bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abundance and mortality of leaf miners on artificially shaded Emory oak
Authors: BULTMAN THOMAS L. , FAETH STANLEY H. 
Published: March 2008

ABSTRACT.

We measured solar radiation reaching ten Quercus emoryi Torr. trees and recorded densities of four leaf‐mining insect species on these trees from June until September 1982.
The measurements showed that densities of two leaf miner species were negatively correlated with solar radiation.
In a field experiment, polypropylene shade fabric was suspended 1.3 m above four experimental trees to test for effects of reduced sunlight.
Leaves of experimentally‐shaded trees were heavier and contained lower percentages of proteins and gallotannins than leaves of control, sun trees, while per cent foliar monomeric, polymeric, and total phenols, and water content did not differ between sun and shaded trees.
Two of four leaf miner species had greater densities on experimentally‐shaded trees than sun trees. One of these two species experienced lower survivorship on sun trees owing to high levels of death from unknown causes on sun trees.
Two leaf miner species had greater densities on sun trees. One of these species had higher survivorship on shaded trees owing to high levels of parasitism on sun trees.
We conclude that even subtle differences in shading influences leaf miner density and mortality; however, the effects of shading vary from positive to negative among leaf miner species.
Hunger, partial consumption of prey and prey size preference in a carabid beetle
Authors: ERNSTING G. , VAN DER WERF D. C. 
Published: March 2008

ABSTRACT.

Partial consumption of prey and prey size preference were studied in females of the carabid Notiophilus biguttatus F., using different size‐classes of the springtail Orchesella cincta (L.) as prey.
Time to ingest a prey increases disproportionately with prey size, mainly as a consequence of satiation.
During consumption of a prey the predator's rate of ingestion decreases, partly because of diminishing returns from the prey over feeding time.
The hypothesis that the diminishing returns from the prey induce partial consumption was refuted.
Partial consumption in the beetle is due to gut limitation; its occurrence depends on prey size.
Average weight of prey remains in four prey size classes were close to weights expected from average intercatch intervals and estimates of hunger.
Prey choice depends on level of food deprivation.
Partial consumption of prey, prey size preference and profitability of prey in relation to hunger of the beetle are discussed.
Dung burial strategies in some South African coprine and onitine dung beetles (Scarabaeidae: Scarabaeinae)
Authors: DOUBE B. M. , GILLER P. S. , CSIRO F. MOOLA 
Published: March 2008

ABSTRACT.

The dung colonization and dung burial behaviour of twelve crepuscular/nocturnal tunnelling (paracoprid) species of beetles were examined in order to identify mechanisms which might facilitate resource (dung) partitioning. The species were selected from a diverse assemblage of dung beetles, the members of which coexist in the sandy‐soil regions of Natal, South Africa.
The pattern of dung colonization in relation to dung age was examined in the field using baited pitfall traps. Some species, e.g. Onitis deceptor Peringuey, Catharsius tricornutus De Geer and Copris elphenor Klug, showed a marked preference for fresh dung (1–2 days old) whereas other species, e.g. O. viridulus Boheman and Copris fallaciosus Gillet, preferred older dung (3–7 days old).
Two distinct patterns of dung burial were recognized. In the Coprini, dung burial was complete within 24–48h of pad colonization, and the level of dung burial was similar in the laboratory and in the field. In the Onitini, dung burial occurred progressively over a 12‐day period, although the timing of initiation of dung burial varied between species: in O. deceptor nearly all individuals had begun burial within 2 days of pad colonization, whereas only 20% of O. viridulus had commenced dung burial by that time. However, nearly all O. viridulus had buried substantial quantities of dung by day 12.
The mass of dung buried per pair by the larger coprine beetles (100–300 g) and onitine beetles (400–1000 g) suggests that there is potential for inter‐ and intraspecific competition, even in pads colonized by relatively few beetles. The colonization and use of dung of different ages are discussed as means of resource partitioning in relation to the relative abilities of species to compete for dung.
Delayed ovarian maturation in the butterfly Hipparchia semele as a possible response to summer drought
Authors: GARCÍA‐BARROS E. 
Published: March 2008

ABSTRACT.

Several references indicate that the period of flight of the European satyrine butterfly Hipparchia semele (L.) (Nymphalidae, Satyrinae) starts earlier in southern latitudes, where summers are longer and drier than in the north. However, summer drought has an adverse effect on the growth of grasses on which larval feeding depends. Growth of the grasses is delayed as long as the drought lasts.
From laboratory and field observations in a mid altitude area near the centre of the Iberian Peninsula, a mechanism that can be interpreted as an adjustment of this insect's life cycle to the host plant's phenology has been observed, i.e. delayed gonadal maturation of adult females. This delay is not associated with female diapause. Although the mean delay in oviposition after copulation was 43 days some captive females were able to oviposit much earlier, and this suggests variability in oviposition dates which might have an environmental or a genetic basis.
A mechanism of delayed ovarian maturation similar to that of H.semele is also known to occur in the satyrine Maniola jurtina (L.); it is suggested that this adaptation enables these species to occupy wider geographical ranges than other univoltine satyrines in Europe.
The photoperiodic responses and phenology of an English strain of the pea aphid Acyrthosiphon pisum
Authors: LEES A. D. 
Published: March 2008

Abstract. 1. The response curves for the photoperiodic induction of the sexual forms (oviparae and males) differ significantly in an English clone of the pea aphid Acyrthosiphon pisum Harris. Male production is sharply peaked. The late summer scotophases (dark periods) that initiate male production are 1.0–1.5 h shorter than those that initiate ovipara production; the induction of males, but not oviparae, virtually ceases at scotophases longer than 12 h. This disparity suggests that there are two photoperiodic clocks.2. All ovipara‐producing aphids switch spontaneously to virginopara production part‐way through the progeny sequence, irrespective of photoperiod. This may confer the ability to overwinter partheno‐genetically under favourable climatic conditions. Since males are always born last in the progeny sequence this possibility would be pre‐empted unless the terminal male sequences were suppressed by long winter scotophases.3. The role of the photoperiodic response in determining the seasonal phenology was tested in the field by exposing a succession of laboratory‐reared aphids to natural photoperiods, in late summer and autumn. Adult males and oviparae developed synchronously in early October, the difference in critical scotophase compensating for the late appearance of males in the progeny sequence. A large part of the ‘civil twilight’ is photoperiodically active.4. Clones propagated outdoors by isolating aphids in each generation from the terminal sequence of virginoparae did not survive the whole winter of 1985/86. The chances of survival were reduced by severe weather and by the inability of the photoperiodic system to ‘turn off’ the production of early born oviparae which are, therefore, ‘wasted’.
Radar observations of the spring migration into northeastern China of the oriental armyworm moth, Mythimna separata, and other insects
Authors: RUI‐LU CHEN , XIANG‐ZHE BAO , DRAKE V. A. , FARROW R. A. , SU‐YUN WANG , YA‐JIE SUN , BAO‐PING ZHAI 
Published: March 2008

