Female-derived sex pheromone mediates courtship behaviour in the parasitoid Lariophagus distinguendus

Brassiceye^®traps baited with ethylisothiocyanate were modified and used to collect live adults of Delia radicum(L.) and Delia floralis(Fallén) (Diptera: Anthomyiidae) from the field to observe the prevalence of Entomophthora muscae(Cohn) Fresenius and Strongwellsea castransBatko & Weiser. The traps were highly effective and selective for D. radicumand D. floralis. Of the flies identified, 98.4% in 1996 and 93.7% in 1997 were either D. radicumor D. floralis. In 1997 the maximum mean catch was as high as 82 flies per trap per day, and more than 80% of these were females.During both seasons E. muscaecaused relatively high levels of mortality in adult populations of D. radicumand D. floralis. The fungus caused a total infection level of 17.9% in 1996 and 47.7% in 1997 with infection peaks of 82.4% in 1996 and 87.5% in 1997. Both years, a significant positive correlation was found between E. muscaeprevalence and temperature. One infection peak was observed for S. castransin 1996, and during that season the total S. castransinfection level was 18.0%. In 1997, the total S. castransinfection level was as low as 8.1%. There is no strong indication that the prevalence of E. muscaeor S. castransdiffers between either the fly species or sexes within species.     

Comparative Development and Performance of Artificially Reared versus Host-RearedDiapetimorpha introita(Cresson) (Hymenoptera: Ichneumonidae) Wasps

Diapetimorpha introita(Cresson) (Hymenoptera: Ichneumonidae), a native ectoparasitoid ofSpodopteraspp. pupae, was reared in the laboratory on an artificial diet devoid of any insect host components. Diet-reared wasps demonstrated a propensity to search for and parasitize natural hosts in a field cage trial. Longevity of the diet-reared wasps was comparable with the longevity of wasps reared on host pupae. Survival rate ofD. introitawas 61.3% when reared on diet and 76.3% when reared on host pupae. Wasps reared on the artificial diet had longer developmental times, reduced fecundity, and reduced adult weights compared to wasps reared on host pupae. These studies suggest that future research efforts should focus on increasing fecundity and weight of diet-reared wasps and decreasing the mortality and developmental time of wasps reared on the artificial diet. The ability to rearD. introitaon an inexpensive, artificial diet significantly enhances the potential of mass rearing this parasitoid for inundative releases againstSpodopteraspp.     

Cytotaxonomic study on two putative hybrids in the genusDuchesnea (Rosaceae)

The karyotypes and chromosome associations at meiosis in two types of natural hybrids, 7x and 8x, betweenDuchesnea chrysantha (2x) andD. indica (12x) were investigated. The 7x hybrid had a haploid chromosome set from each parent plant, whereas the 8x hybrid was considered to have a full set ofD. chrysantha and half a set ofD. indica. In the two hybrids, the chromosomes ofD. chrysantha andD. indica conjugated only slightly at meiosis. It is probable that no common genome set between the diploidD. chrysantha and the dodecaploidD. indica exists. The present evidence indicates thatD. chrysantha andD. indica should be considered to be distinct species, although they have sometimes been treated as a single species.     

Species diversity, abundance, and phenology of aphid natural enemies on spring wheats resistant and susceptible to Russian wheat aphid

The species composition, relativeabundance, and seasonal dynamics of selectednatural enemies of cereal aphids were monitoredin spring wheat fields in Moscow, Idaho in 1997and 1998. Trials also examined the potentialimpact of resistance to Russian wheat aphid(RWA), Diuraphis noxia (Mordvilko)(Homoptera: Aphididae) in wheat, on aphidbiological control agents. Natural enemypopulations were monitored on two springwheats: D. noxia susceptible variety`Centennial' and resistant genotype `IDO488'. Field plots were artificially infested withadult D. noxia, and sampled for cerealaphids and parasitoids weekly. Coccinellidpredators were monitored once in 1997 and twicein 1998. The coccinellids Hippodamiaconvergens Guerin, Coccinellaseptempunctata L., C. transversoguttataBrown and C. trifasciata Mulsant weredetected. No significant differences in adultor immature coccinellid densities were observedbetween the D. noxia resistant andsusceptible genotypes. During both years, themost abundant primary hymenopteran parasitoidswere Diaeretiella rapae (M'Intosh), Aphidius ervi Haliday, A. avenaphis(Fitch), and Lysiphlebus testaceipes(Cresson), Aphelinus varipes (Foerster),Aphidius colemani Viereck, Aphidiuspicipes (Nees), Aphidius sp., Monoctonus washingtonensis Pike & Stary, Praon gallicum Stary, Praon occidentaleBaker, and Praon sp. were also detected. Numbers of both D. noxia and D.rapae were significantly greater on Centennialthan on IDO488 in both years. When all speciesof cereal aphids and parasitoids areconsidered, the total percentage parasitism wasnot significantly different between thegenotypes. There was no interaction betweenD. noxia resistance and the populationdensity of the predators or parasitoidsmonitored. These results suggest that the D. noxia resistant line had no adverse impacton natural enemies under the conditions ofthese field experiments.     

