摘要:

Abstract.1. Mean supercooling points of eleven species of arthropods (three Collembola, seven Acari and one Diptera) ranged from ‐6.2 to ‐9.4°C (high group), and from ‐17.7 to ‐31.0°C (low group). The majority of individuals in the high group had food in their gut systems.2. Freezing was lethal to all species examined except larvalBelgica antarcticaJacobs (Chironomidae).3. Glucose, glycerol and mannitol were found in low concentrations in extracts ofCtyptopygus antarcticusWillem (Collembola) and larvae ofB. antarcrica;it is udikely that these substances had a major effect on the supercooling of either species.4. Two Collembola species possessed significantly (P<0.05) lower supercooling points at locations on the Antarctic Pensinsula than at Signy Island, South Orkney Islands. The converse was observed for two species of Acari.5. It is suggested that whilst gross climatic and also micro‐habitat conditions may influence the cold hardiness of such arthropods, especially seasonally, their full supercooling ability is ra

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1982.tb00638.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract.1. Ecological differences between closely related species and forms of the planthopper genusMueIlerianella(Delphacidae) were studied.2. In the fieldM.brevipennisandM.faimaireiare restricted toDeschampsia cespitosaandHolcus lanahis/H.mollis. respectively.M.extrusais mainly found onMolinia caerulea, but has also been recorded from other grass‐species. Triploid all‐female forms which reproduce by gynogenesis usually live onHolcustogether withM.fairmairei. Other gynogenetic populations were found onBromus ramosus, Deschampsia flexuosaandCalamagrostis canescens.3. Breeding experiments showed that the diploid species cannot be maintained on each other's host‐plants, but accept other grass‐species.4. Due to overlapping habitat requirements of the host‐plants, ecological isolation between theMuellerianellaspecies is incomplete.5.M.extrusalives in bogs, moors and forests on poor acid soil.M.brevipennisis found in forests, carr, fens and in extensively managed grasslands.M.faimaireiand associated triploid forms occur mainly in grasslands and other man‐made habitats. The habitats of all three species are usually wet.6. In most parts of EuropeM.brevipennisandM.extrusaare monovoltine andM.fairmaireiis mostly bi‐o

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1982.tb00639.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract.1. 239 species of leafmining insects have been recorded from thirty‐seven species of trees and large shrubs in Britain.2. A significant species—area relationship was obtained for these insects, but it explained only 19% of the variation about the regression he. A further 23% of the variation may be accounted for by taxonomic relationship of host plants.3. A significant correlation was established between the number of species of leafminers and those of mesophyll‐feeding leafhoppers for twentyeight host tree species. Both guilds are dominated by host specific feeders.4. It is suggested that species—area effects are important in determining species richness of phytophagous insects mainly when groups of closely related host plants are considered. With more diverse arrays of hosts, taxonomic influences, which are probably mainly chemical, may outweigh such area related

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1982.tb00640.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract.1. A survey was made of the distribution of Lonchopteridae over 2 years at forty sites in northern England. Material was collected by pitfall trapping.2. Two species,Lonchoptera luteaandL.furcata, were taken in approximately similar numbers. No other species were recorded.3. Considerable separation of the two species was found, with both species occurring at ten sites, whilst one species only was taken at twenty‐five sites.L.furcataoccurred coinrnonly on upland mineral sods, shallow peat soils and on lowland bogs whilstL.luteawas numerically most abundant on upland blanket bog.4. Almost 39% of theL.luteaspecimens and 14% of theL.furcatacaptures were males.5. The capture of numbers of males ofL.furcatais unusual, since the species is regarded as being parthenogenetic and males occur only in a very small part of the species' range. Confirmation of the association between the males and females ofL.furcatais given, whilst there is close agreement between the cliaetotaxy of British males and females, and British and continental European females. The suggestion that the males belong to an undescribed species is rejected.6. The seasonal captureof L.luteaadults is similar at all altitudes. Captures of males ofL.furcatashow an abrupt seasonal change above and below about 420 m; captures being in mid‐summer in the higher altitude zone and between October and December at lower altitudes. The captures of femalesof L.furcatashow the same trend, but this is partially obscured by the longer life‐span of the females. It is suggested that this difference represents a change in the lifecycle, possibly from an annual to a biannual one at the higher altitudes.7. The biology and distribution of the Lonchopteridae at low altitudes requires investig

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1982.tb00641.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract.1. Competition within and between the larval instars of the yellow fever mosquito,Aedes aegypti, can be measured by its effect on stage duration. In a series of laboratory experiments the relative importance of chemical interference and food exploitation in mediating competition between first and fourth instar larvae was investigated.2. In contrast to the results of three previous studies, I found no evidence that a chemical growth retardant played any part in greatly prolonging the stage durations of larvae in both age classes.3. When competition between the two age classes became important, the relative increase in stage duration wasgreater for first instar larvae than for fourth instar larvae. This result can be reproduced with Gilpin&McClelland's (1979) model of competition by food exploitation alone, providing the range of available food particle size is assumed to be an increasing function of age. An additional, but less important, refinement makes the conversion efficiency of food into larval biomass a decreasing function of age.

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1982.tb00642.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract.1. Species of the genusCordyceps(Ascomycotina; Clavicipitales) are the commonest fungi encountered on arthropods in tropical forests.2. The asexual states ofCordycepsmay occur in conjunction with or separately from the perfect state and are classified in the generaHirsutella, Hymenostilbe, Nomuraea, PaecilomycesandVerticilliumof the imperfect fungi (Deuteromycotina; Moniliales).3. MostCordycepsspecies have a restricted host range and this rigid host specificity, at the generic or tribal level, is especially evident in ant‐fungal associations.4. Pathogenicity was not tested but circumstantial evidence is presented which supports the view thatCordycepsspecies are primary pathogens of arthropods.5. Observations of living, infected ants suggest that behavioural patterns are radically altered, possibly altruistically orientated.6. It is thought that entomogenous fungi are involved in the regulation of arthropod populations and may help to maintain stability in tropical forest ecosystems.7. The value of these organisms to man may be in the metabolites they produce rather than in their direct usage as biological control agents of insect pest

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1982.tb00643.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract.1. We tested the hypothesis that interspecific competition between two grass‐feeding stenodemine bug species (Notostira elongataGeoffroy andMegaloceraeu recticornisGeoffroy) was capable of causing population‐scale mortality in the field.2. N.elongatanymphs were added to two field enclosures in which theM.recti‐cornispopulation was to hatch. In one of these enclosures the grassArrhena‐therum elatiusL., on which onlyM.recticorniscan feed, was also added. Population changes of the bug species were then monitored. An unmanipulated enclosure and an unfenced plot of grassland were used as controls.3. The results demonstrated thatN.elongatalowered the survivalof M.recticornisand that this effect was removed by the addition ofA.elatius. The results also suggested thatN.elongatasuffered less from the effects of competition withM.recticorniswhen the latter had access to the refuge foodplant.4. Interspecific competition was rare among members of the grass‐feeding stenodemine guild in the area studied. Only one out of fifteen possible pairs competed, and this competition occurred only under special circ

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1982.tb00644.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract.1. The lifecycle, mating and larval behaviour ofClunarisare described. Adults appeared in the autumn and nested in the following spring. The female beetle remained in the nest with the brood and could nest again the following year.2. Nesting was initiated when virgin females were mated in the spring. Brood balls were formed by techniques sirnilar to those used by Scarabaeini. The female beetle left the nest soon after the first imagos broke out of the brood balls.3. Nesting behaviour was readily modified by external conditions. Many parts of the sequence could be repeated or omitted. The female beetle left the nest if the brood was removed, but she remained for longer than usual if younger brood was substituted near the end of the normal nesting period.4. Certain experimental conditions released behaviour patterns typical of other species. These were formation of superficial nests or of two‐chambered nests, oviposition before completing the brood ball, and coating of the brood balls with soil (all found in other Coprina), as well as ball rolling and ball burial (found in Scarabaeini). The results are discussed in relation to the evolution ofCoprisnesting behaviou

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1982.tb00645.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract.1. Long‐term changes in the numbersof Zonocerusat oviposition sites reflect changes in the maturity of the general population.2. Short‐term changes in the numbers ofZonocerusat oviposition sites are associated partly with normal diurnal behaviour in which roosting occurs at night.3. Immigration ofZonucems, particularly females, into the oviposition site occurs prior to periods of oviposition activity. Emigration follows oviposition.4. The majority ofZonocerusmove upwind into the oviposition site suggesting an odour and/or sound attraction.5. Periods of intense oviposition activity follow heavy rainf

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1982.tb00646.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract.1. Plant material ofHolcus lanatusL. removed from an artificially fertilized trial was used to rear leafhoppers of three feeding types:Dicrano‐tropis hamataBoheman andEbmana sulphurellaZetterstedt, (phloem feeders),Eucelis incisusKirschbaum (xylem feeder) andZyginidia scutellarisHerrich‐Schaeffer (mesophyll feeder).2. In the laboratory, leafhopper instar durations, adult consumption rate, oviposition rate, and nitrogen utilization efficiency were influenced by the quality of the food consumed. Adult longevity was unaffected by the level of food quality normally found in plants.3.Z.scutellanisconsumed mesophyll contents equivalent to 72% of its body weight each day but only digested about 30% of its intake.Eincicushad a low dry weight consumption rate (12% body weight/day) but digested its food more efficiently (60%) than the other feeding types. The two phloem feeders consumed mounts equivalent to 25% of their body weight each day and digested 40–50% of their intake.4. Each species reached maximum nitrogen utilization efficiencies at different plant nitrogen levels. This suggests that leafhopper species may be associated with a particular nitrogen concentration in the gr

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1982.tb00647.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY