卡氏步甲触角感器的超微结构

利用扫描电子显微镜,研究了卡氏步甲Carabus casaleianus成虫触角感器的类型、数量和分布规律。结果表明:卡氏步甲雌、雄成虫触角的各节长度和总长度差异均不显著;触角表面存在7类、12种感器类型,包括3种刺形感器、3种毛形感器、2种锥形感器、Bhm氏鬃毛、腔锥形感器、腔形感器和钟形感器;两性间触角感器的类型和分布无明显差异,但数量差异明显。研究结果为其后的电生理学、行为生态学等研究提供基础资料。     

Evidence for Horizontal Transmission of Secondary Endosymbionts in the Bemisia tabaci Cryptic Species Complex

Bemisia tabaci (Hemiptera: Aleyrodidae) is a globally distributed pest composed of at least 34 morphologically indistinguishable cryptic species. At least seven species of endosymbiont have been found infecting some or all members of the complex. The origin(s) of the associations between specific endosymbionts and their whitefly hosts is unknown. Infection is normally vertical, but horizontal transmission does occur and is one way for new infections to be introduced into individuals. The relationships between the different members of the cryptic species complex and the endosymbionts have not been well explored. In this study, the phylogenies of different cryptic species of the host with those of their endosymbionts were compared. Of particular interest was whether there was evidence for both coevolution and horizontal transmission. Congruence was observed for the primary endosymbiont, Portiera aleyrodidarum, and partial incongruence in the case of two secondary endosymbionts, Arsenophonus and Cardinium and incongruence for a third, Wolbachia. The patterns observed for the primary endosymbiont supported cospeciation with the host while the patterns for the secondary endosymbionts, and especially Wolbachia showed evidence of host shifts and extinctions through horizontal transmission rather than cospeciation. Of particular note is the observation of several very recent host shift events in China between exotic invader and indigenous members of the complex. These shifts were from indigenous members of the complex to the invader as well as from the invader to indigenous relatives.     

Xiphinema krugi,Species Complex or Complex of Cryptic Species?

Fourteen morphologically putative populations of X. krugi were clearly separated into four different profiles by RFLP analysis (Alu I and Hinf I), sequencing of the ITS-1 region, and subsequent Maximum Likelihood phylogenetic analyses. These four profiles were further supported by a principal component analysis of morphometric characters that yielded four taxonomic clusters matching those produced by the molecular data. Sequence homology was greater amongst populations that represented the same RFLP profile than between profiles and similar both between representative populations of the RFLP profiles and putative closely related Xiphinema species. This study suggests that X. krugi is a potential species complex comprised of at least four distinct genotypes.     

蝗虫触角感受器及其生态学意义

蝗虫触角感受器及其生态学意义陈湖海康乐（中国科学院动物研究所北京１０００８０）关键词蝗虫触角感受器形态分布生态学触角是昆虫感觉系统的重要组成部分,行使着嗅觉、触觉、味觉及感受气流、ＣＯ２、湿度和温度等功能,左右着其选择食物、取食、躲避危险、寻觅配偶及...     

Infection of Bacterial Endosymbionts in Insects: A Comparative Study of Two Techniques viz PCR and FISH for Detection and Localization of Symbionts in Whitefly,Bemisia tabaci

Bacterial endosymbionts have been associated with arthropods and large number of the insect species show interaction with such bacteria. Different approaches have been used to understand such symbiont- host interactions. The whitefly, Bemisia tabaci, a highly invasive agricultural pest, harbors as many as seven different bacterial endosymbionts. These bacterial endosymbionts are known to provide various nutritional, physiological, environmental and evolutionary benefits to its insect host. In this study, we have tried to compare two techniques, Polymerase chain reaction (PCR) and Flourescence in situ Hybridisation (FISH) commonly used for identification and localization of bacterial endosymbionts in B. tabaci as it harbors one of the highest numbers of endosymbionts which have helped it in becoming a successful global invasive agricultural pest. The amplified PCR products were observed as bands on agarose gel by electrophoresis while the FISH samples were mounted on slides and observed under confocal microscope. Analysis of results obtained by these two techniques revealed the advantages of FISH over PCR. On a short note, performing FISH, using LNA probes proved to be more sensitive and informative for identification as well as localization of bacterial endosymbionts in B. tabaci than relying on PCR. This study would help in designing more efficient experiments based on much reliable detection procedure and studying the role of endosymbionts in insects.     

Comparison of Two Steinernematid Species for Control of the Root Weevil Diaprepes abbreviatus

Steinernema carpocapsae Weiser All strain was compared to Steinernema riobravis Cabanillas, Poinar, and Raulston for control of the root weevil, Diaprepes abbreviatus (L.), in the laboratory and in potted citrus. In the laboratory bioassay, D. abbreviatus larvae were exposed to 30, 60, and 120 nematodes/cm³ in sand. Insect mortality 1 week after application was greater (P ≤ 0.05) for S. riobravis than for S. carpocapsae in the laboratory bioassay. In the greenhouse bioassay, D. abbreviatus larvae were exposed to 3 and 9 nematodes per cm³ of soil in potted citrus. Again, at each rate, mortality was greater (P ≤ 0.05) in pots treated with S. riobravis than in pots treated with S. carpocapsae. The results of this study suggest that S. riobravis is a better biological control agent against D. abbreviatus larvae in potted plants than S. carpocapsae.     

Uncovering Cryptic Diversity in Two Amoebozoan Species Using Complete Mitochondrial Genome Sequences

The Amoebozoa are a major eukaryotic lineage that encompasses a wide range of amoeboid organisms. The group is understudied from a systematic perspective: molecular tools have only been applied in the last 15 yr. Hence, there is an undersampling of both genes and taxa in the group especially compared to plants, animals, and fungi. Here, we present the complete mitochondrial genomes of two ubiquitous and abundant morpho‐species (Acanthamoeba castellanii and Vermamoeba vermiformis). Both have mitochondrial genomes of close relatives previously available, enabling insights into recent divergences at a genomic scale, while simultaneously offering comparisons with divergence estimates obtained from traditionally used single genes, SSU rDNA and cox1. The newly sequenced mt genomes are significantly divergent from their previously sequenced conspecifics (A. castellannii 16.4% divergence at nucleotide level and 10.4% amino acid; V. vermiformis 21.6% and 13.1%, respectively), while divergence at the small subunit ribosomal DNA is below 1% within both species. Morphological analyses determined that these lineages are indistinguishable from their previously sequenced counterparts. Phylogenetic reconstructions using 26 mt genes also indicate a level of divergence that is comparable to divergence among species, while reconstructions using the small subunit ribosomal DNA (SSU rDNA) do not. In addition, we demonstrate that between closely related taxa, there are high levels of synteny, which can be explored for primer design to obtain larger fragments than the traditional barcoding genes. We conclude that, although most systematic work has relied on SSU, this gene alone can severely underestimate diversity. Thus, we suggest that the mt genome emerges as an alternative for unraveling the lower level phylogenetic relationships of Amoebozoa.     

Nematicidal Principles from Two Species of Lamiaceae

Aqueous extracts of Ocimum sanctum and O. basilicum leaves contained compounds that killed Meloidogyne incognita larvae in 160 min. Thin layer and gas-liquid chromatography, and infrared spectrophotometry indicated that the essential oils eugenol and linalool were the active nematicidal compounds.     

小地老虎雄蛾触角感受器的扫描电镜观察

利用扫描电镜观察了小地老虎雄蛾触角感受器的种类、形态和分布.结果表明, 小地老虎雄蛾触角为双栉状(端半部为丝状),由1节柄节、1节梗节和82～92节鞭节组成.在触角上分布有毛形感器、刺形感器、鳞形感器、腔锥感器、腔形感器、 耳形感器、B(o)hm's氏鬃毛7种感受器,其中毛形感器数量最多.     

Structure of Antennal Pseudoplacoid Sensilla in the Caddisfly Philopotamus montanus Donovan (Trichoptera,Philopotamidae)

Entomological Review - The structure of pseudoplacoid sensilla characteristic of Amphiesmenoptera was studied by SEM and TEM methods by the example of the mushroom-like sensilla in Philopotamus...     

Wolbachia Infections Mimic Cryptic Speciation in Two Parasitic Butterfly Species,Phengaris teleius and P. nausithous (Lepidoptera: Lycaenidae)

Deep mitochondrial divergence within species may result from cryptic speciation, from phylogeographic isolation or from endosymbiotic bacteria like Wolbachia that manipulate host reproduction. Phengaris butterflies are social parasites that spend most of their life in close relationship with ants. Previously, cryptic speciation has been hypothesised for two Phengaris species based on divergent mtDNA sequences. Since Phengaris species are highly endangered, the existence of cryptic species would have drastic consequences for conservation and management. We tested for cryptic speciation and alternative scenarios in P. teleius and P. nausithous based on a comprehensive sample across their Palaearctic ranges using COI gene sequences, nuclear microsatellites and tests for Wolbachia. In both species a deep mitochondrial split occurring 0.65–1.97 myrs ago was observed that did not correspond with microsatellite data but was concordant with Wolbachia infection. Haplotypes previously attributed to cryptic species were part of the Wolbachia-infected clades. In both species remaining phylogeographic structure was largely consistent between mitochondrial and nuclear genomes. In P. teleius several mitochondrial and nuclear groups were observed in East Asia while a single haplogroup and nuclear cluster prevailed across continental Eurasia. Neutrality tests suggested rapid demographic expansion into that area. In contrast, P. nausithous had several mitochondrial and nuclear groups in Europe, suggesting a complex phylogeographic history in the western part of the species range. We conclude that deep intraspecific divergences found in DNA barcode studies do not necessarily need to represent cryptic speciation but instead can be due to both infection by Wolbachia and phylogeographic structure.     

Scanning Electron Microscopy Studies of the Antennal Sensilla of Metaphycus parasaissetiae Zhang & Huang (Hymenoptera: Encyrtidae)

Metaphycus parasaissetiae Zhang & Huang (Hymenoptera: Encyrtidae) is an important adult parasitoid of Parasaissetia nigra Nietner (Hemiptera: Coccoidea). The external morphology of the antennal sensilla of male and female M. parasaissetiae was examined using scanning electron microscopy. The geniculate antennae of male and female M. parasaissetiae were composed of a scape with a basal radicula, a barrel-shaped pedicel, and a long flagellum. Twelve morphologically distinct types of sensilla were identified, including multiporous placoid sensilla, campaniform sensilla, finger-like sensilla, multiporous basiconic sensilla (BS-1), three aporous types of basiconic sensilla (BS-2, BS-3, and BS-4), two types of aporous trichoid sensilla (TS-1 and TS-3), a type of multiporous trichoid sensilla (TS-2), and two types of sensilla chaetica (CH-1 and CH-2). Sex dimorphism in the sensilla composition of M. parasaissetiae is also observed. Major differences between the sexes were found in the number, distribution, shape, structure, and size of the identified sensilla. We also discuss on the functional aspects of these sensilla to elucidate the mechanisms involved in host searching and courtship behavior of M. parasaissetiae.     

Colonization of Onions by Endophytic Fungi and Their Impacts on the Biology of Thrips tabaci

Endophytic fungi, which live within host plant tissues without causing any visible symptom of infection, are important mutualists that mediate plant–herbivore interactions. Thrips tabaci (Lindeman) is one of the key pests of onion, Allium cepa L., an economically important agricultural crop cultivated worldwide. However, information on endophyte colonization of onions, and their impacts on the biology of thrips feeding on them, is lacking. We tested the colonization of onion plants by selected fungal endophyte isolates using two inoculation methods. The effects of inoculated endophytes on T. tabaci infesting onion were also examined. Seven fungal endophytes used in our study were able to colonize onion plants either by the seed or seedling inoculation methods. Seed inoculation resulted in 1.47 times higher mean percentage post-inoculation recovery of all the endophytes tested as compared to seedling inoculation. Fewer thrips were observed on plants inoculated with Clonostachys rosea ICIPE 707, Trichoderma asperellum M2RT4, Trichoderma atroviride ICIPE 710, Trichoderma harzianum 709, Hypocrea lixii F3ST1 and Fusarium sp. ICIPE 712 isolates as compared to those inoculated with Fusarium sp. ICIPE 717 and the control treatments. Onion plants colonized by C. rosea ICIPE 707, T. asperellum M2RT4, T. atroviride ICIPE 710 and H. lixii F3ST1 had significantly lower feeding punctures as compared to the other treatments. Among the isolates tested, the lowest numbers of eggs were laid by T. tabaci on H. lixii F3ST1 and C. rosea ICIPE 707 inoculated plants. These results extend the knowledge on colonization of onions by fungal endophytes and their effects on Thrips tabaci.     

Heritability and Evolutionary Potential in Thermal Tolerance Traits in the Invasive Mediterranean Cryptic Species of Bemisia tabaci (Hemiptera: Aleyrodidae)

With advancing global climate change, the analysis of thermal tolerance and evolutionary potential is important in explaining the ecological adaptation and changes in the distribution of invasive species. To reveal the variation of heat resistance and evolutionary potential in the invasive Mediterranean cryptic species of Bemisia tabaci, we selected two Chinese populations—one from Harbin, N China, and one from Turpan, S China—that experience substantial heat and cold stress and conducted knockdown tests under static high- and low-temperature conditions. ANOVAs indicated significant effects of populations and sex on heat knockdown time and chill coma recovery time. The narrow-sense heritability (h ²) estimates of heat tolerance based on a parental half-sibling breeding design ranged from 0.47±0.03 to 0.51±0.06, and the estimates of cold tolerance varied from 0.33±0.07 to 0.36±0.06. Additive genetic variances were significantly different from zero for both heat and cold tolerance. These results suggest that invasive B. tabaci Mediterranean cryptic species possesses a strong ability to respond to thermal selection and develops rapid resistance to climate change.     

Long-Term Competitive Dynamics of Two Cryptic Rotifer Species: Diapause and Fluctuating Conditions

Life-history traits may have an important role in promoting species coexistence. However, the complexity of certain life cycles makes it difficult to draw conclusions about the conditions for coexistence or exclusion based on the study of short-term competitive dynamics. Brachionus plicatilis and B. manjavacasare two cryptic rotifer species co-occurring in many lakes on the Iberian Peninsula. They have a complex life cycle in which cyclical parthenogenesis occurs with diapausing stages being the result of sexual reproduction. B. plicatilis and B. manjavacasare identical in morphology and size, their biotic niches are broadly overlapping, and they have similar competitive abilities. However, the species differ in life-history traits involving sexual reproduction and diapause, and respond differently to salinity and temperature. As in the case of certain other species that are extremely similar in morphology, a fluctuating environment are considered to be important for their coexistence. We studied the long-term competitive dynamics of B. plicatilis and B. manjavacas under different salinity regimes (constant and fluctuating). Moreover, we focused on the dynamics of the diapausing egg bank to explore how the outcome of the entire life cycle of these rotifers can work to mediate stable coexistence. We demonstrated that these species do not coexist under constant-salinity environment, as the outcome of competition is affected by the level of salinity—at low salinity, B. plicatilis excluded B. manjavacas, and the opposite outcome occurred at high salinity. Competitive dynamics under fluctuating salinity showed that the dominance of one species over the other also tended to fluctuate. The duration of co-occurrence of these species was favoured by salinity fluctuation and perhaps by the existence of a diapausing egg bank. Stable coexistence was not found in our system, which suggests that other factors or other salinity fluctuation patterns might act as stabilizing processes in the wild.     

Species Delimitation and Analysis of Cryptic Species Diversity in the XXI Century

The potentials and limitations of different approaches to revealing species boundaries and describing cryptic species are discussed. Both the traditional methods of species delimitation, mostly based on morphological analysis, and the approaches using molecular markers are considered. Besides, the prospects of species identification using digital image recognition and machine learning are briefly considered. It is concluded that molecular markers provide very important material for species delimitation; the value of these data increases manifold if they can be compared with information on morphology, geographic distribution, and ecological preferences of the studied taxa. In many cases, only a practicing taxonomist who knows his or her group thoroughly can correctly interpret the molecular data and incorporate them into the existing knowledge system in order to make a taxonomic decision.

     

Spermatozoon Ultrastructure in Two Species of Amphibolus (Eutardigrada,Eohypsibiidae)

We examined the ultrastructure of the spermatozoa from two species of eutardigrades, gonochoristic Amphibolus volubilis and hermaphroditic A. weglarskae, by scanning and transmission electron microscopy. The gametes from the two species were morphologically quite similar, each consisting of a short head, neck and tail. The head included a conic, corkscrew-shaped, bilayered acrosome and a cylindrical nucleus with condensed chromatin. The nucleus is surrounded by cytoplasm organized in ovoid elements with an electron-dense core. The neck is very simple, containing a centriole and unmodified mitochondria. The flagellum contains a 9+2 axoneme and terminates in a tuft of between eight and 10 microtubules. The spermatozoa of Amphibolus, like those of the other eutardigrades, are of the modified type, but nonetheless maintain some primitive aspects of the gametes from heterotardigrades.     

