摘要:

ABSTRACT.1. Studies involving experiments with olfactometers and field experiments have shown that the release of sex‐pheromone by females ofYponomeutaspp. is stimulated by the presence of host plants.2. While inY.evonymellus L.less females emitted pheromone in the absence of host plants, inY.padellusL. the initiation of pheromone release was delayed.3. Females ofY.evonymellus, Y.cagnagellusHüb.,Y.padellusandY.plumbellusD.&S. all preferred a place with host‐plant odour to one with non‐host odours for sex‐pheromone release.4. Male preference for host‐plant odour was demonstrated in the laboratory only forY.cagnagellus.5. Trap catches in the field indicated a reinforcement of female attractiveness by host‐p

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1987.tb01017.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACT.1. The pedunculate oak,Quercus rohurL., suffers high annual levels of spring defoliation in Wytham Woods. near Oxford.2. This spring defoliation affects late season caterpillars through a variety of damage‐induced changes in the leaves.3.Diurnea fagella(D.&S.), one of the commonest late season caterpillars, shows reduced larval survival and pupal weight on regrowth foliage when compared to undamaged primary foliage.4.D. fagellaalso suffer higher larval mortality on naturally damaged primary foliage than they do on undamaged foliage.5. Despite this, the three commonest late season caterpillar species are more abundant on damaged trees than undamaged ones. and their distributions are biased towards damaged leaves within the canopy.6. Other factors that may be more important than leaf damage in determining the distribution and abundance of late season caterpillars are discussed.D.fagellalarvae spin their larval refuges more rapidly on damaged than undamaged foliage, and this may reduce mortality by natural enemies, or ameliorate adverse effects of weathe

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1987.tb01018.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACT.1. Current models of insect oviposition predict that clutch size in parasitoids should correlate with host size, with a continuum from solitary species at one end to large gregarious broods at the other. This prediction is tested for the genusApanteles (sensu lato).2. The distribution of brood sizes inApantelesis bimodal, with peaks at one (solitary species) and at about twenty (gregarious species).3. Brood size of gregarious species correlates with host size, but when a measure of the total volume of a parasitoid brood is plotted against host size, solitary species do not lie on the same regression slope as gregarious species.4. There is a relative shortage of gregarious species on small hosts, and a relative excess of solitary species on large hosts. Solitary species on large hosts do not fully consume the host resource.5. The possible role of evolutionary constraints to adaptive progeny allocation inApantelesis discussed.

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1987.tb01019.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACT.1. We investigated the influence of larval density on egg hatching in the treehole mosquito,Aedes triseriatusSay (Diptera: Culicidae) by submerging laboratory‐produced egg batches in natural habitats stocked with fixed densities of larvae.2. We found a significant decrease in hatching rate as larval density increased. The results suggest that inhibited eggs refrain from hatching into environments in which competitive effects of large larvae are potentially severe, and in which cannibalism may occur.3. The amount of time the egg batches were exposed to experimental conditions (between 2 and 16 days) had no significant influence on hatch rat

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1987.tb01020.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACT.1.Euphydryas editha(Boisduval) (Nymphalidae) butterflies exhibited no consistent pattern of change in egg weight over their lifetimes. This was the case for captive butterflies fed diets containing sugars and amino acids, for butterflies fed diets containing only sugar, and for those left completely at liberty in their natural habitats between ovipositions.2. Two aspects of these results conflict with the findings of a previous study on the same subspecies. First, the previous study found that egg weight decreased with increasing maternal age. Second, this decrease was mitigated by addition of amino acids to the adult diet.3. We accept the findings of these previous workers that egg weight decreased with maternal age under their laboratory conditions. The discrepancy between their data and ours is likely to stem from the more natural conditions under which our insects were kept. Our own data from captive insects are not distinguishable from our field data.4. These results suggest that declines of egg weight with maternal age found in studies of other insects may also result from the artificial nature of laboratory conditions. We question whether such declines are general.5. We suggest that the second discrepancy between the two sets of work (effects of amino acids) stems from a design problem in the previous study.

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1987.tb01021.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACT.1. We test the hypothesis that defoliation has short‐term and long‐term negative effects on performance of winter mothOperophtera brumataL. on two species of food plants: Garry oak (Quercus garryanaDougl.) and apple (Malus domesticusL.).2. Pupal weight (and hence potential fecundity of females) decreased with increased defoliation in the current year on both tree species.3. Pupal weight increased, however, with increased level of defoliation in the previous year.4. Increased weight of pupae from larvae which had fed on previously defoliated trees may buffer population decline by increasing fecundity of moths in the next generat

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1987.tb01022.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACT.1. The nesting behaviour ofKheper platynotus(Bates) was observed in the Tsavo West National Park, east Kenya.2. The construction of the brood ball seemed to be initiated by the female; thereafter, the male joined in. After its construction, the ball was rolled and buried by the male, whilst the female rode on the ball and occasionally helped the male.3. After burying the ball, the male came out on the ground, leaving the female under‐ground. The female coated the ball with soil and her excrement, and let it ferment for about 2 weeks. Thereafter, the female converted the ball into one to four free‐standing brood pears, and laid one egg in each pear. The number of pears produced depended on the size of ball. Even after oviposition, the female remained in the nest to care for the brood.4. Oocytes matured a little before being laid. Excess oocytes were gradually assimilated during brood care.5. Females seemed most likely to breed in two or more successive rainy seasons.6. Although male‐male aggression was observed, size assortative mating was not obs

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1987.tb01023.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACT.1. Two superficially similar species ofMicrobembex, M.monodonta(Say) andM.cubanaBohart (Hymenoptera, Sphecidae, Nyssoninae), occur syntopically on Staniel Cay, a small Bahamian island (15 km2).2. Nesting (female) and territorial (male) aggregations ofM.cubanawere smaller and more numerous than those ofM.monodontain the study site and on the island as a whole.3. Both species had regular patterns of daily activities that required them to use a variety of microhabitats in the study area.4. Males of both species defended territories fromc.09.00 to 12.00 hours EST (in May) and the left to feed on nectar until they retired to sleeping burrows, typically from 13.00 to 15.00 hours. MaleM.monodontawere active longer each day and intermixed feeding and territorial defence more than did maleM.cubana.5. Females of both species were active for longer each day, fromc.08.30 to 15.30 hours, and intermixed their respective activities – hunting for provisions, feeding, and nest digging and maintenance – during each day more than did males. FemaleM.monodontawere active longer each day, rising earlier and retiring later, than femaleM.cubana.6. InM.monodonta, females were larger (length, X =11.00 mm) than males (10.5 mm). InM.cubana, males were larger (11.1 mm) than females (10.4 mm). Although mean differences were small, they were highly significant (F=22.42;P<10−4) for the species‐sex interaction.7. Differences in activity budgets, habitat use, and sexual size dimorphism appear to be related. A combination of factors, particularly thermal constraints, possible competition, and different mating systems, could explain these p

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1987.tb01024.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACT.1. Deme formation is the transformation of a generalist population into one which is adapted to its local conditions. This adaptation has been inferred from many things but should be inferred from higher survival or fecundity of scale insects on their natal tree compared to that of immigrant scales on the same tree.2. Transfers of the scale insectMatsucoccus acalyptusHerbert within and between infested host trees (Pinus monophylla(Torr.&Frem.) resulted in significant differences in scale survivorship among recipient trees. Survival on individual trees was correlated across years, indicating stable differences in tree susceptibility to scale.3. A significant natal tree colonized tree interaction was observed for late stage scale survival in one experiment but the interaction was not caused by superior survivorship of scales transferred back to the natal tree. Hence, we found no evidence of deme formation inM.acalyptus.4. Previous studies have concluded that deme formation occurs in the black pineleaf scale based on a significant natal tree by colonized tree interaction in scale survival. We question this conclusion because the experimental design employed did not include transfers back onto the natal tree. Other indirect evidence for deme formation in scale insects is critically discussed.

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1987.tb01025.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

ABSTRACT.1.Megaloceraea recticornis(Geoffroy) is the most common of seven species of stenodemine bugs on a calcareous grassland in Oxfordshire. Previous work indicated that it competed with a related species,Notostira elongataGeoffroy, by behavioural interference at the feeding site. Both bugs were thought to eat only grass leaves.2. The importance of grass flowers in the diet ofM.recticorniswas studied in the laboratory. This bug completes its development only by feeding on grass flowers; grass leaves do not suffice.3.M.recticornisis unusual among phytophagous insects in that its later instars can eat flowers of the grassBrachypodium pinnatumL. The hard lemma and palea surrounding these flowers inhibit feeding by young bugs. The age of the flowers also affect bug feeding success.4. The result of field experiments, which previously appeared to show competition betweenM.recticornisandN.elongata, are discussed in the light of the present findings. It now seems thatM.recticornismay not suffer from competition withN.elongata.

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1987.tb01026.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY