| 1. |
- Abbott, Jessica, et al.
(författare)
-
Correlated morphological and colour differences among females of the damselfly Ischnura elegans
- 2009
-
Ingår i: Ecological Entomology. - : Wiley. - 1365-2311 .- 0307-6946. ; 34:3, s. 378-386
-
Tidskriftsartikel (refereegranskat)abstract
- 1. The female-limited colour polymorphic damselfly Ischnura elegans has proven to be an interesting study organism both as an example of female sexual polymorphism, and in the context of the evolution of colour polymorphism, as a model of speciation processes. 2. Previous research suggests the existence of correlations between colour morph and other phenotypic traits, and the different female morphs in I. elegans may be pursuing alternative phenotypically integrated strategies. However, previous research on morphological differences in southern Swedish individuals of this species was only carried out on laboratory-raised offspring from a single population, leaving open the question of how widespread such differences are. 3. The present study therefore analysed multi-generational data from 12 populations, investigating morphological differences between the female morphs in the field, differences in the pattern of phenotypic integration between morphs, and quantified selection on morphological traits. 4. It was found that consistent morphological differences indeed existed between the morphs across populations, confirming that the previously observed differences were not simply a laboratory artefact. It was also found, somewhat surprisingly, that despite the existence of sexual dimorphism in body size and shape, patterns of phenotypic integration differed most between the morphs and not between the sexes. Finally, linear selection gradients showed that female morphology affected fecundity differently between the morphs. 5. We discuss the relevance of these results to the male mimicry hypothesis and to the existence of potential ecological differences between the morphs.
|
|
| 2. |
- Anderbrant, Olle
(författare)
-
Gallery construction and oviposition of the bark beetle Ips typographus (Coleoptera : Scolytidae) at different breeding densities
- 1990
-
Ingår i: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 15:1, s. 1-8
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 3. |
- Brattström, Oskar, et al.
(författare)
-
AFLP reveals cryptic population structure in migratory European red admirals (Vanessa atalanta)
- 2010
-
Ingår i: Ecological Entomology. - : Wiley. - 1365-2311 .- 0307-6946. ; 35:2, s. 248-252
-
Tidskriftsartikel (refereegranskat)abstract
- 2. Using the software STRUCTURE 2.2, we found two distinct genotype clusters present in different frequencies at all study sites. The frequencies of these genotypic clusters varied significantly between years within the same site. Remarkably few individuals were of mixed ancestry, indicating that some isolating mechanisms are present. Twenty-seven mtDNA haplotypes were identified but they showed no geographic structure, nor were they related to either of the two genotype clusters identified in the AFLP data. 3. Most field observations of migrating red admirals suggest a regular north-south migration pattern in Europe. Our data indicate both long-distance migration and a more variable pattern in orientation, since the composition of the two genotypic clusters shows dramatic variation between sites and years in the northern part of the distribution range.
|
|
| 4. |
- Kumschick, Sabrina, et al.
(författare)
-
Determinants of local ant (Hymenoptera: Formicidae) species richness and activity density across Europe
- 2009
-
Ingår i: Ecological Entomology. - : Wiley. - 1365-2311 .- 0307-6946. ; 34:6, s. 748-754
-
Tidskriftsartikel (refereegranskat)abstract
- 1. Species richness is influenced by local habitat features and large-scale climatic gradients. Usually, both influences are studied in isolation because of the divergent spatial scales at which they occur. Here, we compared the influence of large-scale climate and local habitat type on European ants using a continent-wide, standardised sampling programme. 2. We investigated species richness and activity density from pitfall traps distributed over four habitat types at 17 locations from northern Sweden to Spain and Greece. Species richness and activity density were analysed with respect to ambient energy [equilibrium evapotranspiration (EET)] and productive energy (net primary productivity). Furthermore, we compared ant richness and activity density between the four habitat types: arable land, scrubland, grassland, and forest. 3. Species richness and activity density of ants increased with equilibrium evapotranspiration (EET), explaining 30.2% of the total variation in species richness and 24.2% of activity density. Habitat type explained an additional 19.2% of the variation in species richness and 20.2% of activity density, and was not related to productivity. Species richness and activity density were highest in scrubland and significantly lower in forest and (marginally significant) in arable land. 4. The increase in EET and the decrease in forest confirms the pronounced thermophily of ants, whereas the decrease in arable land is probably caused by soil disturbance.
|
|
| 5. |
- Larsson, Magnus, et al.
(författare)
-
Estimating the population size of specialised solitary bees
- 2008
-
Ingår i: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 33:2, s. 232-238
-
Tidskriftsartikel (refereegranskat)abstract
- 1. Reliable methods for quantifying population size are crucial for strategies to conserve endangered wild-bee species. Estimates of population size obtained through survey walks were compared with estimates obtained through mark–recapture studies in 10 populations of the red-listed solitary bee Andrena hattorfiana in southern Sweden. 2. The mean number of bees observed during survey walks was strongly correlated with estimates of population size obtained with mark–recapture. It was found that 5.5–23.4% (mean 13.4%) of the total population was observed during an average survey walk. 3. One component in mark–recapture analysis is the measure of survival of individuals. In the largest bee population, females of A. hattorfiana that emerged in early season were found to forage for pollen on average 18.4 days. 4. The findings suggest that during large-scale surveys, for example re-inventories for red-listed species, the population size of solitary bees can be quantified reliably and effectively by performing survey walks in a two-step process. The first step consists of survey walks to establish the relationship between number of bee observations per survey walk and mark–recapture population size for a small set of populations. In the second, simple observation survey walks can be performed for a large set of populations. In each population of A. hattorfiana, it is recommended that at least six survey walks are performed.
|
|
| 6. |
- Albrectsen, Benedicte, et al.
(författare)
-
Does the differential seedling mortality caused by slugs alter the foliar traits and subsequent susceptibility of hybrid willows to a generalist herbivore?
- 2007
-
Ingår i: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 32, s. 211-220
-
Tidskriftsartikel (refereegranskat)abstract
- Abstract. 1. Many Salicaceae species naturally form hybrid swarms with parental and hybrid taxa that differ in secondary chemical profile and in resistance to herbivores. Theoretically, the differential mortality in the seedling stage can lead to changes in trait expression and alter subsequent interactions between plants and herbivores. This study examines whether herbivory by the generalist slug Arion subfuscus, which causes extensive mortality in young willow seedlings, causes shifts in (a) the foliar chemistry of F2 willow hybrids (Salix sericea and Salix eriocephala), and (b) the subsequent susceptibility to Japanese Beetles, Popillia japonica.2. In 2001, two populations of F2 seedlings were generated: those that survived slug herbivory (80–90% of seedlings placed in the field were killed by the slugs) were designated as S-plants, whereas C-plants (controls) experienced no mortality.3. Common garden experiments with cuttings from these populations, in 2001 and 2002, revealed extensive variation in the phenolic chemistry of F2 hybrids, but revealed no significant difference between S- and C-plants, although the levels of foliar nutrients, proteins and nitrogen tended to be higher in S-plants.4. Concentrations of salicortin and 2'-cinnamoylsalicortin explained 55 and 38% of the the variation in leaf damage caused by Japanese beetles, and secondary chemistry was highly correlated within replicate clones (salicortin R2 = 0.85, 2-cinnamoylsalicortin R2 = 0.77, condensed tannins R2 = 0.68).5. Interestingly, Japanese beetle damage and condensed tannins were positively correlated within the S-plants, but not in the C-plants, suggesting that slugs had selected for plants with a positive relationship between tannins and P. japonica damage. This is unlikely to be a consequence of a preference for tannins, but is suggested to be related to the elevated nutrient levels in the S-plants, perhaps in combination with the complex-binding properties of tannins.6. The damage was highly correlated within replicate clones and a model choice analysis suggested that Japanese beetle damage may be explained by four factors: concentrations of salicortin, condensed tannins, and nitrogen, as well as the specific leaf area (thick leaves were damaged less).
|
|
| 7. |
- Ammunét, Tea
(författare)
-
Invading and resident defoliators in a changing climate: cold tolerance and predictions concerning extreme winter cold as a range-limiting factor
- 2012
-
Ingår i: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 37, s. 212-220
-
Tidskriftsartikel (refereegranskat)abstract
- 1. Winter temperatures in northern latitudes are predicted to increase markedly as a result of ongoing climate change, thus making the invasion of new insect defoliators possible. The establishment of new outbreak pest species may have major effects on northern ecosystems that are particularly sensitive to disturbances. 2. Effects of winter minimum temperatures under field and laboratory conditions were examined and limitations by minimum temperatures on future range expansion were investigated for invasive [Operophtera brumata (Lepidoptera: Geometridae)] and potentially invasive [Agriopis aurantiaria (Lepidoptera: Geometridae)] birch-feeding forest pests. The results for the studied invasive and potentially invasive moths were compared with the parameters of the resident moth species Epirrita autumnata (Lepidoptera: Geometridae). 3. The results showed tolerated critical temperatures of the invader (O. brumata) and the resident (E. autumnata) were more similar (differing only by 1 degrees C), whereas the potential invader (A. aurantiaria) was much less tolerant of cold temperatures. Although describing different stages of overwintering, results were consistent between laboratory and field studies except for those at one field location, at which other abiotic conditions are suggested to have significant influence on moth egg survival. 4. Based on the present results and expected changes in winter temperatures over the next 30 years, the range expansion of an established invasive species may be predicted. No limitations were found regarding the possible future invasion of a new pest species to northern Fennoscandia. The importance of studying a species' whole overwintering period is highlighted and further studies devoted to the effects of other abiotic factors in addition to the effects of temperature are suggested.
|
|
| 8. |
- Andersson, Petter, et al.
