Fulltext search in archive



« advanced mode »

 previous    ...   42   43   44   45   46  47   48   49   50   51   ...    next 

Results 1351 to 1380 of 2340:

Quantifying aphid predation rates of generalist predators in the field

James D. HARWOOD, John J. OBRYCKI

Eur. J. Entomol. 102 (3): 335-350, 2005 | DOI: 10.14411/eje.2005.051

The community of predators within agroecosystems has the potential to restrict aphid populations, especially early in the season before exponential increases in density and prior to the arrival of specialist natural enemies. Although direct observations of predation, laboratory feeding trials and manipulative field studies have been used to estimate levels of biological control exerted by different species (or potentially negative interactions between them), it is often difficult to extrapolate results to naturally occurring interactions in the field.
Over 100 investigations have utilized gut-content analysis to estimate aphid predation rates by predators. Throughout the last century, gut dissection, which enables the visual identification of aphid body parts, has been used in over 50% of studies although accurate identification and quantification of predation is difficult. Other techniques have included radio-labelling of prey, dissection of faecal samples, electrophoresis, stable isotope analysis and use of polyclonal antisera. In recent studies of invertebrate predation, monoclonal antibodies have been the most frequently applied technique but advances in molecular biology have enabled the detection of species-specific DNA sequences. The use of these applications to quantify predation by aphidophagous predators will be reviewed, with emphasis on potential sources of error and difficulties of quantitative interpretation. Despite the considerable focus currently directed towards molecular approaches, antibody-based techniques are likely to remain an important tool for studying predation rates of pests in the field, especially when antibodies have already been developed. However, the study of multiple predation events within complex generalist predator food webs is only likely through the detection of species-specific DNA sequences using molecular techniques.

Oviposition-deterring effects of conspecific and heterospecific larval tracks on Cheilomenes sexmaculata (Coleoptera: Coccinellidae)

Zdenìk RÙ®IÈKA

Eur. J. Entomol. 103 (4): 757-763, 2006 | DOI: 10.14411/eje.2006.101

The oviposition deterring effects of fresh larval tracks of Cheilomenes sexmaculata (F.), Ceratomegilla undecimnotata (Schneider), Cycloneda limbifer Casey, and Harmonia dimidiata (F.) on C. sexmaculata females were compared in standard laboratory choice tests. Moreover, the persistence of intraspecific effects of C. sexmaculata larval tracks were investigated. Fresh tracks of C. sexmaculata, C. limbifer and C. undecimnotata larvae effectively deterred C. sexmaculata females from ovipositing. The effect of fresh larval tracks of H. dimidiata was not statistically significant. The oviposition-deterring effects of 10 d-old conspecific larval tracks were considerably lower than those of fresh tracks, but remained significant. Clutch sizes were smaller in the blank test without larval tracks than in choice tests with fresh tracks of conspecific, C. limbifer, C. undecimnotata, H. dimidiata larvae and with 10 d-old tracks of conspecific larvae. The study indicates that semiochemicals in the tracks of conspecific and heterospecific coccinellid larvae can contribute considerably to the spacing of C. sexmaculata offspring among prey resources of differing quality and that conspecific as well as heterospecific larval tracks can influence clutch size.

Winter climates and coldhardiness in terrestrial insects

William J. TURNOCK, Paul G. FIELDS

Eur. J. Entomol. 102 (4): 561-576, 2005

Overwintering insects must avoid injury and death from the freezing of tissues and from metabolic disruptions associated with exposure to low, non-freezing temperatures. The winter climates of the world are classified in relation to insect overwintering on the basis of their minimum temperatures and the duration of the winter (when temperatures are below the thermal range for activity and development). Outside the Tropical Wet zone, the severity of exposure to cold (temperature, snowfall, duration of exposure, predictability, variability) can vary from a few days at 0°C to months below -20°C with extremes as low as -60°C. The severity of the temperature exposure may be ameliorated by the selection by insects of overwintering sites (exposed, partly-exposed, protected). The relationships among overwintering habitats, the minimum winter temperature in climatic zones, and the supercooling points (SCP) of over 350 terrestrial insects from published reports were examined. Variability in the SCP among insects within each climatic zone and habitat was wide. Among the freeze-susceptible species that overwintered in exposed or partly-protected habitats the SCP and the cold severity of climate were correlated. This was not the case for insects that overwintered in protected habitats. The SCP's of freeze-tolerant insects were generally higher than the freeze-susceptible insects, and the SCP's were not tightly linked with the cold severity of climatic zone. Insects, both freeze-susceptible and freeze-tolerant, overwintering in exposed habitats had lower SCP's than insects from habitats that offered some protection from ambient temperatures. Thirty-eight species had reports of SCP's for different geographical locations. Although there were occasionally differences in the SCP's, there was no consistent pattern of insects having lower SCP's when overwintering in colder habitats. The incidence of freeze-tolerance was higher in boreal and polar climatic zones than in climatic zones with warmer winters. Holometabola insects had a higher incidence of freeze-tolerance than hemimetabola insects. Suggestions for future research directions are outlined.

The reproductive behaviour of an aphidophagous ladybeetle, Coccinella septempunctata (Coleoptera: Coccinellidae)

OMKAR, Shefali SRIVASTAVA

Eur. J. Entomol. 99 (4): 465-470, 2002 | DOI: 10.14411/eje.2002.060

The reproductive behaviour of a ladybeetle, Coccinella septempunctata was studied in detail. Males became sexually mature within 8.8 ± 0.3 days at 27°C, while females took 11.2 ± 0.4 days. Males exhibited courtship display in five steps: approach, watch, examine, mount and copulatory attempt. A prominent rejection display was shown by certain females who had not matured sexually, had recently mated or were about to oviposit. Males appeared to recognize females through chemical and some visual cues, such as size and body shape, with the chemical cues possibly playing a more significant role. Multiple matings took place within the same day. There was a gradual decrease with time in reproductive parametres, such as the duration of copulation, the number of copulatory bouts and the latent period from first to subsequent matings on the same day. The interval between mating bouts slightly increased from first to subsequent matings. The sexual status of males and females affected the duration of copulation, which was greatest in the case of unmated males and virgin females. Multiple matings increased the oviposition period, fecundity and percent hatching of eggs.

A study of meiosis and spermiogenesis in the testicular lobes of Antiteuchus tripterus (Heteroptera: Pentatomidae)

Hederson Vinícius de SOUZA, Hermione Elly Melara De CAMPOS BICUDO, Luiz Antônio Alves COSTA, Mary Massumi ITOYAMA

Eur. J. Entomol. 104 (3): 353-362, 2007 | DOI: 10.14411/eje.2007.053

An analysis of testicular morphology and spermatogenesis in the Heteroptera species Antiteuchus tripterus (Pentatomidae) revealed that these traits differ from that recorded for other species of the same family. The testes of A. tripterus have only six lobes, while other species of the same family typically have seven lobes, including a compound lobe, i.e., a lobe containing another in its lumen. A study of meiosis and sperm structure in the different lobes of A. tripterus revealed a conventional meiosis in the lobes numbered one to three. In lobe four, however, prophase I spermatocytes exhibit the morphological characteristics of the so called "diffuse" stage and are larger than those in lobes 1-3 in this and the remaining phases of meiosis. Thus, the resulting spermatids are not only larger but also their head is morphologically different. Lobe 5 exhibits characteristics known from other Pentatomidae species such as an uneven distribution of chromatin to the daughter cells, which give rise to cells of different sizes. This lobe forms spermatozoa of different sizes. Lobe 6, contained within lobe 5, differs from it by having larger cells at a stage similar to the so called "diffuse" and spermatid tails with cross divisions, which are not found in other lobes and unreported in the literature.

Variation in dung beetle (Coleoptera: Scarabaeoidea) assemblages with altitude in the Bulgarian Rhodopes Mountains: A comparison

Jorge M. LOBO, Evgeni CHEHLAROV, Borislav GUÉORGUIEV

Eur. J. Entomol. 104 (3): 489-495, 2007 | DOI: 10.14411/eje.2007.069

Variation with altitude in the composition of dung beetle assemblages and species richness was measured by sampling in spring, summer and autumn, both manually and with pitfall traps at twelve localities in the western Rhodopes Mountains. Non-parametric estimates indicate that most of the regional species pool was collected, some 73% of all taxa previously recorded in the entire region. The rate of species richness decrease with altitude is around 11 species per km, with an evident altitudinal change in the incidence of two main dung beetle functional groups in which Aphodiinae species begin to dominate Rhodopes assemblages at around 1400-1500 m. Species richness of dung pats is dominated by Scarabaeinae in spite of the fact that the number of Aphodiinae species is highest at each locality. Thus, Aphodiinae species are the main contributors to both local and regional pool richness and to species turnover between localities. These characteristics are similar to those observed in the assemblages from another European mountain range, also located near the Mediterranean-Eurosiberian boundary, the Iberian Central System. These results suggest that eastern European dung beetle assemblages are similar in compositional turnover and species richness variation with altitude to that observed in western Europe and North America.

Cleorodes Warren, 1894 does not belong in the tribe Boarmiini (Lepidoptera: Geometridae)

Jaan VIIDALEPP, Toomas TAMMARU, Niina SNÄLL, Kai RUOHOMÄKI, Niklas WAHLBERG

Eur. J. Entomol. 104 (2): 303-309, 2007 | DOI: 10.14411/eje.2007.046

The geometrid genus Cleorodes is shown to belong in the tribe Gnophini (sensu lato) and not in Boarmiini as previously assumed. The conclusion is based on an analysis of morphological characters of a number of genera in these tribes. Moreover, the result is unambiguously supported by a phylogenetic analysis of DNA sequence variation in three nuclear gene regions (segments D1 and D2 of 28S rRNA, and elongation factor 1α) and a mitochondrial gene, cytochrome oxidase-1. The phylogenetic hypothesis is based on a combined sequence data set, which was analysed using direct optimisation.

Geographical versus food plant differentiation in populations of Maculinea alcon (Lepidoptera: Lycaenidae) in Northern Hungary

Judit BERECZKI, Katalin PECSENYE, Zoltán VARGA

Eur. J. Entomol. 103 (4): 725-732, 2006 | DOI: 10.14411/eje.2006.096

The taxonomic status of Alcon Blues in Central and Western Europe (conventionally: Maculinea alcon and M. rebeli) is confused. Some authors distinguish them as separate species within the M. alcon species group, while others consider them to be subspecies or simply ecological forms. Our aim was to study the geographical versus food plant pattern of genetic differentiation among several populations of these taxa in Northern Hungary. Imagines were collected from 11 localities between 2000 and 2003. M. alcon feeding on G. pneumonanthe from three subregions and on G. cruciata from two subregions were analysed. Enzyme polymorphism was analysed at 16 enzyme loci using polyacrylamide gel electrophoresis. In the analysis of the data, F-statistics were computed and the total genetic variation partitioned into within and between population components. Nei's genetic distances were calculated and a UPGMA dendrogram constructed on the basis of the distance matrix. Hierarchical F-statistics and AMOVA were computed to study the pattern of genetic differentiation among the samples. PCA analysis was also carried out using the allele frequencies of the samples. The results of all analyses indicated strong differentiation among the samples. A sizeable portion of this variation was detected among the samples/generations collected from the same population. The distribution of the between population variation did not exhibit a clear split between the two food plant groups. In addition, the FST values computed using a restricted data set suggested significant differentiation among the subregions. The results of AMOVA and PCA also indicated that the geographic pattern was more expressed in the between sample variation than the conventional taxonomic pattern.

Cockroach tergal glands producing female sex attractant pheromones and male aphrodisiacs in particular in the subfamily Blaberinae (Blattaria: Blaberidae)

Leam SRENG

Eur. J. Entomol. 103 (4): 817-829, 2006 | DOI: 10.14411/eje.2006.112

Two principal pheromones are essential in all cockroach sexual behavioral sequences: the volatile sex attractant pheromone released by one partner for long distance attraction and an aphrodisiac sex pheromone produced exclusively by male tergal glands for female mounting and feeding behavior. In the Blaberinae subfamily, the female produces volatile sex attractant pheromones and the male, aphrodisiacs. A close relationship is known to exist between the release of these pheromonal signals from specific glands and the corresponding behaviors (female calling posture and male wing raising). However, in this cockroach group, no data on the glands secreting sex attractant pheromones and aphrodisiacs have been available until now. In seven species of the Blaberinae subfamily: Blaberus colosseus, B. craniifer, B. discoidalis, Blaptica interior, Byrsotria fumigata, Eublaberus distanti and E. posticus; one species of the Zetoborinae subfamily: Schultesia lampyridiformis; one species of the Epilamprinae subfamily: Epilampra maya and one species of the Panesthiinae subfamily, Panesthia sp., the females possess all pygidial glands on the 10 th tergite and the males have tergal glands situated anteriorly, generally on tergites T1 and T2. These glands are formed of type 3 glandular units with two cells, i.e. glandular and canal cells. The uniform presence of female pygidial glands and male tergal glands explains their relationship with their corresponding sexual behaviors.

Metathoracic glands and associated evaporatory structures in Reduvioidea (Heteroptera: Cimicomorpha), with observation on the mode of function of the metacoxal comb

Christiane WEIRAUCH

Eur. J. Entomol. 103 (1): 97-108, 2006 | DOI: 10.14411/eje.2006.015

Structures that assist in spreading secretions produced by the metathoracic glands were examined in Reduviidae and Pachynomidae (Heteroptera). The systematic distribution of a row of long and stout setae on the metacoxa, the metacoxal comb, was reinvestigated in a representative sample in both taxa. Observations on living Dipetalogaster maximus (Reduviidae: Triatominae) corroborated the interpretation of this metacoxal comb as an evaporatory device, which assists in atomizing the gland secretions. In addition to the metacoxal comb, a row of stout setae on the metacetabulum - a metacetabular comb - was found in several Reduviidae, which interacts with the metacoxal comb during rotation of the metacoxa. In addition to those atomizing devices, cuticular modifications surrounding the opening of the metathoracic gland, which presumably form evaporatoria, were discovered in Ectrichodiinae. The meshwork-like structure of this cuticle resembles the cuticular modifications found associated with the opening of the Brindley's gland in Reduviidae, but differs from the mushroom-like evaporatoria around the metathoracic glands in most Cimicomorpha and Pentatomomorpha. Thus, two fundamentally different mechanisms to spread secretions of the metathoracic gland - atomization and evaporation - are present in Reduviidae.

The impact of W. Hennig's

Nils Moller ANDERSEN

Eur. J. Entomol. 98 (2): 133-150, 2001 | DOI: 10.14411/eje.2001.024

Phylogenetic systematics comprise the principles and methods by which we reconstruct the evolutionary history (phylogeny) of organisms and transform this reconstruction into a biological classification of these organisms. The most important progress in designing the tools for phylogenetic reconstruction was initiated by the German entomologist Willi Hennig (1913-1976), who clarified or redefined the goals of phylogenetic systematics in a book published in 1950: Grundzüge einer Theorie der phylogenetischen Systematik. An extensively revised, English translation was published in 1966: Phylogenetic Systematics. W. Hennig's "phylogenetic systematics" undoubtedly was a very significant contribution to systematics, by some systematists and philosophers even characterized as a "revolution". Hennig's redefinition and clarification of the concepts of monophyly and phylogenetic relationships created a sound foundation for systematics in general. After decades of focussing on species-level problems, Hennig redirected the interest of systematists towards the study of higher taxa and the reconstruction of phylogenetic relationships between them. A phylogenetic system is now almost universally accepted as the most useful general reference system for biology. It has been able to accommodate new developments in systematics (such as quantitative cladistics and molecular systematics), evolutionary biology (such as ecological phylogenetics), and historical biogeography.

Feeding conditions modify the photoperiodically induced dispersal of the water strider, Aquarius paludum (Heteroptera: Gerridae)

Tetsuo HARADA, Tatsuya NISHIMOTO

Eur. J. Entomol. 104 (1): 33-37, 2007 | DOI: 10.14411/eje.2007.005

Overwintering adults of the water strider, Aquarius paludum were collected from the field in fall and kept under short days (12L : 12D) at 20°C for a week. A control group was then kept at 12L : 12D and fed daily, and three experimental groups were transferred to 15.5L : 8.5D and fed at different frequencies: daily or every 2nd or 3rd day. Temperature was kept at 20°C. Flight behaviour of the adults in the four groups was recorded every 10 days up to the end of the 5th week when the adults were dissected. State of the flight muscles and reproductive organs (ovaries and testes) was recorded. Flight ability of the adults fed every 3rd day (Group 3) was higher than that of those fed daily (Group 1). Seventy percent of the females that were fed every 3rd day (Group 3) remained in diapause for 5 weeks, in spite of the reproduction promoting long-days, while none of the females fed every day remained in diapause (Group 1). Flight muscle histolysis, promoted by long-days, was inhibited by poor feeding conditions. Thus, they can migrate and seek more suitable water bodies rich in food. The modifying effect of the availability of food on the trade-off between reproduction and flight is recorded here for the first time for a carnivorous insect.

Suitability of various prey types for the development of Propylea japonica (Coleoptera: Coccinellidae)

Shi-Ze ZHANG, Fan ZHANG, Bao-Zhen HUA

Eur. J. Entomol. 104 (1): 149-152, 2007 | DOI: 10.14411/eje.2007.021

The relative suitability of three prey organisms, Bemisia tabaci (Gennadius) eggs, B. tabaci nymphs, and Myzus persicae (Sulzer), to the ladybird Propylea japonica (Thunberg) was evaluated under laboratory conditions. The larvae developed fastest when fed M. persicae, and slowest on B. tabaci eggs. When fed M. persicae, all larvae successfully developed into adult with a growth index (i.e., percent pupation/larval period in days) of 13.16 and development rate of 0.096. The longevity of starving adults was 4.7 ± 0.2 days. In contrast, when fed B. tabaci eggs, all larvae survived to the second instars, 56.7% of which survived to the third instars, 13.3% to the fourth instars; only 6.7% of larvae survived to the pupal stage and the pupae developed into abnormal adults that died shortly. When fed B. tabaci nymphs, all larvae survived and successfully developed into adults with a growth index of 10.71 and development rate of 0.083. The adult body mass was greater when larvae fed M. persicae, compared to adults eclosing from larvae fed B. tabaci nymphs. On the basis of these findings, the order of suitability of three prey organisms for P. japonica is M. persicae > B. tabaci nymph > B. tabaci egg. This is the first record that P. japonica can complete its development when feeding exclusively on whitefly nymphs.

Morphology, bioacoustics and phylogeography of the Isophya major group (Orthoptera: Tettigoniidae: Phaneropterinae): A species complex occurring in Anatolia and Cyprus

Hasan SEVGILI, Battal ÇIPLAK, Klaus Gerhard HELLER, Ali DEMIRSOY

Eur. J. Entomol. 103 (3): 657-671, 2006 | DOI: 10.14411/eje.2006.086

The species of the Isophya major-group (Orthoptera: Tettigoniidae: Phaneropterinae), are reviewed. I. major Brunner von Wattenwyl and I. mavromoustakisi Uvarov are redescribed. Two new species are described; Isophya mersinensis Sevgili & Çiplak sp. n. and Isophya salmani Sevgili & Heller sp. n. from south Anatolia. Illustrations of morphology and male calling song are provided and a detailed comparison of the four species in the group is presented. We conclude that these four species constitute a natural group in sharing male cerci with two or more denticles not ordered in a line, a character unique to this species group within the genus. From an evaluation of their morphology and song characteristics, relationships among the species in the group are I. major + (I. mersinensis sp. n. + (I. salmani + I. mavromoustakisi). Based on the the distribution pattern and habitat preference, we concluded that the division of I. salmani and I. mavromoustakisi was a vicariant event resulting from the separation of Cyprus and Anatolia due to reflooding of the Mediterranean after the Messinian salinity crisis at the beginning of the Pliocene, around 5 My ago.

Phylogeny of Chrysotoxum species (Diptera: Syrphidae) inferred from morphological and molecular characters

Antonio MASETTI, Andrea LUCHETTI, Daniele SOMMAGGIO, Giovanni BURGIO, Barbara MANTOVANI

Eur. J. Entomol. 103 (2): 459-467, 2006 | DOI: 10.14411/eje.2006.059

Relationships of nine Italian Chrysotoxum species were analysed using morphological and molecular data. The morphology-derived cladogram revealed three well-defined groups: (i) C. cautum, (ii) the arcuatum group (C. arcuatum, C. fasciolatum) and (iii) the festivum group (C. festivum - C. vernale, C. bicinctum, C. elegans, C. octomaculatum and C. parmense). Trees inferred from COI-tRNALeu-COII sequences were largely in agreement, but they identified (i) C. parmense as an isolated branch, (ii) C. festivum and C. vernale as separate entities, (iii) C. elegans within a paraphyletic C. festivum clade. ITS2 trees were partially unresolved but C. parmense sequence emerged as a sister to the festivum group. The monophyly of the festivum group derived from morphological data was rejected by a phylogenetic test performed on combined molecular data set. The diagnostic value of some morphological characters commonly used to identify Chrysotoxum species is therefore questioned.

Molecular and morphological phylogeny of the parasitic wasp genus Yelicones (Hymenoptera: Braconidae: Rogadinae)

Buntika AREEKUL, Miharu MORI, Alejandro ZALDIVAR-RIVERÓN, Donald L.J. QUICKE

Eur. J. Entomol. 102 (4): 617-624, 2005

Phylogenetic relationships of the braconid wasp genus Yelicones Cameron are studied using the D2-D3 region of the nuclear 28S rRNA gene, both alone and simultaneously with morphology. The results support a morphology-based phylogeny, presented elsewhere, with Yelicones being divided into two major groups corresponding to the New and Old World faunas. The African and Asian species largely form separate clades except for Yelicones wui Chen & He from China which is associated with the Afrotropical species. Potential molecular synapomorphies are illustrated.

The role of wing veins in colour pattern development in the butterfly Papilio xuthus (Lepidoptera: Papilionidae)

Paul Bernhardt KOCH, H. Frederik NIJHOUT

Eur. J. Entomol. 99 (1): 67-72, 2002 | DOI: 10.14411/eje.2002.012

Naturally occurring veinless specimen of the swallowtail Papilio xuthus show an extremely aberrant colour pattern. In spite of the fact that we have no breeding data, these veinless specimen are provisionally called veins-reduced mutant. In these mutants seven longitudinal veins of the fore wing and five of the hind wing are absent. The absence of wing veins is associated with a loss of the broad black venous stripes that normally are present along the proximal portion of the veins. In addition, missing veins cause a loss of the dislocation of black bands in adjacent wing cells, so that what are discrete black segments in normal wings become continuous bands in the veinless wing. Computer simulations show that the morphology of the striped patterns on both the veinless and veined wing can be explained if the wing margin acts as an inductive source of pattern formation and the veins act simply as boundaries to the propagation of the signal from the wing margin. The vein-dependent patterns by contrast, require that the veins act as inductive sources, at least along their proximal portion. This dual role of wing veins is consistent with prior observations on the biology of colour pattern formation. The unique veinless colour pattern strongly supports the hypothesis that the wing margin is the dominant organiser of colour pattern in this species, and possibly in other Papilionidae.

Review of Ceranisus (Hymenoptera: Eulophidae) of Turkey, with description of a new species

Miktat DOĞANLAR, Serguei V. TRIAPITSYN

Eur. J. Entomol. 104 (1): 105-110, 2007 | DOI: 10.14411/eje.2007.016

Three species of Ceranisus Walker, 1841 (Hymenoptera: Eulophidae: Entedoninae) were collected recently in Turkey, including C. menes (Walker, 1839) and C. pacuvius (Walker, 1841) in southeastern Anatolia. A new species, C. hirsutus Doğanlar & S. Triapitsyn, is described from ªanliurfa Province. The genus Urfacus Doğanlar, 2003 is synonymized under Ceranisus and its type species, U. bozovaensis Doğanlar, 2003 is transferred to Ceranisus as C. bozovaensis (Doğanlar, 2003) comb. n., and the species is redescribed from the new material. An identification key to both sexes of Ceranisus from Turkey and Europe is provided.

Genetic variation in the diamondback moth, Plutella xylostella (Lepidoptera: Yponomeutidae) in China inferred from mitochondrial COI gene sequence

Jianhong LI, Feng ZHAO, Yong Soo CHOI, Iksoo KIM, Hung Dae SOHN, Byung Rae JIN

Eur. J. Entomol. 103 (3): 605-611, 2006 | DOI: 10.14411/eje.2006.081

The diamondback moth, Plutella xylostella (L.), is a notorious insect pest of cruciferous plants. To examine the pattern and magnitude of genetic variation in this species in China a portion of the mitochondrial (mt) COI gene of P. xylostella, collected at six Chinese and two Korean localities, which cover ~2,151,600 km2, was sequenced. Sequence analysis of the 681-bp mt COI gene from 80 individuals resulted in 16 haplotypes, ranging in sequence divergence from 0.1% (one nucleotide) to 0.9% (six nucleotides). One nucleotide position among 16 variable sites was a transversional substitution and the remaining positions were transitional substitutions. No position resulted in amino acid substitution. Phylogenetic analysis showed that all haplotypes were highly interrelated and no discernable haplotype group was found. From a geographical perspective, most haplotypes were found singly at one or two localities, with three haplotypes widely distributed. Little genetic differentiation (FST = -0.038-0.309) and a high rate of female migration (Nm = 1.117 - infinite) between Chinese populations suggests that dispersal over long distances is a major factor in the demography of this species.

A comparison of three trapping methods used to survey forest-dwelling Coleoptera

Esko HYVÄRINEN, Jari KOUKI, Petri MARTIKAINEN

Eur. J. Entomol. 103 (2): 397-407, 2006 | DOI: 10.14411/eje.2006.054

Sampling of insect communities is very challenging and for reliable interpretation of results the effects of different sampling protocols and data processing on the results need to be fully understood. We compared three different commonly used methods for sampling forest beetles, freely hanging flight-intercept (window) traps (FWT), flight-intercept traps attached to trunks (TWT) and pitfall traps placed in the ground (PFT), in Scots pine dominated boreal forests in eastern Finland. Using altogether 960 traps, forming 576 sub-samples, at 24 study sites, 59760 beetles belonging to 814 species were collected over a period of a month. All of the material was identified to species, with the exception of a few species pairs, to obtain representative data for analyses. Four partly overlapping groups were used in the analyses: (1) all, (2) saproxylic, (3) rare and (4) red-listed species. In terms of the number of species collected TWTs were the most effective for all species groups and the rarer species the species group composed of (groups 1-2-3-4) the larger were the differences between the trap types. In particular, the TWTs caught most red-listed species. However, when sample sizes were standardized FWTs and TWTs caught similar number of species of all species groups. PFTs caught fewer species of all species groups, whether the sample sizes were standardized or not. In boreal forests they seem to be unsuitable for sampling saproxylic, rare and red-listed species. However, the PFTs clearly sampled different parts of species assemblages than the window traps and can be considered as a supplementary method. The abundance distribution of saproxylic species was truncated lognormal in TWT and pooled material, whereas unclassified material failed to reveal lognormal distribution in all the trap types and pooled material. The results show that even in boreal forests sample sizes of at least thousands, preferably tens of thousands of individuals, collected by a high number of traps are needed for community level studies. Relevant ecological classification of material is also very important for reliable comparisons. Differences in the performance of trap types should be considered when designing a study, and in particular when evaluating the results.

Ageing trajectory and longevity trade-off in an aphidophagous ladybird, Propylea dissecta (Coleoptera: Coccinellidae)

Geetanjali MISHRA, OMKAR

Eur. J. Entomol. 103 (1): 33-40, 2006 | DOI: 10.14411/eje.2006.005

The ageing trajectory (trend in ageing) and reproduction-longevity trade-off in both sexes of the ladybird Propylea dissecta were studied. The ageing trajectories of both sexes were investigated in terms of reproductive performance, using initial oviposition (egg laying within 24 h of mating) acting as an indicator of the effect of female age and initial viability (percentage of eggs laid within 24 h of mating that hatched) of the effect of male age. Ageing trends were sex dependent, with reproductive performance declining later in females than in males. Initial oviposition of females was largely age dependent and the initial viability of males was age dependent but less so than for females. There is a strong trade-off between number of matings and longevity. Statistical analyses reveal that this trade-off results from an early onset of mortality rather than an increase in mortality rate. A minimum lifespan was observed in this ladybird beyond which the longevity did not further decline.

The Red Admiral butterfly (Vanessa atalanta, Lepidoptera: Nymphalidae) is a true seasonal migrant: an evolutionary puzzle resolved?

Kauri MIKKOLA

Eur. J. Entomol. 100 (4): 625-626, 2003 | DOI: 10.14411/eje.2003.091

Ornithologists in Finland recorded the autumn migration of the Red Admiral butterfly, Vanessa atalanta (L.). In the best year, 1998, 1240 migrants were counted from a bird tower in September. That is, half a million butterflies migrated over a 100-km front. The butterflies were flying above forests riding on cool northerly winds. Radar indicated that a large proportion migrated at high elevations outside the visible range. These records help to resolve an "evolutionary puzzle" of why migrant butterflies and moths travel to northern latitudes when their offspring have limited possibilities of returning south. Until now, the only butterfly for which a high-elevation return migration on northerly winds is known is the American Monarch Danaus plexippus (L.).

Molecular differentiation of the four most commonly occurring Trichogramma (Hymenoptera: Trichogrammatidae) species in China

Zheng-Xi LI

Eur. J. Entomol. 104 (3): 363-367, 2007 | DOI: 10.14411/eje.2007.054


Trichogramma dendrolimi
, T. ostriniae, T. confusum and T. evanescens are the four most commonly occurring Trichogramma species with overlapping distribution in China. They are the most frequently used egg parasitoids for biological control of lepidopterous crop pests in China. It is difficult to differentiate Trichogramma species because of their small size and lack of differences in morphological characters. Different molecular markers were employed to molecularly characterize and differentiate these species, including direct amplification of the internally transcribed spacer 2 (ITS2) of ribosomal DNA by polymerase chain reaction (PCR), restriction fragment length polymorphism (RFLP), random amplified polymorphic DNA (RAPD) and species-specific primers. The results showed that direct amplification of ITS2 could not clearly discriminate these species, but they could be differentiated using RFLP pattern obtained with endonucleases EcoRI and HindIII. The banding pattern produced by RAPD is irreproducible so it is not a suitable way to identify Trichogramma species. Finally, the species-specific primers designed based on ITS2 sequences could unequivocally distinguish the four species. The species-specific primer-based protocol proved to be the most convenient and time saving method for the identification of Trichogramma species by creating a unique PCR product, which can be used in surveying natural populations of Trichogramma species. This is the first report of the prompt identification of the four most commonly occurring Trichogramma species in China.

Prey preference and biomass consumption of Macrolophus pygmaeus (Hemiptera: Miridae) fed Myzus persicae and Macrosiphum euphorbiae (Hemiptera: Aphididae)

Dionyssios P. LYKOURESSIS, Dionyssios C. PERDIKIS, Maria D. GASPARI

Eur. J. Entomol. 104 (2): 199-204, 2007 | DOI: 10.14411/eje.2007.031

The predation rate of the polyphagous predator Macrolophus pygmaeus (Rambur) when offered two aphid species, Myzus persicae (Sulzer) and Macrosiphum euphorbiae (Thomas), was investigated. Equal or unequal numbers of nymphs of each instar of the aphids were offered to the predator alone or together. Aphids were placed on an eggplant leaf, together with a fifth instar nymph of the predator in a plastic Petri dish and kept in growth cabinets at 25°C, 65 ± 5% r.h., and a 16L : 8D photoperiod. The predation rate of M. pygmaeus was always higher on M. persicae than on M. euphorbiae. However, biomass consumption was highest when instars of M. euphorbiae were offered in unequal numbers. The predator showed a strong preference and higher biomass consumption of first and second instar M. persicae. In tests where M. euphorbiae was the prey, preference and biomass consumption were almost always higher for the first instar. Therefore, first and second instar M. persicae and first instar M. euphorbiae provide optimal prey for M. pygmaeus. The implication of the prey preference shown by M. pygmaeus for the biological control of these two aphid species is discussed.

Development of the entomopathogenic hyphomycete Lecanicillium muscarium (Hyphomycetes: Moniliales) on various hosts

Hassan ASKARY, Hamid YARMAND

Eur. J. Entomol. 104 (1): 67-72, 2007 | DOI: 10.14411/eje.2007.011

The present scanning electron microscopy study describes the development of Lecanicillium muscarium, strain DAOM 198499, on the surface of diverse hosts, including Sphaerotheca fuliginea, a fungal host, and Macrosiphum euphorbiae and Aphidius nigripes, insect hosts. The hosts were sprayed with a conidial suspension of L. muscarium (107 conidia/ml). The specimens used in the SEM investigation were collected at particular periods after spraying and prepared for scanning using standard methods. Germination tubes developed twenty-four hours after applying L. muscarium conidia to each host. Hyphae were attached to the host by a thin mucilaginous matrix. Seventy-two hours after spraying, hyphae of S. fuliginea had collapsed and were encircled by the parasite, and primary sporulation of L. muscarium was observed. On the aphid host, colonization started with adherence of the conidia to the host cuticle, followed by conidial germination and growth of mycelium on the surface of the insect's integument. After 48 to 72 h, post colonization, the first sporulation was observed on the cuticle, particularly at articulations. The mode of parasitism of A. nigripes by this fungus was similar to that of the aphid. Development of L. muscarium was observed on both mummified aphids (containing the pupae of parasitoids) and adult parasitoids.

Diapause completion in the almond seed wasp, Eurytoma amygdali (Hymenoptera: Eurytomidae) following early low temperature treatment

John T. MARGARITOPOULOS, Minos E. TZANAKAKIS

Eur. J. Entomol. 103 (4): 733-742, 2006 | DOI: 10.14411/eje.2006.097

Fruit of two almond, Prunus amygdalus Linnaeus, cultivars (Retsou and Truoito) containing diapausing larvae of Eurytoma amygdali Enderlein, were collected in early August from coastal areas in northern Greece. Some larvae were removed from the fruit and maintained singly in open plastic vials and others left in the fruit until the end of the low-temperature period. They were kept at a low temperature of 10°C from the beginning, or after 8 weeks at 20°C. The larvae were subsequently maintained at 20°C and whether they completed the two diapause stages was recorded for 60 more weeks. When the larvae in vials, were kept initially for 8 weeks at 20°C, most of those from Retsou and all of those Truoito almonds completed the first stage of diapause. Of the larvae in the fruits, most of those in Truoito but less than 50% of those in Retsou almonds completed the first stage of diapause after 8 weeks at 20°C. Larvae from different orchards and different almond cultivars differed in diapause intensity. When the larvae were kept at a low temperature of 10°C from the beginning for 4, 8 or 16 weeks and then at 20°C they completed the second diapause stage synchronously, but the time of completion was delayed, and depended on the duration of the low temperature treatment. In several cases the time to diapause completion was bimodally distributed and the relative size of peak depended on the duration of the early exposure to low temperature.

Within and between species scaling in the weight, water, carbon and nitrogen contents of eggs and neonate larvae of twelve satyrine butterflies (Lepidoptera: Nymphalidae)

Enrique GARCÍA-BARROS

Eur. J. Entomol. 103 (3): 559-568, 2006 | DOI: 10.14411/eje.2006.076

The fresh weight, dry weight, and C and N content of the eggs, egg shells and neonate larvae of several satyrines were measured. This was done in order to assess the specificity of the composition of the egg and larvae, the phylogenetic or ecological nature of the variation and the existence of structural constraints on the composition of the offspring. All the traits investigated were found to be highly species-specific. The nature of the variation was not primarily phylogenetic, suggesting that the composition of the offspring has an ecological meaning. However, only a slight association was detected between three life history traits or habitat features and the compositions of the eggs or larvae, namely: female egg dropping was associated with a high C content of the eggs, xerophily with a high C : N ratio, and a high content of N in the larvae with egg diapause. The evidence for intra-specific allometry between the traits investigated and egg weight varied among the species, suggesting that the slope of such relationship may be a specific feature. There was a close to isometric relationship between C and N contents in every species. Therefore simple C : N ratios are independent of egg size, hence they can be used directly in comparative studies. Across species analyses indicated that small offspring contained a proportionally low amount of carbon and had a high dry matter content, suggesting that selection for small eggs was accompanied by selection for an enhanced proportion of nitrogen per egg. Finally, the species with large adult females invested comparatively more nitrogen per egg, which indicates a potential, constraint-based advantage of large adult size.

