bluuebunny/crossref_metadata_2025 huggingface dataset:
Geological and trace element evidence for a marine sedimentary environment of deposition and biogenicity of 3.45 Ga stromatolitic carbonates in the Pilbara Craton, and support for a reducing Archaean ocean
Authors: Van Kranendonk Martin J. , Webb Gregory E. , Kamber Balz S.
Published: October 2003

Bedded carbonate rocks from the 3.45 Ga Warrawoona Group, Pilbara Craton, contain structures that have been regarded either as the oldest known stromatolites or as abiotic hydrothermal deposits. We present new field and petrological observations and high‐precision REE + Y data from the carbonates in order to test the origin of the deposits. Trace element geochemistry from a number of laminated stromatolitic dolomite samples of the c. 3.40 Ga Strelley Pool Chert conclusively shows that they precipitated from anoxic seawater, probably in a very shallow environment consistent with previous sedimentological observations. Edge‐wise conglomerates in troughs between stromatolites and widespread cross‐stratification provide additional evidence of stromatolite construction, at least partly, from layers of particulate sediment, rather than solely from rigid crusts. Accumulation of particulate sediment on steep stromatolite sides in a high‐energy environment suggests organic binding of the surface. Relative and absolute REE + Y contents are exactly comparable with Late Archaean microbial carbonates of widely agreed biological origin. Ankerite from a unit of bedded ankerite–chert couplets from near the top of the stratigraphically older (3.49 Ga) Dresser Formation, which immediately underlies wrinkly stromatolites with small, broad, low‐amplitude domes, also precipitated from anoxic seawater. The REE + Y data of carbonates from the Strelley Pool Chert and Dresser Formation contrast strongly with those from siderite layers in a jasper–siderite–Fe‐chlorite banded iron‐formation from the base of the Panorama Formation (3.45 Ga), which is clearly hydrothermal in origin. The geochemical results, together with sedimentological data, strongly support: (1) deposition of Dresser Formation and Strelley Pool Chert carbonates from Archaean seawater, in part as particulate carbonate sediment; (2) biogenicity of the stromatolitic carbonates; (3) a reducing Archaean atmosphere; (4) ongoing extensive terrestrial erosion prior to ∼3.45 Ga.
Brown planthopper, Nilaparvata lugens, resistance in rice cultivar IR64: mechanism and role in successful N. lugens management in Central Luzon, Philippines
Authors: Cohen Michael B. , Alam Syed N. , Medina Edith B. , Bernal Carmencita C.
Published: October 2003

We investigated the mechanism of brown planthopper, Nilaparvata lugens (Stål), resistance in the popular rice cultivar IR64, and the current level of resistance of IR64 to N. lugens in a large rice growing area with low brown planthopper populations (Central Luzon, Philippines). In greenhouse experiments with N. lugens populations collected from Central Luzon, IR64 showed slight to moderate levels of antibiosis, antixenosis, and tolerance relative to the cultivars IR22 and Azucena, which contain no major genes for N. lugens resistance. IR64 was also more resistant than IR26 in most experiments, despite the fact that both varieties have the same major gene for N. lugens resistance, Bph1. This confirms that IR64 contains one or more additional, apparently minor, genes for brown planthopper resistance. Our findings also demonstrate that, in an area with low insecticide use, it is not necessary to have high levels of N. lugens resistance, even in a rice cultivar grown by the majority of farmers, to maintain low and stable N. lugens populations.
Effects of vegetation and weather on trap catches of Glossina fuscipes fuscipes near Lake Victoria, Kenya
Authors: Mohamed‐Ahmed Mohamed M. , Wynholds Yno
Published: October 2003

Glossina fuscipes fuscipes Newstead was sampled in isolated thickets and forest patches near Lake Victoria, Kenya using unbaited biconical traps, between March 1992 and June 1993. Traps set at 1 m from the forest edge caught 3.3 times as many males and 5 times as many females as those set inside or 10 m away. The corresponding figures at 1 m from the edge of thicket were about 1.43 and 1.64 times, respectively. Hourly catches of males and females were positively correlated with temperature, light intensity and host (monitor lizard) prevalence, and negatively correlated with relative humidity. Light intensity and temperature were the most important variables affecting the catches of each sex. The results are discussed in relation to control and monitoring of G. f. fuscipes using traps.
Flight initiation in Prostephanus truncatus: influence of population density and aggregation pheromone
Authors: Scholz D. , Borgemeister C. , Markham R. H. , Poehling H.‐M.
Published: October 2003

The influence of population density and aggregation pheromone were investigated as possible flight initiating factors for Prostephanus truncatus (Horn) (Col.: Bostrichidae). Maize grains (175 g in glass jars) were infested with 20, 50, 150 or 300 beetles, all of which were removed after 2 weeks. Flight initiation of the progeny was observed over a period of 4 weeks, with and without the synthetic aggregation pheromone of P. truncatus. Addition of the synthetic pheromone had no influence on the number of beetles taking off. The number of beetles dispersing increased with growing initial and progeny densities. Dispersal rates (% of total progeny dispersing) rose with declining rate till they reached a maximum at ca. 33%. Of the beetles dispersing, 74% left the cultures between 18.00 and 20.00 hours. Surviving progeny per female decreased with increasing initial density. Sex ratios in the initial cultures and in the F1 were ca. 1:1, whereas a higher proportion of females (67%) was found among the dispersing beetles.
Genetic variation and covariation among life history traits in populations of Acanthoscelides obtectus maintained on different hosts
Authors: Tucić N. , Mikuljanac S. , Stojković O.
Published: October 2003

