摘要:

Abstract.1. Larvae of two bivoltine species of leaf‐mining Lepidop‐tera,Acrocercopssp. andNeurobathra strigifinitella(Clem.), restrict feeding to young, second‐flush leaves of their host trees in north Florida.2. During 1980 and 1981, densities of both species varied greatly among thirty small water oaks (Quercus nigra), as did timing and extent of secondary leaf production.3. In both years leaf‐miner density at the end of the first generation (mid‐August) was positively correlated with secondary leaf production.4. Five trees abscised their leaves and reflushed new ones at atypical times of the growing season. When refoliation coincided with emergence of ovipositing adults,Acrocercopssp. andN.strigifinitelladensities increased dramatically, indicating that both species are at times limited by availability of young leaves.5. By staggering termination of diapause these leaf miners can exploit a temporally variable

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1984.tb00831.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract.1. A positive correlation between the tongue length of conspecific workers collecting nectar from seven plant species and the corolla length of the flowers probed was found forB.lapidariusandB.pascuommbut notB.terrestris. No simple relationship was found between the volume, sugar weight or concentration of nectar in flowers and the tongue or wing length of probing bees.2.B.terrestrisworkers collecting pollen from four plant species producing pollen only, were found to differ in size according to the type of pollen presentation mechanism and the pollen content per flower. Body size variation was also related to the foraging of pollen plus nectar from two other plant species.

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1984.tb00832.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract.1. In order to gain insight into howDrosophila mojavensisPatterson and Crow (which lives on the rotting tissue of cactus) successfully shifted host plants, from anOpuntiaspecies to columnar cactus species, over evolutionary time, specific components of columnar cactus andOptuniatussue were examined for their effects on adult longevity.2. The availability of free sugars affects the survival of adultD.mojavensis. The addition of a sugar to columnar cactus tissue significantly increased the longevity of adults that fed on those tissues. This increase in adult longevity was equal to the longevity observed on unsupplementedOpuntiatissue, which has free sugars present.3. Live microorganisms added toOpuntiatissue had a slight detrimental effect on adult longevity (longevity was decreased by approximately 1 week).4. Low concentrations of atmospheric ethanol (independent of diet) increased the longevity of adultD.mojavensisto levels comparable in magnitude to that provided by the addition of free sugars to the diet.5. This information and the apparent lack of a year‐round supply of free sugars forD.mojavensisin nature suggests that the ethanol (produced by fermentation) rather than free sugarsper seis the most important component of rotting cactus tissue for the survival of this species and may explain its successful host‐plant sh

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1984.tb00833.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract.1. The presence and quantity of honeydew, produced by the, cereal aphid,Sitobion aveme(Fab.), on the timeCoccinella seprempunctaraL. larvae spent searching ears of wheat and on the number of aphids eaten, was investigated.2. In the presence of honeydew larvae spent longer searching the ears, resulting in a greater exploitation of prey than in the absence of honeydew.3. Larvae did not respond to differences in the amount of honeydew, so that the arrestment response would not result in aggregation in areas of high prey density.

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1984.tb00834.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract.1. Ovipositing females of cinnabar moth lay just as many eggs on regrowth foliage as on normal rosette leaves of ragwort.2. Larvae reared on regrowth tissues achieve the same weight at pupation as insects fed on primary leaves and capitula. Diet affected neither survival rate nor development time.3. Larvae from eggs laid on normal foliage achieve lower pupal weights when fed regrowth tissues, and larvae from eggs laid on regrowth leaves perform less well on a diet of normal foliage.4. The complex of changes associated with re growth following defoliation does not appear to reduce the fitness of this specialist herbivore, nor does it reduce the likelihood that the plant will be attacked by ovipositing adult moths.5. A facultative response which consisted of an increase in ‘qualitative defences’ is unlikely to be effective against adapted herbivo

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1984.tb00835.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract.1.Spulungiu endiusWalker is a solitary parasitoid of house fly puparia.2. The sex and size ofS.endiuswas not related to host size.3. In the laboratory the mean sex ratio of all offspring of nine groups, each comprising twenty females, was consistently female‐biased (x = 83.5%, range 79–87%). The sex ratio in the field was less female‐biased and showed greater fluctuation (61–75%). This may be a consequence of females laying male eggs before mating, some females remaining unmated, possible shorter adult life expectancy in the field than in the laboratory, and, perhaps, the presence of conspecific females.4. The sex ratio of offspring of individual females varied from 66% to 100% females, and males were deposited early in the oviposition sequence.5. Although a large number of fly puparia died before adult flies or parasitoids emerged (64.5%;n= 5874), there was no differential mortality of either sex.6. Our results fit no general sex ratio hypothesis and we conclude that (i) the genetic nature of sex ratios in these insects needs careful examination, and (ii) the prevalence of female‐biased sex ratios in solitary parasitoids needs inve

