Aphis fabae and Myzus persicae (Hemiptera: Aphididae) are insect pests that damage sugar beet and bean crops. Both are responsible for losses in yield and transmission of viral diseases, and may be present on the same host at the same time. Three parasitoid species, Aphidius colemani, Lysiphlebus testaceipes and Lysiphlebus fabarum (Hymenoptera: Braconidae: Aphidiinae) have the potential to be used as biological control agents against at least one of these species of aphids. As a first step prior to the implementation of a biological control program, our aim was to understand the host selection behaviour of the parasitoids, particularly when both aphids are present. We recorded the host acceptance (number of insertions of the ovipositor / number of antennal contacts), suitability (number of mummies / the number of insertions of the ovipositor) and emergence (number of adults emerging from mummies) of these three aphid parasitoids when parasitizing the two aphids. We also analyzed the effect of the host plant on the host preference of the parasitoid. Females of each parasitoid species (n = 15) were exposed to 20 aphids of A. fabae or M. persicae, or a mixture of these two species of aphids, for 15 min, on a leaf disc of each of the two host plants, sugar beet and bean. Higher host acceptance and suitability were recorded for A. colemani attacking both species of aphid: A. fabae (43 and 46%) and M. persicae (43 and 46%) on beet and bean plants respectively, compared to L. testaceipes and L. fabarum. L. testaceipes and L. fabarum showed a clear preference for A. fabae. L. fabarum accepted M. persicae on both plants only when it was mixed with A. fabae, probably due to a confusion effect. We found that the host plant played a significant role in host acceptance, host suitability. We conclude that A. colemani is the better of the three parasitoids studied for the biological control in bean, and particularly, sugar beet crops. and Loulou Albittar, Mohannad Ismail, Claude Bragard, Thierry Hance.
The morphology, physiology, behaviour and ecology of spiralling whitefly, Aleurodicus dispersus Russell (Hemiptera: Aleyrodidae) on different host plants differ greatly. The genetic differences between the A. dispersus populations on 17 host plants were evaluated in the current study. Microsatellite markers were used to identify the presence of host-related genetic variation among A. dispersus populations. Our research clearly shows that there is a significant amount of genetic divergence among the A. dispersus populations on 17 host plants in India. The spiralling whitefly on acalypha and calotropis were genetically more distinct than whiteflies on other host plants. Various population genetic parameters, like heterozygosity, Nei's genetic distance, fixation indices (FST), source of genetic variation in AMOVA, etc. indicate that populations of spiralling whiteflies differ greatly genetically, probably because the spiralling whitefly populations on the Indian sub-continent came from multiple sources. The results of this study have implications for the quarantine protection strategy against this invasive pest.
Myxobolus filamentum sp. n. was found infecting gill filaments of three of 39 Brycon orthotaenia Günther specimens examined (8%), which were taken from the river São Francisco in Minas Gerais state, Brazil. Plasmodia of the parasite were white and long, measuring 5 mm in lenght. Mature spores of M. filamentum sp. n. were oval from the frontal view and biconvex from the lateral view, measuring 7.5-9.7 µm (9.0 ± 0.3 µm) in length and 5.2-7.3 µm (6.2 ± 0.4 µm) in width. The polar capsules were elongated and equal in size, measuring 3.8-5.5 µm (4.7 ± 0.3 µm) in length and 1.3-2.2 µm (1.7 ± 0.1 µm) in width. The development of the parasite led to compression of the adjacent tissues and inflammatory infiltrate with granulocytic cells. Ultrastructural observation revealed that the plasmodia were delimited by two membranes, which had numerous and extensive pinocytotic channels extending into the wide ectoplasm zone. The plasmodial wall exhibited abundant villi-like projections and a thin layer of granular material prevented direct contact between the plasmodial wall and the host tissue. Phylogenetic analysis, based on 18S rDNA, showed M. filamentum sp. n. as a sister species of Myxobolus oliveirai Milanin, Eiras, Arana, Maia, Alves, Silva, Carriero, Ceccarelli et Adriano, 2010, a parasite of other fish species of the genus Brycon Müller et Troschel from South America., Juliana Naldoni, Suellen A. Zatti, Kassia R.H. Capodifoglio, Tiago Milanin, Antônio A.M. Maia, Marcia R.M. Silva, Edson A. Adriano., and Obsahuje bibliografii
Preferences of young caterpillars of three species of Pieris (P. rapae crucivora Boisduval, P. melete Ménétriès, and P. napi japonica Shirôzu) (Lepidoptera: Pieridae) for the upper and lower surfaces of the leaves of their host plants (Brassicaceae) were investigated in the laboratory. On horseradish Armoracia rusticana Gaertn. Mey. et Scherb., which was provided as a common food for three species, second and third instar larvae of the respective species preferred the lower to the upper surface of horizontally placed leaves, irrespective of whether they hatched on the upper or lower surface. First instar larvae seemed to remain on the surface on which they hatched. However, first instar larvae of P. melete on Rorippa indica (L.), a natural food of P. melete in the field, and first instar larvae of P. napi japonica on Arabis flagellosa Miq., a natural food of P. napi japonica, preferred the lower to the upper surface, just as second and third instar larvae did. To elucidate the effects of leaf-surface preference, the percentage parasitism of P. rapae crucivora on Arm. rusticana and Ara. flagellosa by the parasitoid Cotesia glomerata (L.) (Hymenoptera: Braconidae) was investigated. On Arm. rusticana, the percentage parasitism of the larvae on the upper surface was higher than that of larvae on the lower surface. On Ara. flagellosa, however, percentages parasitism were nearly equal on both surfaces. Leaf-surface preference by the larvae of Pieris is discussed in terms of avoidance of parasitism by the parasitoid C. glomerata.
This paper explores the ways in which housing wealth is producing new forms of differentiation among households. In doing so, it will argue that ‘asset based welfare’ is now better conceived as ‘asset based social stratification’ and that social class rather than generation remains the primary social divide. However, these class divides are increasingly shaped by the differential ability to accumulate and deploy primarily housing -based assets. These new forms of social (re) stratification will vary societally, temporally and spatially and are currently most evident in what can be described as older, mature home ownership societies. But similar developments and emerging fissures can be observed in newer, ultra home -ownership societies such as China and in the broader interconnections between the mobilization of family assets and the shift from consumer to market societies.
This special issue expands on the existing research on foreign-currency lending and the forex loan crisis in Eastern Europe by investigating other forms of housing-related finance and post-crisis developments. Bringing together hitherto disparate strands of research, our issue traces the linkages between macroeconomic developments, state measures, class dynamics, and social movements in the aftermath of the forex loan crises in Latvia, Romania, Croatia, Bosnia and Herzegovina, and Hungary as part of their long-term trajectories of housing finance. We find that despite different political-institutional articulations, these trajectories all feature a new expansion of lending based on a bifurcation of the credit market into more secure, often subsidised mortgage lending aimed at better-off debtors and more risky non-mortgage loans used for housing purposes by more precarious households.
The Portuguese housing market underwent major transformations between 2010 and 2020. Until then, a delicate but resentful stability had long existed, with distorted rent schemes and low annual price increases proportional to the national economy and the income of the Portuguese population. After the financial crisis, several internal and external variables converged to dramatically change this scenario. In recent years, a growing number of researchers have centred their attention on the difficulties that the Portuguese urban middle-class populations are facing in trying to find homes. This paper analyses these challenges and their impact quantitatively, focusing on the affordability of housing for purchase or rent and considering synthetic indicators for average household incomes in the Lisbon Metropolitan Area between the beginning of 2016 and the end of 2019. The results show that the cost of buying or renting a house in the main Portuguese urban system has become much more detached from local incomes. The article concludes with reflections on the structural reasons for the enduring inequalities in the housing markets and the difficulties recognising territorial cohesion and spatial justice as important elements shaping urban and housing policies in Portugal.
The adoption of innovative building technologies (IBTs) and social welfare policies in South Africa has facilitated an increase in decent homeownership among low-income groups, thus improving their quality of life. However, due to the escalating costs of building materials, the capital and lifecycle costs of implementing these technologies may no longer be affordable. This research aims to provide a comparative evaluation of the affordability of some readily available IBTs in the South African construction industry, relative to existing homeownership subsidy grants. The method used involved the use of secondary data for these IBTs and the income constraint methods. The results showed that, apart from the technologies suitable for the provision of temporary structures, most of the other technologies were not affordable for the complete subsidisation of the top structure when both capital and lifecycle costs were used, except the Moladi and Robust structure IBTs under some low-income homeownership programmes. Further analysis using credit-linked subsidies revealed that the minimum household income required to achieve affordable homeownership (and their rankings) depends both on the evaluation technique (lifecycle or capital costs) and technology used. To improve affordability, any implementing government can either raise the amount of the top structure subsidy grant, promote the use of cheaper but durable IBTs, or promote the use in incremental building methods, such as the Enhanced People’s Housing Process (EPHP) for the case of South Africa.
This article explores the nexus between the financialisation of housing and socio-economic inequality in Bosnia and Herzegovina (BiH). In this context, since the post-war economic reforms, driven by deindustrialisation, the precarisation of labour, and dependent financialisation, housing loans have become a ‘privilege’ for a restricted group of people with high and stable incomes. Instead, the housing aspirations of Bosnians are generally met with the aid of consumer loans and the ostensibly cheaper FX loans that were introduced in the mid-2000s. Drawing on quantitative and qualitative data, this paper highlights the enduring features of the polarised credit market in BiH. It particularly focuses on the period after the 2008 crisis when lending policies were only mildly re-regulated. FX loans never became the object of an ad hoc law to convert them to Bosnian convertible marks. This institutional approach has been unable to challenge the extreme class segmentation of housing finance and is still fostering indebtedness and precarious housing conditions among the lower-income segments of Bosnian society even after the pandemic.
Quantitative community-wide moth surveys frequently employ flight-interception traps equipped with UV-light emitting sources as attractants. It has long been known that moth species differ in their responsiveness to light traps. We studied how the settling behaviour of moths at a light trap may further contribute to sampling bias. We observed the behaviour of 1426 moths at a light tower. Moths were classified as either, settling and remaining still after arrival, or continually moving on the gauze for extended periods of time. Moths that did not move after settling may not end up in the sampling container of the light trap and therefore are under-represented in automated trap samples relative to their true proportions in the community. Our analyses revealed highly significant behavioural differences between moths that differed in body size. Small moths were more likely to remain stationary after settling. As a corollary, representatives of three taxa, which in Europe are predominantly small species (Nolidae, Geometridae: Eupitheciini, Erebidae: Lithosiini), usually settled down immediately, whereas most other moths remained active on or flying around the trap for some time. Moth behaviour was also modulated by ambient temperature. At high temperatures, they were less likely to settle down immediately, but this behavioural difference was most strongly apparent among medium-sized moths. These results indicate the likely extent of the sampling bias when analysing and interpreting automated light-trap samples. Furthermore, to control for temperature modulated sampling bias temperature should always be recorded when sampling moths using flight-interception traps. and Mirko Wölfling, Mira C. Becker, Britta Uhl, Anja Traub, Konrad Fiedler.