摘要:

Abstract.1. California red scaleAonidiella aurantii(Maskell) and oleander scaleAspidiotus neriiBouché (Homoptera: Diaspididae) are not completely suitable for the development of the encyrtid endoparasiteHabrolepis rouxiCompere.2. Mortality of parasite immatures in California red scale is caused mainly by egg encapsulation. Although oleander scale is unable to encapsulateH. rouxi, it is nutritionally unfavourable for the parasite's development.3. Some immunity to the parasite is conferred to the oleander scale by the particular host plant used.4. The parasite's rate of development is not influenced by the host species studied.5. The mortality of parasite immatures in California red scale is lower than in oleander scale. The former host also is more acceptable and preferred by the parasite for ovipositon. These characteristics of the California red scale render it more suitable than oleander scale as host forH. rouxi.6. Studies on the encapsulation ofH. rouxieggs by the California red scale indicate that (i) encapsulation does not prevent third instar host larvae from maturing and producing progeny; (ii) neither rearing temperature nor host age affect encapsulation frequency

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1979.tb00589.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Abstract.1. Various aspects were studied of two host‐parasitoid interactions:Aphidius urticaeparasitizing the cocksfoot aphidHyalopteroides humilisandAphidius uzbeckistanicusparasitizing the cereal aphidMetopolophmm dirhodum.The work formed part of a study on the population dynamics of grassland and cereal aphids in Berkshire, England.2.A.uzbeckistanicushad a higher instantaneous attack rate but a slightly longer handling time thanA.urticae.In both cases the functional response was curvilinear.3.A.urticaewas specific toH.humilisand failed to develop inM.dirhodum. A.uzbeckistanicuscould develop successfully inH.humilisbut the functional response was sigmoid and the progeny were less fecund than those reared on the natural host. This species showed a clear preference forM.dirhodumwhen supplied with mixtures ofM.dirhodumandH.humilis.4.A.uzbeckistanicushad a faster rate of development and a lower developmental threshold thanA.urticae, a situation paralleled by their natural hosts.5. The results are discussed in relation to field observations.A.uzbeckistanicusmay have considerable potential for reducing cereal aphid numbers. However, its preference forM.dirhodummitigates against a reservoir being maintained in the economically unimportant grassland aphid,H.humili

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1979.tb00590.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Abstract.1. AdultA.rufipesinvade fresh dung pats (mainly in August) and stay for a few days in each pat to feed and oviposit; maximum abundances: 0–100 beetles per cattle dung pat. Larval growth is completed within 40–55 days.2. The dispersion of beetles is contagious or seemingly random. In sunny weather, with rapid crust formation on the dung, pats deposited in the afternoon are invaded by more beetles than those deposited in the morning.3. In the field, the total number of eggs per pat is significantly less variable than the number of adult beetles; this might indicate a density‐dependent, regulatory, rate of oviposition. The subsequent larval mortality is probably density‐independent.4. Experiments confirmed that the number of eggs laid per female‐day in the pats was density‐dependent.5. The non‐opportunistic reproductive strategyof A.rufipesmay have evolved as an adaptation to life in dung pats: at excessive population densities pats might disappear before completion of larval growth.6. Finally,A.rufipesin dung pats is compared with blowflies breedi

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1979.tb00591.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Abstract.1. The responses of third instarPsila rosae(F.) larvae to light, temperature, humidity and soil moisture were investigated in the laboratory.2. Larvae were photonegative and preferred a temperature of about 15°C. Temperatures between 30 and 40°C adversely affected movement and over 40° C were lethal.3. In choice chambers, larvae preferred humidities of 70–100% r.h. and larvae in sand avoided dry conditions (2.5% field capacity). The latter response became more marked as larvae approached the pre‐pupal stage when moistures of 40% field capacity and lower were avoided.4. Most larvae were found at a depth of 8 cm in sand of uniform moisture content and temperature, but variation in moisture content could alter this preference.5. In August, most larval damage in the field occurred near the tip of the carrot tap root but was more evenly distributed over the roots in November. It is uncertain whether this was due to soil near the surface being drier in August or whether it was caused by behavioural differences between the two generations of carrot fly larvae.6. During the summer of 1975, low soil moisture levels resulted in the total absence of larval mines on the carrot roots even though pupae were found at depths of 20–30 cm in the soil. Temperature had no effect on the distribution of mines on carrot roots except at the top 2 cm of the soil

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1979.tb00592.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Abstract.1.Aphytis melinusDeBach andA.lingnanensisCompere were exposed to temperature extremes during development, mating, preoviposition, and opposition to assess the effect of these exposures on the progeny per female and F1sex ratio.2. Both species showed a significant reduction in the expected proportion of F1females when the male parent was exposed to 32°C during its development.3. The proportion of females was further reduced when mating and/or oviposition occurred at 32°C and these effects on sex ratio appeared cumulative.4. Preovipositional exposure of the females of both species to 38°C, 2°C or ‐2°C for 1 5, 4 or 7 h in most cases significantly reduced the expected proportion of females.5. In general our results showed that the sex ratios ofA.melinuswas less severely affected by these exposures than were thoseof A.lingnanensis.6. It is suggested that this difference may be one factor explaining the abilityof A.melinusto excludeA.lingnanensisfrom the climatically more extreme areas of southern Cali

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1979.tb00593.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Abstract.1. Mating of the brown planthopper,Nilaparvata lugens, was investigated in relation to oviposition. Females became unreceptive immediately after mating and showed various types of repelling behaviour to courting males. As a result, females usually did not mate repeatedly in quick succession, but after ceasing to lay fertilized eggs they behaved as virgins and mated again before producing more fertilized eggs.2. Copulation, followed by deposition of fertilized eggs, occurred twice, or in a few cases three times, throughout the adult stage. Copulation lasted about 2 min at the first mating and about 1 min at the second or third mating.3. When the number of fertilized eggs began to decrease rapidly, oviposition rate also decreased, but it increased again immediately after re‐mating. Repeated copulation was also related to the potential rate of population increase. In the present experiments, the estimates of net reproductive rate (R0) in brachypterous females was 287.7 (first mating), 88.3 (second mating) and 7.2 (third mating) and in macropterous females 286.8, 120.6 and 3.6 respectively.4. In a patchy environment, repeated copulation following an invasion may contribute to the increase of a populatio

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1979.tb00594.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Abstract.1. A study was made of larval and adult Mycetophilidae in coppiced beech woodland in southern England. Adult mycetophilids were trapped throughout 1968 using sticky traps at ground level. Larvae inhabiting terrestrial fungi were collected from all sporophores from a defined area of the woodland floor between August and October 1968.2. Larval mycetophilids were extracted from only 12.6% of all sporophores collected and from fifteen of thirty‐eight species of fungi present. Some species of fungi were never inhabited by larval mycetophilids while others appeared to be highly attractive to them. Since it was not possible to identify the larvae beyond the level of tribe it was impossible to ascertain host preferences for different species. Peak numbers of larvae occurred at the beginning of September and the beginning of October.3. Adult mycetophilids had two peaks of activity, the first in March and April when the dominant species wereBoletina griphaandPhronia basalisand the second in autumn when species of the genusMycetophilawere dominant.Phronia basalisis a species whose larvae inhabit dead wood and the abundance of this species (40% of all adults) probably reflects the amount of rotting wood in this type of habitat. The autumn peak of adult activity was due to species known to inhabit agaric sporophores and came about 1 month after the peak of larval numbers in fungi.4. The adult fauna was rich with 107 species representing about a quarter of the known British fauna. However, only twelve species were trapped in sufficient numbers to allow deductions concerning seasonal activity.5. The results were discussed with respect to the problems of assessing populations of insects inhabiting fungal sporophores and to the previous work on this neglected grou

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1979.tb00595.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Abstract.1. Sex regulation and its relevance to the ecology of a k‐selected pupal parasitoid was investigated inCoccygomimus turionellae.2. The ratio varied with host size, females predominating in large hosts.3. Egg transfer experiments and comparative mortality rates among the progeny of virgin and inseminated females demonstrated that the phenomenon was due to parental behaviour.4. The study of the mechanism confirmed Aubert's hypothesis of host size estimation with the addition that the host had to be exposed from the poles and had to contain the proper host kairomones.5. Host size was highly correlated to parasitoid fecundity via influences on size and longevity but not the number of ovarioles per female or daily egg production.6. Host encounters are more limiting than egg production and host size had no effect on host acceptance.7. Sex regulation allows a maximal host encounter rate at the same time that it maximizes the reproductive potential of female progeny.8. Low host density increased the production of female progeny resulting in more offspring searching for the limited resource. Concealed hosts and a high host density resulted in a shift towards a Fisher 1:1 sex rati

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1979.tb00596.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Abstract.1. Resource utilization of time (i.e. seasonal occurrence of adults) and oviposition sites (i.e. heights of the host plant above ground level) have been analysed in five species of leafhoppers commonly associated with the grassHolcus mollis.2. The d/w method proposed by May&MacArthur (1972) has been used and when the values for the two resources are examined together it becomes apparent that much potential competition for oviposition sites is reduced by segregation in time. Moreover, potential competition for common resources is reduced by mobility and dispersal of some species.

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1979.tb00597.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Abstract.1. Natural pupation sites have been found inPapilio polyxenesandP.glaucusby releasing prepupal larvae marked with UV‐fluorescent paint and locating them at night with a UV lamp, and inBattus philenorby searching a forest habitat where the larval foodplant is abundant.2.P.polyxenes, a species of weedy habitats, pupates off the ground on a variety of substrates including grasses, weed stalks, posts, etc. The pupae may be green or brown, resembling the substrate.3.P.glaucus, a species of forest habitats, pupates very close to the ground in the litter and has monomorphic brown pupae.4.B.philenor, also a forest species, pupates on exposed surfaces (chiefly tree‐trunks or cliffs) well off the ground. Its pupae may be brown or green, but the latter were found only on the slenderest twigs.5. The results forpolyxenesandglaucussupport the generalization of Clarke&Sheppard (1972) that species of stable habitats are likely to have monomorphic pupae, while those of habitats in which available sites may not be so similar from one generation to the next will be dimorphic.6.B.philenoris more problematical, but its tendency towards pupal monomorphism (brown) is logical in relation to its common pupation si

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1979.tb00598.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY