bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mating strategy and isolation between the two forms, macrogyna and microgyna, of Myrmica ruginodis (Hym. Formicidae)
Authors: ELMES G. W. 
Published: March 2008

Abstract.

It is shown that the size distribution and degree of overlap between individual queens of the two forms of Myrmica ruginodis, microgyna and macrogyna, is exactly the same in southern England as was originally described from Scotland.
Distinguishing colonies of the two forms is not as easy as distinguishing between individuals, both types can be polygynous and approximately 25% of colonies contain a mixture of queens.
Males of the two forms can be distinguished solely on the basis of size and, in general, macrogyna colonies produce larger males, workers and gynes than microgyna colonies. There is little correlation between the sizes of males, workers and gynes in colonies within the macrogyna and microgyna groups.
If the two forms are separate species and mixing is a parasitic association (as suggested elsewhere), then there should be breeding isolation between the forms. This is tested by examining data from nine mating‐swarms.
All the swarms contain a significant proportion of the microgyna form. There is no evidence of assortative mating, although larger males are more likely to get a mate than smaller ones. This behaviour, combined with the possibility that microgynes mate near to the nest, might prevent complete mixing during mating.
The status of the forms is discussed. Besides the possibility of a‘pre‐parasitic’relationship it is suggested that the forms might represent a polymorphism, present in all populations, the balance between them being the result of selection determined by local environmental factors.
The role of larval nutrition in pre‐imaginal biasing of caste in the primitively eusocial wasp Ropalidia marginata (Hymenoptera: Vespidae)
Authors: GADAGKAR RAGHAVENDRA , BHAGAVAN SEETHA , CHANDRASHEKARA K. , VINUTHA C. 
Published: March 2008

Abstract.

When freshly eclosed females of the primitively eusocial wasp Ropalidia marginata (Lep.) are isolated, only about 50% of them build nests and lay eggs thereby suggesting a pre‐imaginal biasing of caste.
Wasps that lay eggs take a very variable amount of time after eclosion to start doing so.
Females eclosing from nests where larvae are fed at a relatively higher rate are more likely to become egg‐layers and are likely to take less time after eclosion to begin to lay eggs.
Thus, both forms of pre‐imaginal biasing of caste, namely, differences in egg laying capacity and differences in the time taken to attain reproductive maturity, appear to be influenced by larval nutrition.
Searching strategies and attack rates of parasitoids of the ash bark beetle (Leperisinus varius) and its relevance to biological control
Authors: MILLS N. J. 
Published: March 2008

Abstract.

Point estimates of parasitoid behaviour indicated that braconid parasitoids of the bark beetle, Leperisinus varius, spend 70% of their host searching time stationary on the bark surface, in sharp contrast to the chalcidoid parasitoids which spend 60–70% of their host searching time moving across the bark surface.
Aggressive encounters between searching parasitoids are common and the data suggest that they do not occur at random.
The chalcidoid parasitoids, Cheiropachus quadrum and Eurytoma morio, are more frequently involved in aggressive encounters than expected and can displace ovipositing individuals of other species.
Attack rates for the parasitoids were estimated to vary from two hosts per day for the braconid Coeloides filiformis to four hosts per day for E.morio, and net reproductive rates vaned from 6.3 for C.filiformis to 0.8 for Coeloides melanotus.
These data suggest that while all parasitoids of the scolytid can act as primary parasitoids, at least some of the chalcidoid parasitoids are facultative cleptoparasitoids and should be avoided in classical biological control introductions.
The time and egg budget of Leptopilina clavipes, a parasitoid of larval Drosophila
Authors: DRIESSEN GERARD , HEMERIK LIA 
Published: March 2008

Abstract.

For the understanding of the influence of natural selection on the persistence of host selection behaviour in populations of Drosophila parasitoids it is important to know whether parasitoids will become time‐ or egg‐limited. We investigated whether the Drosophila parasitoid Leptopilina clavipes (Hartig) meets egg‐ or time‐limited conditions in the field.
To this end the following aspects of the parasitoid's life were studied: egg load at emergence, travelling velocity between patches, patch residence times, oviposition rates and life expectancy. Together with the results from earlier studies on host and patch distributions, this formed the input of a ‘Monte Carlo’ simulation model, in which the life history of an individual parasitoid can be traced.
The simulations revealed that under the conditions found in the field 12.9% of the parasitoid population is egg‐limited. The model was also run for a number of scenarios which reflect ‘good’ or ‘bad’ circumstances. In most cases a significant proportion of the parasitoid population proved to be egg‐limited.
For the measurement of travelling velocities and patch residence times a marking method, especially applicable to small‐sized parasitoids such as L.clavipes, is described. Marking did not affect survival, host habitat location or host detection rate. Parasitoids were found to be attracted to the odour of fruit‐bodies of Phallus impudicus, the most important breeding substrate of their hosts.
To hatch or not to hatch? Egg hatch response to larval density and to larval contact in a treehole mosquito
Authors: EDGERLY JANICE S. , MARVIER MICHELLE A. 
Published: March 2008

Abstract.

We investigated the effect on egg hatch of exposure to: (1) varying larval density, and (2) larval contact in Aedes triseriatus Say (Diptera: Culicidae). For 2 days in the laboratory we submerged eggs into a treehole water medium containing 0 (control), 4, 12 or 24 larvae that could either contact the eggs directly or were separated from them by a screen. Following treatment, abundance of microorganisms on the egg surfaces, a food source for newly hatched larvae and a proposed hatching stimulus, was assessed by counts made from serial dilutions of samples.
We discovered a complex hatching response to larval contact and to larval density, and an interaction between these two factors in their effect on microbial growth. Hatching was inhibited in the 0‐larva control, even though microorganisms grew abundantly on the eggs. Hatch rate, as well as microbial counts, were high for eggs in direct contact with 4 larvae. As density increased in the larval contact treatment, microorganisms disappeared from the egg surfaces and hatch rate declined.
When protected from larval grazing, eggs supported numerous microbial colonies irrespective of larval density. In contrast to the contact treatment group, egg hatch increased with increasing larval density. These observations suggest that the combination of microbial growth and a larval factor stimulates hatch. This hatching response may have evolved because both abundant microorganisms and numerous larvae reflect a habitat of good quality.
Activity pattern and thermal biology of a day‐flying hawkmoth (Macroglossum stellatarum) under Mediterranean summer conditions
Authors: HERRERA CARLOS M. 
Published: March 2008

Abstract.

The daily activity pattern and aspects of the thermal biology are described for the day‐flying hawkmoth, Macroglossum stellatarum L. (Lepidoptera: Sphingidae), while foraging at a flowering population of Lavandula latifolia (Labiatae) under the dry‐hot summer conditions of a southeastern Spanish locality.
The average abundance of M.stellatarum remained fairly constant from sunrise to about 17.00 hours (GMT), and a distinct peak occurred in the evening (18.00—20.00 hours).
Foraging took place over a broad range of microclimatic conditions, as described by air temperature (Ta; range 19‐36°C) and solar radiation (IR; range 1–1025 Wm‐2).
The thoracic temperature (Tth) of insects remained within relatively narrow limits (39–46°C), with the highest values occurring around noon. Variation in Tth mainly reflected differences in Ta between foraging sites and times. Tth was nonlinearly related to Ta, the rate of increase of Tth with Ta decreasing with increasing Ta.
The unusual tolerance of high Tth exhibited by M.stellatarum, and its enhanced thermoregulatory capacity at high Ta, enable this species to withstand the severe environmental conditions faced during diurnal foraging in the Mediterranean summer.
Density‐dependent egg dispersion in flowers of Silene vulgaris by the seed predator Hadena confusa (Noctuidae)
Authors: PETTERSSON MATS W. 
Published: March 2008

Abstract.

Hadena moths drink nectar from, pollinate, and oviposit into the flowers of the genus Silene. In the gynodioecious Silene vulgaris (Moench) Garcke (Caryophyllaceae), eggs were laid by Hadena confusa (Hufn.) females both in male phase flowers, which could not be pollinated by the moth at the time of oviposition, and in female phase and female flowers that allowed pollination.
Flowers in which an egg had been laid had a lowered probability of receiving a second egg laid by another female during the same night.
The degree of flower discrimination by the moth with respect to the presence of eggs was positively correlated with the proportion of flowers containing eggs.
The oviposition behaviour of H.confusa is moulded by four factors: (1) a high probability of chosen male phase flowers later becoming pollinated by other moths, (2) the presence of conspecific eggs and risk for larval competition, (3) probability of presence of conspecific eggs also in neighbouring flowers, (4) capability of larvae to move to adjacent flowers.
Heterogeneity and density dependence in a field study of a tephritid‐parasitoid interaction
Authors: REDFERN M. , JONES T. H. , HASSELL M. P. 
Published: March 2008

Abstract.

The spatial distributions of two tephritid flies (Urophora stylata (Fabricius) and Terellia serratulae L.) attacking thistle flower heads and the levels of parasitism from their associated parasitoid guilds were studied over a 7‐year period.
Using these data it is possible to seek both temporal, density dependent relationships between average levels of parasitism and host density per generation, and also any spatial patterns of parasitism contributing to stability that may be operating within the same field system.
Parasitism by the two most important generalist parasitoids of T.serratulae is a direct function of average T.serratulae density per year. There is little evidence of any stabilizing heterogeneity arising from the spatial distribution of parasitism within generations.
Temporal density dependence of Urophora stylata cannot be confirmed from the 7 years of study but there is evidence of spatial heterogeneity which may have an important effect on the dynamics of the host population.
Nectarivore foraging ecology: rewards differing in sugar types
Authors: WELLS HARRINGTON , HILL PEGGY S. , WELLS PATRICK H. 
Published: March 2008

Abstract.

Honey bees, visiting artificial flower patches, were used as a model system to study the effects of sugar type (sucrose, glucose, fructose, and mixed monosaccharide), caloric reward, and floral colour on nectarivore foraging behaviour. Observed behaviour was compared to the predictions of various (sometimes contradictory) foraging models.
Bees drank indiscriminately from flowers in patches with a blue‐white flower dimorphism when caloric values of rewards were equal (e.g. 1M sucrose in both colours; 1 M sucrose versus 2 M monosaccharide of either type), but when nectar caloric rewards were unequal, they switched to the flower colour with the calorically greater reward.
In yellow‐blue dimorphic flower patches, on the other hand, bees did not maximize caloric reward. Rather, bees were individually constant, some to blue, others to yellow, regardless of the sugar types or energy content of the rewards provided in the two flower morphs.
The results suggest that optimal foraging theory (maximization of net caloric gain per unit time) is a robust predictor of behaviour with regard to the sugar types common to nectars; such optimal foraging is, however, limited by a superstructure of individual constancy.
The first parasitic Trichoptera
Authors: WELLS ALICE 
Published: March 2008

Abstract.

A parasitoid habit is confirmed in larvae of an Australian micro‐caddisfly, Orthotrichia muscari Wells, being the first known incidence of this habit in the order Trichoptera.
Larvae of O.muscari are non‐specific parasites of pupae of other caddisfly species.
O.muscari is in an Australian/New Guinean/SE Asian species group in Orthotrichia, all members of which probably share the habit. Their larvae and pupae have atypical features that are interpreted as adaptations to their uncharacteristic niche.
Correlates of reproductive success among field colonies of Bombus lucorum: the importance of growth and parasites
Authors: MÜLLER CHRISTINE B. , SCHMID‐HEMPEL PAUL 
Published: March 2008

Abstract.

In natural populations, colonies of bumble bees vary in many important life history traits, such as colony size and age at maturity, or the number and sex of reproductives produced. We investigated how the presence of parasites in field populations of the bumble bee Bombus lucorum L. relates to variation in life history traits and reproductive performance. A total of thirty‐six colonies was placed in accessible nest sites in the field and monitored at regular intervals throughout a season.
Among the life history correlates, early nest foundation was strongly associated with large maximum colony size, old age and large size at maturity, and this in turn with successful production of males and queens, as well as with the number of sexuals produced. Overall, reproductive success was highly skewed with only five colonies producing all the queens. Sixteen colonies failed to reproduce altogether.
The social parasite Psithyrus was abundant early in the Bombus colony cycle and preferentially invaded host nests with many first brood workers and thus disproportionately large size, i.e. those colonies that would otherwise be more likely to reproduce or produce (daughter) queens rather than males. To prevent nest loss, Psithyrus had to be removed soon after invasion. Therefore, the effects reported here can only be crude estimates.
Parasitoid conopid flies are likely to cause heavy worker mortality when sexuals are reared by the colonies. Their inferred effect was a reduction in biomass that could be invested in sexuals as well as a shift in the sex ratio at the population level resulting from failure to produce queens. We suggest to group the inferred correlates into ‘early events’ surrounding colony initiation and social parasitism, and ‘late events’ surrounding attained colony size in summer and parasitism by conopid flies. Our evidence thus provides a heuristic approach to understand the factors that affect reproductive success of Bombus colonies.
Host behaviour modification by the endoparasitoid Aphidius nigripes: a strategy to reduce hyperparasitism
Authors: BRODEUR JACQUES , McNEIL JEREMY N. 
Published: March 2008

Abstract. 1. One possible component of successful parasitism by insect parasitoids is the reduction of predation and hyperparasitism through the modification of host behaviour.2. Just prior to death, potato aphids, Macrosiphum euphorbiae (Thomas), containing diapausing larvae of the parasitoid Aphidius nigripes Ashmead have been shown to leave the host plant to mummify in concealed sites, while those parasitized by non‐diapausing individuals generally leave the aphid colony to mummify on the upper leaf surfaces.3. The present study examines the within plant distribution of aphids and mummies containing non‐diapausing A.nigripes, and compares parasitoid survival among microhabitats under field conditions.4. On potato, Solunum tuberosum L., a significant proportion of aphids were found on lower leaf surfaces, whereas mummies were usually on the upper surfaces, particularly in the apical stratum of the plant canopy.5. In both field surveys and experimental manipulations, parasitoid survival was higher on the upper surface of apical leaves than in other microhabitats, due to lower levels of hyperparasitism and, to a lesser extent, lower predation. This suggests that the pressure exerted by natural enemies has influenced the evolution of host behaviour modification.
The effect of superparasitism on development of the solitary parasitoid wasp, Venturia canescens (Hymenoptera: Ichneumonidae)
Authors: HARVEY JEFFREY A. , HARVEY IAN F. , THOMPSON DAVID J. 
Published: March 2008

Abstract.

The effects of superparasitism on the rate of development, adult size and mortality of Venturia canescens (Hymenoptera: Ichneumonidae) were investigated. Parasitoids were reared from third (L3) and fifth (L5) instars of one of its hosts, Plodia interpunctella (Lepidoptera: Pyralidae) containing one, two or four parasitoid eggs.
Superparasitism increased the development time of Venturia reared from both instars, but the developmental delay was more evident in wasps from L5 hosts.
The size of parasitoids from L3 hosts was unaffected by egg number, but wasps from both superparasitized L5 treatments were significantly smaller than those from singly parasitized hosts.
Parasitoid mortality was significantly higher in L5 than L3, but within instars did not differ significantly with egg number.
The results confirm that superparasitism may affect the fitness of both the adult female wasp and her progeny, and should therefore be incorporated into models of superparasitism as an adaptive foraging strategy.
Phenotypic variation in colour pattern and seasonal plasticity in Eristalis hoverflies (Diptera: Syrphidae)
Authors: HOLLOWAY GRAHAM J. 
Published: March 2008

Abstract.

An examination of phenotypic variation in colour pattern was carried out on four Eristalis hoverfly species using museum material.
The amount of phenotypic variation varied substantially among the species with E.arbustorum being the most variable. The other species showed a wide colour pattern range but less variation within that range (E.abusivus and E.nemorum), or a narrow range of colour variation (E.horticola).
Sexual colour dimorphism was apparent in all four species, but most pronounced in E.abusivus and E.nemorum.
There were good phenotype‐season relationships shown by both sexes in all species, except for female E.abusivus and E.nemorum, with paler insects being more abundant during the warmer summer months.
Female, but not male, E.arbustorum collected at inland sites were on average paler than those collected at coastal sites. This observation is considered with respect to temperature during the developmental stages.
The function of colour plasticity in hoverflies is discussed with reference to the need to maintain optimal thermal conditions for activity.
Density‐dependent regulation of Aedes cantans (Diptera: Culicidae) in natural and artificial populations
Authors: RENSHAW M. , SERVICE M. W. , BIRLEY M. H. 
Published: March 2008

Abstract.

Mortality and size variation (siphon length) in Aedes cantans larvae were examined in natural populations in northern England in 1989 and 1990.
Under crowded conditions, density‐dependent competition led to reduction in the size of both larvae and adults and increased larval mortality.
Larvae were also maintained in cages in the field at different densities. Results paralleled those for the natural populations in the ponds; larvae maintained at high densities showed increased mortality and reduced size.
Possible density‐dependent factors leading to mortality and size reduction include cannibalism and contact inhibition leading to food shortages.
The main density‐independent factor contributing to larval mortality was habitat desiccation.
Asymmetric competition in cattle dung between two species of Onthophagus dung beetle and the bush fly, Musca vetustissima
Authors: RIDSDILL‐SMITH T. J. 
Published: March 2008

Abstract.

Competition in cattle dung pads between two dung beetles, Onthophagus ferox Harold and Onthophagus binodis Thunberg, and the bush fly, Musca vetustissima Walker, was investigated in laboratory experiments, to determine why spring fly abundance in the field did not fall following the introduction of O. binodis.
At low beetle densities, the number of eggs laid by each species was reduced by the second species. A similar amount of dung was buried by each species alone or by both together.
At high beetle densities O. binodis egg production was substantially affected by each additional O.ferox, but O.ferox egg production was not affected by each additional O.binodis. Asymmetric competition occurred because O.ferox buried more dung than O.binodis, and a greater proportion in day 1 (pre‐emptive dung burial).
O.ferox caused greater M. vetustissima egg‐puparia mortality than O. binodis. Mortality mostly occurred in young M. vetustissima larvae less than 1 day old. Total egg‐puparia fly mortality was correlated better with the dung buried on day 1 than dung buried on day 8 (pre‐emptive dung burial). O.binodis did not add to fly mortality by O.ferox at high densities because of asymmetric competition between the beetles.
The frequency of detection of density dependence in insect orders
Authors: HOLYOAK M. 
Published: March 2008

Abstract.

A priori, there are no obvious reasons why patterns should exist in the frequency of density dependence across insect orders. However, orders may reflect related factors which influence population regulation (e.g. life‐history patterns and ecology) and are difficult to quantify. The frequency of occurrence of density dependence is compared in 171 time series (of ten or more generations) from Lepidoptera, Hemiptera, Diptera, Odonata, Hymenoptera and Coleoptera. A posteriori attempts are made to identify the cause of observed patterns.
Buhner's (1975) test found non‐delayed density dependence more frequently in Odonata than Lepidoptera and Hymenoptera, which in turn showed non‐delayed density dependence more frequently than Diptera, Hemiptera and Coleoptera. Similarly, detection was greater for Odonata than other orders using Dennis & Taper's (1993) test for density dependence and Crowley's (1992) test for attraction. Varley & Gradwell's (1960) test found density dependence less frequently in Hemiptera than other orders. These differences were independent of time series length, temporal trends and numbers of generations per year.
The reasons for observed patterns in detection of density dependence (and attraction) in insect orders are not clear; however, plausible explanations are differences in: (i) intrinsic growth rate, which is correlated with body size (although evidence to support this hypothesis is weak); (ii) the sampling method used; or (iii) whether individuals come from a single population or many populations.
Using Turchin's (1990) test, delayed (lag 2) density dependence was detected most frequently in Hymenoptera, which often show delayed diapause or are parasitoids.