The role of plant odours in the leafminer Liriomyza sativae (Diptera: Agromyzidae) and its parasitoid Diglyphus isaea (Hymenoptera: Eulophidae): Orientation towards the host habitat

Yun Xian ZHAO, Le KANG

Eur. J. Entomol. 99 (4): 445-450, 2002 | DOI: 10.14411/eje.2002.056

Electroantennogram responses of the polyphagous leafminer Liriomyza sativae and its generalist parasitoid Diglyphus isaea to host and non-host plant odours of L. sativae were investigated. The odours of healthy leaves can elicit distinct EAG responses in L. sativae. The EAG responses to the odours of the host plants, bean and tomato, were stronger than to non-host plants, Chinese rose and morning glory. Neither healthy host nor non-host plants of the leafminer elicited distinctive EAG responses in the parasitoid, D. isaea. Odours of physically damaged leaves, no matter whether of host or non-host plants, increased strongly the EAG responses of the leafminer and its parasitoid. We compared the EAG responses of D. isaea to bean leaves of different status. The odour of mined leaves elicited distinct EAG responses, which were weaker than those of physically damaged ones. No differences were detected in the EAG response to leaves with empty mines, healthy leaves or an air control. The role of plant odours in host location of the leafminer and its parasitoid is discussed.

A gut-specific chitinase from the mulberry longicorn beetle, Apriona germari (Coleoptera: Cerambycidae): cDNA cloning, gene structure, expression and enzymatic activity

Young Moo CHOO, Kwang Sik LEE, Bo Yeon KIM, Doh Hoon KIM, Hyung Joo YOON, Hung Dae SOHN, Byung Rae JIN

Eur. J. Entomol. 104 (2): 173-180, 2007 | DOI: 10.14411/eje.2007.026

A gut-specific chitinase gene was cloned from the mulberry longicorn beetle, Apriona germari. The A. germari chitinase (AgChi) gene spans 2894 bp and consists of five introns and six exons coding for 390 amino acid residues. AgChi possesses the chitinase family 18 active site signature and three N-glycosylation sites. Southern blot analysis of genomic DNA suggests that AgChi is a single copy gene. The AgChi cDNA was expressed as a 46-kDa polypeptide in baculovirus-infected insect Sf9 cells and the recombinant AgChi showed activity in a chitinase enzyme assay. Treatment of recombinant virus-infected Sf9 cells with tunicamycin, a specific inhibitor of N-linked glycosylation, revealed that AgChi is N-glycosylated, but the carbohydrate moieties are not essential for chitinolytic activity. Northern and Western blot analyses showed that AgChi was specifically expressed in the gut; AgChi was expressed in three gut regions, indicating that the gut is the prime site for AgChi synthesis in A. germari larvae.

Impact of poor host-parasitoid synchronisation on the parasitism of Cameraria ohridella (Lepidoptera: Gracillariidae)

Giselher GRABENWEGER, Hildegard HOPP, Barbara JÄCKEL, Hartmut BALDER, Tanja KOCH, Silke SCHMOLLING

Eur. J. Entomol. 104 (1): 153-158, 2007 | DOI: 10.14411/eje.2007.022

Poor synchronisation is considered to be one important reason for the ineffective control of the invasive horse chestnut leafminer by native parasitic Hymenoptera. Parasitoids hibernating in dry horse chestnut leaves break diapause early in spring and presumably leave the vicinity, since no hosts are available when they emerge. As a consequence, the percentage parasitism of the first generation of the leafminer in early summer is low. The experiments presented below were designed to test this hypothesis. Horse chestnut saplings were brought on in a greenhouse and infested artificially with C. ohridella prior to parasitoid emergence in the field. These saplings were then exposed to parasitoid attack under natural conditions to eliminate the synchronisation problem. In addition, the parasitoid complexes of other leafmining hosts, which appear early in the season, were analysed. The results confirm that the most important parasitoids of the horse chestnut leafminer are active early in the season, long before the larvae of the first generation of the host are present. Nevertheless, poor synchronisation with the invasive host did not significantly influence the abundance of the most important parasitoid in the complex, Minotetrastichus frontalis, and consequently had no impact on the parasitism of C. ohridella. Nevertheless, a detailed analysis of the parasitoid community shows that certain species are affected by poor synchronisation, while others are probably limited by ecological parameters, such as a specialisation to foraging in particular strata of vegetation. Several leafmining flies were found early in spring infesting other host plants commonly planted in urban green areas, including species with a parasitoid complex similar to that of C. ohridella. The role of these alternative hosts in the food web associated with the horse chestnut leafminer should be subject to further study.

 previous    ...   42   43   44   45   46  47   48   49   50   51   ...    next