Abstract. 1. The spring migration of the oriental armyworm moth, Mythimna separata (Walker), and other insects into northeastern China was observed by radar at a site in central Jilin province. Samples of the migrants were obtained in a net flown from a kite, and M.separata populations in the surrounding region were monitored with a trap network.2. The radar regularly detected echoes which were of the type characteristic of large insects, and three out of four large insects in the aerial samples were noctuid moths, including one M.separata. Catches of armyworm moths in the regional trap network peaked during the period of radar observations.3. Migration occurred at night. It commenced with a take‐off flight at dusk and generally continued until dawn, with numbers often being highest around midnight. Most migration took place at altitudes below 500 m, with strong layer concentrations forming at 200–400 m during the middle part of some nights.4. Migration was approximately downwind. The net movement was overwhelmingly to the northeast because southwesterly winds occurred most frequently and were relatively strong, and because migration was more intense and prolonged on these winds. Orientation tended to be to the left of the downwind direction, and was most often to the north or northeast.5. Migration into northeastern China was accomplished in a series of night‐time movements of 100–300 km rather than by a single non‐stop flight.6. The net movement of insects towards the northeast was sufficient to produce the observed regional infestation of M.separata moths. Oviposition by immigrant armyworm moths in vulnerable crops would have been at a level where economically significant damage would be expected from the resulting larval population.7. Analogous springtime migrations of noctuids leading to temporary colonizations of habitats at higher latitudes occur in other continents. Such colonizations may be unproductive if, as appears possibly the case for northeastern China, prevailing winds later in the season are generally unfavourable for a return migration towards overwintering areas at lower latitudes.
Plant resistance, plant traits, and host plant choice of the leaf‐folding sawfly on the arroyo willow
Authors: FRITZ ROBERT S. , NOBEL JENNIFER 
Published: March 2008

Abstract. 1. The hypotheses that genetic variation in host plant resistance of the arroyo willow affected leaf folder (Phyllocolpa sp.) (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.
Taxonomy, attack strategies and host relations in flowerhead Tephritidae: a review
Authors: STRAW N. A. 
Published: March 2008

Abstract. 1. Host relations of Palaearctic flowerhead‐inhabiting tephritids (Diptera: Tephritidae) are reviewed in terms of the interaction between type of attack strategy and flowerhead size.2. Three types of attack strategy are recognized, each associated with a particular phase of Compositae flowerhead development. These strategies are characteristic of a tribe or subfamily, viz the Tephritini (Tephritinae), Terelliini (Tephritinae) and Myopitinae.3. Tephritini species show the most generalized feeding method, and this enables them to attack both large and very small flowerheads. In contrast, the more specialized requirements of members of the Terelliini and Myopitinae apparently restricts these groups to plant taxa with large flowerheads. As a result, over the whole range of Compositae flowerhead sizes, there exists a positive relationship between flowerhead size and the diversity of associated tephritids.4. The occurrence of stem‐feeding tephritids, and differences between a coevolutionary and functional (colonization) explanation for tephritid host‐relations are discussed.
Iridoid glycosides and insect feeding preferences: gypsy moths (Lymantria dispar, Lymantriidae) and buckeyes (Junonia coenia, Nymphalidae)
Authors: BOWERS M. DEANE , PUTTICK GILLIAN M. 
Published: March 2008

Abstract. 1. The effect of increasing concentrations of an iridoid glycoside, catalposide, was tested on a generalist and an adapted specialist lepidopteran, using artificial diets.2. Two strains of the gypsy moth, Lymantria dispar (L.) (Lymantriidae), were tested. Larvae of a wild strain showed a negative dose‐dependent response to increasing concentrations of catalposide (up to 7.2% dry weight), while a laboratory strain showed no such pattern. Choice tests using the laboratory strain showed that these larvae often preferred diets relatively low in catalposide over those with higher concentrations.3. In contrast, larvae of the iridoid glycoside specialist, the buckeye, Junonia coenia Hübner (Nymphalidae), showed a positive dose‐dependent response and grew better on diets with higher doses of catalposide.4. We tested whether the improved growth of J. coenia at higher concentrations of catalposide may have been due to extra glucose yielded by hydrolysis of catalposide. Larvae were fed increasing doses of glucose equivalent to the amount potentially obtained by hydrolysing the quantities of catalposide used in the previous experiment. However, added glucose did not effect growth, suggesting that increased growth at higher catalposide concentrations was due to increased feeding rates.
The potential for interspecific competition between two abundant defoliators on oak: leaf damage and habitat quality
Authors: HUNTER M. D. , WILLMER P. G. 
Published: March 2008

Abstract.1. The pedunculate oak, Quercus robur L., suffers high annual levels of spring defoliation in Wytham Woods, Oxon. The two major defoliators, Tortrix viridana L. and Operophtera brumata L., sometimes reach high enough densities to completely defoliate trees.2. Experiments with larvae of both species enclosed on oak trees in Wytham Woods suggest considerable potential for intra‐ and interspecific competition between T. viridana and O. brumata.3. T. viridana and O. brumata consume equivalent amounts of leaf tissue per unit caterpillar density. Despite this, O. brumata is the superior competitor, measured by mortality during the larval feeding period.4. Evidence is presented that T. viridana larvae depend upon the protected microclimate of leaf rolls to maintain water balance, and that leaf damage may disrupt the construction of, and microclimate within, leaf rolls. O. brumata may therefore be competitively superior because it indirectly interferes with the water balance of T. viridana.5. The importance of interspecific competition in the dynamics of T. viridana and O. brumata populations is discussed. Stochastic mortality factors acting on first instar larvae of both species probably make intense competition a rare event.
Age‐associated male mating success in three swarming caddis fly species (Trichoptera: Leptoceridae)
Authors: PETERSSON ERIK 
Published: March 2008

Abstract. 1. In the three caddis fly species, Athripsodes albifrons (L.), A. cinereus (Curtis) and Mystacides azurea (L.) (Leptoceridae; Trichoptera), males swarm above the water surface of lakes or rivers. Receptive females fly to swarms and are chased and/or courted by males. After one of the swarming males has grasped an approaching female, the pair flies in tandem to the shore where they copulate.2. In males, wing wear indices were negatively correlated with the ratio of fat/dry weight. In the only species in which comparisons were possible between newly emerged and swarming males (M. azurea), the former had significantly lower indices. Unmated females on average had lower wing wear indices than spent females. These facts suggest that wing wear reflects relative age.3. The tandem males had significantly less wing wear than those in swarms, and are probably therefore younger. Age is therefore likely to be significant in relation to mating success.4. Among males of the same relative age, tandem males had higher fat ratio than swarming ones, indicating that male mating success was also influenced by traits other than age. It is suggested that the shortest possible duration of the period of adult prematurity is adaptive, especially in insects with marginal adult food intake.
Field estimation of variation in host plant use between local populations of pea aphids from two crops
Authors: VIA SARA 
Published: March 2008

Abstract. 1. In a reciprocal transplant experiment on pea aphids (Acyrthosiphon pisum (Harris)), the relative performance of clones collected from nearby alfalfa and red clover fields was tested by allowing clonal replicates to develop on both crops under field conditions.2. Populations from alfalfa and red clover differed in relative survivorship and probabilities of reproduction on the two crops. Clones had significantly higher performance on the crop from which they were collected (the ‘home’ crop) than they did on the other crop.3. Evidence is presented that previous experience on these host plants cannot account for the increased probability of reproduction observed on the ‘home’ crop. Thus, the differences between these two populations in their relative performance on alfalfa and clover are likely to be genetically based.4. These results illustrate that local adaptation to different host plants can occur within small geographical areas, despite the high probability that migrants are exchanged between nearby fields of the two crops.5. Experimental designs of the type described here permit estimation of patterns of genetic variation within and between insect populations. When applied to pest species, such designs will facilitate the study of evolution in agricultural systems.
Gallery construction and oviposition of the bark beetle Ips typographus (Coleoptera: Scolytidae) at different breeding densities
Authors: ANDERBRANT OLLE 
Published: March 2008

