bluuebunny/crossref_metadata_2025 huggingface dataset:
Mimicry in the burnet mothZygaena ephialtes: population studies and evidence of a Batesian—Müllerian situation
Authors: SBORDONI V. , BULLINI L. , SCARPELLI G. , FORESTIERO S. , RAMPINI M.
Published: March 2008

Abstract.1. Population size as well as the absolute and relative frequencies of thephegeaandfilipendulaemimetic complexes have been estimated in an area of Central Italy selected because it is: (a) little affected by man, (b) representative of many others in the Central Appennines, and (c) containing an abundant population ofZygaena ephialtes.

2. This distasteful polymorphic species belongs, in Central Italy as in other Southern areas, to thephegeacomplex (Zygaena ephialtes, yellow ephialtoid form), while in Northern and Central Europe it belongs to thefilipendulaecomplex (Z.ephialtes, red peucedanoid form).

3. In the Southern areas thephegeacomplex is much more abundant than thefilipendulaeone, which gives the yellow ephialtoid form ofZ.ephialtesa strong mimetic advantage over the red peucedanoid.

4. In addition,Amata phegeagreatly outnumbers the other distasteful members of its complex and emerges first.

5. Throughout its flight periodZ.ephialtes, which emerges about 20 days later thanA.phegea, never attains a frequency higher than 0.03 in this complex. It is suggested that in such a situation the protection that this species gains as a mimic would be very high regardless of its unpalatability.

6. These findings and others discussed in the present paper, such as the degree of unpalatability, the genetics of the mimetic form as well as the polymorphism for colour and pattern, are examined according to the hypothesis of divergent evolutionary strategies in Batesian and Müllerian mimicry. It is suggested that these are meaningful concepts but that individual mimics, of whichZ.ephialtesis one, can fall between them.
An analysis of the nesting behaviour of Geotrupes spiniger Marsham (Coleoptera, Scarabaeidae)
Authors: KLEMPERER H. G.
Published: March 2008

Abstract. 1. Female G.spiniger adults working alone made nests each consisting of a vertical shaft leading to a series of horizontal brood chambers filled with dung brood masses. Oviposition near the tip of the brood mass occurred while the egg cell was being completed over the expanded ovipositor. The shaft above each brood mass was filled with soil excavated from the next brood chamber. A similar response also filled artificial diverticula. An avoidance reaction towards buried dung prevented damage to pre‐existing brood masses.

2. Virgin females did not make nests and did not avoid buried dung, but after mating (at about 4 weeks after eclosion) both types of behaviour were released within a few hours.

3. The presence of dung was required to initiate but not to maintain nesting behaviour. If dung was removed after oviposition the chamber was filled with soil produced by renewed excavation. Cellulose pulp could substitute for dung in brood mass formation.

4. Beetles interchanged between burrows at different stages before oviposition readily repeated all pre‐oviposition behaviour. They appeared to respond to the length of the shaft and of the brood chamber since they extended short shafts and short brood chambers considerably more than those of normal length. After oviposition the beetles continued to make brood masses even under abnormal conditions.

5. Tilting the cage through 90° caused beetles before oviposition to re‐orientate their burrowing direction, but tilting just after oviposition caused them to make vertical brood masses. Placing the shaft in a horizontal position towards the end of brood mass formation postponed the termination of this phase.

6. Beetles repeatedly excavated shafts and chambers when transferred to new cages. Conversely they repeatedly made brood masses when maintained in preformed plaster‐of‐Paris burrows.

7. This nesting behaviour can be described as a reaction chain in which each action generates its own terminating stimulus and initiates the subsequent response. The behaviour before oviposition could be omitted or repeated as required by the environment, but after oviposition there was little response to external interference. These characteristics have direct relevance to the survival of the larvae.
The role of fungus in the diet of the leaf‐cutting antAtta cephalotes(L.)
Authors: QUINLAN R. J. , CHERRETT J. M.
Published: March 2008

Abstract.1. The workers and queen of the leaf‐cutting antAtta cephalotesfed on the juice of swollen hyphae (staphylae) produced by their cultivated fungus, but neither obtained sufficient energy from this source for their respiratory needs. The number of staphylae eaten by workers increased with worker size but was not enough to satisfy their energy requirements.

2. Larvae fed on whole staphylae and staphylae previously chewed by workers, and obtained sufficient energy from this source for respiration and growth. No evidence of feeding on fungus hyphae or of trophallaxis between worker and larvae was found. Larvae preferred staphylae to hyphae when fed them artificially and they gained more weight on the former.

3. Worker ants imbibed plant sap during the preparation of plant material for the fungus garden and the uptake of carbohydrate during this process was sufficient to supply their energy needs for approximately 24 h.

4. Staphylae were richer in lipid and carbohydrate, and poorer in protein than ant fungal hyphae.

5. The number of staphylae produced by the fungus gardens of two small nests was comparable with the observed consumption rate but would provide only about 4% of the nest's respiratory requirements.

6. In the light of these findings, a revised view of the role of the fungus in the diet of the ant is discussed.
Overwintering ecology of alpine Collembola and oribatid mites from the Austrian Alps
Authors: SØMME LAURITZ
Published: March 2008

Abstract. 1. Collembola and oribatid mites from windswept mountain ridges at about 2700 m a.s.l. in the Austrian Alps were all killed by freezing, and depend on supercooling to survive low winter temperatures. The Collembola Tetracanthella afurcata Handschin, Xenylla acauda Gisin and Isotoma spp. collected in January had average supercooling points between ‐25 and ‐29°C, and the oribatid mites Fuscozetes fuscipes (Koch) and Lepidozetes singularis Berlese of about ‐28 and ‐31°C respectively. The ability to supercool was not increased during storage at ‐5°C, and was generally lower in species collected in March.

2. The oribatid mites Fuscozetes intermedius Caroli and Maffia, F. fuscipes, Damaeus diversipilis (Willmann) and L.singularis contained from 9 to 16 μg glycerol per mg fresh weight after storage at ‐5°C, while no glycerol could be detected in the Collembola Isotoma spp., T.afurcata and Onychiurus vontoernei Gisin.

3. Activity below 0°C was observed in T.afurcata and O.vontoernei, which had chill‐coma temperatures of ‐7.7 and ‐4.9°C respectively.

4. Some specimens of F.intermedius survived more than 90 days of anoxia at 0°C, T.afurcata up to 60 days and O.vontoernei up to 24 days.

5. The overwintering biology of Collembola and oribatid mites from the Austrian Alps appears similar to that of Norwegian species, except that those from Austria have slightly lower supercooling points and higher contents of glycerol.
Foraging byAtta sexdens(Formicidae: Attini): seasonal patterns, caste and efficiency
Authors: FOWLER HAROLD G. , ROBINSON S. W.
Published: March 2008

Abstract.1.Atta sexdenschanges diel periods of foraging, the size of its foraging territory, the numbers and lengths of foraging trails, and its rate of foraging with respect to seasonality in subtropical Paraguay. Leaf loads are significantly larger in warmer months than loads carried in cooler months.

2. Foragers segregate into three labour groups in the field: a small subset climb trees, cut large quantities of vegetation, and drop them to the ground; the second subset of foragers searches out these leaf caches, cut diem into smaller pieces, and carry and deposit the leaf fragments on the foraging trail; the third subset of workers retrieves leaf fragments on the trail and carry them to the nest.

3. Pitfall trapping shows a large degree of patchiness in activity, with media workers dominating the foraging population, more so closer to vegetation which is being harvested.

4. The recovery efficiency of the multi‐staged foraging behaviour is estimated to be only 49%, with the recovery of leaf caches near 50%. The impact ofA. sexdensmay, thus, be twice as great as previous estimates on their herbivory.
Aspects of host—parasitoid interactions of two aphid parasitoids, Aphidius urticae (Haliday) and Aphidius uzbeckistanicus (Luzhetski) (Hymenoptera, Aphidiidae)
Authors: DRANSFIELD ROBERT D.
Published: March 2008

Abstract. 1. Various aspects were studied of two host‐parasitoid interactions: Aphidius urticae parasitizing the cocksfoot aphid Hyalopteroides humilis and Aphidius uzbeckistanicus parasitizing the cereal aphid Metopolophmm dirhodum. The work formed part of a study on the population dynamics of grassland and cereal aphids in Berkshire, England.

2. A.uzbeckistanicus had a higher instantaneous attack rate but a slightly longer handling time than A.urticae. In both cases the functional response was curvilinear.

3. A.urticae was specific to H.humilis and failed to develop in M.dirhodum. A.uzbeckistanicus could develop successfully in H.humilis but the functional response was sigmoid and the progeny were less fecund than those reared on the natural host. This species showed a clear preference for M.dirhodum when supplied with mixtures of M.dirhodum and H.humilis.

4. A.uzbeckistanicus had a faster rate of development and a lower developmental threshold than A.urticae, a situation paralleled by their natural hosts.

5. The results are discussed in relation to field observations. A.uzbeckistanicus may have considerable potential for reducing cereal aphid numbers. However, its preference for M.dirhodum mitigates against a reservoir being maintained in the economically unimportant grassland aphid, H.humilis.
Repeated copulation in the brown planthopper, Nilaparvata lugens Stál (Homoptera; Delphacidae)
Authors: OH ROK JING
Published: March 2008

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 population.
Cold hardiness of some Alpine Collembola
Authors: BLOCK WILLIAM , ZETTEL JÜRG
Published: March 2008

Abstract.

Individual supercooling points ranged from ‐2 to ‐44°C for six species of springtails, five species from the Swiss Alps and one from lowland Britain. Individuals of Isotomurus alticola (Carl) and Isotoma viridis Bourlet without gut contents had substantially lower supercooling points than those containing food material.

Juveniles were more cold resistant than adults in both I.alticola and Isotoma hiemalis Schött, both with respect to supercooling point and to their survival at prolonged subzero temperatures.

Temperature and acclimation time affected the degree of supercooling of four of the Alpine species especially I.hiemalis.

Duration of culture period had no consistent influence on the supercooling potential of all the species.

Tests for glycerol in the body fluids of the five Alpine springtails were negative, but the presence of a sugar, probably glucose, together with a five carbon polyhydric alcohol was indicated by chromatography.
The distribution and abundance of the British fungal‐breeding Drosophila
Authors: SHORROCKS B. , CHARLESWORTH P.
Published: March 2008

Abstract.

The distribution and abundance of five Drosophila species breeding in fungi are examined by attracting adult flies to baited traps and collecting fungal fruit bodies containing the larval stages.

Changes in species frequency follow a temporal (seasonal and yearly), rather than a spatial (between and within woods) pattern.

There is a regular diurnal pattern of activity in D.subobscura but not in D.phalerata. Temperature, light intensity, humidity and wind speed have no effect upon the daily activity of D.phalerata. Only temperature affects the activity of D.subobscura.

Out of 125 species of fungi collected, only forty‐eight species produced Drosophila. However, the flies are even more selective, since only five species of fungi (Phallus impudicus, Polyporus squamosus, Amanita rubescens, Pluteus cervinus and Lactarius quietus) produce 80% of all Drosophila reared.

The commonest species, D.phalerata, has two or three generations per year with a winter diapause. An outline of the yearly life cycle is given, with the major breeding sites for each generation indicated.

Measures of niche overlap calculated from the data on individual fruit bodies are very low, suggesting that the five species are effectively isolated during the larval period. This ecological isolation is achieved by a summation of several niche dimensions, woodlands, seasons, fungal species, and individual fruiting body differences.
Kleptoparasitic behaviour ofAphodius rufipes(L.) larvae in nests ofGeotrupes spinigerMarsh. (Coleoptera, Scarabaeidae)
Authors: KLEMPERER H. G.
Published: March 2008

Abstract.

Third instar larvae ofA.rufipeswere found in short vertical shafts in the soil beneath horse dung and they entered the underground brood masses ofG.spinigerwhen these occurred beneath the same deposit of dung.

A.rufipeslarvae excavated shafts (60–80mm deep) beneath dung in cages. Just before diapause they burrowed down to the floor of the cage. Burrowing was inhibited in compact soil and in very dry soil. The feeding larvae were attracted to dung and to moisture and they readily attacked other larvae with their mandibles.

In cages which containedG. spinigernests theA.rufipeslarvae burrowed down to feed on theG.spinigerbrood masses.G.spinigereggs and larvae did not act as attractants but they were often destroyed if theA.rufipeslarvae encountered them by chance.

In cages which containedG.stercorarxusnestsA.fossorlarvae burrowed down to feed on the brood masses if no dung was provided at the surface.

This non‐obligatory parasitism arises from the normal behaviour of the larvae and is usually of trivial significance, but under certain conditions the protected environment of an underground nest may favour the survival of the invading larvae.
Diel flight periodicities of some Dytiscidae (Coleoptera) associated with California rice paddies
Authors: ZALOM FRANK G. , GRIGARICK A. A. , WAY MICHAEL O.
Published: March 2008

Abstract. Diel flight periodicities of Eretes sticticus (L.), Hygrotus medialis (LeConte), Laccophilus mexicanus atristernalis Crotch, Liodessus affinis (Say) and Thermonectus basillaris (Harris) were monitored with a rotary net machine and a black light trap. All were affected to some extent by air temperature, light intensity, and wind velocity.

Most flights occur at temperatures of 23–24°C when there is no wind. Flights appear to be limited by temperatures as low as 16°C and as high as 32°C, and variously by wind velocities of 8 kph or more. The relative size and the geographical range of each species may influence its period of peak flight. Larger species tended to initiate flights later in the evening, and had a longer period during which peak flight could occur.
The effects of a fluctuating environment on the water relations of larval Lepidoptera
Authors: WILLMER P. G.
Published: March 2008

Abstract. New techniques for haemolymph analysis under field conditions have permitted studies of short‐term changes in the body fluid concentrations of insects, in association with ambient conditions.

The haemolymph of four species of caterpillar changes in relation to the prevailing relative humidity, but the magnitude of these changes was correlated with the degree of exposure to the environment characteristic of each species and instar. In larvae habitually fully exposed to ambient conditions, haemolymph concentrations normally changed predictably through a day in relation to the humidity. However, osmoregulatory mechanisms operated to keep the increments in osmolality within acceptable limits. For those larvae which inhabit protected microenvironments with constant high humidity, either in association with plants or in conspecific aggregations, ambient humidity had little effect on the blood when this was sampled in situ. But when removed from such habitats, blood osmolality increases were large and rapid, and the larvae often succumbed to desiccation.

The role of biochemical, physiological, behavioural and ecological strategies in establishing the water balance of an insect in its natural surroundings are considered in the light of these findings.
Interaction of a population of the black‐kneed capsid, Blepharidopterus angulatus, and its prey, the lime aphid
Authors: GLEN D. M. , BARLOW N. D.
Published: March 2008

Abstract.

The population dynamics of Blepharidopterus angulatus (Heteroptera: Miridae), preying on the lime aphid, were investigated from 1965 to 1974. Numbers increased or remained stable until 1969, then declined, at least intermittently. K‐factor analysis showed that the key factor was k5+6(loss of adult females, eggs and newly‐hatched nymphs).

Detailed study of numbers and mortalities from 1968 to 1971 showed that loss of adult females was the largest part of k5+6. Studies of flight activity showed most females probably emigrated from the trees before laying eggs, but k5+6 was not related to aphid numbers at the time of peak migration. However, variation in k5+6 depended on the length of time that aphid numbers remained favourable for egg‐laying.

Because of the consistently high emigration of adult females, B.anguhtus numbers increased on average by only 10% when aphid numbers favoured egg‐laying. Nett emigration was usually high, probably because the trees were isolated or in rows, with few sources of immigrants to the South‐West (direction of prevailing wind). Since the population declined by 85% in years when aphids favoured egg‐laying for ≤ 20 days, recovery would be slow after a bad year. Since 1969, 1971 and 1973 were all bad years, this explains the intermittent decline in B.angulatus numbers after 1969.

Simulation showed that neither increased numbers nor faster population growth of B.angulatus would enhance stability of predator and prey populations, but would lead to over‐exploitation of the latter. Given its low observed rate of increase, it is unlikely that B.angulatus could persist on lime at levels much above those recorded.
Adaptations to low temperature in high altitude insects from Mount Kenya
Authors: SØMME LAURITZ , ZACHARIASSEN KARL ERIK
Published: March 2008

Abstract. 1. The strategies for low temperature survival in insects on Mount Kenya were investigated. The insects were collected from their natural habitats and their supercooling points and low temperature tolerances determined.

2. Most insects showed no special adaptations to low temperature survival and seem to depend on spending the cold nights in protected habitats, such as beneath stones and fallen trunks of plants, as well as within the wet frills of dead leaves of alpine plants, where they are protected by the heat released from freezing water.

3. Some insects, e.g. Collembola, aphids and a curculionid beetle, which live in relatively unprotected habitats, had low supercooling points, allowing them to remain unfrozen when exposed to low night temperatures. A nucleator free diet is apparently essential for the survival of such species.

4. Two species of curculionid beetles were found to withstand freezing down to ‐7d̀C. These beetles had nucleating agents in their haemolymph and higher supercooling points than most of the other species studied.

5. A moderate freezing tolerance was found in larvae of a midge that lives in the watery liquid between the leaves of Senecio brassica.
Why a cicada, Mogannia minuta Matsumura, became a pest of sugarcane: an hypothesis based on the theory of ‘escape’
Authors: ITÔ YOSIAKI , NAGAMINE MASAAKI
Published: March 2008

Abstract. 1. Life tables were constructed for natural populations of a cicada. Mogannia minuta, during an outbreak in sugarcane fields at Okinawa to determine possible reasons for the outbreak.

2. The highest mortality during the life cycle was during the beginning of the nymphal stage, and was mainly due to predation by ants.

3. The estimated rate of natural increase based on a survivorship—fecundity schedule in sugarcane fields was near unity, but during the increasing period the rate was estimated to be substantially higher than unity.

4. The rate of natural increase in Miscanthus‐grassland was slightly negative, suggesting that the grassland population was maintained by immigration of adults from sugarcane fields.

5. Escape from predation may be the main cause of the special distribution pattern and the maintenance of extraordinarily high densities for many years.
A 9‐year study of the life cycle of Ephemera danica Müll. (Ephemeridae: Ephemeroptera) in the River Lambourn, England
Authors: WRIGHT J. F. , HILEY P. D. , BERRIE A. D.
Published: March 2008

Abstract. 1. The life cycle of the mayfly, Ephemera danica, was studied on two contrasted sites on the River Lambourn between 1971 and 1979.

2. Quantitative samples of nymphs were taken on the five major biotopes of the river bed, gravel, silt, Ranunculus, Berula and Callitriche. Exposed areas of gravel and silt held significantly lower densities of nymphs than the three macro‐phytes with their underlying substrata. The sandy substratum underlying beds of Berula frequently held significantly higher densities than the other macrophytes.

3. Monthly samples from March 1971 to April 1972 followed by samples in June and December from 1972 to 1979 indicated that the nymphal phase normally took 2 years in the River Lambourn.

4. All odd‐numbered years from 1971 to 1979 produced weak year‐classes. In contrast, all even‐numbered years between 1970 and 1978, with the exception of 1972, produced relatively strong year‐classes.

5. Meteorological data for the period of flight activity in E.danica indicated that conditions were colder and damper in 1972 than in the other even‐numbered years of the study, when recruitment was more successful.
Effects of linear furanocoumarins on an adapted specialist insect (Papilio polyxenes)
Authors: BERENBAUM M.
Published: March 2008

Abstract. 1. Examination of phytochemical literature reveals that a disproportionately large number of hostplants for species in the genus Papilio Section II, and in particular the machaon complex, contain linear furanocoumarins.

2. Although the linear furanocoumarin xanthotoxin is known to be toxic to generalist lepidopterous larvae, it failed to affect adversely the growth and survivorship of Papilio polyxenes, a member of the P.machaon complex that feeds primarily on Umbelliferae containing furanocoumarins, when incorporated into an artificial diet.

3. On the contrary, growth rate and weight gain were significantly improved in the presence of xanthotoxin.

4. It is proposed, based on this experimental evidence and on hostplant utilization patterns, that furanocoumarins play a significant role in the behavioural and biochemical adaptation of Papilio species to their umbelliferous hosts.
Effects of voltinism, interspecific competition and parasitism on the population dynamics of the hemlock scales, Fiorinia externa and Tsugaspidiotus tsugae (Homoptera: Diaspididae)
Authors: McCLURE MARK S.
Published: March 2008

Abstract.

Life tables were constructed for solitary and coexisting populations of univoltine Fiorinia externa Ferris and bivoltine Tsugaspidiotus tsugae (Marlatt) (Homoptera: Diaspididae), two exotic scale pests of eastern hemlock, Tsuga canadensis Carriere, in the northeastern United States.

Solitary and coexisting populations of F. externa had similar survivorship and population growth rates resulting in an annual increase in density of 7–16%. Survivorship of solitary and coexisting populations of T. tsugae also was similar, but growth rates differed substantially. While solitary populations increased their density by 68% annually, populations coexisting with F. extema were reduced 74% each year.

The annual reduction in T. tsugae density where it coexists with F. externa was due in part to interspecific competition which resulted in higher mortality to nymphs from dispersal and starvation and in lower fecundity of adult females relative to solitary populations. A host shift by the parasitoid, Aspidiotiphagus citrinus (Crawford) (Hymenoptera: Aphenlinidae) from F. externa to T. tsugae in autumn also accounted for 71% of the annual decrease in T. tsugae numbers. Therefore, F. externa adversely affects the growth of T. tsugae populations not only because of its superior competitive ability but also because adult para‐sitoids which emerge from it subsequently attack nymphs of T. tsugae in autumn.

Parasitism and starvation of nymphs resulting from competition were the key mortality factors in the population dynamics of these exotic hemlock scales.
The ectoparasitization ofColeophora alticolella(Lepidoptera) in relation to its aititudinal distribution
Authors: RANDALL MARTIN G. M.
Published: March 2008

Abstract.1. The parasitization of the larvae ofColeophora alticolella. feeding onJuncus squarrosus, was investigated at a series of altitudes from 15 to 520m above sea‐level in northern England during 1977 and 1978.

2. Six species of primary parasitoid and one hyperparasitoid were reared from this host. Five of the primary parasitoids were ectophagous; only two specimens of the endoparasitoid,Gonotypus melanostoma, were reared.

3. All of the parasitoid species were recorded at 15 m but fewer at sites of higher altitude. Only one species,Scambus brevicomis, was recorded above 305 m, and none above 395 m. The hyperparasitoid,Tetrastichus endemus, waspresent only at 15 m.

4. Percentage parasitization was highest at 15 m; it was reduced from 51% to only 2% between 215 and 305 m in 1978. There was an increase in host density over this altitudinal range.

5. Three species,Scambus brevicomis. Elachertus olivaceusandEuderus viridis, accounted for most of the parasitization, but their relative proportions vaned at different altitudes.

6. The sex‐ratios of the parasitoids reared fromColeophora alticolellaranged from 3.2% females forScambus brevicomis, which is considered to also use larger hosts, to 99.4% females forElachertus olivaceus, which develops by thelytokous parthenogenesis.

7.Euderus viridisandScambus brevicomisstarted to attack theColeophora alticolellalarvae at a later date at 245 m than at 15 m, but attack byElachertus olivacatswas not delayed at the higher site.
An ant—treehopper mutualism: effects of Formica subsericea on the survival of Vanduzea arquata
Authors: FRITZ ROBERT S.
Published: March 2008

Abstract. 1. The numbers of Formica subsericea (Say) were positively correlated with those of the treehopper, Vanduzea arquata Say on branches of black locust.

2. The mean numbers of V.arquata on branches were greater in the second than in the first generation. However, the mean number of ants tending them was significantly lower in the second compared to the first generation.

3. Defoliation of branches resulted in a reduction in the number of mem‐bracids on branches and ant numbers declined similarly.

4. Survival of V.arquata was significantly greater when tended by F.subsericea than when ants were exciuded.

5. Ant attendance significantly reduced the number of predators on branches with Karquata compared to branches lacking both ants and treehoppers. This, in part, explains the greater survival of V.arquata nymphs tended by ants.
The biology of the eumenid mud‐wasp Pachodynerus msidens in trapnests
Authors: JAYASINGH D. B. , TAFFE C. A.
Published: March 2008

Abstract. 1. The biology of the eumenid mud‐wasp Pachodynems nasidens (Latr.) was studied in trapnests.

2. Females nested in traps placed in the shade and some nested in the same traps from which they had emerged.

3. The nesting behaviour and nest structure were generally similar to those of other eumenids that nest in borings, but a temporary crescent‐shaped plug at the nest entrance and the use of both dry soil and mud for nest‐building seems unique to P.nasidens.

4. Like most other eumenids, P.nasidens collected caterpillars, mainly Pyral‐idae, Olethreutidae, Alucitidae and Thyrididae.

5. In linear nests, the innermost cells contained females and the outermost cells males, resulting in proterandry. One female can make several nests, each showing proterandry.

6. Female immatures were larger and took more time to develop than males. Also, their cells were larger and stocked with more food than male cells, hence needing more time to be provisioned.

7. The greater ‘cost’ to produce a female and a sex ratio biased toward females in short traps and about unity in longer traps, leads to a comment on parental investment.
On the failure of two butterfly species to respond to the presence of conspecific eggs prior to oviposition
Authors: SINGER MICHAEL C. , MANDRACCHIA JOANNE
Published: March 2008

Abstract. 1. The eggs of Euptychiine butterflies are laid singly, but their distributions tend to be contagious. However, these insects do not discriminate between egg‐laden and egg‐free plants.

2. Response to conspecific eggs is not part of the mechanism responsible for clumped egg distribution.
Patterns of parasitism by insect parasitoids in patchy environments
Authors: HASSELL M. P.
Published: March 2008

Abstract. 1. This paper shows how the different spatial patterns of per cent parasitism in patches of different host density can be explained within a single model framework that takes into account the parasitoid's aggregative response, and the factors limiting the degree of host exploitation within patches.

2. Two contrasting laboratory examples are presented in which the distribution of searching parasitoids and the resulting levels of parasitism in different patches are both known for a range of parasitoid densities.

3. A model is described predicting the number of hosts parasitized per patch, in which the number of parasitoids searching is determined from a simple expression allowing different degrees of aggregation.

4. The model generates patterns of parasitism encompassing the two laboratory examples and a wide range of examples from the field.

5. The importance of density dependent spatial distributions of parasitism to population stability is briefly discussed.
Wind dispersal and settling of first‐instar crawlers of the cochineal insect Dactylopius austrinus (Homoptera: Coccoidea: Dactylopiidae)
Authors: MOW V. C. , GUNN B. H. , WALTER G. H.
Published: March 2008

Abstract. 1. The efficiency of D.austrinus as a biological control agent depends on successful colonization of the cactus weed Opuntia aurantiaca.

2. Unlike other coccoid insects, the female crawlers (first‐instar larvae) of cochineal insects develop long wax fiaments on the dorsal surface of the body that reduce their terminal velocity in air and enhance wind dispersal.

3. Dactylopiid males are dispersed as winged adults and male crawlers of D.austrinus have fewer and shorter filaments than the females and they are blown a shorter distance in a wind tunnel.

4. Vertical and horizontal wind dispersal of D.austrinus from O.aurantiaca in the field is usually very limited, but was greatly improved when crawlers were launched from an elevated ‘tower’.

5. Preparatory to dispersal, female crawlers climb to the top of the host plant and ‘take‐off’ from there. This behaviour is most marked in crawlers 2–3 days old at which stage the wax filaments are best developed: the behaviour is never manifest following artificial ‘dispersal’.

6. Final settling on cladodes of the host plant is a function of the age of the female crawlers and of the condition of the cladodes.

7. When given a choice, approximately equal numbers of crawlers settled on cladodes that had received high and low fertilizer treatments. More crawlers settled on cladodes that had been kept in the shade than on those kept in the sun, and on basal rather than terminal cladodes.

8. The highest percentage of crawlers settled on cladodes that were 20% dehydrated. Settling success was much lower on more desiccated cladodes.
Survivorship of the sexual and agamic generations of Andricus quercuscalicis on Quercus cerris and Q.robur
Authors: COLLINS M. , CRAWLEY M. J. , McGAVIN G. C.
Published: March 2008

ABSTRACT.

Survivorship within the galls of the sexual and agamic generations of Andricus quercuscalicis (Burgsdorf) is estimated from field populations.

The sexual generation on Turkey oak suffers a 20% death rate through parasitism by Mesopolobus spp. The emerging parasitoids are virtually all males.

The agamic generation on the acorn cups of English oak is not attacked by any parasites or inquilines at our Berkshire site despite the fact that most of the species which parasitize the gall in continental Europe are on the British list.

Agamic galls cause average losses of between 30% and 50% of the total acorn crop in different years. Individual trees differ greatly in their rates of loss, many losing over 90%, others losing virtually none.
Absence of wing polymorphism in the arboreal, phytophagous species of some taxa of temperate Hemiptera: an hypothesis
Authors: WALOFF N.
Published: March 2008

ABSTRACT.

Most arboreal Cicadellidae (Homoptera) and the arboreal, phytophagous Heteroptera are macropterous and capable of flight.

The low incidence of flightless morphs in the above insects is compared with its frequency in the species living on low vegetation.

It is suggested that in spite of the permanence of arboreal habitats, the almost complete absence of flightless morphs in these groups of the temperate Hemiptera is related to the architectural complexity of trees.
Larval aestivation and direct development as alternative strategies in the speckled wood butterfly, Pararge aegeria, in Sweden
Authors: WIKLUND CHRISTER , PERSSON ANN , WICKMAN PER OLOF
Published: March 2008

ABSTRACT.

Sweden has two disjunct populations of the speckled wood butterfly, Pararge aegeria L. The southern population has two generations per year but the central Swedish population is univoltine. When rearing larvae from central Sweden under normal photoperiodic conditions but at temperatures slightly above the ambient, 42% of the larvae developed directly and produced a second generation of adults the same summer. The egg—larval development time of the directly developing individuals was about 40 days, whereas that of the individuals developing along the univoltine pathway was about 100 days.

Larvae of the central Swedish population normally aestivate during part of the summer even though abundant food is available. In the closely related Lasiommata petropolitana F., which is the only Swedish satyrid that overwinters in the pupal stage besides P.aegeria, larvae do not aestivate, indicating that there does not seem to be any obligatory association between pupal hibernation and larval aestivation.

Development rates of aestivating and directly developing P.aegeria are equal up to the third larval instar. During the third and fourth instars, however, the development rate of aestivating individuals is retarded and females also have an additional fifth instar.

Since the central Swedish P.aegeria have the capacity to develop directly, and the southern Swedish ones have the capacity to aestivate, the evidence indicates that the outcome of the cost/benefit balance of univoltine versus bivoltine development differs between the two areas.
Why is one of the periodical cicadas (Magicicada septendecula) a comparatively rare species?
Authors: LLOYD MONTE , WHITE Jo ANN
Published: March 2008

ABSTRACT.

The same woodland rarely supports two different broods of 17‐year cicadas, and never two that appear in successive years. Theoretically, this is because a build‐up of predators, generated by the leading brood, would eliminate the lagging one, or because nymphs of the lagging brood would suffer a competitive disadvantage, or both.

Nevertheless, substantial numbers of 17‐year cicadas of all three species (Magicicada septendecim, M.cassini and M.septendecula) did appear in Grant County, Kentucky, in 1974 (Brood XIV, expected) and 1975 (not expected). This is interpreted to mean that many individuals delayed their emergence until the eighteenth year.

Dissected eggnests show that the expected build‐up of hymenopterous egg parasitoids failed to occur, although there may have been a build‐up of dipteran parasitoids, which may leave no trace in the eggnest.

Excavated young nymphs show that establishment rate was poorer in 1975 than in 1974, which is attributed to nymphal competition.

Identification of eggnests from the two years shows that one of the species (M.septendecula, which is usually the rarest in mixed‐species populations) is much more susceptible to delaying its development by a year than are the other two species.

It is predicted that the 1975 emergence will produce no adult progeny, i.e. that there will be no emergence in 1992.

The sporadic occurrence of this phenomenon, other factors being equal, would be sufficient to explain the comparative rarity of M. septendecula, or even its local extinction.

Historical records from northern Illinois show frequent emergences one year behind schedule. These delayed individuals never produce progeny that survive to the next generation. M.septendecula is absent from northern Illinois and indeed absent from the northern areas of all periodical cicada broods in the northern part of the range.
The biogeography of herbivorous arthropods: species accrual on tropical crops
Authors: McCOY EARL D. , REY JORGE R.
Published: March 2008

ABSTRACT.

The size of range of host plants and animals has been shown repeatedly to be the best single correlate of number of associated parasite species. For a single species of host distributed over many regions, there should exist two important additional correlates: the sizes of source pools of potential colonists within regions and the distribution of the host's close relatives among regions.

Certain tropical crops are useful in examining these ideas because they are widely‐cultivated and the relevant data are available. A comparison of the data for the herbivorous arthropods of cacao, citrus, coconuts, coffee, cotton, rice and sugar cane shows that regions in Amazonia, Southern Asia/Australia and sub‐Saharan Africa consistently fall above species‐area regression lines, whereas regions in North and South America (except Amazonia), Western Asia and Europe tend to fall below them.

The pattern implicates the importance of source pool size of potential colonists and taxonomic isolation of the host in influencing arthropod accrual.

Cultivation methods, sampling effects and latitude conceivably could also influence accrual, but their importance is questionable for the seven crop/parasite systems examined.
Flight duration of the brown planthopper, Nilaparvata lugens (Homoptera: Delphacidae)
Authors: ROSENBERG L. J. , MAGOR J. I.
Published: March 2008

ABSTRACT.

The brown planthopper, Nilaparvata lugens (Stål), is a major pest of rice in Asia. It is known to make wind‐assisted migratory flights each year to colonize the summer rice growing areas of China, Japan and Korea.

Modelling windborne displacements between rice growing areas in Asia requires migratory behaviour and flight duration to be established for this insect.

Field and laboratory observations suggest that N. lugens take‐off at dusk and that some continue flying for up to 24–26 h if the temperature is ≥ 17°C.

Trajectories for 10 m above ground level and 1.5 km above mean sea level are used to identify possible sources and, hence, to estimate the flight times of N.lugens caught in nets on ships on the East China Sea in 1973 and 1981.

Estimated flight times between the sources and the ships ranged from about 9 to 30 h.

Results suggest that long‐distance migration can occur in surface winds, when they are strong, but that long‐distance migration is more likely at 1.5 km.

When simulating windborne displacements of N.lugens, it can be assumed that in areas and at heights where the temperature is ≥ 17°C, some migrants will fly downwind for up to 30 h after a dusk take‐off. Others will fly for shorter periods, giving the population as a whole the opportunity to colonize all the rice crops flown over.
Intraspecific variation in beech scale populations and in susceptibility of their host Fagus sylvatica
Authors: WAINHOUSE D. , HOWELL R. S.
Published: March 2008

ABSTRACT.

Within a seed orchard in southern England, beech trees (Fagus sylvatica L.) belonging to three clones were artificially infested by introducing beech scale larvae (Cryptococcus fagisuga Lind. Homoptera: Coccidae) into small cages attached to the bark.

Some larvae developed to fecund adults on trees of two susceptible clones but all failed to develop on a third, resistant clone.

Within susceptible clones, survival of larvae on individual trees was positively related to their degree of natural infestation.

Larvae deriving from several separate trees differed significantly in their ability to survive when inoculated onto trees of susceptible clones.

Five forest trees which acted as both donors of larvae and as hosts for artificial inoculation were each inoculated with larvae from all five trees.

There was significant variation in survival of inoculated larvae both between the host trees and between sources of larvae on each host.

Survival of larvae reinoculated onto their original host was significantly higher than that of larvae originating from other trees.

Fecundity of adults on the forest trees was positively correlated with the probability of inoculated larvae surviving to the adult stage.
A comparative analysis of Chrysoperla carnea catches in light‐ and suction‐traps
Authors: PERRY J. N. , BOWDEN J.
Published: March 2008

ABSTRACT.

The lacewing C.carnea was caught weekly at Rothamsted in six traps, in 1973 and between 1975 and 1980. The traps were in three pairs: two light‐traps in woodland, two light‐traps in open fields, and two suction‐traps, sampling at 12 m and 1.2 m above the ground.

Standardized trap phenologies were compared seasonally, for each year, using multivariate methods. Trap environments caused the greatest phenological difference, which was between the woodland and the other traps. The suctiontraps and the light‐traps in open fields also differed. The greatest similarity was between the woodland light‐traps, the next between the suction‐traps, but the two light‐traps in open fields were relatively dissimilar.

These results were supported by analysis of the sex‐ratio of catches in each trap. We suggest an overall phenology in which the wood is important as an overwintering site for adults in autumn and as a source in spring.

Assessment of consistency over years showed no year was typical, but 1979 was markedly dissimilar from other years; 1976 was particularly similar to 1975.

The use of generalized Procrustes analysis (Gower, 1975) is recommended for similar sets of ecological data.
Observations of the flight behaviour of the army worm moth, Spodoptera exempta, at an emergence site using radar and infra‐red optical techniques
Authors: RILEY J. R. , REYNOLDS D. R. , FARMERY M. J.
Published: March 2008

ABSTRACT.

Studies were made in Kenya of the flight behaviour of African armyworm moths which had emerged from areas previously infested with‘gregarious’caterpillars. The use of radar and an infra‐red optical detector permitted quantitative, direct observations of the flying moths, over all of their flight altitudes, without disturbing their behaviour.

Almost all of the successfully emergent moths climbed to altitudes of several hundred metres above ground level and migrated from the emergence sites. Their migratory flights sometimes started on the night of emergence, but on other occasions the moths remained roosting in trees until dawn, then engaged in short dispersal flights, concealed themselves during the day. and commenced migration in mass flights at dusk the following night.

The onset of these‘dusk flights’occurred when the irradiance level fell on average to 2.7 × 10−5Wm−2 nm−1 in the 450–800 nm range (in the photometric units appropriate for human vision this corresponds approximately to 2 lux). The‘dawn flights’began with the first sustained increase in irradiance at dawn, and terminated at the end of dawn twilight.

Migratory flight in the strong, easterly winds which usually occurred during the first half of the night resulted in rapid, down‐wind displacement to the west. Observations of groups of flying moths passing successively over two radars demonstrated that these migrations could cover at least 20 km.

In the second half of the night, winds were usually weak and variable, and up‐wind or cross‐wind directions of displacement were sometimes observed.

Moths were observed to disperse rapidly during their migration, so that the mass influxes which lead to outbreaks must be a consequence of subsequent reconcentration. The importance of meso‐scale wind convergence zones in reconcentrating flying moths, and the role of rainfall in inducing descent, and possibly landing, are discussed.
Ecologically seIective coIoured traps
Authors: KIRK WILLIAM D. J.
Published: March 2008

Abstract. 1. This paper analyses catches of flower thrips, grass thrips and predatory flies in water‐traps of seven colours.

2. A correlation is demonstrated between type of host‐plant of thrips and the relative numbers caught by traps of different colours.

3. The literature is reviewed and some general relationships with the effectiveness of different trap colours are hypothesized for: non‐grass foliage insects and their predators and parasites; grass foliage insects; flower‐dwelling insects; predators and parasites not associated with foliage; biting insects; and wood‐borers.

4. This may permit trap colours to be chosen, in particular circumstances, that are ecologically selective for different types of insect.