摘要:

ABSTRACT.1Larval gypsy mothLymantria dispar(L.) mortality depends upon the number and type of plant species consumed as well as the sequence in which they are consumed.2When a two‐species diet is composed of a favourable and an unfavourable species, larval mortality is higher on the two‐species diet than on the diet of the favourable species alone.3When a two species diet is composed of a favourable and unfavourable coniferous species, larval mortality is higher on the single conifer species diet than on the two‐species diet.4Two‐species diets, in which one species is a conifer, produce individuals with a greater fecundity than diets of either species alone.5The influence of diets composed of two favourable species, on development, size and fecundity, depends both on the relative quality of each of the two plant species and which of the two is consumed by older

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1986.tb00273.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACT.1This study first examines the reproductive strategy of femaleSpeyeria mormoniaEdwards (Lepidoptera: Nymphalidae):2Egg weight and number laid per day decrease with age.3Survival and daily egg number may be affected by temperature; mean daily egg weight is not affected by temperature.4Daily egg number is not correlated with body size. In the central range of body size, egg weight is also not correlated with body size. However, exceptionally large or small females lay respectively heavier or lighter eggs than average.5A simple trade‐off between offspring size and number does not occur within females on a daily basis, or among females averaged over their lifespans.6Fat body resources are depleted at a rate independent of body size.7Females are essentially monogamous.8Age‐specific fecundity data reported here forS.mormoniaare next compared with data for other Lepidoptera with different adult feeding habits and egg maturation patterns, and hence different possibilities for adult feeding to play a role in egg production. Based on these comparisons, I propose that the shape of the age‐specific fecundity curve for each species under optimal conditions is constrained by the potential importance of adult nutrients in egg produ

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1986.tb00274.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACT.1Mandible tip length has been used to estimate the age of individualC.problematicusHerbst caught over an altitude range of more than 700 m in northern England.2At 100 m the great majority of females laid eggs in the summer of their emergence as adults. The female life‐cycle is predominantly annual and 24% only of the egg‐bearing individuals were in their second year.3Above 250 m, most females did not reproduce until the summer of the year following emergence, giving a biennial life‐cycle. 96% of egg‐bearing females caught above 830 m were in their second year.4All the males caught during the breeding season at 100 m had emerged within that calendar year and it is concluded that the male life‐cycle is annual at this altitude.5Above 250 m, 83% of the males caught during the breeding season were in their first calendar year, suggesting that recently emerged males may inseminate second year females and also that the male life‐cycle is predominantly annual over the whole altitude range studied.6At the higher temperatures of the lowland site females not only produce eggs in the year of emergence, they also produce more eggs per individual than at the higher sites. Egg production depends on food intake which involves mandible wear and individuals at the lowland site have significantly higher rate of mandible wear than at the sites

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1986.tb00275.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACT.1Adults of the lacewingChrysopa regalisNavás were caught in north Spain, Huesca province, Aragon.2Their progeny reared in the laboratory under short‐ and long‐day light conditions at 20°C, entered a long diapause as prepupae within the cocoon.3Transferred outdoors after spinning up, only a few (12%) became active again in the following spring, whereas the rest remained in diapause for one more year and waited for the end of the second spring to resume their morphogenetic development. Thus most of the studied strain exhibited a 2–year life cycle. This semivoltine strategy is new to chrysopid biology.4The predaceous larval phase did not exceed 3% of the total individual lifespan, though the duration of the free‐living larval instars averaged 19.9±1.1 (SD) days.5During the extended diapause, weight loss was very small, no more than 6.6% of the initial weight, 16.9±2.7 (SD) mg, at the end of diapause, and 8.8% at the time of pu

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1986.tb00276.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACT.1Higher numbers of feeding and restingRibautiana ulmi(L.) were found on the more highly illuminated areas of the canopy of a wych elm tree,Ulmus glabraHuds. cv.Camperdownii.2Higher numbers were also found on the basal leaves of each branch when compared with the distal leaves, and on exposed areas of individual leaves when compared with the shaded areas which they overlapped.3Leaf thickness, tannin concentrations and leaf toughness were greater, and water content lower, in leaves from exposed areas of the canopy than from shaded ones.4R.ulmifeeds selectively on the contents of the palisade mesophyll cells, and therefore was assumed to ingest the highest available levels of tannins.

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1986.tb00277.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACT.1The eggs of the cowpea seed bettleCallosobruchus maculatus(Fab.) are attached to cowpeas. On hatching, the larvae penetrate the testa and remain in the seed until development is complete and adult eclosion has occurred. The adults do not need to feed and were not allowed to do so.2Strains from Brazil and Nigeria can produce more than twelve adults from a seed bearing numerous eggs, whereas a strain from the Yemen Republic rarely produced more than three.3In all three strains the mean weight of the adults produced from a single cowpea declined with increasing initial larval density in the seed.4Egg production by females is positively correlated with their weight at the time of mating, shortly after emergence.5Lifetime egg production by females of the Brazilian and Nigerian strains was lower if they came from cowpeas with higher initial larval densities. No such relationship could be demonstrated in the Yemen strain.6The fecundity of one generation of these beetles, at least in some geographical strains, is significantly affected by the number of larvae entering the hosts in which the adults of that generation have developed.

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1986.tb00278.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACT.1The elemental composition of 249 adult Brimstone butterflies (Gonepteryx rhamniL.) was studied by wavelength dispersive X‐ray fluorescence spectrometry, to determine whether site/population‐specific differences could be detected. The chemical elements studied were K, Ca, Fe, Cu, Zn, Ti, P, CI and S.2Marked differences were found in the chemical composition of the two sexes, and between individuals caught on different sites and in different years and seasons.3Multivariate analyses of the data using principal component analysis and canonical variate analysis showed a clear separation of the butterflies by sex, and within each sex, by seasons. Of the elements studied, the main discriminating ones for this butterfly were K, Ca, P, Zn, CI and S.4Whilst differences in chemical composition appear to result from variations in the composition of soil and food‐plants in different localities, any site/population‐specific differences are soon masked by the passage of time, as adults age and feed. This makes the technique of limited value in the study of dispersal in this

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1986.tb00279.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACT.1Pheidole militicidaWheeler, a seed‐harvesting species of the southwestern United States, possesses a major worker caste (soldiers) with unusually large heads. Previous work suggested that these large major workers are specialized defenders against large seed‐harvesting species in the genusPogonomyrmex.2Experimental introductions ofPogonomyrmex maricopaWheeler and the omnivorous fire ant,Solenopsis xyloniMcCook, demonstrate thatP. militicidacolonies alarm‐recruit major workers againstS.xyloniworkers but not against the largerPogonomyrmexworkers.3P.militicidais the second species in which enemy‐specific defence againstSolenopsisfire ants has been detected. I suggest that the special role ofSolenopsisas both competitor and predator in ant communities frequently favours major worker specialization against this genus.4Major workers ofP.militicidaandPheidole dentataMayr, the other species with enemy‐specific defence againstSolenopsis, are morphologically very different from one another. It is suggested that interspecific variation in major worker morphology is not necessarily associated with variation in behavioural speci

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1986.tb00280.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACT.1Pegomya nigritarsisZetterstedt is a gregarious leaf‐mining fly attackingRumexsp. The larvae from one clutch of eggs all inhabit the same mine.2Egg‐batch size varies between host plants and is correlated with leaf size.3OnRumex obtusifoliusL. larval survival as a function of clutch size was measured in the field. This measure was incorporated in an optimal clutch size model and a clutch size prediction obtained.4The predicted optimal clutch size, three, is that most frequently found in the fi

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1986.tb00281.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACT.1A comparison was made of the insect fauna on pairedTerminalia sericea, Burkea africanaandOchna pulchratrees; one tree in each pair was treated with Formex® to exclude ants from the canopy, and the other was designated the control.2Treatment with Formex banding to exclude ants did not influence plant phenology.3Pyrethrum knockdown samples from control trees had generally more insect individuals and insect species than samples from trees where ants were excluded.4Formex‐treated trees had significantly less homopterous individuals and species than the control trees.5With the exception of ants and Homoptera, there was no difference in the insect guild composition and dominance ranking of various insect taxa, sampled by pyrethrum knockdown, between the control and Formex‐treated trees.6T.sericeahad significantly greater populations of both sessile and mobile Homoptera on the control trees than on the Formex‐treated trees. A similar trend could be seen onB.africana.There were significantly more sessile homopterans on the control trees ofO.pulchrathan on the Formex‐treated trees. Low numbers of mobile Homoptera were recorded on both control and Formex‐treatedO.pulchratrees, and numbers on control trees were fewer in comparison to numbers of mobile Homoptera on controlT.sericeaandB.africanatrees.7It is concluded that the ants have similar effects on the insect communities of trees in a natural, undisturbed savanna as has been demonstrated on trees in agro‐ecosystems, and on plants that are structurally adapted for mutualistic associations with ants.8Although slight, leaf damage by some leaf‐feeding insects was greater on trees where ants had been excluded than on control trees that supported foraging a

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1986.tb00282.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY