摘要:

Abstract.1. Seventeen species of phytophagous arthropods (sixteen insects and one gall‐forming eryiophyid mite) were found feeding on the above‐ground parts of bracken (Pteridium aquilinum(L.) Khun.) in surveys throughout the geographic range of the plant in South Africa. A further thirteen species of insects may possibly feed on the plant in this region.2. Given the area over which bracken grows in South Africa, this is very close to the number of species expected on the plant, based on species‐area calculations and comparisons with bracken in other geographic regions.3. The species‐richness of bracken‐feeding arthropods in local communities reflects the size of the regional pool of species in different geographic areas. Local richness in South Africa is intermediate between that in south‐western U.S.A. and Britain.4. In both Britain and South Africa there is a weak tendency (0.05

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1989.tb00937.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ATLAS OF ENTOMOPATHOGENIC FUNGI. By Robert A. Samson, Harry C. Evans and Jean‐Paul Latge.THE GENETICS OF SOCIAL EVOLUTION. Edited by Michael D. Breed and Robert E. Page, Jr.THE MONARCH BUTTERFLIES: INTERNATIONAL TRAVELLERS. By Fred A. Urquhar

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1989.tb00938.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Abstract.1. Patterns of locomotion of three species of arctiid caterpillars,Diacrisia virginica, Fabr.,Pyrrharctia Isabella(J. E. Smith) andEstigmene congruaWalk, were studied in the field and laboratory in an attempt to understand factors determining foraging behaviour.2. Tracks were recorded on artificial substrates indoors, in the open, and in the normal habitat under the following conditions: in darkness, in bright sunlight, under heavy overcast, under blue sky with the substrate intermittently rotated, with an overhead sheet of polaroid rotated, on a substrate with asperities, in natural field conditions with a variety of forbs in dispersed and clumped distributions.3. Tortuosity and general directions of paths were analysed.4. The effects of various levels of deprivation were also analysed.5. In the absence of photic and chemical stimulation paths on smooth surfaces are straight and direction is random.6. Obstacles perturb the paths and impart a meandering pattern. Patterns of locomotion induced by obstacles on a smooth substrate are indistinguishable from patterns of locomotion in the field. Unless food plants are closer than 1cm they have no effect on locomotion. Patterns of locomotion in dispersed and clumped foodplants are the same.7. What appears to be food‐related search behaviour is primarily the result of physical features of the environment perturbing a central neuronal pattern of locomotion. Stimuli from foodplants appear to be irrelevant unless actually enountere

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1989.tb00939.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Abstract.1. The cabbage root fly,Delia radicum(L.), was deterred from laying eggs on brassica plants with>250 cabbage aphid,Brevicoryne brassicae(L.), or peach‐potato aphid,Myzuspersicae(Sulz.).2. Flies did not lay on plants infested with>250 aphids.3. Preparations of (E)‐β‐farnesene, the aphid alarm pheromone, deterred the flies from laying only at the extremely high dose of 32 mg/plant.4. AlthoughM. persicaesecreted large (1 ng/insect) amounts of alarm pheromone andB. brassicaeextremely small (<0.01 ng/insect) amounts, both aphids equally deterredD. radicumfrom laying.5. The deterrent effect appeared to result from the aphids physically disturbing the flies during host‐plant s

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1989.tb00940.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Abstract.1. The hypotheses that genetic variation in host plant resistance of the arroyo willow affected leaf folder (Phyllocolpasp.) (Hymenoptera: Tenthredinidae) density and that genetic variation in shoot length and leaf length was correlated with resistance were tested.2. Willows grown in pots and exposed to ovipojsition by the leaf folding sawfly in cages had significantly different densities among clones, indicating variation in resistance caused by genetic differences among conspecific host plants.3. There was a general correspondence between leaf folder density on potted cuttings and on the plants in the field that were the sources of cuttings.4. In behavioural choice experiments, susceptible clones (with highest leaf fold densities) had the highest oviposition activity of female leaf folders compared to clones that were resistant to the leaf folder.5. Clones differed significantly in shoot length and leaf length among clones grown in pots, among clones in the field, and between shoots with galls and shoots without galls on clones in the field.6. Leaf folder density was significantly positively correlated with mean shoot length on field clones in 1985 and 1986, but was not correlated with leaf length, although leaf length and shoot length were correlated.7. Leaf length variation among willow clones accounted for a significant portion of the variation in resistance of potted willows, but shoot length was unimportant.

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1989.tb00941.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Abstract.1. The water bugPlea minutissimaLeach (Hemiptera: Pleidae) from time to time crawls out of the water and distributes secretion from its metathoracic glands over the ventral part of its body. By this ‘secretion‐grooming’ antiseptic gland substances, mostly hydrogen peroxide, are applied to the hydrofuge hairs which hold the respiratory air bubble.2. When the bugs are prevented from leaving the water, their mortality increases significantly, and individuals lacking the air bubble are observed. Examination of such bugs with Scanning Electron Microscopy techniques reveals bacteria growing on their hydrofuge hairs, whereas in bugs allowed to secretion‐groom the hairs are not contaminated by microorganisms.3. Artificial application of diluted metathoracic gland secretion on the body surface ofP. minutissimakills bacteria, while specific ciliates, which never colonize the respiratory region, are not harmed by the secretion.4. It can be concluded that secretion‐grooming prevents the contamination of the hydrofuge respiratory region that leads to the wetting of the hydrofuge respiratory regions, resulting in the loss of the air bubble, and, finally, the drowning of the animals.5. Other possible functions of the secretion, such as chemical defence against predators or wetting of the body surface, could not be demonstrated or seem

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1989.tb00942.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Abstract.1. ViableMansoniaegg masses occur in nature on both the upper and under surfaces ofPistia stratiotes(L.) leaves. Upper‐surface masses were fromMansonia dyariBelkin, Heinemann&Page, but lower‐surface oviposition was attributable to bothM. dyariandM. titillansWalker.2. Upper‐surface egg masses were often out of water but were concentrated near a wet‐dry stain line on the leaf. Lower‐surface masses were laid underwater within 3 mm of the leaf edge, except for those oviposited through fenestrations caused by insect damage.3. Oviposition varied seasonally and masses were most numerous between August and December when water lettuce plants were large and crowded. Egg masses were clumped on plants and leaves and concentrated on mature or mature‐old leaves that subtended mean angles of 28–34° from the horizontal.4. On intact plants in cages,M. dyarilaid egg masses on both leaf surfaces in approximately the same proportions as observed in nature. On detached leaves floating flat on the water,M. dyarilaid all masses on under surfaces.5. At 20 and 25°C, egg development ofM. dyarirequired 17.4 and 8.8 days (means), these being significantly longer than the mean times forM. titillans.Some larvae from eggs that hatched in the absence of water survived 72 h in the eggshell.6. Upper‐surface oviposition byM. dyarimay be an adaptation to the crowded growth of water lettuce, the mosquito's favoured host plant, whose leaves are largely out of water. Leaf ageing and subsidence cause submergence of most upper‐surface eggs by t

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1989.tb00943.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Abstract.1. OvipositingEurema brigitta(Wallace) andEurema herla(W. S. Macleay) butterflies were followed in the field to determine the nature and extent of the pre‐alighting discrimination shown by these insects towards their only host plant,Cassia mimosoides(L).2. Both species tended to search in areas where plants with long, thin leaves (primarily grasses) were less common, on average, than in randomly placed quadrats. Both species were also more likely to alight on non‐host plants with leaves of a similar size and shape to those of the host plant than on non‐hosts with leaf shapes dissimilar to that of the host.3. The search behaviour of these monophagous insects was not so specialized that the butterflies never alighted on non‐hosts; in fact the majority of alightings were on non‐host plants and the pre‐alighting discrimination shown by these insects is clearly not the prime behavioural determinant of thei

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1989.tb00944.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Abstract.1. Seasonal patterns of adult emergence, host‐seeking and reproductive ageing in a population of the woodland mosquitoAedes punctor(Kirby) are described from field studies in northern Britain in 1984 and 1985.2. The pattern of emergence showed little variation between years but duration did vary. Males started emerging before females. Sex ratios at emergence showed a marked female bias. A late, second period of emergence apparently represented a second generation in this normally univoltine species.3. Host‐seeking females were first caught at human bait within a few days of the start of emergence and peak numbers at bait occurred 3–4 weeks later. High numbers lasted forc.2 weeks. The duration of host‐seeking activity was related to weather. The second emergence in 1985 resulted in a second peak of activity in early September and probably extended the flight season.4. As the season progressed the proportion of females that were parous increased. However, this proportion never reached 1.0, indicating variation in individual reproductive success, which differed between years.5. The reproductive biology of individuals within the population was investigated. No autogeny was detected, suggesting that the population was entirely anaut

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1989.tb00945.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Abstract.1. The relationships between the timing of oviposition, larval establishment and host development were studied in the tephritidsTephritis bardanae(Schrank) andCerajocera tussilaginis(Fab.) which attack flowerheads ofArctium minus(Hill) Bernh. (Compositae).2.T. bardanaelaid eggs in small sized flowerheads that were at an early stage of development, and appeared to use the external dimensions of the head as an oviposition cue. In contrast,C. tussilaginisfemales laid eggs into heads that were near to flowering and the timing of their attack was most closely related to particular lengths of florets and achenes inside the head. Both tephritids apparently recognized suitable heads by comparing aspects of their own body size with the size of particular flowerhead structures.3. Individual heads were suitable for oviposition for a period of 10–11 days for both species, but the periods of susceptibility to each species did not overlap.4. Attack byT. bardanaewas timed to exploit the flowering phase of flowerhead development. Larval establishment and early development were synchronized with increasing nutrient availability occurring during the rapid growth of the florets and achenes before and during anthesis.5. In contrast, the later attack byC. tussilaginiswas timed to exploit the seed maturation phase of head development. IndividualC. tussilaginislarvae operated as highly specialized ‘achene parasites’, utilizing the influx of nutrients into single achenes after fertilization.6. Larvae of both tephritids induced abnormal host‐tissue growth, but oviposition in both species was timed primarily to synchronize larval development with natural periods of high nutrient availability inside flowerheads, rather than with the presence of tissues suitable for gall in

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1989.tb00946.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY