Yeast communities associated withDrosophila species and related flies in an eastern oak-pine forest: A comparison with western communities

Summary Intestinal yeast mycobiota were studied in 14 species ofDrosophila and in the drosophilid speciesChymomyza amoena, captured at Pinery Provincial Park, Ontario. Over 56 yeast species, some undescribed, were isolated. These yeast communities were compared with those from two similar surveys conducted in western portions of North America. The community structures were influenced significantly by the habitat rather than phylogeny of the flies. Geographic separation was a factor affecting yeast taxa frequencies in the fly species, but it was largely overshadowed by ecological factors when the communities were described physiologically. The notion that habitats are filled by yeasts which add up to a suitable physiological potential, more or less independently of their taxonomic affinities, was thus confirmed.This paper is dedicated to Professor Herman Jan Phaff in honor of his 50 years of active research which still continues.     

Host fruit chemical stimuli eliciting distinct ovipositional responses from sibling species of Rhagoletis fruit flies

Laboratory experiments tested whether two economically-important sibling species of tephritid fruit flies have evolved distinct egg-laying responses to chemical stimuli on the fruits of their respective hostplants. The egg-laying preferences displayed by apple maggot flies, R. pomonella, and blueberry maggot flies, R. mendax, on artificial fruits treated with apple and blueberry extract paralleled their egg-laying responses to whole apples and blueberries. R. pomonella flies laid more eggs than R. mendax flies in artificial fruits treated with extract from ripe McIntosh apples, and vice versa for artificial fruits treated with extract from ripe Bluehaven blueberries. Furthermore, both species laid more eggs in artificial fruits treated with extract from their respective host fruits than control artificial fruits which were not treated with fruit extract. Prior electroantennogram recordings from R. mendax and R. pomonella flies exposed to volatiles from pentane extracts of apples and blueberries indicate that the antennal sensitivity of both species is selectively tuned to their respective host fruit odors. This differentiation in their olfactory responses to fruit odors could be important in mediating their distinct ovipositional responses to blueberry and apple fruits. Extract from unripe McIntosh apples also elicited egg laying by R. pomonella flies, however, artificial fruits treated with unripe apple extract received 1.9 times fewer eggs than those treated with ripe apple extract. Moreover, the numbers of R. pomonella ovipositor punctures and eggs placed in wax artificial fruits were increased when the artificial fruits were treated with a blend of 7 identified apple esters. Black coloration on these artificial fruits and the presence of apple esters had a synergistic effect on the egg-laying behavior of R. pomonella flies, which caused them to lay substantially more eggs per black fruit than white fruit treated with the same concentration of apple esters. In summary, our results indicate that the egg-laying responses of R. pomonella flies are mediated by the integration of information from fruit chemical and visual cues, and that R. mendax and R. pomonella flies have evolved divergent egg-laying responses to chemical stimuli on the fruits of their respective hostplants. These findings are discussed in the context of other studies on plant compounds which influence the ovipositional behavior of phytophagous Diptera.

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Stimuli chimiques des pommes et des myrtilles induisant la ponte des espèces jumelles, Rhagoletis pomonella et R. mendax

Résumé Des fruits artificiels en cire traités avec des extraits de fruits ont provoqué chez les espèces jumelles de R. mendax (Curran) et R. pomonella (Walsh) des réactions de ponte différentes suivant les stimulations chimiques par les fruits. Le comportement de ponte sur des fruits artificiels traités avec des extraits au pentane des myrtilles mûres (Vaccinium corymbosum L.) et de pommes mûres (Malus pumila Miller = Pyrus malus L.), est le même que sur des fruits naturels, ce qui montre que la réponse aux stimulations chimiques provenant du fruit constitue un aspect important de la reconnaissance de l'hôte. R. pomonella pond plus d'ufs que R. mendax sur les fruits artificiels traités à l'extrait de pommes mûres; c'est l'inverse pour les fruits traités aux extraits de myrtille. Les fruits artificiels traités avec des pommes ou des myrtilles provoquent la ponte de R. pomonella, tandis que les myrtilles mûres seules provoquent la ponte de R. mendax. Les extraits de pommes vertes stimulent la ponte de R. pomonella mais elle est alors 2 fois plus faible qu'avec des extraits de pommes mûres. Un mélange de 7 esters identifiés dans l'extrait de pomme induit aussi la ponte de R. pomonella. Le nombre de piqûres de tarièresfli dans les fruits artificiels en cire et le nombre d'ufs par fruit ont été augmentés par addition d'esters de pommes à des fruits blancs ou noirs. La couleur des fruits artificiels influence aussi la réaction de ponte de R. pomonella; la fréquence des piqûres de tarière contenant un uf et le nombre d'ufs par fruit étaient significativement plus élevés sur les fruits noirs que sur les fruits blancs traités avec la même concentration d'esters de pomme. Les fruits artificiels noirs traités avec la concentration la plus stimulante d'esters de pommes ont reçu 2, 3 fois plus d'ufs que les fruits blancs avec les mêmes concentrations en esters. Ces résultats montrent que les esters de pomme et la couleur noire stimulent synergiquement la ponte de R. pomonella sur des fruits artificiels.

     

Quantitative analyses of C-banded karyotypes,and systematics in the cultivated species of theScilla siberica group (Liliaceae)

Quantified C-band karyograms are presented for the related speciesScilla siberica, S. mordakiae, S. ingridae, S. amoena, andS. mischtschenkoana. Chromosome structure, banding style, and heterochromatin characters suggest a systematic grouping of two more closely related species pairs:S. siberica andS. mordakiae, S. ingridae andS. amoena; they are part of a larger aggregate, well separated fromS. mischtschenkoana. Four different heterochromatin fractions can be recognized inS. siberica and its relatives, but only two inS. mischtschenkoana. C-bands do not replace, but they are added to euchromatin. The particular origin and history of the cultivatedS. amoena and the triploidS. siberica cv. Spring Beauty appear to be responsible for their karyotype constancy, but chromosome conservatism obviously is genuine inS. mischtschenkoana. The banding data support the systematic grouping proposed on a morphological basis, and provide additional evolutionary evidence.Evolution ofScilla and Related Genera, IV.     

Feeding Ecology of Black-headed Uacaris (Cacajao melanocephalus melanocephalus) in Pico da Neblina National Park,Brazil

From June 1994 to October 1995, I conducted a study of the feeding ecology of one group of black-headed uacaris (Cacajao melanocephalus melanocephalus) in Pico da Neblina National Park, Brazil, near the Venezuelan border (01°10N to 00°26S, 65°03W to 66°52W). Of a total of 429 feeding records, 89% corresponded to fruits from which black-headed uacaris ate ripe and unripe seeds, mesocarps and arils. Seeds were the single most important food item year-around, corresponding to 81% of the feeding records for fruits. Black-headed uacaris used 120 different plant species in 32 families as food. The 3 most important plant species in their diet, Micrandra spruceana, Eperua leucantha, and Hevea braziliensis (all trees), accounted for 38% of the feeding records for fruits. These species produced fruits that were protected by very hard green husks, were barochorous, did not have fleshy mesocarps, and were slow to mature, thus being available as unripe fruits for long periods. The second and third most important species in the diet of black uacaris, Eperua leucantha and Hevea braziliensis, were dominant in the forest: approximately 30% of trees 10 cm dbh sampled in a 2-ha botanical transect at the study site. I discuss the formation of large social groups of black-headed uacaris in Pico da Neblina National Park in light of the peculiar floristic composition of the study site.     

P element excision in Drosophila melanogaster and related drosophilids

Summary The frequency of P element excision and the structure of the resulting excision products were determined in three drosophilid species, Drosophila melanogaster, D. virilis, and Chymomyza procnemis. A transient P element mobility assay was conducted in the cells of developing insect embryos, but unlike previous assays, this mobility assay permitted the recovery of excision products from plasmids regardless of whether the excision event was precise or imprecise. Both quantitative and qualitative differences between the products of excision in the various species studied were observed. The frequency with which P element excision products were recovered from D. melanogaster was 10-fold greater than from D. virilis and C. procnemis; however, the proportion of all excision events resulting in the reversion of a P-induced mutant phenotype was the same. Virtually all excision products recovered, including those resulting in a reversion of the mutant phenotype, did not result in the exact restoration of the original target sequence. Sequence analysis suggested that duplex cleavage at the 3 and 5 termini of the P element, or their subsequent modification, occurred asymmetrically and interdependently. P element-encoded transposase was not absolutely required for P element excision.     

Characterization of the EstP Protein in Drosophila melanogaster and Its Conservation in Drosophilids

The -esterase cluster of D. melanogaster comprises two tandemly duplicated genes. Est6 encodes the well-characterized 5 gene, but the product of the second gene, denoted EstP, had not previously been identified. Here we show that the EstP gene encodes the carboxylesterase EST7. Expression of EstP using the Baculovirus system led to production of a carboxylesterase biochemically indistinguishable from EST7. Furthermore, a naturally occurring EstP variant produces greatly reduced amounts of EstP mRNA and no detectable EST7 protein. Finally, introduction of a wild-type copy of EstP by germline transformation into the variant strain confers the wild-type EST7 phenotype. We show that EST7 differs from EST6 in its substrate and inhibitor specificities and tissue distribution. Germline transformation experiments show that EstP expression is controlled by sequences located between 192 bp 5 and 609 bp 3 of the EstP coding region. Data comparisons with other drosophilid esterases suggest that the site of expression, and hence the function, of EST7 has been conserved across lineages in both the subgenera Drosophila and Sophophora.     

Eusynaptomyces benjaminii,spec. nova, (Ascomycetes,Laboulbeniales) und seine Anpassungen an das Fortpflanzungsverhalten seines WirtesEnochrus testaceus (Coleoptera,Hydrophilidae)

Eusynaptomyces benjaminii is described as a new species of the ectoparasiticLaboulbeniales (Ascomycetes). It exists only on two very restricted areas of the body (= position specifity) of its hostEnochrus testaceus (F.) (Coleoptera, Hydrophilidae): on the claws of the right fore-leg and on the lower side of the frontal border of the pronotum. In these two habitatsEu. benjaminii develops two extremely different growth-forms. Male and female hosts are parasitized on somewhat different parts of their body. This can be explained by their mating behaviour. The growth-forms ofEu. benjaminii are so different that one ignorant of the biology of hosts and parasites, might regard them as members of different species or even genera. They are to be interpreted as adaptations of one species to growth positions and mating behaviour of the host. There is no sex-of-host specifity as assumed by certain authors for several species of theLaboulbeniales.

     

Meiotic studies ofElymus nutans andE. jacquemontii (Poaceae,Triticeae) and their hybrids withPseudoroegneria spicata and seventeenElymus species

Hybridizations ofElymus nutans andE. jacquemontii were carried out with one species ofPseudoroegneria (S genome), and 20Elymus species, each containing either of the SH, SY, SYH, or SYW genomes. Chromosome configurations were analysed at metaphase I of the two target taxa and their interspecific hybrids. It is concluded that (i)E. nutans is an allohexaploid containing the SYH genomes, andE. jacquemontii is an allotetraploid having the SY genomes; (ii) the genomic affinity is associated with the geographic distance between the species studied; (iii) minor genomic structural rearrangements have occurred within the hexaploid taxon ofE. nutans.     

Chitin production by Ampelisca (Amphipoda) populations from a fine sand community in the Bay of Morlaix (English channel)

We measured chitin biomass and production in five species of Ampelisca (Crustacea Amphipoda) living on a fine sand community at Pierre Noire Station in the Bay of Morlaix (Western English Channel, Brittany, France). Taking into account the maxima of their mean total production, the annual chitin production was estimated at between 600 and 900 mg m^–2 yr^–1. These values are close to those of the chitin production of pioneering benthic communities growing on naked substrates in the coastal waters of Calvi bay (Mediterranean, Corsica) between 7 to 28 meter depth, and of the zooplankton of that same area.     

Contact Kairomones Mediating the Foraging Behavior of the Aphid Hyperparasitoid Alloxysta victrix (Westwood) (Hymenoptera: Charipidae)

A variety of host-related substances was assessed in relation to their ability to induce arrestment and antennal examination behavior in adult females of the aphid hyperparasitoid Alloxysta victrix (Westwood). In laboratory bioassays, whole-body homogenates of both unparasitized host aphids [Myzus persicae (Sulzer)] and those parasitized by the primary parasitoid Aphidius colemani Viereck failed to elicit a response. However, significant kairomonal activity was associated with aphid cornicle secretions, aphid honeydew, and solvent extracts of parasitized aphids. Solvent extracts of unparasitized aphids (in either hexane or butan-1-ol) failed to elicit arrestment or antennal examination behavior in hyperparsitoid females. The response to aphid honeydew was significantly lower in experienced females than in naive individuals, suggesting that even relatively strong innate responses can be modified by learning.     

Further studies on the metabolism of gibberellins (GAs) A9, A20 and A29 in immature seeds of Pisum sativum cv. progress No. 9

Seed maturation of Pisum sativum cv. Progress No. 9 proceeds more slowly in winter than in summer even when the parent plants are grown in greenhouse conditions with light-and heat-supplementation. For parent plants grown under summer and winter conditions the metabolism of [³H]GA₉ in cultured seeds is qualitatively different in seeds of equivalent age and qualitatively the same in seeds of equivalent weight. 13-Hydroxylation of [³H]GA₉[³H]GA₂₀ is restricted to early stages of seed development. 2-Hydroxylation of [³H]GA₉2-OH-[³H]GA₉ has only been observed at a stage of development after endogenous GA₉ has accumulated. 2-OH-GA₉ has been shown to be endogenous to pea and is named GA₅₁. H₂-GA₃₁ and its conjugate have not been shown to be present in pea and may be induced metabolites of [³H]GA₉. The metabolism of GA₂₀GA₂₉ is used to illustrate a technique of feeding [²H][³H]GAs in order to distinguish a metabolite from the same endogenous compound. The in vitro conversion of [³H]GA₂₀[³H]GA₂₉, and the virtual non-metabolism of [³H]GA₂₉ have been confirmed for seeds in intact fruits. These results are discussed in relation to the apparent absence of conjugated GAs in mature pea seeds.Abbreviations GA_n gibberellin A_n - GC gas chromatography - GC-MS combined gas chromatography-mass spectrometry - GC-RC combined gas chromatography-radio counting - Me methyl ester - R_T etention time - SICM selected ion current monitoring - TLC thin layer chromatography - TMS trimethyl silyl ether The author is née Frydman     

Cytotaxonomy and karyotype evolution inPhleum sect.Phleum (Poaceae) in Poland

Three taxa are distinguished in the sectionPhleum Griseb. in Poland:P. nodosum (2n = 14),P. pratense (2n = 42), and the third one unformally named hereP. commutatum (2n = 14). It corresponds morphologically toP. commutatum Gaud. reported as a tetraploid taxon (2n = 28) from other geographic regions. Giemsa C-banded karyotypes of these three taxa help clarify the taxonomic status ofP. commutatum and the origin of the hexaploidP. pratense. It is suggested that changes in the amount of telomeric heterochromatin played an important role in the evolution ofPhleum karyotypes.     

The origins and evolutionary history of feral apples in southern Canada

Feral populations of domesticated crops can establish through two nonmutually exclusive pathways: hybridization with native relatives and recruitment of and recombination between known cultivars. The extent and relative importance of these pathways is not known, especially for woody fruit crops. Here, we examined the evolutionary origins of feral populations of Malus domestica (domestic apple) in southern Canada using a population genetic analysis. We characterized genotypes of 578 putative feral apple trees and evaluated them in relation to genotypes of 156 commercial cultivars, 28 non‐native, ornamental crabapples and 47 native Malus coronaria trees using 14 microsatellite markers. No feral trees were genetic admixtures between domestic and native Malus; however, a minority of trees were admixed with introduced ornamental Malus. Feral trees and commercial cultivars both occurred in two major genetic groups and seven subgroups distributed throughout all commercial growing regions. A total of 42 cultivars, both heritage and currently grown, occurred in probable parental pairs for feral trees, with nine heritage varieties accounting for 72% of parental assignments. We conclude that feral apples in southern Canada are not products of hybridization with native M. coronaria but we cannot exclude ornamental apple species as contributing to the naturalization process. Nonhybrid feral domestic apples have multiple origins, with a prominent signature of early heritage cultivars. These lineages have spread and coexist throughout Ontario, rather than being derived strictly from local sources.     

Morphological and molecular comparisons ofCampsis grandiflora andC. radicans (Bignoniaceae), an eastern Asian and eastern North American vicariad species pair

Morphological and molecular comparisons were made forCampsis grandiflora (Thunb.)K. Schumann (Bignoniaceae) from eastern Asia andC. radicans (L.)Seemann from eastern North America. Chloroplast DNA (cpDNA) variation was surveyed with 20 restriction endonucleases. The cpDNA divergence between the two vicariad species was 2.44%, which is the highest reported among North Temperate disjunct taxa and one of the highest reported for infrageneric taxa. Detailed morphological comparisons also suggest a high level of divergence. Cluster analyses based on 22 morphological characters and 39 OTUs revealed two distinct groups corresponding with the two species. The average taxonomic distance between the two species was 1.806. Analyses of variance (ANOVA) revealed that 12 of the 18 quantitative characters differed significantly ( 0.01) betweenC. grandiflora andC. radicans. Divergence time based on cpDNA data was estimated as 24.4 million years. The Bering land bridge hypothesis was favored over the North Atlantic land bridge hypothesis based on the estimated divergence time and the geological history of the North Temperate region. The high levels of morphological and cpDNA divergence are not consistent with morphological stasis, which has been proposed as a common mode of evolution for North Temperate disjunct taxa.     

Inoculative releases of Trichogramma ostriniae for suppression of Ostrinia nubilalis (European corn borer) in sweet corn: field biology and population dynamics

The effectiveness of inoculative releases of Trichogramma ostriniae Pang and Chen for suppression of Ostrinia nubilalis (Hübner) in sweet corn was assessed. Early-season, low-density (75,000 females ha⁻¹) releases were made, and establishment, levels of parasitism and sex ratios of emerging T. ostriniae quantified. T. ostriniae established effectively for each season that they were released, but appeared to be unable to overwinter. Parasitism levels tracked egg mass numbers closely, and T. ostriniae persisted in fields even where insecticides were applied. Parasitism by indigenous Trichogramma species was 3%. Field populations of T. ostriniae were distinctly female biased (78%), with males produced in the majority of broods. Numbers of males did not increase linearly with number of O. nubilalis eggs parasitized, but appeared to remain constant above an egg mass size of about 20 eggs. A Type-I functional response to increasing egg and egg mass density was found under field conditions, where the proportion of egg masses parasitized remained constant with increasing egg mass density. A relatively consistent percentage of eggs per egg mass was parasitized, with a linear increase in number of eggs parasitized with increasing number of eggs per egg mass. These results show that T. ostriniae established viable reproductive populations in sweet corn following inoculative release, with the potential to contribute to reduced dependence on insecticides for the control of O. nubilalis in an integrated pest management program.     

Spore formation in the Actinoplanaceae (Actinomycetales)

Spore development in four genera, Actinoplanes, Dactylosporangium, Planomonospora, and Streptosporangium, was studied by transmission and scanning electron microscopy. Actinoplanes and Streptosporangium formed spores by fragmentation of a hypha within its expanded outer sheath, as do many other actinomycetes. Dactylosporangium and Planomonospora formed spores endogenously by development of wall material within the parent hypha. In this respect, they resembled the genera Actinobifida and Thermoactinomyces. The term sporangium has therefore been used to describe structures which are not homologous. It was suggested that the term should be confined to structures in which endogenous spore formation occurs.     

Seed oil fatty acid patterns of theAconitum-Delphinium-Helleborus complex (Ranunculaceae)

Many members ofRanunculaceae contain unusual fatty acids in their seed oils. This leads to rather typical genus-specific fatty acid patterns or fingerprints in these seed oils. The members of theDelphinioideae and/orHelleboroideae, however, do not contain highly unusual fatty acids. Nevertheless, their seed oil fatty acid fingerprints are also fairly typical and genus-specific, and the patterns found are rather consistent throughout several species of one genus. It was found that species ofAconitum do not contain fatty acids with 20 carbon atoms.Delphinium, Consolida, Helleborus, Nigella and others do contain C₂₀ fatty acids. In allHelleborus species, for example, there was a consistent C₂₀ fatty acid pattern of 20:020:120:2>20:3. Species ofNigella andGaridella contain high levels,Helleborus low levels, of 20:2n-6 in their seed oils.Delphinium andAconitum both contain low levels of 18:3n-3, whereasHelleborus spp. consistently show high levels of this fatty acid. The genus-specific fatty acid patterns found are discussed, and a correlation with the subfamily and tribe affiliation of the genera investigated here is attempted.     

New Substrates for Enteropeptidase: I. Biologically Active Hepta-, Octa-, and Nonapeptides

Enteropeptidase (enterokinase, EC 3.4.21.9) hydrolyzes peptide bonds formed by carboxyl groups of Lys or Arg residue if less than four negatively charged amino acid residues are in positions P ₂–P ₅ of its substrate. We determined the kinetic parameters of three substrates of this type: human angiotensin II (AT) (DR VYIHPF) and the Hb(2–8) (LTAEEK A) and Hb(1–9) (MLTAEEK AA) peptides of the cattle hemoglobin -chain. The K _m values for all the substrates (10^–3 M) were one order of magnitude higher than those of the typical synthetic substrates of enteropeptidase or chimeric proteins with the –DDDDK– full-size linker (K _m 10^–4 M). The k _cat values for AT and Hb(2–8) were also close and low (30 min^–1). The general hydrolysis efficiency of such substrates is no more than 1% of the corresponding value for the typical peptide and protein substrates of the enteropeptidase. However, the elongation of Hb(2–8) peptide by one amino acid residue from both its N- and C-termini results in a dramatic increase in the catalytic efficiency of the hydrolysis: the k _cat value for Hb(1–9) is 1510 min^–1, which means that it is hydrolyzed only three times less effective than the chimeric protein with the full-size linker.     

The distribution of Heterotrissocladius oliveri Saether (Diptera: Chironomidae) in Lake Michigan

Fifty one chironomid species were identified from 504 samples collected at depths ranging 8 to 267 m in Lake Michigan, U.S.A. Heterotrissocladius oliveri Saether occurred in 32% of these samples and had an average abundance of 22 m^–2 which was similar to other estimates from the Great Lakes. Maximum average lake-wide density was at 30 to 60 m (41 m^–2). At depths 60 m, H. oliveri was the dominant chironomid species comprising 75% of total Chironomidae. The substrate preference of H. oliveri differed within each depth regime considered: at 30–60 m, 2–3 ; at 60–120 m, 3–5 , 7–9 ; and at 120–180 m, 6–8 . Abundance was notably reduced at all depths in substrates characterized as medium silt (5–6 ). On a lake-wide basis, the distribution pattern suggested H. oliveri was most numerous from 30 to 60 m along the southwestern, eastern, and northern shorelines and at 60–120 m depths along the southern and eastern shorelines. Increased abundance in the South Basin was concurrent with evidence of increased sedimentation at 60 to 100 m. However, in several other areas of the lake, high densities were associated with medium to very fine sands relatively free of silts and clays. This observation suggested occurrence of H. oliveri was minimally affected by sediment type.Widely variable, but generally elevated water temperatures likely prevent H. oliveri from establishing a substantial population density at depths < 30 m. With increased depth, temperature fluctuation is negligible and food is more stable, though the source is variable. Factors limiting abundance of H. oliveri at depths 30 m were related to decreased food supply due to distance from shore, food sources of lower value (clays), and, most importantly, to reproductive replenishment.Although still oligotrophic in nature, high density occurrences in both high and low sedimentation areas of the lake suggest the trophic indicator status of H. oliveri might be broader than previously thought.     

Diet of the red howler monkey (Alouatta seniculus) in French Guiana

We report the feeding behavior and food preferences of a troop of red howler monkeys (Alouatta seniculus) over two annual cycles in primary tropical rain forest in French Guiana. The monkeys used 195 plant species from 47 families as food. Major food categories were young leaves (54%), mature fruits (21.5%), and flowers (12.6%). Other food categories included old leaves, immature fruits, termitarium soil, bark, and moss. The monkeys were less selective than other howler groups, since 19 plant species contributed 1% to their diet and accounted for only 35.7% of their total diet. The Sapotaceae was the most frequently eaten plant family and represented >10% of the total diet.