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1984.tb00836.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract.1.P.badiusLatreille, a harvester ant of the southern U.S.A., surrounds its nest mound with small bits of charcoal, previously believed to be incidental refuse, along with other components of the colony's midden.2. Charcoal middens were removed from the nest mounds of colonies in northern Florida. These colonies collected new charcoal and replaced the middens within 7 days.3. Activity rhythms, use of space, and interspecific aggression were compared in experimental and control colonies. When middens were removed, the frequency of invasions of the nest mounds by other species of ants increased. Foreign ants circled the nest mound and interfered with colony activities. Increased numbers of invading ants led to an increase in patrolling and defensive behaviour by theP.badiuscolonies.4. The charcoal midden is not merely refuse. Instead, it acts as a boundary that deters ants of other species from coming onto theP.badizlsnest mound. Ants may use charcoal bits as a repository of a chemical substance functioning as a territorial marker.

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1984.tb00837.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract.1. Factors affecting cultivar preferences by the carrot flyPsila rosaeF. were examined in choice tests using foliage from carrot lines representing extremes of resistance and susceptibility to attack.2. Flies were offered a choice to oviposit on foliage, artificial substrates impregnated with leaf surface extracts or enclosed in vapours of different cultivars to establish the importance of contact and olfactory stimuli. Susceptible cv. Danvers Half Long 126 foliage was preferred over that of resistant cvs. Clause's Sytan Original and Tip‐Top. But, whereas the Sytan leaf surface extract was as effective as that of Danvers, the surface extract of Tip‐Top was very much inferior as an oviposition stimulant. By contrast, Sytan and Tip‐Top foliar vapours were both more attractive to the fly than that from Danvers.3. Headspace vapours over Sytan foliage evoked significantly higher electroantennogram responses than those from Danvers.4. Cold‐trapped foliar volatiles of Sytan and Danvers were analysed by gas chromatography linked with antennographic detection. Foliage of Sytan released, among other chemo‐stimulants, higher levels of host plant attractants, i.e. green leaf aldehydes and the phenylpropanoids, trans‐asarone and trans‐methylisoeugenol.5. These findings indicate that olfactory and contact chemostimuli may be involved in preferences shown by the carrot fly for carrot cultivars, but these factors alone do not fully account for the prefere

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1984.tb00838.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract.1. In the Sydney area of New South Wales, dry weights of reproductive monarch butterflies averaged 156 mg and were higher during winter than in other seasons. Dry weights of non‐reproductive monarchs ranged from 216 to 324 mg and declined by 15–25% during over wintering.2. Fat in reproductive butterflies ranged from 0.009 to 0.017g/0.1g dry weight and was lower during winter than in other seasons. Fat content of non‐reproductive monarchs was higher (0.019–0.037 g/0.1g) and declined by 24–51% during over wintering.3. Lean dry weights of reproductive monarchs were lower than those of non‐reproductive individuals. Lean dry weights of non‐reproductive butterflies increased rapidly at the beginning of over wintering and remained high throughout the winter. Analysis of protein content indicated the higher lean weight of non‐reproductive monarchs was due to greater protein levels.4. Moisture content of monarchs did not vary with season or reproductive status and appeared to be correlated with ambient humidity.5. Non‐reproductive monarch butterflies in New South Wales adjust bio chemically during over wintering. Energy reserve dynamics of these butterflies are comparable to those that occur in non‐reproductive monarc

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1984.tb00839.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract.1. Nymphs ofVanduzeea arquataSay have been found to be more host‐specific in nature and to show a higher degree of selectivity in host discrimination experiments than nymphs ofEnchenopa binotata(Say), It was hypothesized that this differential selectivity would be reflected in the probing behaviour of individuals placed on twigs of host and non‐host plants. Probing behaviour was examined by direct observation of nymphs and by sectioning and staining the probed plant tissues.2. All nymphs probed readily and for extended periods on both host and non‐host twigs.E.binotutanymphs showed no consistent differences in probing behaviour on hosts versus non‐hosts, butV.atquutanymphs were more likely to withdraw their stylets within 60 s when on non‐host twigs and produced honeydew only when on their host species.V.urquatunymphs reached the phloem sieve elements only when on host twigs and broke many cells in peripheral plant tissue layers while probing.E.binotatanymphs broke few cells and often reached the phloem of non‐host as well as host plants.3. Nymphs ofV.arquataalways reject non‐host plants, apparently in the course of probing and prior to encountering the phloem sap. Chemical compounds released from ruptured parenchyma cells may act as probing stimulants or inhibitors.E.binoturanymphs often feed on non‐host plants in a non‐choice situation; their preferential settling on host twigs in discrimination experiments may reflect a tendency to abandon non‐host twigs more read

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1984.tb00840.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY