Hierarchical comparative analysis of genetic and genitalic geographical structure: testing patterns of male and female genital evolution in the scarab beetle Phyllophaga hirticula (Coleoptera: Scarabaeidae)

It is generally accepted that genitalia are among the fastest evolving characters in insects and that selection on these structures may increase speciation rates in groups with polygamous mating systems. If selection is causing genitalic divergence between or among populations of a species, one prediction is that geographical structure of genitalic morphology would be in place before genetic structure of a rapidly evolving neutral marker. The current study tests this hypothesis in the geographically widespread scarab beetle Phyllophaga hirticula by evaluating whether standing variation in male and female genitalia is more or less geographically structured than a mitochondrial genetic marker. Geographical structure of mitochondrial (mt)DNA and male and female genitalic shape were analysed using analysis of variance, multivariate analysis of variance, Mantel tests, and tests of spatial autocorrelation. The results show that, although female genitalia are more geographically structured than mtDNA, male genitalia are not. This pattern suggests that selection on female genitalic variation may be causing divergence of these structures among populations.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 135–149.     

The Mecyclothorax beetles (Coleoptera,Carabidae, Moriomorphini) of Tahiti,Society Islands

The 101 species of Mecyclothorax Sharp known to inhabit Tahiti Island, French Polynesia are taxonomically revised, including 28 species that are newly described: Mecyclothorax claridgeiae sp. n., Mecyclothorax jeanyvesi sp. n., Mecyclothorax poria sp. n., Mecyclothorax aano sp. n., Mecyclothorax papau sp. n., Mecyclothorax manina sp. n., Mecyclothorax everardi sp. n., Mecyclothorax ramagei sp. n., Mecyclothorax pitohitiensis sp. n., Mecyclothorax curtisi sp. n., Mecyclothorax hoeahiti sp. n., Mecyclothorax ninamu sp. n., Mecyclothorax kokone sp. n., Mecyclothorax paahonu sp. n., Mecyclothorax kayballae sp. n., Mecyclothorax ehu sp. n., Mecyclothorax papuhiti sp. n., Mecyclothorax tuea sp. n., Mecyclothorax taatitore sp. n., Mecyclothorax konemata sp. n., Mecyclothorax arboricola sp. n., Mecyclothorax rahimata sp. n., M. oaoa sp. n., Mecyclothorax maninapopoti sp. n., Mecyclothorax hunapopoti sp. n., Mecyclothorax fefemata sp. n., Mecyclothorax maninamata sp. n., and Mecyclothorax niho sp. n. Mecyclothorax muriauxioides Perrault, 1984 is newly synonymized with Mecyclothorax muriauxi Perrault, 1978. Lectotypes are designated for: Thriscothorax altiusculus Britton, 1938; Thriscothorax bryobius Britton, 1938; Mecyclothorax globosus Britton, 1948: and Mecyclothorax sabulicola Britton, 1948. Dichotomous identification keys augmented by dorsal habitus and male aedeagal photographs are provided to the various species-groups and all included species. The spermatophore of Mecyclothorax papau sp. n. is described, with the ampulla and collar found to correspond dimensionally to the length of the internal sac flagellar plate. Variation among characters of the female reproductive tract is presented for all newly described plus other representative species comprising the radiation. Taxa are assigned to species groups, modified from the classification of G.G. Perrault, based on derived character states polarized using the Australian outgroup taxon Mecyclothorax punctipennis (MacLeay). Much of the species-level diversity on this small Pacific island is partitioned allopatrically over very small distributional ranges. No species is shared between Tahiti Nui and Tahiti Iti, and nearly all species in Tahiti Nui are geographically restricted to one ridgelike massif of that volcano. Cladistically similar species are often distributed on different massifs suggesting that vicariance associated with erosional valley formation has facilitated speciation, however several instances in which sister species occupy sympatric distributions on the same ridge system demonstrate that speciation may also occur across extremely localized landscapes. Such localized differentiation is facilitated by the low vagility of these small-bodied, flightless predators whose fragmented populations can persist and diverge within spatially limited habitat patches. The intense philopatry of Tahitian Mecyclothorax spp. coupled with the highly dissected landscape has produced the geographically densest adaptive radiation on Earth. This radiation has occurred very rapidly, with species durations averaging 300,000 yr; a speciation rate similar to that observed in Hawaiian Oliarus planthoppers and Laupala crickets, and East African Rift lake cichlid fishes.     

The male reproductive system of Costelytra zealandica (White)(Coleoptera: Scarabaeidae: Melolonthinae)

Abstract

The morphology and histology of the male internal reproductive organs of Costelytra zealandica show many similarities to other Scarabaeoidae, and are particularly close to other Melolonthinae and to Rutelinae. Testes follicles of C. zealandica have the usual structure for Melolonthinae with basal lobes surrounding the ends of the vasa efferentia. Epithelial cells of the vasa efferentia, vasa deferentia, and vesiculae seminales have similar densely basophilic cytoplasm but muscle layers are best developed around the latter. Accessory glands lack muscle and are not differentiated histologically into regions but do differ from their reservoirs. The ejaculatory duct has a cuticular intima and is differentiated into anterior and posterior regions. Both are surrounded by a muscular sheath which expands in the posterior region to enclose fluid. This forms a hydraulic mechanism for everting the internal sac during intromission. The parameres hook into the female’s genital chamber during copulation and have no pincer action. Probable homologies are listed between muscles of the external genitalia and anus of C. zealandica and other Scarabaeoidea.     

Evolution of male and female genitalia following release from sexual selection

Despite the key functions of the genitalia in sexual interactions and fertilization, the role of sexual selection and conflict in shaping genital traits remains poorly understood. Seed beetle (Callosobruchus maculatus) males possess spines on the intromittent organ, and females possess a thickened reproductive tract wall that also bears spines. We investigated the role of sexual selection and conflict by imposing monogamous mating on eight replicate populations of this naturally polygamous insect, while maintaining eight other populations under polygamy. To establish whether responses to mating system manipulation were robust to ecological context, we simultaneously manipulated life-history selection (early/late reproduction). Over 18-21 generations, male genital spines evolved relatively reduced length in large males (i.e., shallower static allometry) in monogamous populations. Two nonintromittent male genital appendages also evolved in response to the interaction of mating system and ecology. In contrast, no detectable evolution occurred in female genitalia, consistent with the expectation of a delayed response in defensive traits. Our results support a sexually antagonistic role for the male genital spines, and demonstrate the evolution of static allometry in response to variation in sexual selection opportunity. We argue that further advances in the study of genital coevolution will require a much more detailed understanding of the functions of male and female genital traits.     

Antenna morphology and sensilla microstructure of the male and female scarab beetle,Lepidiota mansueta Burmeister (Coleoptera: Scarabaeidae)

Studies on Lepidiota mansueta Burmeister were conducted to describe and compare the external morphology of the antenna and its sensilla of male and females. Distinct variations were observed in antennal segments between the sexes with males possessing longer scape, pedicel, flagellum and lamellar club segments. Variation was also seen in the antennal sensilla, with males possessing three different types of sensilla while the females possessed seven types of sensilla. Sensilla trichodea (TRS), sensilla placodea (PLAS) type I and sensilla placodea (PLAS) type II were common in both sexes while sensilla chaetica (CHS), sensilla auricilica (AUS) type I, sensilla auricilica (AUS) type II and sensilla auricilica (AUS) type III were found only in females.     

Directional asymmetry reversal of male copulatory organs in chafer beetles (Coleoptera: Scarabaeidae): implications on left–right polarity determination in insect terminalia

During large‐scale examinations of male genitalia for taxonomic studies of Sericini chafers (Coleoptera: Scarabaeidae), we have found that reversals of directed left–right (LR) asymmetry in male copulatory organs are compared to other insects not common. However, such inversions do occur occasionally and they must be considered a significant ‘source of error’ in taxonomic studies. Our data indicate asymmetry reversal of male genitalia affects only the abdominal segments (genitalia) as changes in asymmetric structures of the head and thorax were not observed. Based on these observations, we believe that this partial abdominal LR asymmetry reversal of terminalia could be due to a local change in the polarity determining LR patterning in the growth zone of posterior abdominal segments as development of these segments begins.     

狭胸天牛类雄性外生殖嚣分类研究——附一新种

该文就狭胸天牛类3属6种雄性外生殖器的形态结构,比较研究其系统发育及其归属,并记录太谷芫天牛Mantitheus tazguensts sp. nov.一新种和重新描述细点音天牛的雄性外生殖器。狭胸天牛类属较原始的类群,祖征为中茎突中央加厚,边缘极薄;阳基侧突基部还保留着一条横裂。狭胸天牛属与音天牛属和芫天牛属关系较密切,应为姊妹群,狭胸天牛属较始,其衍征为中茎突较长的分开,内囊具基骨片、骨化细长管和大小较一致骨化微刺。音天牛属和芫天牛属为姊妹群,芫天牛较原始,音天牛较进化,其衍征为阳基侧突背面因基部裂缝消失而完全合并,骨化细长管较细;外部形态表现为触角较短,较圆;中胸发音器中央无缝;而芫天牛内囊基骨片明显易见。     

Diagnosis, classification, and phylogenetic relationships of the orphnine scarab beetles (Coleoptera, Scarabaeidae: Orphninae)

Orphnine scarab beetles (Orphninae) are widely distributed in the tropical and subtropical regions of the southern continents except for Australia. The catalogue of nominal taxa of orphnines includes 2 tribes, 15 genera, and 195 species. Diagnosis of the group, based on adult morphological characters, is as follows: antennae 10-segmented with 3-segmented club; mandibles with 2?C4 scissorial teeth and well developed mola; labrum and mandibles protruding past clypeus and visible from above; scutellum well developed in winged species, reduced but distinct in wingless species; wings with distinct anal area; apices of anterior tibia in males without spur but normally with a few robust setae; anterior coxa with longitudinal hollow on anterior surface; tarsi with 2 similar claws; middle and hind tibiae with 2 apical spurs; abdominal sternite 2 with sub-triangular to rounded plectrum; dorsal surface of hind coxae with oval flat stridulatory file; pygidium partly hidden under elytra; parameres symmetrical; bursa copulatrix sacciform, membranous; spermatheca C-shaped, not sclerotized; accessory vaginal glands developed; abdomen with 2 sclerotized tergites (VII?CVIII) and 6 visible sternites (III?CVIII). Preliminary phylogenetic analysis based on 47 characters of adult morphology shows that the tribe Aegidiini Paulian is a natural, monophyletic group. The genus Stenosternus Karsch described from a single specimen from S?o Tomé Island (Gulf of Guinea), is morphologically more similar to the New World taxa than to the Old World ones and is provisionally placed in Aegidiini. The tribe Orphnini Erichson seems non-monophyletic and has no synapomorphies. The genus Orphnus is apparently a polyphyletic group and it needs taxonomic revision. The hypothesis on sister-group relationship of Orphninae and Allidiostomatinae, based on molecular data, is not supported by the morphological characters. The stridulatory organs (the putative synapomorphy of Orphninae + Allidiostomatinae) are not identical in these groups; the mouthparts and female genitalia are essentially different. Orphninae have chewing mouthparts with large scissorial teeth and well developed mola, which is characteristic of generalist saprophagous species. Allidiostomatinae have mandibles with scissorial teeth and mola reduced; they also have sclerotized bursa copulatrix and sclerotized mandibular duct which opens on the dorsal side near condyle. Considering the present day development of alpha-taxonomy of most orphnine taxa, especially the speciose genus Orphnus, it seems premature to propose changes in higher classification of the subfamily. To clarify the phylogenetic position of the Orphninae among scarab beetles it is essential to include representative members of all taxa of orphnine lineage (sensu Browne, Scholtz, 1998) into the analysis.     

Chroniodiplogaster aerivora (Cobb) (Rhabditida: Diplogasteridae), a natural enemy of white grubs,Phyllophaga Harris (Coleoptera: Scarabaeidae)

Chroniodiplogaster aerivora (Cobb) was isolated from immature pest June beetles Phyllophaga spp., in southern Quebec. The natural occurrence of the entomogenous nematode in the damaging grub stage of the beetle was frequent and widespread in the study area. Laboratory and small field plot infectivity tests, and behavioral studies confirmed the parasitic nature of the nematode. It was successfully maintained in cold storage for 22 months and was easily cultured on nutrient agar supplemented with grub tissues. A modified Baermann funnel was efficient in extracting large numbers of live C. aerivora from infected grubs. Chroniodiplogaster aerivora demonstrated sufficient tolerance to environmental factors for it to be retested on a larger scale and even considered for field control of Phyllophaga and possibly other scarabaeid beetles.     

Seasonal distribution and prevalence of dung beetles (Coleoptera: Scarabaeidae) in Kurukshetra,Northern India

A total of 8306 individuals as 29 species from 3 subfamilies (Hybosorinae, Aphodiinae, Scarabaeinae) were trapped by pitfall bait trapping. The maximum number of species of Scarabaeinae (68.97%) and number of individuals of Aphodiinae (56.84%) take part in the formation of a community. The number of species, number of individuals, diversity and dominance changes throughout the season. Seasonal prevalence of 82.76% of species and 50.81% of individuals was found in June. Aphodius campestris was found to be more attracted to the pitfall bait traps. The beetle community found in May shows the maximum Shannon's Diversity Index (2.46) but Margalef's Diversity Index was highest in August (3.06). Environmental factors play an important role in the occurrence and abundance of dung beetles. In the present study non-significant but positive correlations between temperature and species richness, abundance and diversity were found. Percent relative humidity showed a positive correlation with abundance only, and negative correlations with species richness and diversity.     

Entomopathogenic nematodes for control of Phyllophaga georgiana (Coleoptera: Scarabaeidae) in cranberries

A series of laboratory and greenhouse experiments evaluated the entomopathogenic nematodes Steinernema scarabaei Stock & Koppenhöfer, Heterorhabditis bacteriophora Poinar, and H. zealandica Poinar for control of second- and third-instar cranberry white grub, Phyllophaga georgiana Horn (Coleoptera: Scarabaeidae), in cranberries. Steinernema scarabaei was the most effective species with 76–100% control at a rate of 2.5×10⁹ IJ/ha in the greenhouse experiments. H. zealandica and especially H. bacteriophora were generally less effective and required rates of 5×10⁹ IJ/ha for acceptable control. Larval stage had no effect on H. zealandica and H. bacteriophora performance, whereas S. scarabaei was more effective against third instars than second instars in the laboratory but not in the greenhouse experiments. Steinernema scarabaei, should it become commercially available, could be an effective alternative to chemical insecticides for P. georgiana management.     

Larvae of scarab beetles of the subfamily Trichiinae (Coleoptera,Scarabaeidae) from the Russian Far East

Previously unknown larvae of three species (Osmoderma davidis Fairmaire, Gnorimus subopacus Motschulsky, and Lasiotrichius succinctus (Pallas)) of the subfamily Trichiinae are described and illustrated. Original keys to larvae of the subfamilies Trichiinae, Cetoniinae, and Valgiinae and to the genera of the subfamily Trichiinae of the Russian fauna are compiled. The larva of Osmoderma davidis differs from that of O. barnabita Motschulsky in the shape of the frontal sutures and chaetotaxy of the frontal triangle and clypeus. The larvae of Gnorimus subopacus differ from those of G. nobilis (L.) and G. octopunctatus (F.) in the position of symmetrical rows of setae on the anal sternite. The larvae of representatives of the genus Lasiotrichius Reitter, described for the first time, differ from those of all the other genera of the subfamily Trichiinae in the smooth head capsule and in the absence of tubercles on the labrum. These larvae differ from those of the genus Trichius in the completely pale brown basal membrane at the antennae (the membrane of Trichius bears black stripe).     

Novelty and emergent patterns in sperm: Morphological diversity and evolution of spermatozoa and sperm conjugation in ground beetles (Coleoptera: Carabidae)

The beetle family Carabidae, with about 40,000 species, exhibits enough diversity in sperm structure and behavior to be an excellent model system for studying patterns and processes of evolution. We explore their potential, documenting sperm form in 177 species of ground beetles using light microscopy and collecting data on one qualitative and seven quantitative phenotypic traits. Our sampling captures 61% of the tribal-level diversity of ground beetles. These data highlight the notable morphological diversity of sperm in ground beetles and suggest that sperm in the group have dynamic evolutionary histories with much morphological innovation and convergence. Sperm vary among species in total length (48–3,400 μm), head length (0.5–270 μm), and head width (0.2–6.3 μm). Most ground beetles make sperm with heads that are indistinct from the flagella at the gross morphological level. However, some or all Omophron, Trachypachus, and Dyschiriini make broad-headed sperm that show morphological differences between species. Most ground beetles package their sperm into groups of sperm, termed conjugates, and ground beetles show variation in conjugate form and in the number and arrangement of sperm in a conjugate. Most ground beetles make sperm conjugates by embedding their sperm in a hyaline rod or spermatostyle. The spermatostyle is remarkably variable among species and varies in length from 17 to 41,000 μm. Several unrelated groups of ground beetles make only singleton sperm, including Nebriinae, Cicindelinae, many Trechinae, and the tribe Paussini. In order to study patterns in sperm evolution, we combine these data with a low-resolution phylogeny of ground beetles. Results from modern comparative analyses suggest the following: (a) sperm differ from conjugates in some aspect of their underlying evolutionary process, (b) sperm have influenced conjugate evolution and vice versa, and (c) conjugation with a spermatostyle likely evolved early within the history of Carabidae and it has been lost independently at least three times.     

Comparative morphology study of the male genitalia in the tribe Astathini from China (Coleoptera: Cerambycidae)

The male genitalia of 13 species from four genera of Astathini were described and analyzed. The result showed that five genital characters, such as shape of the apex of 8th abdominal tergaum and sternum, ratio of the length of lateral lobes to tegmen, can be used to identify genera of Astathini; six characters, such as ratio of the length of lateral lobes to tegmen, ratio of the length of roof to lateral lobes, shape of the apex of ventral plate of median lobe, can be used to identify species in Bacchisa.     

两种光源对金龟子的诱捕效果

为了解探照灯和测报灯两种光源对金龟子的诱捕效果,2015-2018年,在漯河市农业科学院五里岗试验基地设置探照灯和测报灯,对金龟子种群进行了诱捕监测。结果表明:暗黑鳃金龟和铜绿丽金龟是漯河地区上灯金龟子的优势种。探照灯监测到的暗黑鳃金龟年度首现日比测报灯早7±7.80 d,年均诱捕数量比测报灯多出24137.75±12724.78头,占金龟子总量的百分比增加20.8±4.4(SE);探照灯监测到的铜绿丽金龟年度首现日比测报灯晚5±3.60 d,年均诱捕数量比测报灯减少1793.75±504.02头,占金龟子总量的百分比减少12.4±1.6;全光谱(380~680 nm)的探照灯对暗黑鳃金龟的诱捕作用显著高于紫外光(主波长365 nm)的测报灯,而对铜绿丽金龟诱捕作用显著低于测报灯。这一结果暗示着可见光具有对暗黑鳃金龟相对专性的诱捕潜能。     

Structure and function of the mandibles of adult dung beetles (Coleoptera : Scarabaeidae)

The mouthparts of adult dung beetles (Coleoptera : Scarabaeidae) are adapted for manipulation of soft, pasty food—usually the excrement of vertebrates. Nutrients are derived primarily from micro-organisms contained in the food and these must be broken up before ingestion. The mandibles, particularly the molar lobes, are designed to finely grind these particulates; the molae function as a mortar-pestle system, which mills the organic “grist” contained in the food by a combination of squeezing and grinding actions. The ability of the molae to finely grind food particles resides primarily in the structure of the molar surface, which consists of a series of ridges bearing rows of submicroscopic scrapers (“tritors”). The incisor lobes of the mandibles scrape food from the surfaces of the galeae and lacinae, which bring food into the preoral cavity. The structure of the mouthparts of Canthon pilularius (L.), which is described in detail, is basically the same as that of 10 other species examined. Those of Aphodius and Geotrupes are similar in some respects to those of scarabaeines but are obviously less well specialized for microphagy.     

Differences in genitalia structure and function between subfamilies of longhorn beetles (Coleoptera: Cerambycidae)

Beetle genitalia are usually described only for taxonomic purposes without considering the possible function of structures. Exceptions are sporadic detailed studies on single species. We studied genital structures in the subfamilies of Cerambycidae and outlined assumptions on the function of these structures and the implications for the phylogeny of the Cerambycidae. We found that male genitalia in particular are taxon-specific on a higher taxonomic level; e.g., the parameres are widely variable in Cerambycinae, while in most Lamiinae species they appear relatively uniform and differ from those of the Cerambycinae. Internal sac structures are very different among the various subfamilies. Small backwards-pointing spines are the most common armature of the internal sac. The female genitalia are less variable, although ovipositor morphology may differ among subfamilies. In most species, the connection between the mates during copulation is achieved by the long internal sac and the ovipositor only, whereas the median lobe and parameres are in contact with the female abdomen only at the beginning of copulation. Cerambycinae and Lepturinae have a basal swelling of the endophallus to prevent it from sliding back into the male abdomen during copulation. The long internal sac functions in connecting the mates and guaranteeing the sperm transfer.     

On the utility of female genitalia in the systematics of Curculionidae: examples from Entimini and Hylobiina (Coleoptera: Curculionidae)

The utility of the female genitalia and associated sclerites (tergite and sternite VIII) in the systematics of the Curculionidae is discussed. Examples from the tribe Entimini (Entiminae) and subtribe Hylobiina (Molytinae: Hylobiini) are given. The female characters prove to be informative for establishing the phylogenetic relationships among genera of Entimini. They are essential in determining species groups within the genus Arniticus Pascoe, Hylobiina.