Water lilies and scarabs: faithful partners for 100 million years?

Night-flowering water lilies (Nymphaeaceae) in South America are pollinated by Cyclocephala scarab beetles (Scarabaeidae: Cyclocephalini) in a specialized relationship involving synchronized flowering movements, strong floral scent, food tissues, and heat-producing flowers. We report that a similar and closely related association exists in West Africa between Nymphaea lotus L. and Ruteloryctes morio Fabricius (Cyclocephalini). This finding strongly supports a late Early Cretaceous origin of a symbiosis between the night-flowering water lilies and pollinating Cyclocephalini beetles. We believe that this is the first unambiguous evidence of a plant-pollinator relationship of this age.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 80 , 539–543.     

Haplotype diversity of the nematode Pristionchus pacificus on Réunion in the Indian Ocean suggests multiple independent invasions

Pristionchus pacificus has been established as a nematode model system in evolutionary developmental biology and evolutionary ecology. Field studies in North and South America, Asia, Africa and Europe indicated that nematodes of the genus Pristionchus live in association with scarab beetles. Here, we describe the first account of soil‐ and beetle‐associated nematodes on an island setting by investigating the island of Réunion in the Indian Ocean. Réunion has high numbers of endemic insects and is one among several attractive islands for biodiversity studies. Being of volcanic origin, Réunion is 2–3 million years old, making it the youngest of the Mascareigne islands. We show that beetle‐ and soil‐derived nematodes on Réunion are nearly exclusively hermaphroditic, suggesting that selfing is favoured over gonochorism (outcrossing) during island colonization. Among members of four nematode genera observed on Réunion, Pristionchus pacificus was the most prevalent species. A total of 76 isolates, in association with five different scarab beetles, has been obtained for this cosmopolitan nematode. A detailed mitochondrial haplotype analysis indicates that the Réunion isolates of P. pacificus cover all four worldwide clades of the species. This extraordinary haplotype diversity suggests multiple independent invasions, most likely in association with different scarab beetles. Together, we establish Réunion as a case study for nematode island biogeography, in which the analysis of nematode population genetics and population dynamics can provide insight into evolutionary and ecological processes. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100 , 170–179.     

Linear and threshold-dependent expression of secondary sexual traits in the same individual: insights from a horned beetle (Coleoptera: Scarabaeidae)

Elaborate horns or horn‐like structures in male scarab beetles commonly scale with body size either (a) in a linear fashion with horn size increasing relatively faster than body size or (b) in a threshold‐dependent, sigmoid fashion; that is, males smaller than a certain critical body size develop no or only rudimentary horns, whereas males larger than the threshold size express fully developed horns. The development of linear vs. sigmoid scaling relationships is thought to require fundamentally different regulatory mechanisms. Here we show that such disparate regulatory mechanisms may co‐occur in the same individual. Large males of the south‐east Asian Onthophagus (Proagoderus) watanabei (Ochi & Kon) (Scarabaeidae, Onthophagini) develop a pair of long, curved head horns as well as a single thoracic horn. We show that unlike paired head horns in a large number of Onthophagus species, in O. watanabei the relationship between head horns and body size is best explained by a linear model. Large males develop disproportionately longer horns than small males, but the difference in relative horn sizes across the range of body sizes is small compared to other Onthophagus species. However, the scaling relationship between the thoracic horn and body size is best explained by a strongly sigmoid model. Only males above a certain body size threshold express a thoracic horn and males smaller than this threshold express no horn at all. We found a significant positive correlation between head and thoracic horn length residuals, contrary to what would be expected if a resource allocation tradeoff during larval development would influence the length of both horn types. Our results suggest that the scaling relationship between body size and horn length, and the developmental regulation underlying these scaling relationships, may be quite different for different horns, even though these horns may develop in the same individual. We discuss our results in the context of the developmental biology of secondary sexual traits in beetles. © 2004 The Linnean Society of London, Biological Journal of the Linnean Society, 2004, 83 , 473–480.     

Diversity patterns of soil macro-Coleoptera in Mexican shaded and unshaded coffee agroecosystems: an indication of habitat perturbation

The soil Coleoptera community was sampled with pitfall traps in shaded and unshaded coffee agroecosystems in Veracruz, Mexico. The insect collection resulted in a total of 31 species which belong to nine families. The most frequent families collected in this study (in terms of species and number of organisms) were Scarabaeidae and Carabidae.Species diversity was measured using the Hill's family of diversity numbers. The Coleoptera community was more diverse in shaded than in unshaded coffee. Also, the collected organisms were more evenly distributed between species in shaded coffee.The diversity of the scarab beetles was shown to be strongly affected by the degree of forest perturbation. The richness and evenness of scarab beetles was correlated with the diversity of shade trees present in coffee agro-ecosystems; scarab richness drops from 19 species collected in virgin tropical rain-forests, to five species in polyspecific shade (more than ten species of shade trees) and six species in monogeneric shade (three species of shade trees) coffee agro-ecosystems, and to three scarab species in unshaded coffee. Evenness in scarab beetles follows a similar pattern: a single species tends to gradually become dominant as more shade trees are removed from the agro-ecosystem. It is suggested that some shade trees should be preserved within the agro-ecosystem during the intensification of coffee production in Mexico.     

Morphological traits as predictors of diet and microhabitat use in a diverse beetle assemblage

We explored how morphological traits can complement phylogenetic information to extend our predictions of the ecology of a diverse beetle assemblage. We analysed ten morphological traits from an assemblage of 239 species from 35 families, and identified three axes of morphological variation that were independent of body length: (1) relative robustness; (2) relative appendage length; and (3) relative abdomen length. The trait associations defining these axes of morphological variation did not change after adjusting for family‐level phylogeny. We detected significant differences in morphological variation across the beetle assemblage according to diet and microhabitat use, and these patterns were only partially influenced by family membership. Further analysis within dominant families showed that species of Carabidae, Curculionidae, Scarabaeidae and Staphylinidae had greater body length in open versus tree litter microhabitat, and species of Carabidae and Curculionidae had greater relative robustness, but shorter relative appendage length, in open versus tree litter microhabitat. Although it is clear that family‐level phylogeny and morphology share some explanatory power for predicting the diet and microhabitat use by beetles, we demonstrate that body length, robustness and appendage length are correlated significantly with microhabitat use when comparing members of the same family. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 301–310.     

Speciation and evolution of eco‐climatic ranges in the intertropical African dung beetle genus,Diastellopalpus van Lansberge

We investigate how late Cenozoic orogenics and climatic change might have influenced the history of taxon diversification and current species ranges of an endemic, Afrotropical, insect genus. Diastellopalpus van Lansberge is a near basally‐derived taxon in the dung beetle tribe Onthophagini (Coleoptera: Scarabaeidae: Scarabaeinae) that has diversified into 32 known species primarily centred on intertropical forests. Basal dichotomies in both published and re‐analysed phylogenies divide the species into clades that are geographically centred either to the east or west of the south‐east highlands that underwent uplift from the Miocene. There is broad climatic overlap between many of the species but clear separation along a minimum spanning tree in ordinal space where they are divided into taxa with either lowland or highland centres of distribution. Observed spatial distributions of six defined species groups mostly differ from predicted climatic ranges, presumably as a result of historical constraints on species dispersal. A trend from dominance of montane or wet lowland forest associations in species lineages derived from more basal nodes (Groups A–C) to dominance of drier upland forest and moist woodland associations in species lineages derived from a more terminal node (Groups D–F) is perhaps linked to the stepped trend to cooler, dryer climate in the late Cenozoic. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 407–423.     

Attraction of a kleptoparasitic sphaerocerid fly (Norrbomia frigipennis) to dung beetles (Phanaeus spp. andCanthon sp.)

Norrbomia frigipennis (Diptera: Sphaeroceridae) is phoretic on dung-feeding scarab beetles (Coleoptera: Scarabaeidae). In this study we investigate the attractiveness of three beetle species,Phanaeus ignius, P. vindex, andCanthon pilularis, to the fly. Stationary, moving-dead, and live beetles were used. More flies were attracted toPhanaeus. However, this attractiveness may be due to the larger average size ofPhanaeus. A preference for larger individuals was found withinPhanaeus, though not withinC. pilularis. Flies mounted beetles on the thorax and the elytra at similar rates.Phanaeus males that possesed horns did not attract more flies than did hornless ones, and there was no effect of host sex on attractiveness. In hornedPhanaeus, about 11–16% of the flies mounting those beetles landed on the horn.     

Red anemone guild flowers as focal places for mating and feeding by Levant glaphyrid beetles

Several species of glaphyrid (Scarabaeoidea: Glaphyridae) beetles forage and mate on Mediterranean red bowl‐shaped flowers. In red anemones and poppies in Israel, female beetles occupy only a subset of the flowers, do not aggregate, and are hidden below the petals. This raises the question of how males find their mates. In the present study, we investigated the hypothesis that males and females orient to similar plant‐generated cues, thereby increasing their mate encounter prospects. Previous studies have demonstrated that beetle attraction to red models increases with display area. Choice tests with flowers and with models indicate that both male and female beetles prefer large displays. In anemones, beetles rest, feed, and mate mainly on male‐phase flowers, which are larger than female‐phase flowers. Poppies that contain beetles are larger than the population average. These findings support the hypothesis that males and females meet by orienting to large red displays. Corolla size correlates with pollen reward in both plant species, suggesting that visits to large flowers also yield foraging benefits. Male beetles often jump rapidly among adjacent flowers. By contrast to the preference for large flowers by stationary individuals, these jump sequences are random with respect to flower sex‐phase (in anemone) and size (in poppy). They may enable males to detect females at close range. We hypothesize that males employ a mixed mate‐searching strategy, combining orientation to floral signals and to female‐produced cues. The glaphyrids' preference for large flowers may have selected for extraordinarily large displays within the ‘red anemone’ pollination guild of the Levant. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 808–817.     

How long can insect species exist? Evidence from extant and fossil Micromalthus beetles (Insecta: Coleoptera)

Six new fossils of Micromalthus (Coleoptera: Archostemata) from Dominican amber are compared with extant and previously described fossil micromalthid beetles. The amber inclusions are well preserved and all important morphological features are visible. Taking into account the morphological variability of the extant species Micromalthus debilis LeConte, 1878 , it is not possible to find any morphological features that distinguish the fossils from the extant species. This also applies to the Dominican amber inclusion described as Micromalthus anasi Perkovsky, 2008, which therefore is considered a junior synonym of M. debilis. The lack of morphological change in M. debilis over time might possibly be explained by unusually stable environmental conditions, as this species occupies a very specialized ecological niche in decaying timber. A general survey of fossil insects indistinguishable from extant species is presented. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 158 , 300–311.     

Dung beetle (Scarabaeus (Pachysoma)) biology and immature stages: reversal to ancestral states under desert conditions (Coleoptera: Scarabaeidae)?

The unique feeding biology of the unusual flightless Namib Desert dung beetle species belonging to Scarabaeus ( Pachysoma ) MacLeay (Scarabaeidae: Scarabaeinae) has been studied in the past but in this report we document breeding biology, larval feeding and immature morphology for the first time. Females provision burrows with fragments of dry herbivore dung and detritus, in which the larvae develop and on which they feed. This is a novel deviation, and a probable reversal to the ancestral state, from the obligatory brood ball constructed from wet dung in which scarab larvae usually develop. The free-living larvae and pupae have several unique attributes that distinguish them from relatives that develop within the confines of a brood ball and provide additional support for monophyly of the group. Many of these also appear as reversals to a probable ancestral condition. Unique larval characters include a left mandible with two teeth, the absence of a 'coprine' hump, small spiracles, and two- or indistinctly three-segmented antennae. Those unique to the pupa are the presence of peculiar prothoracic projections, the absence of lateral tergal supporting projections on the abdomen, and the perpendicular elytra and wings relative to the median bodyline.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 83 , 453–460.     

Distribution and adult activity of Popillia quadriguttata (Coleoptera: Scarabaeidae) on golf courses in Korea

Japanese beetle traps baited with the Popillia japonica Newman (Coleoptera: Scarabaeidae) pheromone lure and a eugenol feeding attractant were placed at five golf courses in Korea to determine how well they work for detecting activity of a closely related species, Popillia quadriguttata (F.) (Coleoptera: Scarabaeidae), a turf pest in Korea. The traps also were used to determine the time of day and time of year that P. quadriguttata is most active. Nineteen scarab species of 13 genera were attracted to the Japanese beetle traps with P. quadriguttata clearly being the most abundant (383 beetles per trap), followed by Adoretus tenuimaculatus Waterhouse (10 per trap), Popilliaflavosellata Fairmaire (seven per trap), Exomala orientalis Waterhouse (four per trap), and Maladera japonica (two per trap). Other scarab species were trapped at a rate of <1.0 per trap. Popillia quadriguttata adults were active over a 5-wk period in late June and early July. At Yongwon Golf Club in 2002, peak adult activity was during the last week of June in visual counts and approximately 1 wk later in the Japanese beetle traps. In Korea, P. quadriguttata adults are most active between 12:00 p.m. and 4:00 p.m. This information should be helpful to golf course superintendents in Korea and to entomologists interested in finding natural enemies of P. quadriguttata to evaluate as potential biocontrol organisms for the very closely related species, the Japanese beetle.     

铜绿丽金龟对圆偏振光的行为和视网膜电位反应

圆偏振光在地球环境中是很少见的, 来自珠宝金龟甲体壁反射圆偏振光是稀有的自然资源之一。铜绿丽金龟Anomala corpulenta Motschulsky与其他珠宝金龟甲一样其体壁能够反射左旋圆偏振光。为了解铜绿丽金龟对圆偏振光的感知能力, 本研究利用室内行为、 田间诱集与视网膜电位(electroretinogram, ERG)等方法研究了铜绿丽金龟对圆偏振光的响应。室内行为研究结果表明, 铜绿丽金龟对左旋圆偏振光与右旋圆偏振光的趋光反应明显低于非偏振光, 避光反应明显大于非偏振光, 且对左旋圆偏振光的趋、 避光反应均大于右旋圆偏振光。田间选择试验结果显示, 铜绿丽金龟对左旋和右旋圆偏振光的选择明显低于非偏振光, 且右旋大于左旋圆偏振光。电生理学研究结果表明, 左旋和右旋圆偏振光与非偏振光一样, 均能引发铜绿丽金龟的ERG反应, 且无明显差异。这些研究结果表明铜绿丽金龟体壁能够反射产生左旋圆偏振光, 且能够感知和区分左旋和右旋圆偏振光, 说明铜绿丽金龟存在偏振视觉, 具有圆偏振光敏感性。     

A cladistic analysis of the Stygnicranainae Roewer, 1913 (Arachnida,Opiliones, Cranaidae) – where do longipalp cranaids belong?

A character survey compiling the morphological information of the subfamily Stygnicranainae was carried out. Two new species of Stygnicranaus Roewer, 1913 are described from Colombia and the new genus Agathocranaus is described from Ecuador. All known species of the subfamily are included in a matrix of 46 morphological characters. Parsimony analysis under implied weights recovered a monophyletic Stygnicranainae including Tryferos Roewer, 1931 plus Stygnicranaus and Agathocranaus. However, the usage of the four subfamilies of Cranaidae as currently defined is abandoned because the two largest subfamilies of Cranaidae – Cranainae and Prostygninae – represent paraphyletic groups (grades), whereas Heterocranainae is a superfluous subfamily, including only the genus Heterocranaus Roewer, 1913. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 157 , 470–494.     

Large‐sized insects show stronger seasonality than small‐sized ones: a case study of fruit‐feeding butterflies

Animal species have a restricted period during the year when conditions for development are optimal, and this is known as the temporal window. Duration of the temporal window can vary among species, although the causes of variation are still poorly understood. In the present study, examining butterflies, we assume that the temporal window duration is correlated with the seasonal period of flight (termed seasonality). To understand how species characteristics are correlated with this, we examine whether there is a relationship between body size and length of flight period of fruit‐feeding butterflies in forest fragments, and whether these two parameters have a phylogenetic signal. Using wing size as a measure of body size and the period of adult flight as a measure of seasonality, we found significant positive correlations between body size and seasonality among subfamilies but not within subfamilies. We also found a clear phylogenetic signal in size but not in seasonality. The results obtained suggest the existence of a trade‐off between insect size and seasonality, with size limiting flight period length. The relationship between body size and seasonality and the synchrony with their resources may be one factor explaining the vulnerability of large insects to forest fragmentation. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104 , 820–827.     

Spatial density‐dependent parasitism and specificity in the robber fly Mallophora ruficauda (Diptera: Asilidae)

The density‐dependence in parasitism by the robber fly Mallophora ruficauda (Diptera: Asilidae) on scarab beetle larvae (Coleoptera: Scarabaeidae) populations was studied in the present research. Mallophora ruficauda is a pestiferous species common in the open grasslands of the Pampas region of South America. Adults are predators of insects and larvae are solitary parasitoids of third instar larvae of several species of scarab beetle (Coleoptera: Scarabaeidae). In contrast with most studied host‐parasitoid interactions, host searching by M. ruficauda is carried out by both larvae and adults. Typically, robber fly females lay eggs on tall grasses from where larvae drop to the ground, and attack hosts which are buried in the soil. We carried out our study at two spatial scales close to 14 apiaries located in the provinces of Buenos Aires and Entre Ríos (Argentina). We found that parasitism is density‐independent at the larger spatial scale and inversely density‐dependent at the smaller one. We also found that M. ruficauda selects Cyclocephala signaticollis among several scarab beetle species. Specificity is observed both at large and small spatial scales. We discuss the implications of both host specificity and host searching behaviour on the observed parasitism patterns.     

Potential effects of climate change on the distribution of Scarabaeidae dung beetles in Western Europe

Dung beetles are indispensable in pasturelands, especially when poor efficiency of earthworms and irregular rainfall (e.g. under a Mediterranean climate) limit pad decomposition. Although observed and projected species range shifts and extinctions due to climate change have been documented for plants and animals, little effort has focused on the response of keystone species such as the scarab beetles of dung beetle decomposers. Our study aims to forecast the distribution of 37 common Scarabaeidae dung beetle species in France, Portugal and Spain (i.e. more than half of the western European Scarabaeidae fauna) in relation to two climate change scenarios (A2 and B1) for the period leading to 2080. On average, 21 % of the species should change in each 50-km UTM grid cell. The highest faunistic turnover rate and a significant increase in species richness are expected in the north of the study area while a marked impoverishment is expected in the south, with little difference between scenarios. The potential enrichment of northern regions depends on the achievement of the northward shift of thermophilous species, and climate change is generally likely to reduce the current distribution of the majority of species. Under these conditions, the distribution of resource—i.e. the extent and distribution of pastures—will be a key factor limiting species’ responses to climate change. The dramatic abandonment of extensive grazing across many low mountains of southern Europe may thus represent a serious threat to dung beetle distribution changes.     

Not all dung beetles feed on dung: Scarabaeinae (Coleoptera: Scarabaeidae) attracted to different carrion types in contrasting habitats at Brazilian Amazon

By understanding how assemblages segregate according to food types, it is possible to depict and understand species distribution and exploitation of similar food resources. Although it is well known that dung beetles may feed on carrion, but the attractiveness of different carrion types for these beetles is still poorly understood. In this study, we compared the dung beetle (Coleoptera: Scarabaeidae: Scarabaeinae) diversity attracted to two carrion types in different habitats in an Amazonian landscape. Dung beetles were captured by using pitfall traps baited with decaying cattle beef and cattle liver in native forest, peach palm plantation, teak plantation and exotic pasture. Overall, we captured 582 dung beetles of 43 species, where Canthidium aff. lentum was classified as a specialist of cattle beef, Deltochilum sp. One was considered specialist of liver carrion, 11 were considered generalists and for the 30 remaining species, it was not possible to determine their carrion preference due to the low number. Abundance, but not species richness, was affected by carrion type, and a higher number of beetles was recorded in beef-baited traps compared to liver-baited traps. According to functional groups, endocoprid beetles were more abundant in traps baited with decaying beef, while paracoprid and telecoprid beetles did not show preference for any carrion type. This study suggests a novel scenario of intra-resource segregation, where species vary their preferences depending to the part of the dead corpse being exploited. The amount of food resource, the maintenance of stable populations and trophic preference mediated by chemical cues are some mechanisms that may explain the segregation of dung beetles among carrion types.     

金龟甲性信息素的化学成分及其应用

金龟甲Scarabaeoidae性信息素研究主要集中在丽金龟亚科Rutelinae和鳃金龟亚科Melolonthinae。丽金龟亚科金龟甲的性腺由臀板和腹片顶端的上皮细胞组成,其性信息素成分主要是脂肪酸衍生物;而鳃金龟亚科金龟甲的性腺可以从腹部外翻,性信息素成分主要是氨基酸衍生物和萜烯类化合物。一些存在地理或季节隔离的物种具有结构相同的性信息素成分,但手性不同。在某些种类中,性信息素成分的手性对映体可能具有行为拮抗作用。本文综述了金龟甲性信息素的化学结构与应用的新进展。     

Conserved, highly specialized olfactory receptor neurons for food compounds in 2 congeneric scarab beetles, Pachnoda interrupta and Pachnoda marginata

Few studies have systematically addressed evolutionary changes in olfactory neuron assemblies, either by genetic drift or as an adaptation to specific odor environments. We have studied the sense of olfaction in 2 congeneric scarab beetles, Pachnoda interrupta Olivier and Pachnoda marginata Drury (Coleoptera: Scarabaeidae: Cetoniinae), which are both opportunistic polyphages, feeding mainly on fruit and flowers. The 2 species occur in dissimilar habitats: P. interrupta is found in dry savannah, and P. marginata in tropical parts of equatorial Africa. To study how these species may have adapted their sense of olfaction to their odor environments, we utilized single-unit electrophysiology on olfactory sensilla with a wide selection of food-related compounds. Despite the differences in habitat, we found that the species shared most of the physiological types of olfactory receptor neurons (ORNs) encountered, although their proportions frequently varied between the species. The high degree of conservation in olfaction between the species implies that a similar sensory strategy is efficient for food search in both habitats. However, shifts in proportions of receptor neuron classes, and slight shifts in response profiles and/or presence of some ORN classes unique to either species, may reflect adaptation to a different set of hosts.     

Chromosome numbers and DNA content in Bromeliaceae: additional data and critical review

For the large Neotropical plant family Bromeliaceae, we provide new data on chromosome numbers, cytological features and genome size estimations, and combine them with data available in the literature. Root‐tip chromosome counts for 46 species representing four subfamilies and a literature review of previously published data were carried out. Propidium iodide staining and flow cytometry were used to estimate absolute genome sizes in five subfamilies of Bromeliaceae, sampling 28 species. Most species were diploid with 2n = 50 in Bromelioideae, Puyoideae and Pitcairnioideae, followed by 2n = 48 observed mainly in Tillandsioideae. Individual chromosome sizes varied more than tenfold, with the largest chromosomes observed in Tillandsioideae and the smallest in Bromelioideae. Genome sizes (2C‐values) varied from 0.85 to 2.23 pg, with the largest genomes in Tillandsioideae. Genome evolution in Bromeliaceae relies on two main mechanisms: polyploidy and dysploidy. With the exception of Tillandsioideae, polyploidy is positively correlated with genome size. Dysploidy is suggested as the mechanism responsible for the generation of the derived chromosome numbers, such as 2n = 32/34 or 2n = 48. The occurrence of B chromosomes in the dysploid genus Cryptanthus suggests ongoing speciation processes closely associated with chromosome rearrangements. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 176 , 349–368.