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Results 1351 to 1380 of 1606:

The effect of heat stress on the survival of the rose grain aphid, Metopolophium dirhodum (Hemiptera: Aphididae)

Chun-Sen MA, Bernhard HAU, Hans-Michael POEHLING

Eur. J. Entomol. 101 (2): 327-331, 2004

The rose grain aphid, Metopolophium dirhodum (Walker) (Hemiptera: Aphididae) is one of the three most important cereal aphid species in Europe. High temperature is detrimental for the survival of this species. Detailed experiments were conducted on the effect of high temperature (27, 28, 29, 30, 31, 31.5, 32.5, 33 and 34°C), period of exposure (2, 3, 4, 6 and 8 h per day for 1, 2, 4, 6 days) and developmental stage (2nd, 3rd, 4th instar nymph and adult) on the survival of the aphid. The results show that all three factors significantly affect survival. Temperatures over 29°C for 8 h significantly reduced survival, which decreased generally as the temperature increased. The survival was inversely related to the period of exposure. Exposing aphids to 32.5°C for 4 h or longer significantly reduced survival. Mature aphids had a lower tolerance of high temperatures than nymphs. Periods of high temperature experienced by 4th instar and adult aphids can greatly affect their survival. The value of these results for forecasting and determining control thresholds, the effect of global warming on cereal aphid abundance and the dropping off behaviour of the aphids are discussed.

The comparative biology of the solitary endoparasitoid Meteorus gyrator (Hymenoptera: Braconidae) on five noctuid pest species

Fiona SMETHURST, Howard A. BELL, H. June MATTHEWS, John P. EDWARDS

Eur. J. Entomol. 101 (1): 75-81, 2004 | DOI: 10.14411/eje.2004.016

The comparative biology of the solitary endoparasitoid Meteorus gyrator (Thun.) was investigated in five noctuid pest species. Meteorus gyrator parasitized all larval stages of the noctuid pests Lacanobia oleracea, Mamestra brassicae, Spodoptera exigua, Spodoptera littoralis and Chrysodeixis chalcites. When female parasitoids were offered host larvae of all developmental stages, host larvae in their third stadium were parasitized most frequently in all species. When the parasitoid was offered a choice of third stadium larvae from each of the five lepidopteran host species, L. oleracea was the most frequently parasitized, followed by M. brassicae. The growth of L. oleracea and M. brassicae was markedly reduced when larvae were parasitized by M. gyrator, with the effect of parasitism on the remaining species being much less pronounced. In excess of 94% of parasitized hosts gave rise to live wasps in L. oleracea, whilst in M. brassicae only 52% of parasitized hosts gave rise to a live wasp, the remainder dying (44.6%) or pupating (3.1%).
The larval development of the parasitoid was also strongly influenced by the host species. Thus, the development (egg to cocoon) of female wasps was most rapid in C. chalcites (9.7 ± 0.09 days), and longest in M. brassicae (17.2 ± 1.08 days). The cocoon weight of wasps was also significantly affected by host species, with the heaviest female cocoons being derived from C. chalcites (10.4 ± 0.16 mg) and the lightest female cocoons being derived from M. brassicae (7.0 ± 0.14 mg). In all cases, the development times and cocoon weights of male parasitoids were less than those of female wasps.

Characterisation of the luciferase gene and the 5' upstream region in the European glow-worm Lampyris noctiluca (Coleoptera: Lampyridae)

John C. DAY

Eur. J. Entomol. 102 (4): 787-791, 2005

Beetle luciferase, a mono-oxygenase within the AMP-binding superfamily, is synthesized by bioluminescent beetles in concentrated levels within specialised cells clustering in the abdominal light organs. In vivo expression of luciferase has been rarely investigated and little is known about the role of enhancers and promoters in the expression of this gene. In order to investigate the gene structure and potential control of gene expression the luciferase gene along with 6 kb of upstream genomic sequence was characterised from the European glow-worm Lampyris noctiluca. Three TATA box motifs and a CAAT repeat were identified, two of these were found to be conserved in two other species of bioluminescent beetle. Although no enhancer regions were identified in the upstream sequence a region coding for a putative transposase DDE domain was identified 686 bp from the start codon of the luciferase gene. Although disrupted, the open reading frame also shared extensive identity to an mRNA transcript from the mosquito Anopheles gambiae. The remnants of an ancient transposase provide support for an ancestral luciferase transposition/insertion event that may have occurred within the genome of bioluminescent beetles.

The link between food and reproduction in aphidophagous predators: a case study with Harmonia axyridis (Coleoptera: Coccinellidae)

Edward W. EVANS, Derrick I. GUNTHER

Eur. J. Entomol. 102 (3): 423-430, 2005 | DOI: 10.14411/eje.2005.060

For polyphagous predators, the link between food consumption and reproduction is not always straightforward, and instead may reflect that even predators with very broad diets may have reproductive tactics that are tied to consumption of a restricted range of prey. We studied the consumption and use of two prey species for reproduction by the ladybird, Harmonia axyridis Pallas. This polyphagous predator feeds on both pea aphids [Acyrthosiphon pisum (Harris)] and larvae of the alfalfa weevil [Hypera postica (Gyllenhal)] that it encounters when foraging in alfalfa fields. When provided a diet of pea aphids or of alfalfa weevils and/or sugar water, females of H. axyridis laid eggs in large numbers only on the diet of aphids. Females laid no eggs on diets of weevils or sugar alone, and laid only small numbers of eggs when the two foods were provided together. When placed on a diet of aphids, females began laying eggs earlier, and laid more eggs altogether, when they had previously fed on weevils versus sugar water. The predators' consumption rates of aphids were greater than their consumption rates of weevils, and they produced less frass per mg of prey consumed on an aphid versus weevil diet. The predators searched more actively when maintained on a weevil versus aphid diet. Hence, lower rates of food intake and assimilation, and greater allocation of nutrients and energy to searching, appear to contribute to the reduced egg production of H. axyridis females that feed on weevils versus aphids. Alfalfa weevils are also less suitable prey than pea aphids for larval survival and development of H. axyridis. Thus, the differing responses of H. axyridis adults to these two prey types may reflect that these predators are well adapted in the linking of their feeding and reproductive behavior.

Ecological and seasonal patterns in the diversity of a species-rich bee assemblage (Hymenoptera: Apoidea: Apiformes)

Sabine OERTLI, Andreas MÜLLER, Silvia DORN

Eur. J. Entomol. 102 (1): 53-63, 2005 | DOI: 10.14411/eje.2005.008

Meaningful ecological studies on insect communities require sampling protocols that take into consideration temporal fluctuations in abundance and species composition. Bees with their specific requirements for nutrition and nesting are good indicators of landscape structure and overall biodiversity, provided the ecological and seasonal patterns they show are taken into consideration. The present two year study traced the ecological and seasonal patterns on 2 km2 of a southern slope in the Swiss Alps, ranging from 1150 to 1550 m above sea level. The study area consisted mainly of grassland under different regimes, mostly hay meadows and pastures. By direct netting at five monthly intervals in each year a total of 247 bee species were recorded. This comprehensive sampling scheme identified one of the most diverse bee faunas in Central and Northern Europe, consisting of a statistically estimated 280 species. Most species were rare with 14.6% represented by a single individual. Ecological analysis of the bee community showed that the primitively eusocial species were over represented among the abundant species and the parasitic species among the rarest.
Both abundance and species richness were subject to marked seasonal variations. A substantial turnover in species composition as well as changes in ecological patterns were observed. More than 25% of all species were recorded in only one of the two years, in particular many of the parasitic species. Singletons accounted for a higher proportion when individual years rather than the pooled data were analysed. All these findings underline the importance of season-long sampling and sampling over more than one year if bees are to be used as indicators in ecological and studies on bee communities.

Immature stages of New Caledonian Tingidae (Heteroptera): Description and development

Eric GUILBERT

Eur. J. Entomol. 101 (2): 261-271, 2004

Second to fifth instars of nine New Caledonian species of Tingidae are described. A key to fifth instars is provided. The comparison of immature stages among the known larvae shows that translocation of marginal tubercles in larvae, considered as the general rule, is absent in New Caledonian larvae. Also, external morphology of larvae becomes more complex through development, by the addition and ramification of tubercles, as it does also through evolution. Such a tendency is reminiscent of a heterochronous phenomenon, like peramorphosis. Translocation phenomenon could be an intermediate stage of evolution in terms of aquiring more tubercles.

Kin recognition and avoidance of kin cannibalism by the larvae of co-occurring ladybirds: a laboratory study

Ahmad PERVEZ, Avanish K. GUPTA, OMKAR

Eur. J. Entomol. 102 (3): 513-518, 2005 | DOI: 10.14411/eje.2005.073

The role of relatedness and diet in kin recognition was investigated in the aphidophagous ladybirds Propylea dissecta and Coccinella transversalis. Third instar larvae of both species exhibited kin recognition, as they were reluctant to consume related first instar larvae. They spent significantly more time prior to cannibalism when interacting with genetically related victims; this indicates the presence of a kin recognition system. Kin recognition, however, was not evident in fourth instar larvae as they ate both related and unrelated victims. This result reveals that the need of fourth instar larvae to attain a critical weight for pupation might subdue kin recognition. The diet of cannibals did not affect cannibalism, number of encounters or time that elapsed prior to cannibalism. This indicates that kin recognition is not dependent on exogenous cues derived from the diets of the cannibal and victim.

Ability of primary and secondary reproductives to inhibit the development of neotenics in Kalotermes flavicollis (Isoptera: Kalotermitidae)

Jiøí KINDL

Eur. J. Entomol. 101 (2): 227-230, 2004

The inhibitory potential of primary and secondary reproductives was studied using half-orphaned colonies of Kalotermes flavicollis. Both primary and secondary reproductives (neotenics) were equally effective in inhibiting the development of replacement reproductives. Single females totally inhibited the development of female secondary reproductives but did not affect the development of male secondary reproductives. Single males had neither a stimulatory nor inhibitory effect on the development of secondary reproductives. The inhibitory ability of pairs of primary reproductives shortly after dealation and at the stage of incipient colony formation (couple with the first batch of eggs) was also examined. While pairs of freshly dealated reproductives were not able to inhibit the development of neotenics, pairs of primary reproductives that had their first batch of eggs, fully inhibited the development of neotenics.

Diet composition and body size in insect herbivores: Why do small species prefer young leaves?

Luká¹ ÈÍ®EK

Eur. J. Entomol. 102 (4): 675-681, 2005

The hypothesis that small body size is correlated with preference for young leaves was tested in a community of leaf-chewing insect herbivores feeding on Ficus wassa in a humid tropical forest in Papua New Guinea. Feeding experiments on 48 species of herbivorous insects revealed a negative correlation between body size and a preference for feeding on young leaves. While small species preferred young leaves, large species showed no preferences, or preferred young leaves only slightly. This relationship was found for the entire leaf-chewing community, as well as for many of the constituent taxa on several taxonomic levels, from orders to genera. Taxonomic position of a species played little role in determining its preferences. It is proposed that higher toughness and lower nutrient content may act as complementary defences, which prevent small insects from feeding on mature foliage. While the low nutrient content of mature leaves may affect smaller herbivores due to their relatively higher metabolic rate and lower digestion efficiency, their toughness complicates feeding mechanically and may prevent the compensatory feeding necessary to offset the low nutritive value of mature leaves.

Anthropogenic induced changes in nesting densities of the dune-specialised digger wasp Bembix rostrata (Hymenoptera: Sphecidae)

Dries BONTE

Eur. J. Entomol. 102 (4): 809-812, 2005

Data on nesting densities of Bembix rostrata, a digger wasp inhabiting dynamic coastal dunes, were used to document the detrimental effects of trampling by cattle and vacationers. Both types of disturbance resulted in similar sand displacement and prey availability. Nesting densities of Europe's largest digger wasp declined dramatically with increasing trampling, probably below the critical population size. Hence, additional human disturbance, although resulting in similar environmental conditions compared to natural disturbance, significantly affected local population sizes. As a result, anthropogenic has to be avoided disturbance in order to restore or conserve natural dynamics and efforts to restore natural dynamics in a more natural way should be promoted. Although this is here only documented for one, large specialised invertebrate, the application of traditional management techniques, such as grazing by large herbivores, within newly evolved landscapes may introduce new pressures that affect pre-adapted species to natural disturbances negatively within short time spans.

Geographical distribution of three oceanic Halobates spp. and an account of the behaviour of H. sericeus (Heteroptera: Gerridae)

Tetsuo HARADA

Eur. J. Entomol. 102 (2): 299-302, 2005 | DOI: 10.14411/eje.2005.043

Halobates spp. are the only insects inhabiting the open sea. One sea skater species, Halobates sericeus, was collected at 18 locations in the East China Sea area (27°10´N- 33°24´N, 124°57´E-129°30´E), and H. micans and/or H. germanus at only 8 locations in the area south of 29°47´N, where water temperatures were more than 25°C. At three locations, where the water temperature was less than 23°C, neither H. micans nor H. germanus were caught. The effect of photoperiod on the aggregation and mating behaviour of the sea skater, H. sericeus, was studied under laboratory conditions during a one-month cruise. Adults and 5th instar larvae of H. sericeus, collected between 29°02´N and 30°29´N, were kept under long (14.5L : 9.5D) or short-day (10.5L : 13.5D) conditions at 23 ± 2°C for 20 days. Aggregation and mating behaviour of these sea skaters were recorded over a period of 150 min during the daytime. To analyze the data, the observation period of 150 min was divided into 50 intervals of 3 min. Aggregation was observed more under short than long-days. Duration of a group was much longer under the short (mean ± SD : 43.0 ± 108.1 sec) than long-days (7.6 ± 3.1 sec).

Eothalassius, a new genus of parathalassiine flies (Diptera: Empidoidea: Dolichopodidae) from Southeast Asia and Papua New Guinea

Igor V. SHAMSHEV, Patrick GROOTAERT

Eur. J. Entomol. 102 (1): 107-118, 2005 | DOI: 10.14411/eje.2005.016

A new genus of parathalassiine-like flies, Eothalassius gen. n., and two new species, Eothalassius platypalpus sp. n. (type species), E. gracilis sp. n., are described from the coasts of Southeast Asia and Papua New Guinea. The phylogenetic relationships of the new genus with other genera assigned to Parathalassiinae and Dolichopodidae are discussed.

Water loss of male and female Alphitobius diaperinus (Coleoptera: Tenebrionidae) maintained under dry conditions

David RENAULT, Yann CORAY

Eur. J. Entomol. 101 (3): 491-494, 2004 | DOI: 10.14411/eje.2004.069

Survival under dry conditions was examined in males and females of Alphitobius diaperinus Panzer (Coleoptera: Tenebrionidae), a beetle of tropical origin. The range of individual responses and the effect of gender on water loss were also evaluated. Females exhibit significantly longer survival (Lt50 and Lt90) than males under desiccating conditions. Larger females beetles have a greater initial water mass and hence can tolerate greater water losses. Such beetles have longer survival under dry conditions. Males and females loose an average of 54.8 and 58.9% of their body water prior to death. The insects were inactive most of the time, when kept under dry conditions; the rate of decrease in body water was thus reduced. Beetles of both gender display a negative correlation between the rates of water loss under desiccating conditions and the duration of survival. We conclude that the difference in survival period between males and females is due to a combination of greater female tolerance to desiccation and larger body size.

Life-history parameters of Encarsia formosa, Eretmocerus eremicus and E. mundus, aphelinid parasitoids of Bemisia argentifolii (Hemiptera: Aleyrodidae)

Yu Tong QIU, Joop C. VAN LENTEREN, Yvonne C. DROST, Connie J.A.M. POSTHUMA-DOODEMAN

Eur. J. Entomol. 101 (1): 83-94, 2004 | DOI: 10.14411/eje.2004.017

Life-history parameters (juvenile development time, adult longevity, host instar preference and rate of parasitism) of four parasitoids of Bemisia argentifolii (two strains of Encarsia formosa (D and B), Eretmocerus eremicus and Eretmocerus mundus) were studied in the laboratory. At 15°C juvenile development time was the shortest for E. formosa B (48 days), longest for E. eremicus (79.3 days) and intermediate for E. formosa D (62.8 days) and E. mundus (64 days) at 15°C. With increase in temperature, development time decreased to around 14 days for all species/strains at 32°C. The lower developmental threshold for development was 11.5, 8.1, 13.0 and 11.5°C for E. formosa D, E. formosa B, E. eremicus and E. mundus, respectively. E. formosa D and B, and E. mundus all appeared to prefer to parasitize 3rd instar nymphs. The presence of hosts shortened adult longevity in most of the parasitoids, with the exception of E. formosa B, which lived longer than other species/strains irrespective of the presence of hosts. At 15°C daily parasitism was very low by all parasitoids. The two Encarsia strains had a constant, but low rate of reproduction during adult life, while the two Eretmocerus species had a very high rate of reproduction when one-day old, which then decreased very quickly. Lifetime fecundity, estimated using a non-linear model, indicated that it was higher for the two Encarsia strains than for the Eretmocerus species. Life history parameters reported in the literature for the four parasitoids are reviewed and compared with our results. Finally, the potential value for the biological control of whiteflies on greenhouse crops of parasitoids having either a high reproductive rate over a short period (Eretmocerus spp.) or a low rate of reproduction over a long period (Encarsia spp.) is discussed.

Detection of predation on Euzophera pingüis (Lepidoptera: Pyralidae) using an enzyme-linked immunosorbent assay

Estefanía RODRÍGUEZ, Carlos LOZANO, Mercedes CAMPOS

Eur. J. Entomol. 102 (4): 793-796, 2005


Euzophera pingüis
(Lepidoptera: Pyralidae) is a secondary olive pest, which has increased in importance during recent years. In this study, more than 1300 predatory arthropods were collected from a Spanish olive orchard over two years and assayed using a pest-specific ELISA. Abundance and the percentage of positive responses to E. pingüis obtained using ELISA showed spiders to be the main predator, especially in 1998, when they accounted for 18% of the predation, followed by Scymnus suturalis (Coleoptera: Coccinellidae) and Brachinotocoris ferreri (Heteroptera: Miridae). Neuroptera and ants were less important as predators of E. pingüis.

Role of (E)-β-farnesene in systematic aphid prey location by Episyrphus balteatus larvae (Diptera: Syrphidae)

Frédéric FRANCIS, Thibaut MARTIN, Georges LOGNAY, Eric HAUBRUGE

Eur. J. Entomol. 102 (3): 431-436, 2005 | DOI: 10.14411/eje.2005.061

The foraging behaviour of beneficials such as aphidophagous predators depend largely on volatile compounds emitted by potential preys. Even if polyphagous predatory species are considered, all the potential preys are not systematically localised and accepted. In this work, chemical cues from different aphids and plants, each alone or in association, were studied to elucidate their role in prey location. Using a four-arm olfactometer, attraction of combinations of three aphid (Megoura viciae, Acyrthosiphon pisum and Aphis fabae) and one plant (Vicia faba) species for Episyrphus balteatus larvae was observed. Predatory hoverfly larvae were attracted by all tested stimuli in the presence of aphids, whatever the species. Whole or crushed aphids and also aphids on bean plant parts were attractive to syrphid larvae, but the host plant alone did not present any infochemical role for E. balteatus. Identification and quantification of the volatile releases from aphid and plant species, alone or in association, were performed using SPME and GC-MS methods. Aphid alarm pheromone, (E)-β-farnesene, was found in the volatile pattern of each aphid and was tested for its role as an effective kairomone for the hoverfly.

Phenotypic plasticity of elytron length in wingless two-spot ladybird beetles, Adalia bipunctata (Coleoptera: Coccinellidae)

Suzanne T.E. LOMMEN, Peter W. DE JONG, Paul M. BRAKEFIELD

Eur. J. Entomol. 102 (3): 553-556, 2005 | DOI: 10.14411/eje.2005.079

Winglessness in the two-spot ladybird beetle Adalia bipunctata (L.) is determined by a single locus with the wingless allele recessive to the winged wildtype allele. The expression of the wingless trait is highly variable, with individuals missing a variable part of elytra and flight wings; the elytra and wings appear to be truncated rather than miniature in form. The degree of winglessness is partly determined genetically. Here we report on the phenotypic plasticity of the degree of winglessness. The environmental effect on elytron length relative to maximal elytron length in wingless phenotypes was studied by rearing offspring of single pair crosses of this form at a low (19°C) or high (29°C) temperature. Offspring reared at 19°C showed relatively longer elytra than those reared at 29°C.

Review of larval morphology of beetles of the suborder Archostemata (Insecta: Coleoptera), including first-instar chaetotaxy

Vasily V. GREBENNIKOV

Eur. J. Entomol. 101 (2): 273-292, 2004

This paper presents a synthesis of morphological information on larvae of the beetle suborder Archostemata. Larvae of the following families and species were studied: Ommatidae: Omma sp.; Micromalthidae: Micromalthus debilis LeConte, 1878; Cupedidae: Priacma serrata LeConte, 1861, Distocupes varians (Lea, 1902), Rhipsideigma raffrayi (Fairmaire, 1884), Tenomerga cinerea (Say, 1831) and Tenomerga mucida (Chevrolat, 1829). Morphological characters of the suborder and three families are described. Monophyly of the suborder is strongly supported by more than 10 larval autapomorphies. A close relationship between Micromalthidae and Cupedidae is confirmed. New larval characters are introduced, including chaetotaxy of first instar larvae of Micromalthus LeConte, 1878, Priacma LeConte, 1874 and Distocupes Neboiss, 1984. An identification key to families and subfamilies of Archostematan larvae is provided, along with a checklist of extant Archostemata taxa. The work is illustrated with 120 morphological drawings.

BOOK REVIEW: Jolivet P., Santiago-Blay J.A. & Schmitt M. (eds): NEW DEVELOPMENTS IN THE BIOLOGY OF CHRYSOMELIDAE.

J. BEZDÌK, A. BEZDÌK

Eur. J. Entomol. 102 (4): 606, 2005

SPB Academic Publishing bv, The Hague, 2004, 804 pp., 793 figs, 80 tables. ISBN 90-5103-142-4. Price EUR 290.00, USD 345.00.

The quality of aphids as food for generalist predators: implications for natural control of aphids

Søren TOFT

Eur. J. Entomol. 102 (3): 371-383, 2005 | DOI: 10.14411/eje.2005.054

The paper reviews existing data on the food quality of cereal aphids for generalist predators. Data are presented for spiders, harvestmen, carabid and staphylinid beetles, cockroaches, ants and one species of bird. All results agree that cereal aphids are low-quality food compared to alternative prey types (in most studies fruit flies). This is associated both with a low consumption capacity for aphids and a low utilization efficiency of the aphid food. A pure aphid diet allows full juvenile development in only a few species. Aphids as part of mixed diets can have negative, neutral or positive effects, which depends on the quality of the remaining diet. The low consumption capacity for aphids is due to the development of a specific feeding aversion. Genetic variation in the ability to tolerate aphids has been documented, indicating that predators may be able to adapt to a higher proportion of aphids in the diet in areas where outbreaks are frequent. A consequence of these findings is that predator populations rely on alternative prey (e.g. Collembola and Diptera) for maintenance and reproduction, and are probably unable to benefit nutritionally from an aphid outbreak. The low food quality of aphids to generalist predators explains why generalist and specialist predators have widely different roles in aphid biocontrol, but does not rule out that under some conditions the generalists may be able to inhibit aphid population growth sufficiently to prevent an outbreak, as field experiments have indicated. Simulation modelling shows that a low consumption capacity for aphids has little influence on the ability to prevent aphid population increase at low aphid immigration rates, but a great influence at high aphid immigration rates. Modelling also indicates that there may be an optimal availability of high-quality alternative prey that maximizes the impact of generalist predators on aphid population growth.

Epigeal aphidophagous predators and the role of alfalfa as a reservoir of aphid predators for arable crops

Xavier PONS, Eva NÚÑEZ, Belén LUMBIERRES, Ramon ALBAJES

Eur. J. Entomol. 102 (3): 519-525, 2005 | DOI: 10.14411/eje.2005.074

The relative occurrence and seasonal abundance of aphidophagous predators (Insecta and Arachnida) were determined in alfalfa fields at two locations in the northeast Iberian Peninsula, using D-Vac and sweep-net sampling techniques. Among the insects, Heteroptera, Dermaptera, Neuroptera, Coleoptera and Diptera were found. The relative abundance of predators was similar at the two locations. Polyphagous predators were much more abundant than aphid specific species. Heteroptera were the most abundant order of insect predators: members of the Nabidae, Anthocoridae and Miridae were very common. Coleoptera were also abundant, represented mainly by the family Staphylinidae. Coccinellidae were less abundant and their occurrence coincided with maximum aphid presence. There was a low occurrence of other aphid-specific predators, i.e. Diptera: Syrphidae and Neuroptera: Chrysopidae. Arachnida varied between localities (from 35% to 65%). Over a five-year period, numerical responses by Orius spp., Nabis provencalis and Coccinellidae to aphids were found using polynomial regression models; however the abundance of predators was weakly explained by aphid abundance. Alfalfa, maize and winter cereals share similar aphid predator groups and these crops partially coincide in time, enabling the movement of predators among crops. The persistence of several predatory groups (Anthocoridae, Nabidae, Staphylinidae, Araneae) during most of the season suggests that alfalfa plays a major role as a reservoir of aphid predators.

Fluctuating asymmetry as a measure of ecological stress in Drosophila melanogaster (Diptera: Drosophilidae)

Vincenzo TROTTA, Federico Corrado Fulceri CALBOLI, Flavio GAROIA, Daniela GRIFONI, Sandro CAVICCHI

Eur. J. Entomol. 102 (2): 195-200, 2005 | DOI: 10.14411/eje.2005.031

Fluctuating asymmetry (FA), the small and random departures from perfect symmetry of an organism's bilateral traits, has been used as a measurement of developmental stability and an indicator of stress in endangered populations. We were interested in testing if the level of developmental stability is the same in different populations experiencing the same conditions, as the use of FA as an indicator of ecological stress is only meaningful if this is true. In order to do this, the effect of thermal stress on wing size FA over a range of temperatures was determined on three different lines of Drosophila melanogaster: two lines were maintained at one of two different constant temperatures (18°C or 28°C) and one under a fluctuating thermal regime (18°C and 28°C) for eight years. The differences in viability of these lines, when reared at a range of different temperatures, are associated with the temperature conditions they previously experienced. All lines showed a similar increase in FA at the two ends of the thermal range but with significantly different mean values. The two units of wing development (compartments) differed in their FA response depending on the selective history of each line. We discuss the implication of our results for the use of FA as an indicator of ecological stress.

