The effect of photoperiod on parasitization of the eggs of the Angoumois grain moth, Sitotroga cerealella (Olivier, 1789) by Trichogramma principium Sugonyaev & Sorokina, 1976 was investigated under several photoperiodic regimes of L : D = 3 : 21, 6 : 18, 9 : 15, 12 : 12, 15 : 9, 18 : 6 and 21 : 3. In all regimes, certain wasps delayed ovipositing in this non-preferred host. Potential fecundity of T. principium females (the number of mature ovarial eggs at emergence) and subsequent oogenesis (estimated by the number of mature ovarial eggs in non-ovipositing females) was independent of photoperiod. However, the percentage of females that oviposited was higher for females that developed and were kept under 6-12 h long photophase than for those that developed and were kept under ultra short (3L : 21D) and under long (18L : 6D and 21L : 3D) photophases. The average duration of the pre-oviposition (egg retention) period showed the opposite pattern to the photoperiodic response. A possible explanation of this reaction is that the delay in oviposition is adaptive if the probability of finding a better host is high. In autumn, when the last Trichogramma females are still active but their lepidopteran hosts are already much less abundant, then parasitization of any suitable host is the best strategy.

In the highly sexual-dimorphic nocturnal moth, Acentria ephemerella Denis & Schiffermüller 1775, the aquatic and wingless female possesses a refracting superposition eye, whose gross structural organization agrees with that of the fully-winged male. The possession of an extensive corneal nipple array, a wide clear-zone in combination with a voluminous rhabdom and a reflecting tracheal sheath are proof that the eyes of both sexes are adapted to function in a dimly lit environment. However, the ommatidium of the male eye has statistically significantly longer dioptric structures (i.e., crystalline cones) and light-perceiving elements (i.e., rhabdoms), as well as a much wider clear-zone than the female. Photomechanical changes upon light/dark adaptation in both male and female eyes result in screening pigment translocations that reduce or dilate ommatidial apertures, but because of the larger number of smaller facets of the male eye in combination with the structural differences of dioptric apparatus and retina (see above) the male eye would enjoy superior absolute visual sensitivity under dim conditions and a greater resolving power and ability to detect movement during the day. The arrangement of the microvilli in the rhabdom of both genders suggests that their eyes are polarization-sensitive, an ability they would share with many aquatic insects that have to recognize water surfaces. Although sexual recognition in A. ephemerella is thought to chiefly rely on pheromones, vision must still be important for both sexes, even if the females are wingless and never leave their watery habitat. Females swim actively under water and like their male counterparts, which fly above the surface of the water, they would have to see and avoid obstacles as well as potential predators. This, together with a small incidence of winged females, we believe, could be the reason why the eyes of female A. ephemerella are less regressed than those of other sexually dimorphic moths, like for instance Orgyia antiqua. Another, but difficult to test, possibility is that male and female A. ephemerella have diverged in their behaviour and habitat preferences less long ago than other sexually dimorphic moths.

An Erratum has been published for this article: https://doi.org/10.14411/eje.2008.065

The Kanzawa spider mite, Tetranychus kanzawai (Acari: Tetranychidae) constructs webs over leaf surfaces and usually lives under these webs. T. kanzawai produces two types of excreta, black and yellow pellets, and uses its webs as a place for excretion. T. kanzawai also uses its webs as a refuge when the predatory mite, Neoseiulus womersleyi (Acari: Phytoseiidae) is present. To clarify what factors deter N. womersleyi from foraging on T. kanzawai webs, I experimentally examined the effects of T. kanzawai excreta on its own fitness (fecundity) and the foraging behaviour of N. womersleyi. When the excreta of T. kanzawai was put on leaf surfaces, the fecundity of T. kanzawai adult females was reduced by the black but not the yellow faecal pellets. On the other hand, predation by N. womersleyi was reduced by the yellow but not the black pellets. Although this effect of the yellow pellets on N. womersleyi did not last on leaf surfaces, it deterred N. womersleyi from staying on the web regardless of its freshness. These results suggest that T. kanzawai deposits black pellets on webs to avoid its negative effect on their own fitness, and yellow pellets are deposited on webs to reduce the risk of predation.

The hypothesis that small species of aphidophagous coccinellids need lower aphid population densities for reproduction than large species (Dixon, 2007) was tested in the field. In 2006 we compared seasonal changes in the oviposition behaviour of two coccinellid species regularly found in cereal stands in central Europe, the large Coccinella septempunctata L. and the small Propylea quatuordecimpunctata (L.). Adults of both species were collected at 2-3 day intervals from stands of winter wheat and spring barley, females were allowed to deposit eggs for 24 h following collection and the percentage that laid eggs and the number of eggs were recorded. Both species colonized the cereal crop simultaneously in the middle of May. After colonization of the crop, while the aphid density was still low, few females of C. septempunctata oviposited and laid only a few eggs. Oviposition increased up to a maximum c. 1 month later and was closely associated with prey abundance. Of the females of P. quatuordecimpunctata, whose mass is about one quarter of that of the former species, the percentage ovipositing and number of eggs laid varied less in time and was less associated with prey abundance than in C. septempunctata. As predicted by theory, the small P. quatuordecimpunctata was more effective at exploiting the lower prey densities as it produced proportionally more of its eggs during the early stages of the aphid infestation than the larger C. septempunctata.

In the Noctuidae, the owlet moths, the internal genitalia, i.e. the aedeagus and vesica (penis) in the males, and the bursa copulatrix in the females, together form a lock-and-key mechanism (LKM). The species-specific structures have their counterparts in the opposite sex. The internal LKM constitutes a specific reproductive isolation mechanism (lock-and-key hypothesis), which seem to be the rule in the ditrysian Lepidoptera, and also occurs in the Carabidae (Coleoptera) and some other insects. In contrast, the external genitalia rarely have species-specific counterparts in the sexes. Several results indicate the presence of LKMs: In the Noctuidae, (1) heterospecific differences in the male vesica may prevent sperm transfer or lead to mechanical failure during copulation, (2) the more complicated the specific genitalia structures, the more aberrations may occur even in conspecific copulations, and (3) in many species pairs and groups, and in one large genus, Apamea, the structures in the opposite sexes show a strictly specific correspondence, but, (4) when there is precopulatory isolation due to differences in pheromone production or perception, the internal genitalia may be identical. Conversely, in the Colias butterflies (Pieridae), (5) frequent heterospecific hybridization is associated with the similarity of the internal genitalia. The LKMs seem to protect genomes against alien genes, supposedly selected for because of the lower fitness of specimens with an imprecise LKM and/or inferiority of hybrids. In the literature, the diversity of the noctuid genitalia has been ascribed to sexual selection, because the females were classified as polyandrous. Most species produce the main part of their eggs monandrously, and remate, if at all, in their old age, and are thus successively monandrous and polyandrous. The allopatric divergence in the structure of the internal genitalia of 39 Holarctic pairs of sister species of Noctuidae is suggested to be due to genetic drift. The insecure function of the female pheromones and external genitalia of males are illustrated with the aid of original photographs.

We examined oviposition decisions by Hippodamia convergens Guérin in semi-natural arenas in the laboratory. Gravid females were presented individually with an array of four young sorghum plants, Sorghum bicolor, bearing (1) no additional stimulus, (2) an established colony of greenbug, Schizaphis graminum Rondani, (3) residues of conspecific larvae, and (4) greenbugs plus residues of conspecific larvae. Females laid no egg masses on type 3 plants, significantly fewer than expected by chance on type 4 plants, and significantly more on type 1 plants, with type 2 plants receiving expected numbers. Females laid 50% of egg masses on elements of the arena other than the plants, especially the cage screen, suggesting that females sought to distance their eggs farther from larval residues than the spacing of plants in the arena permitted (15 cm). When the experiment was repeated with plants exposed to larvae of Coleomegilla maculata DeGeer, the repellency was weaker. Once again, clean plants were the most preferred and aphids did not increase the acceptability of plants with larval residues. Nevertheless, only 18% of egg masses occurred off the plants and larval residues did not reduce the acceptability of aphid-bearing plants as did conspecific larval residues. Simultaneous choice tests conducted with individual third instars of both species revealed that C. maculata larvae consumed H. convergens eggs as readily as conspecific eggs, but H. convergens larvae preferred conspecific eggs to those of C. maculata. We conclude that H. convergens oviposition decisions are shaped by the risks of both egg cannibalism and predation.

Dispersal of the sevenspotted lady beetle, Coccinella septempunctata, was measured in a series of mark-release-recapture experiments in Utah alfalfa. In three experiments, samples were taken in a radial pattern around the release point. Released beetles for the most part left the 0.36 ha (68 m diameter) sample area within 24 hours, and their average residence time in the sample area was calculated as 12, 6 and 1.6 h in the three experiments, respectively. The spatial distribution of beetles around the point of release could be described with normal distributions whose variance increased linearly in time with 3.8, 1.1 and 0.34 m² per hour. In three additional field experiments the departure of marked beetles was compared between sugar-sprayed plots and control plots. Residence time was 20-30% longer in sugar-sprayed plots than in control plots, with mean residences of 5.3, 3.6, and 2.9 h in the sugar-sprayed plots in the three experiments, respectively, and means of 4.4, 2.7, and 2.4 h in the control plots. The density of unmarked beetles rose by a factor of 10-20 in the sugar sprayed plots during the first 4 to 6 hours following early morning spraying of sugar. This rapid and substantial increase in density cannot be explained by the slightly longer residence time in sugar-sprayed plots. We hypothesize that the aggregation in sugar-sprayed plots is mostly due to greatly increased immigration into those plots, in response to volatiles produced by the plant-pest-predator assembly.

Aphidophagous ladybirds exhibit a broad range of body sizes. Until now this has been thought to be a function of the different prey densities that they feed at, with smaller ladybirds feeding at lower prey densities. The size of the prey species they feed on has been considered to have no relationship with ladybird body size. However, these arguments possess a limited capacity to explain observed data from the field. I here demonstrate a more realistic, complex approach incorporating both prey density and the size of prey species. Small ladybirds can feed on small aphids at both low and high densities. However when the aphid species is large they cannot catch the older, bigger, more energy-rich aphid instars due to their small size. They are thus unable to feed on large aphid prey at low densities, although at higher densities numbers of the smaller instars may be sufficient to sustain them. By contrast large ladybirds can feed on large aphids at both low and high densities due to their superior ability to catch the bigger, more energy-rich older aphids; however they cannot be sustained by low densities of small aphids due to food limitation consequent on their large size. This more complex association between ladybird size, prey size and prey density possesses a better explanatory power for earlier field data. Because of this relationship, ladybird body size also provides an important trade-off determining dietary breadth and specialization in the aphidophagous Coccinellidae. Dietary specialists more closely match the size of their limited prey species, have higher overall capture efficiencies and can thus continue to reproduce at lower aphid densities for longer. By contrast dietary generalists adopt a one-size-fits-all strategy, are medium-sized and have lower capture efficiencies of individual prey species, thus requiring higher aphid densities. The role of body-size in dietary specialization is supported by data from the British fauna. Rather than trade-offs related to prey chemistry, which have hitherto been the centre of attention, body size trade-offs are the likely most important universal factor underlying dietary specialization in aphidophagous coccinellids.

During 1989-2006 the number of live aphid, mummies, aphid specialist predators and their parasitoids in cereal fields in Serbia were recorded. S. avenae and M. dirhodum were the most common, both on wheat and rye crops. Maximum numbers of cereal aphids were detected between the end of May and the middle of June. A low percentage of mummified aphids was recorded during May and June, but increased rapidly at the beginning of July, when aphids left the wheat crop. Here, we record over 60 species of cereal aphid natural enemies, including primary and secondary parasitoids, aphid specific predators and a wide spectrum of their parasitoids in Serbian cereal crop systems. Aphidius uzbekistanicus Luzhetzki, Aphidius rhopalosiphi De Stefani, Aphidius ervi Haliday and Praon gallicum Starý were the most abundant species of primary parasitoids. Of the secondary parasitoids, six species were dominant with Asaphes suspensus (Nees) and Dendrocerus carpenteri (Curtis) generally the most often recorded. Coccinella septempunctata L. was the most abundant coccinellid and syrphid flies were represented by 11 species, two of which, Sphaerophoria scripta (L.) and Episyrphus balteatus (DeGeer), were the most common.

Cuticular parts of the spermatheca and associated vaginal structures (chiefly the ring sclerites of the parietovaginal glands) have been examined and compared in 190 cydnid species representing 65 genera and all five subfamilies currently recognized in the family (Amnestinae, Cephalocteinae, Cydninae, Garsauriinae, Sehirinae). Four species belonging to genera formerly included within the Cydnidae (Dismegistus, Parastrachia, Thaumastella, Thyreocoris) were also examined. Morphology of the three main parts of the spermatheca [seminal receptacle (distal bulb), intermediate part (pump apparatus), spermathecal duct] is described. Four main types of spermathecae can be recognized from the distal receptacle and the intermediate part: the amaurocorine type (in Sehirinae: Amaurocorini), amnestine type (in Amnestinae), garsauriine type (in Garsauriinae), and "cydnoid" type (in Cephalocteinae + Cydninae: Cydnini, Geotomini + Sehirinae: Sehirini). No synapomorphy of these types was found which suggests that the currently conceived Cydnidae are not monophyletic. Moreover, out of these four types only the "cydnoid" is typically pentatomoidean due to the presence of an intermediate part usually well delimited by two flanges and having always an unsclerotized flexible zone as well as two internal cuticular structures (septum and fretum) partly obstructing the lumen. The simple tubular amaurocorine type is unusual and aberrant within all Pentatomoidea. The amnestine and garsauriine types display some similarities with taxa outside the Pentatomoidea, especially with some lygaeoid or coreoid spermathecae, mainly in the structure of the intermediate part not delimited proximally (absence of flanges) and devoid of the flexible zone. Within the "cydnoid" type, six spermathecal facies can be characterized principally according to the shape of both the apical reservoir along with the intermediate part, and the differentiations of the spermathecal duct. It has been impossible to find any synapomorphy for all species and for the six facies belonging to the "cydnoid" type of spermatheca. We suggest that the Cydnidae as defined presently are probably a polyphyletic group; moreover its main "cydnoid" branch, called by us Cydnidae sensu stricto (Cephalocteinae + Cydninae + Sehirinae: Sehirini) seems to be relatively recent among the Pentatomoidea. Nishadana and Nishocoris are transferred from Garsauriinae back to Cydninae: Cydnini and the tribe Amaurocorini (Sehirinae) is upgraded to a separate subfamily Amaurocorinae stat. nov. Moreover, we regard the Geotomini and the Sehirini both as non-monophyletic and we indicate that by appending them sensu lato (Geotomini "s. l.", Sehirini "s. l.")

Sycophila pistacina (Rondani), which was previously synonymized with Sycophila biguttata (Swederus), is revalidated. Morphological, morphometric and molecular data confirm its status as a separate species. Diagnostic characters are provided for distinguishing it from S. biguttata. The nomenclature of the S. biguttata complex is updated.

Southern-African Longitarsus capensis species-group, which is closely related to the Mediterranean anchusae species-group is revised. L. capensis species-group includes 15 species, 8 of which are new to science: Longitarsus capensis Baly, 1877, L. cedarbergensis Biondi, 1999, L. luctuosus Biondi, 1999, L. lugubris Biondi, 1999, L. melanicus Biondi, 1999, L. neseri Biondi, 1999, L. transvaalensis Biondi, 1999, L. afromeridionalis sp.n., L. debiasei sp.n., L. grobbelaariae sp.n., L. hexrivierbergensis sp.n., L. malherbei sp.n., L. piketbergensis sp.n., L. rouxi sp.n., and L. sudafricanus sp.n. A key to all the species is presented as well as line drawings of male and female genitalia, scanning electron micrographs of some diagnostic morphological characters, and auto-ecological and zoogeographical data. Relationships within the capensis-group, and between the anchusae and capensis-group are better defined and hypotheses explaining the separate distributions of Mediterranean and south African anchusae and capensis species-groups proposed. Finally, the host-plant shift from native Lobostemon spp. to the introduced plant Echium plantagineum L. shown by some species of the capensis group is also discussed.

The predatory lacewing Dichochrysa prasina Burmeister can feed and reproduce on various aphid species. However, other species such as the two spotted spider mite Tetranychus urticae Koch may serve as an alternative prey for this predator in the field in periods when the population density of aphids is low. In peach orchards in Northern Greece D. prasina larvae are often found during the summer months on leaves infested with T. urticae. The development and reproduction of D. prasina fed on T. urticae at a series of different constant temperatures were studied. The percentages of D. prasina larvae that completed their development when fed on T. urticae ranged from 12 to 60% depending on the temperature over the range from 20 to 30°C, whereas at temperatures above 33°C no larvae survived. Longevity and egg production of D. prasina females fed during the larval stages on T. urticae were also determined and certain demographic parameters such as the intrinsic rate of increase (r_m), mean generation time and net reproductive rate were estimated. Over the range of temperatures from 20 to 27°C, the r_m values were not significantly different and varied from 0.06629 to 0.07030. Based on the results of the present study, the possible effect of the availability of T. urticae as prey for D. prasina during summer, when its main prey species is scarce, is discussed.

We have studied the effect of different light gradient regimes on host-plant selection of the carrot psyllid, Trioza apicalis Förster. In both a strong and a weak light gradient, carrot psyllids preferred a carrot leaf placed in higher light intensity. When the choice was between the host (carrot Daucus carota L.) and a non-host (barley Hordeum vulgare L.) virgin adults settled significantly more often on non-host in higher light intensity than on carrot in lower light intensity. In a weak light gradient, none of the gravid females settled on a non-host. In an experiment without light gradient, gravid females showed a preference for carrot, whereas virgin females settled approximately equally on Norway spruce Picea abies Karst. (winter shelter plant) and carrot. Our results show that virgin and gravid individuals have different host-plant selection behaviour, and that they are sensitive to small differences in light intensity. Both factors can create a source of variation in behavioural assays, and should be taken into consideration in future experiments with this and probably also related species. Our results suggest that carrot psyllids can utilize visual cues (light intensity or wavelength) in host-plant selection, and the role of visual cues should be more thoroughly studied.

Flight is important for insects but also incurs costs in terms of reduced reproductive reserves. Recent studies on butterflies have shown that thorax mass and nitrogen content decrease over the adult lifespan, suggesting that flight muscle breakdown may also occur in butterflies. However, unlike other insects known to resorb flight muscles, butterflies will continue to fly throughout the reproductive period. Nonetheless, use of nutrients from flight muscles for reproduction has the potential to improve the reproductive output considerably. In this study we have tested to what extent female Pieris napi L. (Pieridae) butterflies actually do breakdown flight muscles. By comparing muscle mass in recently emerged and older free-flying females we show that mass and nitrogen content of the two most important groups of flight muscles each decrease by more than 50% over the adult lifespan. The significance of this finding is discussed in relation to reproduction and flight in butterflies.