Morphological Comparison and Taxonomic Utility of Copulatory Structures of Selected Nematode Species

Spicules of 9 Meloidogyne, 2 Heterodera, 3 Globodera, and 12 other plant-parasitic, insect-parasitic, and free-living nematodes were excised and examined using scanning electron microscopy (SEM). Gubernacula of some of the species were also excised, and their structure was determined. The two spicules of all species examined were symmetrically identical in morphology. The spicule typically consisted of three parts: head, shaft, and blade with dorsal and ventral vela. The spicular nerve entered through the cytoplasmic core opening on the lateral outer surface of the spicule head and generally communicated with the exterior through one or two pores at the spicule tip. Spicules of Xiphinema sp. and Aporcelaimellus sp. were not composed of three typical parts, were less sclerotized, and lacked a cytoplasmic core opening and distal pores. Spicules of Aphelenchoides spp. had heads expanded into apex and rostrum and had very arcuate blades with thick dorsal and ventral edges (limbs). Gubernaculum shapes were stable within a species, but differed among species examined. The accessory structures of Hoplolaimus galeatus consisted of a tongue-shaped gubernaculum with two titillae at its distal end and a plate-like capitulum terminating distally in two flat, wing-like structures. A comparison of spicules of several species of Meloidogyne by SEM and light microscopy revealed no striking morphological differences.     

Transient Receptor Potential Is Essential for High Temperature Tolerance in Invasive Bemisia tabaci Middle East Asia Minor 1 Cryptic Species

Temperature is an important factor in affecting population dynamics and diffusion distribution of organisms. Alien species can successfully invade and colonize to various temperature environments, and one of important reasons is that alien species have a strong resistance to stress temperature. Recently, researchers have focused on the mechanisms of temperature sensing to determine the sensing and regulation mechanisms of temperature adaptation. The transient receptor potential (TRP) is one of the key components of an organism’s temperature perception system. TRP plays important roles in perceiving temperature, such as avoiding high temperature, low temperature and choosing the optimum temperature. To assess high temperature sensation and the heat resistance role of the TRP gene, we used 3′ and 5′ rapid-amplification of cDNA ends to isolate the full-length cDNA sequence of the TRP gene from Bemisia tabaci (Gennadius) MEAM1 (Middle East Asia Minor 1), examined the mRNA expression profile under various temperature conditions, and identified the heat tolerance function. This is the first study to characterize the TRP gene of invasive B. tabaci MEAM1 (MEAM1 BtTRP). The full-length cDNA of MEAM1 BtTRP was 3871 bp, and the open reading frames of BtTRP was 3501 bp, encoding 1166 amino acids. Additionally, the BtTRP mRNA expression level was significantly increased at 35°C. Furthermore, compared with control treatments, the survival rate of B. tabaci MEAM1 adults was significantly decreased under high temperature stress conditions after feeding with dsRNA BtTRP. Collectively, these results showed that MEAM1 BtTRP is a key element in sensing high temperature and plays an essential role in B. tabaci MEAM1 heat tolerance ability. Our data improved our understanding of the mechanism of temperature sensation in B. tabaci MEAM1 at the molecular level and could contribute to the understanding of the thermal biology of B. tabaci MEAM1 within the context of global climate change.     

Cryptic species of Paracoccidioides brasiliensis: impact on paracoccidioidomycosis immunodiagnosis

We aimed to evaluate whether the occurrence of cryptic species of Paracoccidioides brasiliensis, S1, PS2, PS3 and Paracoccidioides lutzii, has implications in the immunodiagnosis of paracoccidioidomycosis (PCM). Small quantities of the antigen gp43 were found in culture filtrates of P. lutzii strains and this molecule appeared to be more variable within P. lutzii because the synonymous-nonsynonymous mutation rate was lower, indicating an evolutionary process different from that of the remaining genotypes. The production of gp43 also varied between isolates belonging to the same species, indicating that speciation events are important, but not sufficient to fully explain the diversity in the production of this antigen. The culture filtrate antigen AgEpm83, which was obtained from a PS3 isolate, showed large quantities of gp43 and reactivity by immunodiffusion assays, similar to the standard antigen (AgB-339) from an S1 isolate. Furthermore, AgEpm83 was capable of serologically differentiating five serum samples from patients from the Botucatu and Jundiaí regions. These patients had confirmed PCM but, were non-reactive to the standard antigen, thus demonstrating an alternative for serological diagnosis in regions in which S1 and PS2 occur. We also emphasise that it is not advisable to use a single antigen preparation to diagnose PCM, a disease that is caused by highly diverse pathogens.