Action of fenoxycarb on metamorphosis and cocoon spinning in Chrysoperla carnea (Neuroptera: Chrysopidae): identification of the JHA-sensitive period

Laura BORTOLOTTI, Anna MICCIARELLI SBRENNA, Giovanni SBRENNA

Eur. J. Entomol. 102 (1): 27-32, 2005 | DOI: 10.14411/eje.2005.004

Fenoxycarb is an insecticide with a juvenile hormone mimicking effect, which disturbs metamorphosis in several insect species, including the neuropteran Chrysoperla carnea. Administration of different doses of fenoxycarb to third instar larvae causes a dose dependent inhibition of metamorphosis and cocoon spinning. When treated within 48 h of the last larval ecdysis, this insect shows a temporary inhibition of metamorphosis and cocoon spinning, which leads to a prolongation of the third larval instar. When treated after 60 h into the last instar, most of larvae were unable to metamorphose and spin a cocoon. Thus, C. carnea is most sensitive to this juvenoid in the period after 60 h into the last larval instar.

Decreased mating propensity of macropterous morph in a flightless wing-polymorphic insect, Pyrrhocoris apterus (Heteroptera)

Radomír SOCHA

Eur. J. Entomol. 101 (4): 539-545, 2004 | DOI: 10.14411/eje.2004.077

The effect of wing length (brachyptery and macroptery) on mating activity was investigated in adult males and females of a flightless wing-polymorphic insect, Pyrrhocoris apterus (L.). Mating activity of the brachypterous and macropterous adult bugs was assessed according to 14 different parameters. The competition tests revealed higher numbers of copulations and greater duration of mating activity in brachypterous than in macropterous males. Brachypterous males are between two to four times more successful in competition for females than their macropterous counterparts, depending on the wing morph and physiological status of the females. Decreased mating success of macropterous males is associated with the smaller size of their accessory glands. Lowered competitive ability for mates is a likely penalty associated with macroptery. Receptivity tests showed the highest tendency to mate in reproductive brachypterous females, lower in macropterous females and the least in diapausing brachypterous females. This is the first report of decreased mating propensity of macropterous morphs in insects with non-functional wing polymorphism. The association of lowered mating success with the higher dispersal activity of the macropterous morph in this bug and a trade-off between the ability to reproduce and to disperse in the flightless wing-polymorphic insects is discussed.

Influence of slug defence mechanisms on the prey preferences of the carabid predator Pterostichus melanarius (Coleoptera: Carabidae)

Pavel FOLTAN

Eur. J. Entomol. 101 (3): 359-364, 2004 | DOI: 10.14411/eje.2004.050

Two-choice experiments on prey preferences of a generalist predator Pterostichus melanarius, and five species of slug prey, were conducted in the laboratory. Different preferences of P. melanarius for each of the slug species are described. They are interpreted as the outcome of differing slug species-specific defence mechanisms. The influence of hunger level, temperature, day/light period, condition of slugs and beetles, weight of slugs and beetles, and the sex of beetles were controlled experimentally or statistically. The order of slug species preference for predation by P. melanarius was: Deroceras reticulatum (Agriolimacidae), Malacolimax tenellus, Lehmania marginata (Limacidae), Arion distinctus and A. subfuscus (Arionidae). Efficiency of slugs' species-specific defence mechanisms reflected their phylogeny. Defence mechanisms of slugs from the superfamily Arionoidea were significantly more effective at deterring an attack of non-specialised ground beetles than the defence mechanisms of slugs from Limacoidea superfamily. P. melanarius significantly preferred Agriolimacidae to Limacidae, and Limacidae to Arionidae. Slug species was the strongest factor influencing prey preferences of P. melanarius amongst slug prey. Surprisingly, this preference was much more significant than the slug weight. Weight and sex of P. melanarius had no impact on its prey preference.

Proceedings of the International Symposium Ecology of Aphidophaga

Edward Evans, Francis Gilbert, Ivo Hodek, J.P. Michaud, John Obrycki

Eur. J. Entomol. 102 (3): 313-315, 2005 | DOI: 10.14411/eje.2005.048

This series of symposia has traditionally been a unique scientific forum for discussions on ecological and behavioural interactions within the guild of insects feeding on aphids. Its focus is to understand how natural control works, with the aim to improve it. After the initial two meetings in Czechoslovakia, symposia were organised in Poland, Hungary, France, Belgium, Canada and Portugal. The ninth meeting was held once again in the Czech Republic.
Details on history of the meetings, with bibliographic data from all Proceedings, can be found at . News will appear there continually.
This issue is the outcome of the 9th meeting that was attended by 56 participants from 21 countries. Abstracts of the presentations not included in this issue appeared under ISBN 80-86668-02-09, Ecology of Aphidophaga 9, Abstracts, 2004, Inst. Entomol. Acad. Sci. Czech Rep., 92 pp.
We look forward to the 10th meeting in 2007 that will be organised by N. Kavallieratos, E. Lucas and J.P. Michaud.

July 10, 2005
The Editors

Mate searching in the scale insect, Dactylopius coccus (Hemiptera: Coccoidea: Dactylopiidae)

Luis C. RODRÍGUEZ, Eric H. FAÚNDEZ, Hermann M. NIEMEYER

Eur. J. Entomol. 102 (2): 305-306, 2005 | DOI: 10.14411/eje.2005.045

Dactylopius coccus is a sessile scale insect living on cladodes of Opuntia ficus indica which has commercial importance as a source of carminic acid. We herein present behavioural evidence of the existence of a sex pheromone in D. coccus, based on olfactometric experiments using both biological sources of odours and collected chemical extracts.

Coprophagous hydrophilid beetles (Coleoptera: Hydrophilidae) as carriers of phoretic deutonymphs of Uropoda orbicularis (Acari: Mesostigmata) in Poland

Daria BAJERLEIN, Marek PRZEWO¬NY

Eur. J. Entomol. 102 (1): 119-122, 2005 | DOI: 10.14411/eje.2005.017

During a study 20 hydrophilid beetle species and 2,457 individuals of beetles belonging to 4 genera: Cercyon, Cryptopleurum, Megasternum and Sphaeridium were collected. On the surface of the bodies of 59 beetles (2.40% of the beetles collected) belonging to six species, 174 cases of phoresy [55 deutonymphs of Uropoda orbicularis (Müller, 1776) and 119 pedicels without deutonymphs] were observed. New hydrophilid beetle carriers of phoretic deutonymphs of U. orbicularis are given. Most mites were carried by Sphaeridium species. The population dynamics of both groups of arthropods was also studied. Most cases of phoresy were recorded in May and in the second half of July. However, phoretic deutonymphs were not present on the body surface of hydrophilid beetles throughout the whole period of this study.

Systemic effects of phytoecdysteroids on the cabbage aphid Brevicoryne brassicae (Sternorrhyncha: Aphididae)

Roman PAVELA, Juraj HARMATHA, Martin BÁRNET, Karel VOKÁÈ

Eur. J. Entomol. 102 (4): 647-653, 2005

The systemic effects of phytoecdysteroids were investigated by applying tested compounds to the roots of the rape plants. Evaluation of the effects was based on mortality, longevity, rate of development and fecundity of the cabbage aphid (Brevicoryne brassicae L., Sternorrhyncha: Aphididae) feeding on the shoot of the treated plants. The major ecdysteroid compounds tested were natural products isolated from a medicinal plant Leuzea carthamoides DC (Willd.) Iljin (Asteraceae): 20-hydroxyecdysone (20E), ajugasterone C (ajuC) and polypodine B (polyB). The compounds were tested in two concentrations (0.07 and 0.007 mg/ml) in water. In addition, we have also investigated the systemic effects of a special Lc-Ecdy 8 fraction isolated from L. carthamoides, which contained 20E, ajuC and polyB and at least six other minor compounds in addition to the above indicated ecdysteroids. HPLC analysis of the Lc-Ecdy 8 fraction indicated the presence of makisterone A and inokosterone in minor quantities. It appeared that all ecdysteroid compounds tested, with the exception of the most common, 20E, decreased the fecundity of cabbage aphids which fed on the contaminated rape plants. The mortality of larvae and adults significantly increased on plants treated with the Lc-Ecdy 8 fraction, and with ajuC or polyB compounds containing structural substituents in rather unusual positions. The most common phytoecdysteroid, 20E, with the typical and characteristic ecdysteroid structure, was the best tolerated of all phytoecdysteroids tested.

Natural prey of the jumping spider Menemerus taeniatus (Araneae: Salticidae)

Elchin F. HUSEYNOV

Eur. J. Entomol. 102 (4): 797-799, 2005

The natural prey of the jumping spider Menemerus taeniatus (L. Koch, 1867) was studied on the Absheron Peninsula, Azerbaijan. The percentage of specimens of M. taeniatus found feeding was low (10.7%). This investigation showed that M. taeniatus is a polyphagous predator feeding on a wide range of arthropods, including representatives of eight arthropod orders. The primary food of M. taeniatus was Diptera and Lepidoptera, which collectively made up about two thirds of total prey. The length of prey killed by M. taeniatus ranged between 1.10 and 13.00 mm (mean 6.14 mm), which is between 15.2 and 216.7% (mean 90.3%) of the length of their captors. Most frequently taken prey (50%) were medium-sized arthropods varying between 50-100% of the spiders' body length.

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