Karyotypes of 16 Eupelminae species were analyzed. The haploid chromosome number was found to be much more diverse than the n = 5 previously recorded for three studied species. All species investigated of Eupelmus (Eupelmus), Eupelmus (Macroneura), Merostenus excavatus and three species of Anastatus have a karyotype of n = 5; n = 7 in Eupelmus (Episolindelia) linearis, n = 8 in Arachnophaga picardi, and n = 10 in Anastatus ruficaudus. The modal chromosome number is n = 5 and this is considered to be the plesiomorphic character state for the subfamily; karyotypes with higher chromosome numbers are hypothesized to be derived independently from the ancestral state by centric fission. This cytogenetical data provides important information on the subfamily systematics, especially the subgeneric classification of Eupelmus and generic placement of Eupelmus rostratus.

This study determined the effect of larval density-dependent competition for food on development and adult fitness in Sesamia nonagriodes Lef. (Lepidoptera: Noctuidae). Different numbers (5, 10, 15, 20 and 30 individuals) of larvae of the pink stalk borer were reared on a constant amount of food. Although crowding during the immature stages did not significantly increase mortality, it prolonged the larval developmental period and resulted in reduced pupal weight. Females were more adversely affected by high density than males, resulting in lighter females, indicating that female growth is more sensitive to density. The fecundity of the adults reared in the various larval crowding treatments was analysed. Total female fecundity was correlated negatively with increasing larval density. The effects of crowding on fecundity were not caused by the reduced pupal weight, indicating that food shortage during larval development may affect adult traits. Female longevity was negatively affected by density and positively related to pupal weight. Thus, larval density may affect the allocation of food resources and adult fitness. We conclude that crowding related changes during larval development directly affect larval life and reduce female fitness.

The life tables of the aphid predators Coccinella septempunctata L., Ceratomegilla undecimnotata (Schneider) and Propylea quatuordecimpunctata (L.) (Coleoptera: Coccinellidae), fed on Aphis fabae Scopoli (Hemiptera: Aphididae), were constructed at constant conditions (25 ± 1°C, 65 ± 2% RH; 16L : 8D). The average total fecundities of C. septempunctata, C. undecimnotata and P. quatuordecimpunctata were 1996.8, 1160.5, and 724.6 eggs / female, and the average longevities were 94.9, 88.3, and 68.9 days, respectively. The net reproductive rates (R_o) were 1004.1, 544.3, and 375.1 females/female, and the intrinsic rates of increase (r_m) 0.118, 0.142 and 0.166 females/female/day, respectively.

The honeybee (Apis mellifera L.) has a large number of geographic subspecies distributed across Europe, Africa and Asia, many of which have been described. This identification is important for bee breeding and preserving honeybee biodiversity. To investigate the origin of Jordanian honeybees, 32 samples collected from different locations in Jordan were analyzed using four different enzyme systems: Bg/II site in cytochrome oxidase b (Cytb), EcoRI site in large ribosomal (lsRNA) subunit, XbaI site in cytochrome c oxidase I (COI) subunit and HinCII site in cytochrome c oxidase I (COI) subunit. The first three enzymes were found to be polymorphic. The DNA banding pattern analyses revealed that Jordanian honeybees belong to the East Mediterranean and Middle Eastern mitochondrial lineages.

Under continuous light (LL) of low intensity (up to 2.0 lux), the free-running period of the blow fly activity rhythm lengthened for flies whose initial τ_DD was less than about 25 h, but shortened for longer-period flies. Light intensity above about 2.0 lux led to an overt behavioural arrhythmicity. A comparison of phases of the oscillation after LL as a function of phases before LL, however, indicated that the oscillation continued its motion even though overt behaviour was arrhythmic. As the intensity during LL increased to 48 lux, phases after LL became centred on a narrow range close to CT 12. Extended periods of brighter light are considered to have two effects: (a) an exogenous "masking" effect occurring at intensities greater than about 2.0 lux, and (b) at intensities between about 2.0 and 48 lux, a gradual resetting of the covert oscillator to CT 12. Between 2.0 and 48 lux, therefore, the circadian oscillation governing locomotor activity in C. vicina continues its motion despite the superficial arrhythmicity in behaviour.

The recently described and originally monotypic genus Discheramocephalus Johnson, 2007 from the Solomon Islands is revised. Six new species are described, illustrated and keyed: Discheramocephalus brucei sp. n. (Cameroon), D. elisabethae sp. n. (Cameroon), D. mikaeli sp. n. (Tanzania), D. stewarti sp. n. (Bolivia), D. jarmilae sp. n. (Bolivia), D. minutissimus sp. n. (Indonesia). Adults of D. minutissimus have a body length of about 400-426 µm, which is at the lower limit among non-egg-parasitoid insects. Evidence is provided that an egg size large enough to produce a viable larva is the main factor limiting miniaturisation of female insects. Females and males of egg-parasitoids are able to overcome the 400 µm threshold and reach limits of 180 µm and 130 µm, respectively. Brain size is likely the second most important factor limiting miniaturisation in insects.

The activities of three enzymes involved in polyol biosynthesis (aldose reductase, AR; ketose reductase, KR; and polyol dehydrogenase, PDH) were studied in adult females of the linden bug, Pyrrhocoris apterus, collected from the field during 2005/2006. While the activities of three enzymes were low in reproductive females, activities greater by one or two orders were seen in reproductively arrested females. AR and KR showed similar seasonal trends in activity. Activities were low during diapause initation and later increased and stabilized during autumnal diapause development. Further increases of AR and KR activities were seen during low temperature quiescence and finally the activities sharply decreased during vernal resumption of direct development. The activity of PDH was relatively high (but fluctuating) during diapause, then decreased in quiescent insects and almost disapeared in reproductively active females. Insects collected in February were subjected to laboratory de-acclimation (exposure to high temperatures) followed by re-acclimation (exposure to low temperatures) which resulted in loss of activity in all three enzymes and no regain. High activities of AR, KR and PDH in reproductively arrested females thus conform well with their previously observed high capacity to synthesize and accumulate polyol cryoprotectants.

Brill, Leiden-Boston, 2008, 430 pp., 38 colour plates. ISBN 978-90-04-15204-5. Price EUR 169.00/USD 270.00.

Polygraphus grandiclava (Thomson, 1886) is a unique scolytid species in that it infests both Pinaceae and Rosaceae. The utilization of such different host trees lead to the designation of two species at the beginning of the last century. Later on, these two species were synonymised. Here we investigated the genetic identity of populations collected from pine and cherry trees by sequencing a partial region of the mitochondrial COI gene. The phylogenetic study presented reveals no indication of host-induced differentiation within the mitochondrial sequences of the populations collected from the two host plants.

The aim of the present study was to test the hypothesis that short-winged (brachypterous) and long-winged (macropterous) adult males of a flightless bug Pyrrhocoris apterus differ in fertilization success. For this purpose, 5, 10 and 28 days old brachypterous and macropterous males were mated for the same period of time with reproductively active 5 days old brachypterous females. The average hatchability of five egg batches of these females was used as a measure of the fertilization success of the males. The results revealed significantly higher hatchability of the eggs laid by females that copulated with 5 or 10 days old brachypterous males than with same-aged macropterous males. In contrast, the average hatchability of eggs of females that copulated with 28 days old brachypterous males was significantly lower than of those mated with same-aged macropterous males. It is the first report of wing morph- and age-related differences in fertilization success of males in insects with a non-functional wing-polymorphism. The possible relationship between wing- and age-related differential fertilization and the mating success of P. apterus males, and differences in the amount of secretion transferred from their accessory glands into the reproductive tract of females during copulation, is discussed.