(författare)
-
What shapes local density? : The importance of migration rates and local growth for density-patch size relationships in two Cionus weevils
- 2012
-
Ingår i: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 37:1, s. 90-98
-
Tidskriftsartikel (refereegranskat)abstract
- 1. The relative effect of migration and local growth on the spatio-temporal density-distribution of two co-existing herbivorous weevils, Cionus scrophulariae L. and C. tuberculosus Scop., in 32 host plant Scrophularia nodosa L. patches of varying sizes was investigated. 2. Predictions of the temporal development of the slope in the density-patch size relationships were derived from a basic population model with scale-dependent migration rates. The model indicated that the slopes in the density-patch size relationships during the early season should be reflected by the net scaling of immigration and emigration rates, whereas the slopes during the later season should increase as a result of local growth. 3. Emigration rates of the weevils were estimated in a field experiment, were the weevils coexisted in space and time. These results were then combined with a previous estimate of immigration rates in order to determine the net scaling of migration rates. 4. The emigration rate differed between species, caused by different movement rates in small patches, which could explain differences in the general slope of the density-patch size relationships of the weevils in the natural figwort patches throughout the summer. The slopes in the relationships in the early season were largely predicted by the net scaling of migration rates. The slope also increased in the later season for C. tuberculosus, whereas the slope decreased for C. scrophulariae. 5. It was concluded that the understanding of both inter- and intra-specific variations in density-patch size relationships of insect herbivores can be improved using population models incorporating scale-dependent migration and local growth.
|
|
| 9. |
- Baba, Yuki G., et al.
(författare)
-
Host-dependent differences in prey acquisition between populations of a kleptoparasitic spider Argyrodes kumadai (Araneae: Theridiidae)
- 2007
-
Ingår i: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 32:1, s. 38-44
-
Tidskriftsartikel (refereegranskat)abstract
- 1. A kleptoparasitic spider, Argyrodes kumadai, is known to use phylogenetically unrelated host species in different regions - Cyrtophora moluccensis (Araneidae) in south-west Japan and Agelena silvatica (Agelenidae) in north-east Japan. The work reported here examined whether differences in host characters affect prey acquisition of A. kumadai. 2. Field surveys showed that prey-biomass capture rate of Argyrodes was significantly higher in populations parasitising Cyrtophora than in populations parasitising Agelena. Although Argyrodes appeared to catch fewer prey within Cyrtophora webs, they were able to feed upon substantially larger prey. 3. Differences in prey-biomass capture rate were found to reflect differences in host traits rather than regional differences in potential prey availability. Individuals in populations parasitising Cyrtophora were observed to acquire prey via a number of foraging tactics that included stealing wrapped food bundles, feeding upon prey remains and, in the case of large prey items, feeding together with the host. In contrast, individuals in populations parasitising Agelena were only ever observed to feed upon small prey items ignored by its host. 4. This variability in prey acquisition between kleptoparasite populations reflected different opportunities for feeding within their respective host webs - opportunities that were primarily determined by the foraging behaviour of the host. One key trait associated with host foraging behaviour was host-web structure, namely the presence/absence of a retreat.
|
|
| 10. |
- Bergström, Anders, et al.
(författare)
-
Putting more eggs in the best basket : clutch size regulation in the comma butterfly
- 2006
-
Ingår i: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 31:3, s. 255-260
-
Tidskriftsartikel (refereegranskat)abstract
- 1. Many studies have identified different factors influencing clutchsize regulation, primarily within various groups of insects. One prediction is that ovipositing females should increase clutch size with host quality. However, in many studies it is not clear whether ovipositing females are responding to host quality or quantity. 2. Females of the polyphagous comma butterfly, allowed to oviposit on two hosts differing greatly in quality: the preferred host, stinging nettle (Polygonia c-album (L.), wereUrtica dioica L.), and the low-ranked host, birch (Betula pubescens Ehrh). Ovipositing females were observed visually and clutch sizes were recorded. The experiment was repeated in three different years; in total, 938 observations of oviposition events were made. 3. In all three years, females ovipositing on (median 1.6–1.85) compared with females ovipositing on 1.0–1.3) three years were pooled. 4. Thus, on better hosts. It is suggested that the proximate mechanism is likely to be a response to the same stimuli used for female ranking of host plants in the preference hierarchy. U. dioica laid larger clutchesB. pubescens (median. The difference was significant in two out of three years and when allP. c-album females exhibit clutch-size regulation, with larger clutches
|
|