Effect of Two Opiine Parasitoids (Hymenoptera: Braconidae) Introduced for Fruit Fly Control on a Native Hawaiian Tephritid,Trupanea dubautiae(Diptera: Tephritidae)

Diachasmimorpha longicaudata(Ashmead) andPsyttalia fletcheri(Silvestri) are opiine parasitoids introduced into Hawaii for control of the Oriental fruit fly,Bactrocera dorsalis(Hendel) and the melon fly,Bactrocera cucurbitae(Coquillett), respectively. Both species have recently been mass-reared and released for research in augmentative biocontrol programs. Laboratory and field sleeve cage experiments were conducted to investigate the potential impact of mass-producedD. longicaudataandP. fletcherion a native Hawaiian tephritid,Trupanea dubautiae(Bryan), infesting the flowerheads of the native composite shrubDubautia raillardioidesHillebrand. Gravid females ofD. longicaudataandP. fletcheriwere confined with bloomingD. raillardioidesflowerheads infested with late instarT. dubautiae.BothD. longicaudataandP. fletcherilacked positive oviposition responses toT. dubautiaelarvae in infested flowerheads and caused neither parasitism nor mortality to the flies. However, when larvae were removed from the flowerheads and presented in screened dishes containing artificial diet of the parasitoids' normal rearing hosts (B. dorsalisandB. cucurbitae), bothD. longicaudataandP. fletcherireadily oviposited in the test larvae. Oviposition byD. longicaudatadid not significantly affect the percentage pupation ofT. dubautiae,but did reduce the emergence of adult flies. Oviposition byP. fletcherisignificantly reduced both pupation and adult fly emergence. All progeny of both parasitoid species died as eggs or first-instar larvae. Results from our experiments demonstrate that biological control programs targeted against frugivorous tephritid pests byD. longicaudataandP. fletcherihave no harmful impact on flowerhead-infestingT. dubautiae.     

Abnormal egg-laying behaviour of female carrot flies (Psila rosae) induced by the fungus Entomophthora muscae

Female carrot flies (Psila rosae F.) infected with Entomophthora muscae (C.) Fres. on days 1 to 4 of adult life were unable to lay their eggs near the food plant. Flies infected on day 5 of adult life showed an egg-laying behaviour similar to that of uninfected flies. E. muscae-infected female carrot flies caught in the field showed an egg-laying behaviour comparable to that of the flies infected in the laboratory during the first day of their live.Eggs laid by infected females were equally as fertile as eggs laid by uninfected females, and developed into normal flies.It is concluded that female carrot flies infected with E. muscae in the field do not in general contribute to the development of the carrot fly population, due to their abnormal egg-laying behaviour.

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Zusammenfassung Wenn Weibchen der echten Möhrenfliegen (Psila rosae) zwischen den ersten und der vierten Tag in dem Laboratorium mit E. muscae infiziert worden waren, könnten sie ihre Eier an den Futterpflanze nicht ablegen. E. muscae-infizierte Weibchen, die ins Feld gefangen worden waren, zeigten auch ein abweichendes Eiablageverhalten. Ihr Behalten war mit dem Verhalten von Fliegen vergleichbar, die an ihrem ersten Lebenstag im Laboratorium infiziert worden waren.Von infizierten Weibchen gelegte Eier waren ebenso fruchtbar wie die von nicht infizierten Weibchen gelegten Eiern. Es wird konkludiert, dass E. muscae-infizierten Weibchen der echten Möhrenfliegen der Entwicklung der Population keinen Beitrag leisten.

     

Laboratory transmission and in vivo incubation of Entomophthora muscae (Entomophthorales: Entomophthoracae) in the onion fly,Delia antiqua (Diptera: Anthomyiidae)

A high-moisture infection chamber was used for the in vivo transmission of Entomophthora muscae within laboratory populations of the onion fly, Delia antiqua. This cadaver-to-fly transmission procedure provided an average experimental infection rate well above 95%. Laboratory infection and temperature-dependent incubation rates of E. muscae were further examined in adult populations of D. antiqua. The time from initial exposure until host death and pathogen sporulation was accurately predicted using a second-order function of the incubation temperature. A developmental base temperature of approximately 5°C was estimated, with 105 degree-days being the average number of heat units required between host infection and death. E. muscae transmission between D. antiqua and D. platura, two insect pests typically associated with Michigan onion production, was verified under laboratory conditions.     

Genetic relationships between European and Siberian larch,Larix spp. (Pinaceae), studied by allozymes. Is the Polish larch a hybrid between these two species?

Thirteen populations ofLarix decidua subsp.decidua and subsp.polonica, and three populations ofL. sibirica were investigated by starch-gel electrophoresis. In the populations assayed 61 alleles at 17 loci were revealed. The allozyme data support the earlier observations about close relationships between these two larch species. Nei's genetic distances betweenL. decidua andL. sibirica were relatively small (D = 0.057), however, almost five times larger, on average, than those between populations of the same species. Results obtained in this study disagree withBobrov's hypothesis about the hybrid origin of the Polish larch and suggest a direct origin from the European larch.     

Larval mortality of pine sawflies [Hymenoptera: Diprionidae] in relation to pollution level: A field experiment

Larval mortality ofNeodiprion sertifer (Geoffroy),Diprion pini (L.) andGilpinia pallida (Klug) were studied in field experiments around a factory complex in southwestern Finland. Larval colonies were transferred on the shoots of Scots pines growing at different distances from the emission source. Larval mortality was highest near the factories. InN. sertifer, larval mortality caused by the nuclear polyhedrosis virus was higher and cocoon mortality caused by parasitoids was lower near the pollutant source. The most abundant parasitoid species wereSynomelix scutulata (Hartig) andLamachus eques (Hartig). 16–67% of theN. sertifer, 0–5% of theD. pini and the 73–100% ofG. pallida cocoons contained parasitoids oviposited during the larval period of the sawflies.      

Pathogenicity, formulation and storage of insect pathogenic hyphomycetous fungi tested against Diabrotica speciosa

Studies were conducted tosearch for fungal strains with potentialpathogenicity against Diabrotica speciosa(Germar) (Coleoptera: Chrysomelidae).Among sixteen fungal isolates screenedthe most virulent was a Beauveria bassiana(Balsamo) Vuillemin isolate (FHD13) thatcaused 70% mortality of D. speciosathird instar larvae. The LC₅₀ value ofB. bassiana isolate FHD13 was3.48 × 10¹⁰ conidia/ml.Different temperatures (4, 17 and 26 °C)and vegetable oils (corn, sunflower and canola)used for storage did not significantly affectviability of conidia. A pathogenicity trialagainst D. speciosa larvae performed withthe corn oil formulation (1 × 10⁸ conidia/mlof oil) caused 65% of mortality.     

The influence of natural enemies on brood production inIps typographus (Col. scolytidae) with special reference to egg-laying and predation byThanasimus formicarius (Col.: Cleridae)

The predatorThanasimus formicarius (L.) (Coleoptera, Cleridae) and its preyIps typographus (L.) (Coleoptera, Scolytidae) were studied in the laboratory and the field. In the laboratory, 11T. formicarius laid 71–132 eggs (mean=162) during 66–123 days. During this time they ate 66–132I. typographus adults per pair (male +female). The number of eggs laid per female was not correlated with life span or the number ofIps eaten. In the field, predation byT. formicarius larvae and other natural enemies onI. typographus brood was studied in the last year of an outbreak. Caged and uncaged spruce bolts attacked byI. typographus were used, and pairs ofT. formicarius were released in the cages. The treatments were: uncaged bolts, caged bolts withoutT. formicarius, caged bolts with 4T. formicarius pairs, and caged bolts with 8T. formicarius pairs. The productivity ofI. typographus was highest in the caged bolts withoutT. formicarius (mean=4.5 offspring/female) and lowest in the uncaged bolts (mean=0.9 offspring/female). The density ofI. typographus galleries was similar in the different treatments. Hence, the variation in productivity between treatments could not have been due to differences in the levels of intraspecific competition. There was no difference in bark beetle productivity or density ofT. formicarius larvae between bolts with 4 pairs ofT. formicarius and bolts with 8 pairs (mean=2.5 offspring/female). This indicates that some kind of interference occurred betweenT. formicarius individuals (e.g. cannibalism) and that a maximum level of predation was reached. Predation by larvae ofMedetera spp. (Diptera, Dolichopodidae),Thanasimus spp. and other beetles, and parasitism by wasps (Hymenoptera, Pteromalidae) probably caused the low productivity in the uncaged bolts.      

Gypsy homologous sequences inDrosophila subobscura (gypsyDS)

Summary Characterization of sequences homologous to theDrosophila melanogaster gypsy transposable element was carried out inDrosophila subobscura (gypsyDS). They were found to be widely distributed among natural populations of this species. From Southern blot and in situ analyses, these sequences appear to be mobile in this species.GypsyDS sequences are located in both euchromatic and heterochromatic regions. A completegypsyDS sequence was isolated from aD. subobscura genomic library, and a 1.3-kb fragment which aligns with the ORF2 of theD. melanogaster gypsy element was sequenced. Comparisons of this sequence in three species (D. subobscura, D. melanogaster, and D. virilis) indicate that there is greater similarity between theD. subobscura-D. virilis sequences than betweenD. subobscura andD. melanogaster. Molecular divergence ofgypsy sequences betweenD. virilis andD. subobscura is estimated at 16 MY, whereas the most likely divergence time of these two species is more than 60 MY. These data strongly suggest thatgypsy sequences have been horizontally transferred between these species.Offprint requests to: T.M. Alberola     

Studies on theStellaria longipes complex (Caryophyllaceae): Isozyme variability and the relationship betweenStellaria longipes andS. longifolia

Genetic variation within and the relationship betweenStellaria longipes Goldie andS. longifolia Muhl. were studied. Ten enzyme systems were assessed in eight natural populations ofS. longipes (25 loci) and three ofS. longifolia (20 loci) using starch and polyacrylamide gel electrophoresis. Patterns of population differentiation corresponded to geographic distance. There was no evidence that polyploidS. longipes had greater electrophoretic variability than diploidS. longipes. The isozyme data confirmed extensive population differentiation in these species and, within that context, a relatively close relationship betweenS. longipes andS. longifolia. It was postulated that diploids of these two species might be the progenitors of tetraploidS. longipes.     

Evidence for intergeneric incompatibility in ferns

The archegonial mucilage ofAthyrium filix-femina andA. distentifolium paralyses spermatozoids ofDryopteris filix-mas (and in one caseD. inaequalis) before they penetrate the archegonial venter. The archegonial mucilage ofDryopteris filix-mas has a weak positive chemotactic influence on the spermatozoids of the twoAthyrium species. The spermatozoids ofDryopteris were never observed in the archegonia ofAthyrium. Incompatibility was not observed within and between the twoAthyrium species, withinDryopteris filix-mas or betweenAthyrium filix-femina and twoAsplenium species.Contribution No. 327.     

Courtship behavior and discrimination between potential mates by maleDelia antiqua (Diptera: Anthomyiidae)

The repertoire of courtship behaviors of male onion maggots,Delia antiqua (Meigen), in a laboratory bioassay chamber, was analyzed by direct observation and by video recordings, in conjunction with a multichannel event recorder. Seven courtship behaviors were categorized: inspection from the substrate, aerial inspection, contact from the substrate, contact from the air, genital alignment, copulation, and male-male interaction. The frequency distribution of copulation bouts was best described by a Poisson distribution; peak mating activity occurred about 1 h into the bioassay. The duration in copulo, however, was extremely variable. On average, males spent 30 sin copulo (n=183); <30% of bouts were >50 s. The ability of males to discriminate between sexes, sexually immature and mature females, and between females ofD. antiqua and the cabbage maggot,Delia radicum (L.), was most pronounced in the elements of genital alignment and attempted copulation. The courtship and mating behavior inD. antiqua is consistent with a sequence that relies initially primarily on indiscriminate visual recognition of a potential mate, followed by species-and sex-specific semiochemical recognition upon contact.     

Notes on the capsule dehiscence inAcanthophyllum (Caryophyllaceae) and allied genera

The shape and the mode of dehiscence of the capsule had been regarded as good differential characters betweenAcanthophyllum and related genera.—Studies of these characters, including the shape of the ovary, in species ofAcanthophyllum, Diaphanoptera, Ochotonophila andScleranthopsis show, however, that they cannot be used as differential characters for the genusAcanthophyllum. Dedicated to Prof.K. H. Rechinger on the occasion of his 80th birthday.     

Tamarin polyspecific associations: Forest utilization and stability of mixed-species groups

Niche separation is likely to play a key role in the formation of mixed-species groups. Saddle-backed tamarins (Saguinus fuscicollis) were studied at three sites with different primate communities in northern Bolivia: (1) with red-bellied tamarins,S. labiatus; (2) with emperor tamarins,S. imperator; and (3) without a congeneric species. The degree of association is higher betweenS. labiatus andS. fuscicollis than betweenS. imperator andS. fuscicollis and is related to differences in forest utilization between associating pairs. Niche separation is found to be greater betweenS. labiatus andS. fuscicollis than betweenS. fuscicollis andS. imperator. The mean height and habitat utilization ofS. fuscicollis does not differ greatly across the three sites, nor does the height of tamarins in and out of association. It is concluded that combined with differences in body size and dietary overlap, vertical segregation plays an important role in tamarin polyspecific associations (increasing the potential of both foraging and anti-predatory benefits) and that this is not a consequence of vertical displacement ofS. fuscicollis by its dominant congeners.     

Phylogenetic relationships of the enigmatic fern families Hymenophyllopsidaceae and Lophosoriaceae: Evidence fromrbcL nucleotide sequences

Nucleotide sequences fromrbcL were used to infer relationships of Lophosoriaceae and Hymenophyllopsidaceae. The phylogenetic positions of these two monotypic fern families have been debated, and neither group had been included in recent molecular systematic studies of ferns. Maximum parsimony analysis of our data supported a sister relationship betweenLophosoria andDicksonia, and also betweenHymenophyllopsis andCyathea. Thus, both newly-examined families appear to be part of a previously characterized and well-supported clade of tree ferns. The inferred relationships ofLophosoria are consistent with most (but not all) recent treatments. However,Hymenophyllopsis includes only small delicate plants superficially similar to filmy ferns (Hymenophyllaceae), very different from the large arborescent taxa. Nevertheless, some synapomorphic characteristics are shared with the tree fern clade. Further studies on gametophytes ofHymenophyllopsis are needed to test these hypotheses of relationship.     

The Bionomics ofCoptera Haywardi(Ogloblin) (Hymenoptera: Diapriidae) and Other Pupal Parasitoids of Tephritid Fruit Flies (Diptera)

The endoparasitoidCoptera haywardi(Ogloblin) (Diapriidae) was discovered in Mexico attacking the pupae of the Mexican fruit fly,Anastrepha ludens(Loew). Typically, parasitoids of Diptera Cychlorrhapha pupae develop as ectoparasitoids and are generalists that attack hosts in a number of families. Aspects of the bionomics ofC. haywardiwere compared to those of two chalcidoid ectoparasitoids,Dirhinus himalayanusWestwood andSpalangia geminaBoucek.C. haywardideveloped in three genera of Tephritidae, but not in species of other families. The two species of chalcidoids developed in all the calypterate and acalypterate hosts to which they were exposed. In an olfactometerC. haywardipreferredAnastrepha suspensa(Loew) pupae, while the chalcidoids preferred the pupae ofMusca domestica L.This preference inS. geminawas diminished in insects that had been reared onA. suspensa. C. haywardioviposited in theA. suspensapupae that had been previously parasitized by the braconidDiachasmimorpha longicaudata(Ashmead). However, it completed development only in unparasitized pupae. Mortality of the primary parasitoid due toD. himalayanuswas approximately two-thirds the mortality inflicted on the host fly.S. geminadid not discriminate between parasitized and unparasitized pupae ofA. suspensaand developed in both.C. haywardiappears to have a more restricted host range relative to chalcidoid pupal parasitoids and this may be due to its endoparasitic development.     

Quantitative comparison of foliage development amongDryopteris monticola,D. tokyoensis and a putative hybrid,D. kominatoensis in Northern Japan

Developmental leaf architecture was quantitatively described in terms of measurements of various parameters on leaf blade from different size of sporophytes inDryopteris monticola, D. tokyoensis and a putative hybrid,D. kominatoensis in the natural site of Hokkaido, to compare the ontogenetic differentiation in foliage structure among allied ferns. The morphological stage of leaf and sporophyte was tentatively quantified by the number of midrib branches of the leaf (NV, number of veins), which exhibited a significant correlation to the leaf-shape complexity from a circle (DI=marginal length/2×(3.14×square)^1/2) of leaf blade. D. kominatoensis showed intermediate values between others in following characters; DI increase, maximum NV (also blade length), maximum number of costa branches of pinnae (NVMP), number of costa branches of the lowest pinna (NVLP), difference between NVMP and NVLP (NVMP-NVLP), during heteroblastic leaf development. A larger number of leaves per sporophyte was found inD. kominatoensis than in others. The fertility rate (%) and initiation of fertility (IF) in the relative developmental stage (RDS) ofD. kominatoensis shifted to that ofD. tokyoensis, while the order of pinnae with NVMP shifted to that ofD. monticola. Even in the intermediate characters inD. kominatoensis, slight shifts in characters to those of putative parents were found during heteroblastic leaf development. Contribution No. 3145 from the Institute of Low Temperature Science, Hokkaido University.