Abstract. 1. The bole of a Norway spruce, Picea abies(L.) Karst., was cut in 25 cm sections and infested in the laboratory with 2 or 8 females/dm2 of Ips typographus (L.) and an equal number of males.2. One log of each beetle density was dissected every second day, beginning 2 days after female introduction.3. The oviposition rate was highest at the beginning of the breeding period for both densities and then declined, especially at the high density. Residence time is a useful approximation for the number of laid eggs in the beginning of the oviposition period or when the density is low.4. Final gallery length and egg number per gallery were on average significantly smaller at density 8 than at density 2.5. Linear relationships between total gallery length and number of egg niches were found to be similar for the two densities.6. An estimate of the egg to adult mortality at different densities was found by using data from a field study that related gallery length to breeding density in attacked living trees, together with published relationships between density and egg niches or emergence of new adults.7. It was concluded that both decreased oviposition rate and earlier re‐emergence at higher densities contribute to a declining oviposition with increasing density. The final offspring production is futher reduced by lower survival due to larval competition as density increases.
Colony success of the submissive ant Formica fusca within territories of the dominant Formica polyctena
Authors: SAVOLAINEN RIITTA 
Published: March 2008

Abstract. 1. Twenty‐three nests of the submissive ant Formica fusca L. were sampled in two adjacent territories of the dominant wood ant Formica polyctena Först. The nests were dug up at different distances from the wood‐ant mounds. Distance is assumed to be inversely related to the extent of disturbance of F. fusca by F. polyctena.2. Colony success of F. fusca was assayed by counting the numbers of workers (colony size), and worker and sexual offspring in a nest. For individual size, the head width and dry weight of fifty workers per nest were measured.3. Colony size correlated positively with the numbers of worker and sexual offspring in one territory, but only with worker offspring in the other.4. Distance from the wood‐ant mound correlated positively with colony size and numbers of worker and female offspring in one territory. In the other territory distance correlated positively with number of females, but negatively with number of worker offspring. No significant correlations between distance and the size measurements were obtained.5. Because of its nonaggressive behaviour F. fusca may nest fairly close to a wood‐ant mound but is likely to show reduced abundances in terms of nest density and forager number, and, ultimately, lowered fitness.
Nuptial gift size prolongs copulation duration in the dance fly Empis borealis
Authors: SVENSSON BO G. , PETERSSON ERIK , FRISK MICHAEL 
Published: March 2008

Abstract. 1. The time that pairs of the dance fly Empis borealis (L.) (Diptera: Empididae) spent in copula was positively correlated with the volume of the nuptial gift.2. In some cases the copulation duration was short although prey volume was large. Females engaged in these matings had more worn wings, were therefore older, and most probably had sperm already stored in the spermatheca. It is suggested that these copulations were interrupted because either the spermatheca was full of sperm and the male was not able to transmit any sperm, or because prey content was depleted (males may have fed on the prey or the prey had been used in a previous mating). The latter explanation seemed more probable.3. A male providing a large nuptial gift may transfer larger quantities of sperm. Quantitative sperm competition is more likely than last‐male sperm predominance.
Variation of density‐dependence with spatial scale in the leaf‐mining fly Liriomyza commelinae (Diptera: Agromyzidae)
Authors: FREEMAN B. E. , SMITH D. C. 
Published: March 2008

Abstract. 1. Mortality imposed on the leaf mining fly, Liriomyza commelinae (Frost) was studied at three spatial levels: (1) the leaf, (2) the stem, and (3) a metre quadrat of the food plant.2. Real mortality (R.M.) (death as a percentage of eggs laid) during development for five sites over 3 years (forty‐seven generations) was 96.3 + 1.9% ‐2.5% (±95% c.l.), due mainly to parasitoids and predatory ants, with a small component due to competition and other causes.3. Real mortality due to the parasitoid complex averaged 41.2%. It was not related to population density in leaves or stems but was positively dependent on density in one metre quadrats.4. Predation by Crematogaster brevispinosa Mayr was 21.2% and was independent of population density at all spatial levels.5. Mortality due to other causes (e.g. competition and exposure to high temperature resulting from insolation) was positively dependent on the number of mines per leaf at three out of five sites studied and the number of mines per stem at two of the three sites studied; however, such mortality was independent of density per metre quadrat.