We explored the extent to which two populations of Acanthoscelides obtectus (Coleoptera: Bruchidae), maintained in the laboratory for about 60 generations on common bean (Phaseolus vulgaris) and chickpea (Cicer arietinum) seeds, differ genetically in life history traits. Using a half‐sib breeding design, we screened for genetic variation in oviposition preference for two hosts within both populations, and examined whether this variation is correlated with weevil pre‐adult (egg‐to‐adult viability and egg‐to‐adult developmental time) and adult (female fecundity and longevity) fitness components on these two hosts. Significant differences between the Phaseolus and Cicer population were detected in viability, developmental time and oviposition preference, but not in female fecundity and longevity. The absence of a significant population × host interaction in all traits, except for developmental time in males, indicates that the Cicer population has not attained the status of ‘host race’. The estimated narrow‐sense heritabilities within population within host plant were in the low‐to‐moderate level (range: 1%–79%), with an overall average of about 24%. Within the population maintained on the chickpeas we detected significant genetic correlations between female developmental time on chickpea seeds and preference for chickpeas. In the population maintained on the primary host of this weevil species (the ‘Phaseolus’ population) we found no significant preference/performance genetic correlations. Data are also presented on the genetic correlations of preference and performance across host seeds within both populations. These correlations are found to be positive for all traits in both populations, indicating the absence of trade‐offs in either performance or behavioural response that might impose selection for host specialization within populations.
The responses of the cabbage seed weevil Ceutorhynchus assimilis to volatile compounds from oilseed rape in a linear track olfactometer
Authors: Bartlet E. , Blight M. M. , Lane P. , Williams I. H.
Published: October 2003

The cabbage seed weevil, Ceutorhynchus assimilis Payk. [syn. Ceutorhynchus obstrictus (Marsham)] (Coleoptera: Curculionidae), a crucifer‐feeding insect, is a pest of oilseed rape (Brassica napus L.). It is known to be attracted by isothiocyanates, crucifer‐specific volatiles that are metabolites of the glucosinolates. The responses of this insect to other electrophysiologically‐active volatiles from rape were tested in a linear track olfactometer. Attraction was demonstrated to nitriles (phenylacetonitrile, 4‐pentenenitrile and 5‐hexenenitrile), which are also glucosinolate metabolites, and to volatiles emitted by a wider spectrum of plant families ((Z)‐3‐hexen‐1‐ol and methyl salicylate). Combination of an isothiocyanate mixture with phenylacetonitrile increased attraction, but there was no such increase when the isothiocyanate mixture was combined with methyl salicylate. A mixture of 23 volatiles, emulating an attractive air‐entrainment extract of oilseed rape, was not significantly attractive, although a high proportion of weevils (60%) turned towards it. The potential of these volatiles for inclusion into an isothiocyanate‐based monitoring system is discussed.
In vitro rearing of Campoletis sonorensis, a larval endoparasitoid of Heliothis virescens from egg to third instar in an artificial medium devoid of insect sources
Authors: Hu J. S. , Vinson S. B.
Published: October 2003

Campoletis sonorensis is a solitary larval endoparasitoid of several Heliothis spp. pests. This study was carried out to develop media devoid of insect sources for in vitro rearing the parasitoid. Trehalose, lysine, threonine, asparagine, glutamine, hydroxyproline, serine, bovine serum albumin, and lactalbumin were beneficial to C. sonorensis. Addition of fresh chicken egg yolk at a low level improved the artificial media. Addition of 20‐hydroxyecdysone increased the molting rate, reduced the critical size at molt and decreased development time. Parasitoid development in vitro was dependent on eggs that had been in the host for at least 22 h. Luminosity was also critical for the development of C. sonorensis in vitro. Optimal development occurred in a L14:D10 photoperiod at 43 Lux light intensity. Utilizing the best media and conditions, 100% of the parasitoid larvae reached the second instar and over 37% molted to the third instar. However, no further development occurred.
Environmental effects on cytoplasmic incompatibility and bacterial load in Wolbachia‐infected Drosophila simulans
Authors: Clancy David J. , Hoffmann Ary A.
Published: October 2003

The effects of high temperatures, antibiotics, nutrition and larval density on cytoplasmic incompatibility caused by a Wolbachia infection were investigated in Drosophila simulans. Exposure of larvae from an infected stock to moderate doses of tetracycline led to complete incompatibility when treated females were crossed to infected males; the same doses only caused a partial restoration of compatibility when treated males were crossed to uninfected females. In crosses with treated females, there was a strong correlation between dose effects on hatch rates and infection levels in embryos produced by these females. Ageing and rearing males at a high temperature led to increased compatibility. However, exposing infected females to a high temperature did not influence their compatibility with infected males. Male temperature effects depended on conditions experienced at the larval stage but not the pupal stage. Exposure to 25 °C reduced the density of Wolbachia in embryos compared with a 19 °C treatment. Low levels of nutrition led to increased compatibility, but no effect of larval crowding was detected. These findings show the ways environmental factors can influence the expression of cytoplasmic incompatibility and suggest that environmental effects may be mediated by bacterial density.
Mobility of salivary components as a possible reason for differences in the responses of alfalfa to the spotted alfalfa aphid and pea aphid
Authors: Madhusudhan V. V. , Miles P. W.
Published: October 2003

