considerable specialisation on spiders as prey. The unique prey-catching behaviour in which a gummy secretion is spat onto prey items is considered as an important characteristic of this specialisation. Pholcus phalangioides, a pholcid with convergent morphology and a different specialised prey-catching behaviour, is discussed as an ecological equivalent to Scytodes longipes.     

Seasonal pattern of insect abundance in the Brazilian cerrado

Abstract In Brazil, a severe dry season lasting for approximately 5 months and frequent fires make life difficult for cerrado insects. In certain aspects, the cerrado can be considered to be an understudied ecosystem; even basic information such as knowledge about the annual peak in abundance of different insect orders is unknown. Insect abundance patterns have only been investigated for a few groups in the cerrado region. Thus, our study concerns the temporal distribution of insect abundance in the savanna‐like vegetation of the central Brazilian cerrado (sensu stricto) in Distrito Federal. The region has a well‐defined, long dry season between May and September. The insects were sampled by window, malaise tent and pitfall traps within 1 year. We used a multiple linear regression to analyse the relationship between abundance of insects of each order and climate variables. A total of 50 127 individuals from 15 orders was collected. The orders were Coleoptera (26%), Hymenoptera (23%), Diptera (20.5%), Isoptera (20%), Homoptera (4%), Lepidoptera (4%), Orthoptera (1.5%) and Hemiptera (1%). The abundance of Diptera, Homoptera, Lepidoptera and Orthoptera was randomly distributed over time, Isoptera peaked in the first half of the wet season, Coleoptera and Hemiptera in the second half of the wet season and Hymenoptera in each season. A significant correlation was found only between Coleoptera and delayed climatic variables. There were no obvious trends that might help explain the abundance patterns observed. The study provides baseline information about phenological patterns of insect abundance and permits evaluation of this group as a resource for various food chains and different trophic levels.     

Anthropoentomophagic biodiversity of the Zongolica region, Veracruz, Mexico

Anthropoentomophagic biodiversity of the Zongolica region, Veracruz, Mexico. During two and a half years (2003-2005) we recorded the insect species used as food at Zongolica, Veracruz State, Mexico. Interviews were made among people (200) of this municipality to know which insects they consumed. The total of registered species was 57 (Orthoptera, Hemiptera, Homoptera, Megaloptera, Coleoptera, Lepidoptera and Hymenoptera). The Orthoptera was the most frequently ingested. Twenty-four of these species were new records for edible insects of Mexico. They are eaten in immature stages or as adults, generally only roasted. Consumption is seasonal. Some species are commercialized in the "tianguis" (little town markets) and/or in the larger Zongolica market. There is a "protoculture" of three species, one cockroach (Periplaneta australasiae Fabricius) and two moths (Latebraria amphipyroides Guenée and Arsenura armida armida Cramer). In Zongolica, anthropoentomophagy is an ancestral habit.     

Predation of insects by feral cats (<Emphasis Type="Italic">Felis silvestris catus</Emphasis> L., 1758) on an oceanic island (La Palma,Canary Island)

Predation of insects by feral cats (Felis silvestris catus) on a heterogeneous oceanic island (La Palma, Canary Islands) was studied. A total of 127 invertebrates were identified in the analysis of 500 scats (100 from each habitat of the Island). Invertebrates appear in 18.00% of the scats, representing an insignificant percentage of the total consumed biomass by feral cats on La Palma Island (0.05%). Insects were the most common invertebrate prey both in percentage of occurrence (90.6%) and invertebrate biomass (93.53%), with a total of 115 prey items. Orthoptera, Lepidoptera and Coleoptera were the main prey groups. Among the five main habitats present in La Palma Island, the temperate forest shows the lowest consumption of invertebrates, although insect consumption did not show statistical differences. However Orthoptera and Lepidoptera were more frequently preyed on in the pine forest and in the xerophytic shrub, respectively. Moreover, applying the Simplified Morisita index, a different insect composition of the diet was observed among habitats. Although, none of insects predated by feral cats are threatened, the identification of invertebrate component of the feral cats’ diet is an important tool for the correct understanding of predation significance and to prevent damage to endangered insect species.     

广西扁颅蝠与褐扁颅蝠的食物选择

2002年3～10日在广西南宁地区的宁明县和龙州县,用超声波监测和网捕法确定扁颅蝠与褐扁颅蝠的捕食区,在捕食区内用粘捕法调查潜在的食物量;用粪便分析法确定食物组成。在宁明县和龙州县扁颅蝠和褐扁颅蝠的潜在食物量都是以双翅目昆虫为主(45．93％以上),其次为鞘翅目(12．59％以上)和膜翅目(7．47％以上);但双翅目、膜翅目在两地差异显著。宁明县扁颅蝠的食物组成以双翅目(40．33％)和膜翅目(38．46％)为主,鞘翅目(16．07％)次之;龙州县扁颅蝠和褐扁颅蝠食物组成中以膜翅目(63．37％,62．34％)为主,其次为双翅目(21．57％,29．62％)、鞘翅目(11．59％,5．96％);对比两地扁颅蝠的食物组成发现,膜翅目和双翅目差异极显著。对比食物组成与潜在食物量发现,两种蝙蝠对膜翅目为正选择,对其他目负选择或无选择,均为选择性捕食者。     

Stage-based mortality of grassland grasshoppers (Acrididae) from wandering spider (Lycosidae) predation

Mortality rates in insects, including grasshoppers (Acrididae), are often stage- or size-specific. We estimated stage-specific mortality rates for three common grasshopper species from a Nebraska (USA) sandhills grassland (Ageneotettix deorum, Melanoplus sanguinipes and Phoetaliotes nebrascensis), and partitioned the impact due to wandering spider predation from remaining sources. Survivorship was estimated for multiple developmental stages (3rd instar through adult) under experimental conditions that either prevented or permitted predation from free-living, wandering spiders (primarily Schizocosa species). Total stage-specific mortality, including spider predation, examined over the period of single stages was greatest for the youngest stages (91% for 3rd instar, 73% for 4th instar, 63.5% for 5th instar and 30.4% for adults). For the developmental stages considered and averaged for all species, the contribution to total mortality from spider predation over the 10-d period (approximately the length of a developmental stage) ranged from 17% for 3rd instar nymphs to 23% for 4th and 5th instars, and an undetectable level for adults. While spiders may depress grasshopper numbers, contributions from spider predation to grasshopper population dynamics are uncertain.     

On the insect fauna of the Kichiga River basin, northeastern Kamchatka

189 species of insects from 55 families and 9 orders were found in the Kichiga River basin, northeastern Kamchatka Peninsula in 1987–1994: 7 species of Plecoptera, 7 of Odonata, 1 of Orthoptera, 4 of Homoptera, 6 of Heteroptera, 54 of Coleoptera, 73 of Lepidoptera, 15 of Hymenoptera, and 22 species of Diptera. Most of the insect species present in the Kichiga basin have wide ranges: 55 species and subspecies are Holarctic, 52 species have a broad Palaearctic distribution, 10 are Eastern Palaearctic, 8 are Amphi-Pacific, 8 are circumboreal or circumpolar, 4 are Far Eastern or Pacific; 5 species are endemic or subendemic to Kamchatka or some part of the peninsula.     

枣园害虫、捕食性和中性昆虫群落结构及动态研究

对山西省太谷地区枣园的害虫、捕食性和中性昆虫群落结构及动态进行研究,结果表明,不同年份枣园的害虫、捕食性和中性昆虫种类与数量均有明显差异(P<0.05),且树上明显大于地面.不同年份捕食性和中性昆虫与害虫的物种数和个体数比例也不同,其物种数和个体数随季节的暖和冷而增加和减少.相同亚群落不同季节的垂直分层结构相似程度不同,不同亚群落在同一季节的垂直分层相似性也不同.总体上垂直分层明显.枣园害虫、捕食性和中性昆虫的多样性指数随季节变化而波动.捕食性和中性昆虫与害虫数量起伏跟随紧密,总体呈极显著相关(r=0.9833,P<0.05).层次间差异明显,以中层相关最显著(r=0.9887,P<0.01)     

The biocontrol potential of Philodromus (Araneae,Philodromidae) spiders for the suppression of pome fruit orchard pests

A number of different generalist (polyphagous) predators occur in agroecosystems. Yet their biocontrol potential has been little investigated in detail. Philodromus species (Philodromidae) belong to the dominant spider species occurring in commercial orchards. We studied in detail the trophic functional traits of Philodromus albidus, Philodromus aureolus, and Philodromus cespitum (Philodromidae) by means of (1) the analysis of natural prey; and (2) experiments on acceptance of a variety of prey taxa. We found that the three philodromids are euryphagous. We classified prey species into three categories according to their function in the orchard: beneficial species, indifferent species, and pests. Philodromid spiders captured mostly other spiders in the field because spiders were most available. As concerns pests, the philodromids preyed mostly on Brachycera and Sternorrhyncha. They selected Acari and Brachycera. Indifferent species, such as Collembola and Nematocera, were also highly selected. In the laboratory, philodromids accepted mostly pests, such as lepidopterans, brachycerans, and aphids, while other spiders were accepted the least. The three philodromids have differentiated trophic niches with respect to prey size not only in the adult stage but throughout their ontogenetic development: P. albidus utilized smaller prey than the other two species. We conclude that the philodromids have a potential as biocontrol agents because they prey mostly on pests but their predation pressure is reduced due to higher selectivity for the indifferent fauna.     

Foraging behaviour of the slender loris (Loris lydekkerianus lydekkerianus): implications for theories of primate origins

Members of the Order Primates are characterised by a wide overlap of visual fields or optic convergence. It has been proposed that exploitation of either insects or angiosperm products in the terminal branches of trees, and the corresponding complex, three-dimensional environment associated with these foraging strategies, account for visual convergence. Although slender lorises (Loris sp.) are the most visually convergent of all the primates, very little is known about their feeding ecology. This study, carried out over 10 (1/2) months in South India, examines the feeding behaviour of L. lydekkerianus lydekkerianus in relation to hypotheses regarding visual predation of insects. Of 1238 feeding observations, 96% were of animal prey. Lorises showed an equal and overwhelming preference for terminal and middle branch feeding, using the undergrowth and trunk rarely. The type of prey caught on terminal branches (Lepidoptera, Odonata, Homoptera) differed significantly from those caught on middle branches (Hymenoptera, Coleoptera). A two-handed catch accompanied by bipedal postures was used almost exclusively on terminal branches where mobile prey was caught, whereas the more common capture technique of one-handed grab was used more often on sturdy middle branches to obtain slow moving prey. Although prey was detected with senses other than vision, vision was the key sense used upon the final strike. This study strongly supports the notion that hunting for animal prey was a key ecological determinant in selecting for visual convergence early on in primate evolution. The extreme specialisations of slender lorises, however, suggest that early primates were not dedicated faunivores and lend further support to the emerging view that both insects and fruits were probably important components of the diet of basal primates, and that exploitation of fruits may account for other key primate traits.     

贵州玉米田害虫绿色灯光防控技术研究

为探明贵州玉米田昆虫群落结构和杀虫灯对害虫的防治效果,选取贵州玉米田3个具有代表性的点分别安装诱虫灯,进行诱集调查,并对近灯区（距离灯20 m以内）、远灯区（距离灯20~150 m）和对照区的昆虫种群消长情况进行田间调查。结果表明,贵州玉米田昆虫共有11目66科132种,主要为同翅目、鞘翅目、鳞翅目、膜翅目、直翅目、双翅目和半翅目类昆虫;灯诱共获得89个种类,其中害虫占64.77%,益虫占15.91%,中性昆虫占19.32%。田间调查结果显示,近灯区物种丰富度最高,对照区次之,远灯区最低;近灯区玉米螟Ostrinia furnacalis、黏虫Mythimna seperata (Walker)、灰飞虱Laodelphax striatellus和条赤须盲蝽Trigonotylus coelestialium (Kirkaldy)等趋光性昆虫的种群数量长期高于其他区域。综上所述,风吸式诱虫灯对玉米田害虫有较好的防治效果,为玉米田害虫的绿色防控提供了参考。     

Occurrence of Erwinia amylovora on Insects in a Fire Blight Orchard

In order to screen for natural dissemination of fire blight under field conditions, insects were caught in an experimental orchard and assayed on semi-selective agar plates and by BIO-polymerase chain reaction for their contamination with Erwinia amylovora , the causative agent of the bacterial disease. The pathogen was detected on 15 out of 348 insects collected (4.3%). The insects contaminated with E. amylovora have different living habits and belong to four different orders (Homoptera, Coleoptera, Hymenoptera and Diptera) and at least eight insect families (Aphididae, Psyllidae, Coccinellidae, Curculionidae, Ichneumonidae, Formicidae, Apidae, and Muscidae) and to other Brachycera. After contact of insects with E. amylovora , the pathogen could survive at least 5 days in/on the green lacewing ( Chrysoperla carnea ) and 12 days on aphids ( Aphis pomi ).     

Spider mite web mediates anti-predator behaviour

Herbivores suffer significant mortality from predation and are therefore subject to natural selection on traits promoting predator avoidance and resistance. They can employ an array of strategies to reduce predation, for example through changes in behaviour, morphology and life history. So far, the anti-predator response studied most intensively in spider mites has been the avoidance of patches with high predation risk. Less attention has been given to the dense web produced by spider mites, which is a complex structure of silken threads that is thought to hinder predators. Here, we investigate the effects of the web produced by the red spider mite, Tetranychus evansi Baker & Pritchard, on its interactions with the predatory mite, Phytoseiulus longipes Evans. We tested whether female spider mites recognize predator cues and whether these can induce the spider mites to produce denser web. We found that the prey did not produce denser web in response to such cues, but laid more eggs suspended in the web, away from the leaf surface. These suspended eggs suffered less from predation by P. longipes than eggs that were laid on the leaf surface under the web. Thus, by altering their oviposition behaviour in response to predator cues, females of T. evansi protect their offspring.     

Ecological Life Table of Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae)

An ecological life table was constructed, aiming to determine the critical stages and key mortality factors of Tuta absoluta (Lepidoptera: Gelechiidae). The total population mortality of this tomato leafminer was 92.3%. During the egg stage the mortality was 58.7%, mainly due to egg inviability. A total of 8.6% egg parasitism by Trichogramma pretiosum (Riley) (Hymenoptera: Trichogrammatidae) and 5.0% egg predation by Xylocoris sp. (Heteroptera: Anthocoridae), Cycloneda sanguinea (L.) (Coleoptera: Coccinellidae) and members of the family Phlaeothripidae (Thysanoptera) was observed. The mortality of the larval stage was 33.0%. This was considered to be the critical stage as it showed the highest apparent mortality (79.8%). Larval parasitism was low (0.1%), and was only found with Goniozus nigrifemur Ashmead (Hymenoptera: Bethylidae). Predators were responsible for 79.4% of larval mortality. Therefore, their attraction to and maintenance in the target area are important management tactics to be considered for T. absoluta control. The first and second instars were considered to be the most critical, and predation by the above mentioned species was the key mortality factor. The mortality at the pupal stage was low (0.6%) and was due to malformation.     

Use of arthropods for the evaluation of the olive-orchard management regimes

Abstract 1 The presence and abundance of arthropods were compared in three olive orchards under organic, integrated and conventional management regimes. In each olive orchard, trees were sampled in the canopy by beating branches and soil arthropods by placing pitfall traps. Contrary to expectations, the highest abundance of arthropods occurred in the integrated management orchard. The most abundant groups were Formicidae and the species Euphyllura olivinae (Homoptera: Psyllidae). 2 Canopies and the soil under the tree canopy (interior soil) were selected as the most informative sites for sampling. The months with the strongest differences were May, June and July, especially June. In the canopy, Araneae, Coleoptera, Diptera, Heteroptera, Hymenoptera, Homoptera, Lepidoptera, Neuroptera and Thysanoptera were the most abundant, and showed significant differences in abundance among orchards with different management regimes. Moreover, in the canopies, Coleoptera and Lepidoptera showed a seasonal pattern of abundance and consistent significant differences between the organic orchard vs. the integrated and conventional ones in both years of study. In the soil, 12 orders showed significant differences in abundance among management regimes at some point of the sampling season. 3 In a search for biological indicators that could help to distinguish between management regimes, a discriminant analysis applied to the data indicated that only the samples from the canopy were classified according to their management regime in a consistent way over time. The groups selected by the analysis to establish differences among management regimes were Coleoptera, Diptera, Heteroptera, Lepidoptera and Thysanoptera. The analysis applied to compare organic vs. non‐organic olive orchards, again identified Coleoptera and Lepidoptera as suitable groups. The results suggest that these two orders are potential bioindicators to distinguish, in a simple way, organic olive orchards from non‐organic ones.