The importance of interspecific competition as a force promoting specialization in phytophagous insects has been long debated. Myzus persicae sensu stricto (Hemiptera: Aphididae) is one of the most polyphagous aphids. Its subspecies, M. persicae nicotianae, is found mainly on tobacco, although it can survive and reproduce on a relatively wide range of plant species in the laboratory. Since life history traits of these taxa make competitive interactions likely, we hypothesize that asymmetrical competition occurs between M. p. nicotianae and M. persicae s.s., and accounts for the exclusion of the former when they share a common resource. This hypothesis was tested in laboratory experiments, which examined the population growth of colonies of both taxa coexisting on sweet pepper. A replacement series experiment was set up with both aphid taxa on sweet pepper plants, and the rates of population growth (RPG) evaluated at 5 day intervals for 25 days. M. p. nicotianae showed a significantly lower RPG when interacting with M. persicae s.s. than when in monotypic colonies, while M. persicae s.s. RPG was unaffected by competition. The relative population growth from the second census onwards of M. persicae s.s. was consistently higher than that of M. p. nicotianae. Finally, the RPG of M. p. nicotianae was significantly reduced when the plant was infested with M. persicae s.s. The results suggest that the absence of M. p. nicotianae from sweet pepper in the field in Chile can be partly explained by competitive exclusion by M. persicae s.s.

In a laboratory experiment, we investigated the preference of larvae and adults of Coccinella septempunctata (Coleoptera: Coccinellidae) for three aphid species: two essential prey, Acyrthosiphon pisum and Aphis philadelphi, and a toxic prey Aphis sambuci. Surprisingly, the toxic aphid was consumed at twice the rate of the two essential prey species. The stages and genders of the ladybirds did not differ in their preference for aphid species. In the tritrophic interaction, in the field, on the elder host plant Sambucus nigra, A. sambuci is usually avoided by C. septempunctata. To measure ladybird preference, apterous females of the three selected aphid species were released in a Petri dish followed by a ladybird. After four hours, we removed the ladybird, counted the number of aphids of each species that survived, and calculated the number of aphids of each species consumed in total. We examined preference by considering separately the first two aphids consumed by a predator (early feeding), and all remaining aphids consumed thereafter (late feeding). The consumption rates of the first two individuals did not deviate from expected values with no preference; i.e., ladybirds fed on aphids without choice in the beginning of experiment when they were hungry. The ladybirds did express preference thereafter, but our hypothesis that the ladybirds should be able to distinguish among the aphids during later phase of the experiment and choose the most profitable species, or at least distinguish between essential and toxic prey, was rejected.

During the years 1994-1999, several hundreds of thousands of H. axyridis adults were released at various cultivations infested by aphids (citrus, vegetable and bean crops, maize etc.) and on ornamental plants in urban settings in central and southern Greece (mainly Attica and Peloponessos region) as well as on several islands. Between 1995-1999, spring sampling was conducted in some areas, just prior to releases, in order to determine if H. axyridis overwintered in the field. No presence of H. axyridis was recorded in any of the orchards where the predator had been released save in spring of 1998 and 1999 when small colonies (<50 individuals) of overwintered H. axyridis adults were observed in the Attica region. The above results suggest an inability of released H. axyridis populations to establish in Greece, although in some areas this species became an important biocontrol agent during the growing season.

Experimental hybridization of X0 and XY chromosome races of the brachypterous grasshopper P. sapporensis did not reveal pre-zygotic reproductive isolation. However, a partial zygotic barrier was found between the X0-standard race from Shimokawa and XY-standard chromosome race from Akan. Approximately 40% of embryos from females crossed with males from other chromosome races developed parthenogenetically, the remaining embryos were normal heterozygotes. Adult F₁ males and females from crosses of this type had properly developed testes and ovaries. Non-sister associations and other irregularities in meiosis were not observed in male meiosis. Crossing experiments demonstrated that hybrids between X0 and XY races occur to some extent. The absence of a hybrid zone between the X0 and XY chromosome races may be the result of selection against heterozygotes. Crosses between the XY-Tanno and X0-standard (Teine) subraces resulted in F₁ and F₂ generations in spite of the many chromosome differences between them such as a X-A translocation and fixed pericentric inversions in four pairs of autosomes. These results do not support the hypothesis that chromosomal differences play a key role in restricting gene flow between the X0 and XY races of P. sapporensis.

Blackwell, Malden, MA & Oxford, 2008, 445 pp., ISBN 978- 1-4051-6347-7. Price EUR 60.80, GBP 45.00.