The spotted alfalfa aphid (SAA), Therioaphis trifolii maculata (Buckton), causes a characteristic veinal chlorosis and necrosis in the growing tips of susceptible cultivars of alfalfa. The pea aphid, Acyrthosiphon pisum (Harris), causes general degenerative changes in alfalfa but no specific, local symptoms. Biochemical and electrophoretic analyses detected similar enzymes in the ejected saliva of either species: pectin methylesterase, endopolygalacturonase and at least three isozymes of a copper dependent oxido‐reductase that showed both catechol oxidase and peroxidase activity. Pectinase and catechol oxidase activities per unit of soluble protein were much greater in the saliva of pea aphid compared with that of SAA. The isozymes of the oxidase from SAA were roughly half the molecular weights of the corresponding isozymes from pea aphid, however, and radiotracer studies showed that soluble secretions injected into alfalfa by SAA travelled to growing tips considerably faster than the secretions of pea aphid. It is suggested that differences in the lesions caused by these aphids may be due to reaction kinetics rather than specific salivary toxins; that the rate of arrival of salivary components, possibly the oxidases, at phloem unloading sites may determine whether the plant's local defensive system is able to repress the immediate challenge or undergoes a run‐away reaction leading to necrosis.
Photoperiodic control of larval diapause in the yellow‐spotted longicorn beetle, Psacothea hilaris: analysis by photoperiod manipulation
Authors: Shintani Yoshinori , Ishikawa Yukio
Published: October 2003

The photoperiodic control of diapause induction in the larvae of the yellow‐spotted longicorn beetle, Psacothea hilaris (Pascoe), was investigated using a west Japan‐type population collected from Ino, Kochi Prefecture, Japan. In this population, the larvae expressed a long‐day photoperiodic response with a critical daylength between 13.5 and 14 h at 25 °C; under a long daylength, the larvae pupated after the 4th or 5th instar, while the larvae entered diapause under a short daylength after 2.3 additional molts on average. When the photoperiod was changed from a short (L12:D12) to a long (L15:D9) daylength, pupation occurred in most of the individuals irrespective of the time of the change. When the photoperiod was changed from long to short at 1 or 2 weeks after hatching, all of the larvae entered diapause, whereas when the photoperiod was changed at 5 weeks after hatching or later, most of the larvae pupated. The 2 weeks exposures to a long daylength against a ‘background’ of a short daylength at various times revealed that the larvae of this insect are most sensitive to the photoperiod from 4 to 6 weeks after hatching.
Genetic basis of photoperiodic control of summer and winter diapause in geographic ecotypes of the rice stem maggot, Chlorops oryzae
Authors: Takeda Mitsuyoshi
Published: October 2003

Chlorops oryzae Matsumura (Diptera: Chloropidae) is bivoltine in northern Japan but trivoltine in the southern part of the country. Larvae of the bivoltine strain (Akita, 39° N) develop without delay under L14:D10 but enter summer diapause in the mature larval stage under L15:D9. In contrast, larvae of the trivoltine strain (Aichi, 35° N) develop quickly under L15:D9 but enter summer diapause under L14:D10. The genetic basis of their different summer‐diapause behavior was analyzed by reciprocal crossing between the two ecotypes and backcrossing to the hybrids. Although a polygenic system seems to be involved, there is a single gene on the X‐chromosome exerting a major effect on summer diapause. The northern bivoltine ecotype has a longer critical photoperiod for the induction of winter diapause in the first larval stage and remains in diapause longer than the southern trivoltine ecotype. The differences in the critical photoperiod and the winter diapause duration between the two ecotypes seem to be controlled by a polygenic system but again a sex‐linked or closely linked gene (or genes) plays a major role. The two geographic ecotypes differ significantly in summer‐ and winter‐diapause traits, both of which are characterized by sex‐linked inheritance. Despite this, no apparent sterility or inviability in hybrids between the ecotypes occurs.
Phloem specific aphid resistance in Cucumis melo line AR 5: effects on feeding behaviour and performance of Aphis gossypii
Authors: Klingler John , Powell Glen , Thompson Gary A. , Isaacs Rufus
Published: October 2003

The feeding behaviour, excretion rate, and life history traits of the cotton‐melon aphid, Aphis gossypii (Glover) (Homoptera, Aphididae), were measured on a resistant melon, Cucumis melo L., breeding line, AR 5. The site of resistance detection by the aphids was determined using the electrical penetration graph (EPG) technique. EPG recordings showed that resistance is expressed within the host plant, rather than on its surface, because the time to first stylet penetration was not significantly different between AR 5 and the closely related susceptible breeding line, PMR 5. EPG patterns associated with stylet pathway activities of the aphids were not significantly different between the resistant and susceptible lines. Significant behavioural differences were observed only after stylets contacted phloem sieve elements. On AR 5, the duration of salivation after sieve element puncture (waveform E1) was significantly longer, and the number of aphids showing phloem sap ingestion (waveform E2) was significantly reduced. We conclude that the resistance mechanism producing the effects seen in this study acts within the phloem sieve elements. Monitoring of excretion rates on the two genotypes showed that aphid feeding was delayed and greatly reduced on the resistant genotype. Comparisons of aphid life history traits and population development between host plant genotypes showed that the effects of resistance act throughout aphid development and are highly effective at slowing down population increase.
Chemoreception of amino acids by female fourth‐ and sixth‐instar larvae of the spruce budworm
Authors: Panzuto M. , Albert P. J.
Published: October 2003

An electrophysiological approach was used to record the responses of maxillary styloconic sensilla of fourth‐ and sixth‐instar larvae of the spruce budworm Choristoneura fumiferana to 14 amino acids. One cell in the lateral styloconic sensillum was identified as an amino acid‐sensitive neuron. All of the amino acids tested, except l‐proline and l‐arginine, were detected by this cell. Arginine did not evoke a response from either the medial or lateral styloconic sensilla. Proline evoked responses from a cell in the medial styloconic sensillum. It is known from previous behavioural work that l‐proline is a phagostimulant and l‐valine inhibits feeding in Choristoneura; we thus further characterized the responses to these two amino acids. For both instars, l‐proline was detected as low as 0.001 mmol/l and the maximal response was at 50 mmol/l. Stimulation of fourth‐ and sixth‐instar larvae with l‐valine showed that the maximum firing frequency was obtained at 1 mmol/l. Above and below this concentration, firing frequency decreases. Sensory responses to the amino acids stimuli did not correlate with known behavioral responses to similar stimuli.
Wolbachia transmission in a naturally bi‐infected Drosophila simulans strain from New‐Caledonia
Authors: Merçot Hervé , Poinsot Denis
Published: October 2003

Wolbachia are maternally‐transmitted endocellular bacteria infecting several arthropod species. In order to study the possibility of Wolbachia segregation in a naturally bi‐infected host, isofemale lines from a bi‐infected Drosophila simulans (Sturtevant) strain from Nouméa (New Caledonia) were backcrossed using uninfected males carrying the same nuclear background. Uninfected males were used to avoid the cytoplasmic incompatibility syndrome (CI) associated with the presence of Wolbachia in males. Each line was established using a female infected simultaneously by the two different Wolbachia variants wHa and wNo. The backcross led to some individuals carrying only one type of infection being recovered among the progeny of the bi‐infected foundress females. Rarely, uninfected individuals were also recovered. Isolated for the first time in its natural host, wNo exhibited a significantly weaker CI phenotype than the isolated wHa variant. Infection fate when backcross conditions were relaxed varied depending on rearing conditions of the host. Under favourable conditions, the infection was generally maintained, while it was frequently lost under unfavourable conditions. This result probably reflects the direct fitness dependence of the symbiont on its host.
Role of chlorophyll content of prey diets in prey‐locating behavior of a generalist predatory stink bug, Eocanthecona furcellata
Authors: Yasuda Tetsuya
Published: October 2003

Feeding preferences of nymphs of a predatory stink bug, Eocanthecona furcellata, to Spodoptera litura larvae fed with various food items were examined. Bugs preferred larvae fed with spinach leaves to those feeding on bean sprouts. Solvent extracts of S. litura larvae given spinach or lettuce leaves contained a large amount of (E)‐phytol which was found to elicit the proboscis‐protruding behavior of this bug. (E)‐Phytol was not detected in similar extracts of larvae fed with bean sprouts containing no (E)‐phytol. When S. litura larvae fed with artificial diets containing various amounts of chlorophyll, the (E)‐phytol contents in those larvae and their feces increased in proportion to the dietary chlorophyll contents, indicating that (E)‐phytol was derived from the chlorophyll ingested through hydrolysis. Bugs showed the proboscis‐protruding behavior in response to extracts of larvae fed with spinach and lettuce leaves or a kidney‐bean artificial diet, and their response depended on (E)‐phytol contents. On the other hand, extracts of larvae fed with bean sprouts were not effective. When a larva fed with bean sprouts was treated with (E)‐phytol and presented together with a larva fed with spinach leaves, bugs failed to distinguish between the two. These results indicate that (E)‐phytol originating from chlorophyll in the prey diet serves as an important cue in the prey‐locating behavior of E. furcellata.
Effects of fumonisin B1 on growth and metabolism of larvae of the yellow mealworm, Tenebrio molitor
Authors: Abado‐Becognee K. , Fleurat‐Lessard F. , Creppy E.E. , Melcion D.
Published: October 2003

The chronic and acute toxicity of fumonisin B1 (FB1), a mycotoxin from Fusarium moniliforme, to the larvae of the yellow mealworm, Tenebrio molitor, was assessed. The toxin was administered via the diet or injected directly into the larvae. Young T. molitor larvae fed on a diet containing 450 μg FB1 per g diet exhibited reduced growth performance but only after consuming the fumonisin‐contaminated diet for several weeks. FB1‐contaminated diet also reduced the rate of carbon dioxide production, food consumption and protein metabolism. The concentrations of FB1 in the diet did not increase mortality, even when tested at the highest dose of 450 μg FB1 per g of diet. Injection of 25 ng FB1 per larva decreased the CO2 production, but became significant only 11 days after the injection and was reversible with time. A parallel analysis of the retention of FB1 by the larvae indicated that about 40% of the ingested FB1 was excreted in the faeces.
Effects of Pieris host species on life history parameters in a solitary specialist and gregarious generalist parasitoid (Cotesia species)
Authors: Brodeur Jacques , Geervliet Jacqueline B. F. , Vet Louise E. M.
Published: October 2003

Host specificity and host selection by insect parasitoids are hypothesized to be correlated with suitability of the hosts for parasitoid development. The present study investigates the correlation between host suitability and earlier studied host‐finding behaviour of two closely related braconid larval parasitoid species, the generalist Cotesia glomerata (L.) and the specialist C. rubecula (Marshall) (Hymenoptera: Braconidae). We compared the capability of both parasitoid species to parasitize and develop in three Pieris host species, i.e. P. brassicae (L.), P. rapae (L.) and P. napi (L.) (Lepidoptera: Pieridae). In laboratory experiments, we measured the effect of host species on fitness parameters such as survival, development, sex ratio and size of parasitoid progeny. The results show that C. glomerata is capable of developing in the three host species, with significant differences in parasitoid survival, clutch size and adult weight among Pieris species. The host range for development was more restricted for C. rubecula. Although C. rubecula is physiologically able to develop in P. brassicae larvae, parasitoid fitness is negatively affected by this host species, compared to its most regular host, P. rapae. A comparison of the present data on host suitability with earlier studies on host‐searching behaviour suggests that the host‐foraging behaviour of both parasitoid species not only leads to selection of the most suitable host species for parasitoid development, but also plays a significant role in shaping parasitoid host range.
Plant architecture and the foraging success of ladybird beetles attacking the Russian wheat aphid
Authors: Clark Teresa L. , Messina Frank J.
Published: October 2003

We examined the interaction between the fourteen‐spotted ladybird beetle, Propylea quatuordecimpunctata (L.), and the Russian wheat aphid, Diuraphis noxia (Mordvilko), on two grasses with divergent leaf architectures. Like wheat, crested wheatgrass bears flat, broad leaves, whereas Indian ricegrass produces slender, tightly rolled leaves. In the absence of aphid prey, residence times and time budgets of larvae and adults of P. quatuordecimpunctata were similar on the two hosts, although larvae tended to remain longer on crested wheatgrass. When aphids were present, both predator stages dislodged, contacted, and captured aphids at higher rates on Indian ricegrass than on crested wheatgrass. Predator time budgets and behavior sequences also reflected a greater predation risk for D. noxia on Indian ricegrass, and were consistent with earlier, population‐level experiments in the field. Comparisons between aphid‐free and aphid‐infested plants suggest that the effect of host plant in this tri‐trophic system largely depended on differences in the availability of prey refuges rather than on differences in predator searching behavior; proportionally more aphids fed in exposed locations on Indian ricegrass than on crested wheatgrass. Plant architecture is likely to be an important component of the predation risk of D. noxia because of the aphid's tendency to feed in relatively concealed locations.
Sensitivity of two greenhouse pests to vapours of essential oils
Authors: Tunç I. , Şahinkaya Ş.
Published: October 2003

Vapours of essential oils extracted from cumin, Cuminum cyminum L., anise, Pimpinella anisum L., oregano, Origanum syriacum var bevanii (Holmes) Ietswaart and eucalyptus, Eucalyptus camaldulensis Dehn., were found to be toxic to two greenhouse pests, viz. the carmine spider mite, Tetranychus cinnabarinus (Boisd.) (Tetranychidae, Tetranychini) and cotton aphid, Aphis gossypii Glov. (Aphididae, Aphidini). In general, a minimum dose of 0.5 μl/l air and 2–3 days of exposure was required for 99% mortality using essential oils of the first three plants.
Effects of prey density, prey instar, and patch size on the development of the predatory mosquito, Toxorhynchites towadensis
Authors: Yasuda Hironori , Hagimori Kyoko
Published: October 2003

Effects of prey density, prey instar, and patch size on the development of the predatory mosquito larva, Toxorhynchites towadensis, were investigated in the laboratory. Survivors of T. towadensis showed different developmental patterns in relation to prey age structure. All predatory larvae in containers with only second instar prey developed into the third instar. However, in several containers with fourth instar prey, mortality of predators was observed. During the third instar, no predatory larva died, but both prey density and prey instar significantly affected the survival of predators during their fourth instar. Large prey size promoted large predator adults, and predatory larvae which grew up in small surface containers responded by developing to large sizes than those in large containers. Larval developmental time of the predators differed in each treatment. During first and second instars, faster predator development was observed in containers with small surface areas and containing young prey individuals. However, when development was enhanced by the presence of old prey individuals, no surface effect was observed. The fastest predator development was observed with prey of mixed instars and high density. This study suggests that a small surface container containing prey of mixed instars and high density is suitable for development of predators.
Plant virus and parasitoid interactions in a shared insect vector/host
Authors: Christiansen‐Weniger Petra , Powell Glen , Hardie Jim
Published: October 2003

Interactions between barley yellow dwarf luteovirus (BYDV) and the aphid parasitoid, Aphidius ervi Haliday (Hymenoptera: Aphidiidae), were investigated while sharing the vector/host, Sitobion avenae (F.) (Homoptera: Aphididae). Aphids, which were parasitized during their second larval stadium, had access to virus‐infected plants before, immediately after, or several days after parasitoid attack. The larval development of A. ervi in S. avenae was significantly delayed when virus acquisition took place before or shortly after the parasitoid had hatched, but not when the parasitoid was at the second larval stage during virus acquisition. Similarly, the presence of BYDV led to a significantly higher aphid mortality when they acquired virus up to and including the time that A. ervi was at the first larval stage. Adult female parasitoids deposited fewer eggs in viruliferous aphids. Virus transmission was not reduced by parasitization, and in some experiments aphids which were subjected to parasitoid attack transmitted BYDV more efficiently than unattacked insects.
Infochemicals influencing the host foraging behaviour of Dahlbominus fuscipennis, a pupal parasitoid of the European spruce sawfly (Gilpinia hercyniae)
Authors: Rostás Michael , Dippel Cornelia , Hilker Monika
Published: October 2003

The chalcidoid wasp Dahlbominus fuscipennis Zett. (Hymenoptera: Eulophidae) parasitises pupae of the European spruce sawfly Gilpinia hercyniae Htg. (Hymenoptera: Diprionidae). In this parasitoid‐host system the role of infochemicals for successful parasitisation was studied. Olfactometer experiments and dual choice bioassays in petri dishes showed that D. fuscipennis was not attracted by volatiles from a plant‐host complex consisting of spruce, sawfly larvae and pupae. On the other hand, odours from needles of Picea abies (L.), that were collected from the ground, attracted D. fuscipennis to the habitat of the sawfly. Volatiles from host pupae were not attractive, whereas a contact kairomone from sawfly pupae elicited frequent antennal drumming, a behaviour that indicates host recognition. This contact kairomone was extracted with methanol from the outer cocoon layer of the pupa. The kairomone is not produced by the silk glands of the last instar larva spinning the cocoon, since a methanolic extract of silk gland secretion did not elicit any response in D. fuscipennis. Further bioassays revealed that non‐volatile components of the integument of the prepupa within the cocoon also elicited antennal drumming. We suggest that chemicals of the prepupal integument diffuse from inside the cocoon to the outside where they inform the parasitoid on the suitability of the host.
Control of codling moth in small plots by mating disruption: alone and with limited insecticide
Authors: Vickers R. A. , Thwaite W. G. , Williams D. G. , Nicholas A. H.
Published: October 2003

Mating disruption alone and mating disruption supplemented with limited applications of either azinphos‐methyl or fenoxycarb was evaluated in 0.11–0.30 ha plots for the control of codling moth Cydia pomonella (L.) (Tortricidae: Olethreutinae) populations.

Where populations were low, mating disruption alone was sufficient to keep codling moth damage levels below 1% at harvest. ‘Low’ was defined as no more than 0.2% damage at harvest and fewer than 1.3 larvae/metre of trap band from January–March inclusive in the previous season. Neither mating disruption alone nor when supplemented with azinphos‐methyl or fenoxycarb during the first spring generation gave commercially acceptable levels of control in other than low density populations. Small plot size may have contributed to the failures.

At the high density site unintentional supplementary control provided by drift of azinphos‐methyl from border areas to which it was applied throughout the season gave excellent control in the first year and suggested an interaction between low dosages of insecticide and pheromone treatments that enhanced the disruptive effect of the latter.
Stimulation and attenuation of induced resistance by elicitors and inhibitors of chemical induction in tomato (Lycopersicon esculentum) foliage
Authors: Stout Michael J. , Workman Kathi V. , Bostock Richard M. , Duffey Sean S.
Published: October 2003

Elicitors and inhibitors of chemical induction were used to manipulate the activities of several putative defense‐related proteins in leaves of the tomato, Lycopersicon esculentum Mill. The four presumptive defenses manipulated were proteinase inhibitors, polyphenol oxidase, peroxidase, and lipoxygenase. The elicitors used were jasmonic acid, methyl jasmonate, ultraviolet light, and feeding by larvae of the noctuid, Helicoverpa zea Boddie; the inhibitors used were salicylic acid and acetylsalicylic acid. These chemical manipulations were combined with short‐term growth assays using larvae of the generalist noctuid, Spodoptera exigua Hubner, in order to assess the relative roles of the proteins in induced resistance to S. exigua. When activities of proteinase inhibitors and/or polyphenol oxidase in leaf tissue were high (e.g., in damaged or elicited plants), growth rates of larvae of S. exigua were low; when activities of polyphenol oxidase and proteinase inhibitors were low (e.g., in undamaged or damaged, inhibited plants), growth rates of larvae were high. In contrast, high activities of peroxidase and lipoxygenase were not associated with decreases in suitability of leaf tissue for S. exigua. The association of high levels of proteinase inhibitors and polyphenol oxidase with resistance to S. exigua– irrespective of the presence or absence of damage – strongly implicates these proteins as causal agents in induced resistance to S. exigua.
Electroantennogram responses of male Sphinx perelegans hawkmoths to floral and ‘green‐leaf volatiles’
Authors: Raguso Robert A. , Light Douglas M.
Published: October 2003

Electroantennograms (EAGs) from field‐collected male Sphinx perelegans hawkmoths were recorded in response to 10 individual floral scent compounds identified from Clarkia breweri (Onagraceae), 21 additional volatiles characteristic of other night‐blooming flowers, and eight ‘green leaf’ volatiles. Measurable EAG responses were elicited to all compounds tested, but the most effective antennal stimulants were benzyl acetate, linalool, methyl salicylate and trans‐2‐hexenal. Mean, pooled EAGs to oxygenated terpenoids, aromatic esters and fatty acid derivatives were larger in magnitude than those in response to aromatic aldehydes/alcohols, monoterpenes and nitrogen‐bearing compounds. The rank order of male S. perelegans' EAGs did not differ significantly from that of previously recorded responses of male Hyles lineata to the same scent compounds, and EAG magnitudes were generally larger for S. perelegans than for H. lineata. Both hawkmoth species are shown to have broad olfactory receptivities and could potentially respond to a wide array of plant volatiles as floral attractants.
Behavioural and olfactory variations in the leek moth, Acrolepiopsis assectella, after several generations of rearing under diverse conditions
Authors: Lecomte C. , Pierre D. , Pouzat J. , Thibout E.
Published: October 2003

Three strains of the leek moth, Acrolepiopsis assectella, were compared: two reared on leek leaves (Allium porrum) for which generations 10 to 12 (L) or generation 2 (G2) were used, the third one (D) reared on an artificial diet incorporating leek powder, for which generation ca 140 was examined. The walking behaviour (L and D) and the antennal responsiveness (L, G2 and D) were compared between individuals subjected to leek leaf odour and 4 volatiles identified in these leaves: 2 specific sulphur ones (dipropyl thiosulphinate and dipropyl disulphide) and 2 ‘general green leaf volatiles’ (cis‐3‐hexen‐1‐ol and trans‐2‐hexen‐1‐ol). The walking behavioural thresholds to leek odour, dipropyl thiosulphinate, and cis‐3‐hexen‐1‐ol were lower for L than for D females. The chemoanemotactic responses to dipropyl disulphide are almost identical, and trans‐2‐hexen‐1‐ol has nearly no activity. Accordingly, the olfactory sensitivity (assessed by EAG) to sulphur volatiles and cis‐3‐hexen‐1‐ol was higher for L and G2 females than for D ones. The threshold for thiosulphinate was at a concentration (v/v) of 4 ×10−4 M/l for D females, 4 × 10−5 M/l for L females and 4 × 10−8 M/l for G2 ones. It may be hypothesised that laboratory rearing conditions cause variations in the thresholds of antennal sensitivity and walking behaviour to specific and more efficient leek volatiles. This may result from the selective pressures experienced by the larvae reared in the laboratory.
Identification of the sex pheromone of Ostrinia palustralis
Authors: Huang Yongping , Tatsuki Sadahiro , Kim Choon‐gon , Hoshizaki Sugihiko , Ishikawa Yukio
Published: October 2003

By means of gas chromatography with electroantennographic detection, gas chromatography‐mass spectrometry and a series of bioassays, (E)‐11‐tetradecenyl acetate (E11‐14:OAc) and (Z)‐11‐tetradecenyl acetate (Z11‐14:OAc) at a ratio of 99:1 were identified as female sex pheromone components of Ostrinia palustralis. The average amounts of E11‐ 14:OAc and Z11‐14:OAc in a single sex pheromone gland were 37.2±24.4 ng and 0.3±0.2 ng, respectively. In a wind‐tunnel bioassay, the binary blend of E11‐ and Z11‐14:OAc elicited the same male behavioral responses as did virgin females.
Proximate and ultimate factors influencing oviposition site selection by endoparasites on conifer seed cones: two sympatric dipteran species on larch
Authors: McClure Martha , Quiring Dan T. , Turgeon Jean J.
Published: October 2003

A three‐year field study was carried out to investigate proximate and ultimate influences on oviposition site selection by Strobilomyia laricis Michelsen and S. viaria (Huckett) (Diptera: Anthomyiidae), two sympatric flies whose maggots develop in young seed cones of eastern larch, Larix laricina (Du Roi) K. Koch. In 1990 and 1991, when the cone crop was light, the egg distribution at peak egg lay was uniform for both species, suggesting that females of both species recognized and avoided oviposition sites previously occupied by conspecifics. Strobilomyia viaria, which emerged two weeks after S. laricis, also avoided ovipositing on seed cones occupied by S. laricis. Thus, the egg distribution of S. laricis determined, to a large extent, the distribution of S. viaria. In 1992, a year when the cone crop was very light, and egg densities per cone were high, ovipositing females of both species apparently preferred cones with few versus many conspecifics. Host size also influenced oviposition site selection in S. laricis and S. viaria. In two of three years, both species selected longer cones for oviposition. A significant proportion of the variation in egg densities of both species was attributable to trees but not to cone density per tree. Egg distribution was influenced occasionally by cone phenology and cone location within tree crowns.

During the only year when egg densities per cone were high, preference for unoccupied oviposition sites resulted in increased larval survival, and in one of the other two years, preference for longer cones resulted in greater weight by the end of larval development, suggesting that oviposition preferences were adaptative. Cone phenology (at the time of oviposition) and position (crown aspect or level) had no significant influence on larval weight. Our results are consistent with the hypothesis that oviposition preference and offspring performance should be closely linked when females oviposit on the host in which their offspring must complete development.
Plant penetration by pea aphids (Acyrthosiphon pisum) of different plant range
Authors: Wilkinson T.L. , Douglas A.E.
Published: October 2003

Plant penetration by the stylets of six clones of the pea aphid, Acyrthosiphon pisum, on Vicia faba (acceptable to all clones) and Pisum sativum (acceptable to 3/6 clones) was investigated by the DC electrical penetration graph technique. In a 10 h recording period, 93% of 144 aphids exhibited sustained feeding on phloem sap. Significant interclonal differences were observed for the incidence of potential drops (indicative of brief punctures of plant cells) and the duration of waveform E1 (insect salivation into a sieve element). In addition, the total duration of the sieve element phase and the duration of completed ‘bouts’ of sustained feeding differed between the two test plants, in a fashion varying between clones. However, these differences could not be related to the acceptability of plants to the different aphid clones. The duration of the stylet pathway phase preceding the first sustained feeding on phloem sap did not vary significantly with either aphid clone or plant. It is concluded that the resistance of P. sativum to certain A. pisum clones does not arise from factors impeding either stylet penetration through the plant tissues or the maintenance of feeding from the sieve elements. It is proposed that host plant affiliation of A. pisum may be mediated primarily by specific olfactory or gustatory cues, before the aphid initiates stylet penetration of the plant.
Experimental induction and termination of non‐reciprocal reproductive incompatibilities in a parahaploid mite
Authors: Johanowicz Denise L. , Hoy Marjorie A.
Published: October 2003

Two experiments were conducted to investigate the relationship between rearing temperatures, the presence or absence of Wolbachia endosymbionts, and non‐reciprocal reproductive incompatibility in inbred lines of the parahaploid phytoseiid mite Metaseiulus occidentalis (Nesbitt) (Acari: Phytoseiidae).

Heat‐treated females crossed with infected males reared at room temperature produced few eggs and high proportions of shriveled eggs. No female progeny were produced. The reciprocal cross was normal. A second experiment showed that the incompatible cross from the first experiment could be made compatible if the infected line was heat‐treated and those males crossed with the original heat‐treated females. Furthermore, a new incompatibility was induced in a formerly compatible cross when the newly heat‐treated females were crossed with males from their base colony. Heat‐treatment was correlated with the loss of Wolbachia in both experiments. Wolbachia may thus affect non‐reciprocal reproductive incompatibility in M. occidentalis, and may produce a unique incompatibility phenotype in this parahaploid species, including both reduced numbers of male progeny and a lack of female progeny.
Performance and feeding behavior of Ceratitis capitata: comparison of a wild population and a laboratory population
Authors: Bravo Iara Sordi Joachim , Zucoloto Fernando Sérgio
Published: October 2003

Experiments were carried out to test the performance and some aspects of feeding behavior in two populations of Ceratitis capitata (a population reared in the laboratory for 16 years, i.e., approximately 160 generations, and a wild one obtained from infested coffee, Coffea arabica grains). Two types of food were used in the experiment: an artificial yeast diet used for laboratory rearing and papaya (Carica papaya), a natural host of the fly. The performance parameters tested were percent emergence, time to emergence, adult female size, and egg production during the pre‐oviposition phase (first five days of adult life). The behavioral aspects tested were food preference by newly hatched larvae, induction, estimated ingestion of the two diets, whether the larvae placed on one diet stayed there or moved to the other diet, and acceptance of food for oviposition. The results indicated that the performance of the wild population was superior when the flies fed on papaya, whereas the performance of the laboratory population was similar with the two diets; the wild population showed a strong preference for papaya in all choice experiments, whereas the laboratory population showed no diet preference; the females of the wild population only oviposited on pieces of papaya that had not been peeled, and did not oviposit in the artificial diet; the females of the laboratory population oviposited indiscriminately on unpeeled and peeled papaya and on the artificial diet.
Experimental studies to evaluate spray applications of a mycoinsecticide against the rice grasshopper, Hieroglyphus daganensis, in northern Benin
Authors: Thomas M. B. , Blandford S. , Gbongboui C. , Lomer C. J.
Published: October 2003

Three experiments were conducted to examine the effects of spray applications of a mycoinsecticide against the rice grasshopper, Hieroglyphus daganensis, in northern Benin. The experiments were designed to expand on previous evaluation studies and contribute to a better understanding of the overall impacts of mycoinsecticide applications. The first experiment showed that acquisition of spores from the spray residue had a significant effect on mortality rate and a greater single influence on mortality than direct contact with spores from the spray aerosol. The second and third experiments revealed the mycoinsecticide to have sub‐ and pre‐lethal effects, causing a significant reduction in per capita feeding rate and increasing susceptibility to predation. The significance of these results for the overall impact of spray applications and for development of comprehensive evaluation methods are discussed.
Variable growth and reproduction response of the spruce shoot aphid, Cinara pilicornis, to increasing ozone concentrations
Authors: Holopainen Jarmo K. , Kössi Sonja
Published: October 2003

Spruce shoot aphid, Cinara pilicornis Hartig (Homoptera: Lachnidae), is an aphid species that has shown enhanced performance on trees exposed to SO2 or mixtures of air pollutants, whereas results with ozone have been contradictory. Using a 4‐week chamber fumigation experiment, we tested how different population dynamic parameters of aphids are affected by ozone (O3). Mean relative growth rate (MRGR), development time and reproduction rate of C. pilicornis were determined using 7h day‐time O3 concentrations of 0, 40, 80 and 160 ppb. Development period from birth to reproductive stage was fastest at 80 ppb during early shoot elongation, while reproduction and intrinsic rate of population increase was not significantly affected by ozone concentration. There was a significant negative correlation between ozone concentration and the MRGR of first instar nymphs in the third fumigation week. In feeding test performed on seedlings after fumigation, the MRGR was reduced on shoots which had been exposed to 80 ppb O3. The results suggest that elevated O3 concentration during early shoot elongation period may stimulate population development of C. pilicornis, but on maturing shoots, high O3 concentration has a negative effect on aphid performance. This might be due to accelerated ageing of O3 exposed shoots.