Defensive responses by a social caterpillar are tailored to different predators and change with larval instar and group size

Gregariousness in animals is widely accepted as a behavioral adaptation for protection from predation. However, predation risk and the effectiveness of a prey’s defense can be a function of several other factors, including predator species and prey size or age. The objective of this study was to determine if the gregarious habit of Malacosoma disstria caterpillars is advantageous against invertebrate natural enemies, and whether it is through dilution or cooperative defenses. We also examined the effects of larval growth and group size on the rate and success of attacks. Caterpillars of M. disstria responded with predator-specific behaviors, which led to increased survival. Evasive behaviors were used against stinkbugs, while thrashing by fourth instar caterpillars and holding on to the silk mat by second instar caterpillars was most efficient against spider attacks. Collective head flicking and biting by groups of both second and fourth instar caterpillars were observed when attacked by parasitoids. Increased larval size decreased the average number of attacks by spiders but increased the number of attacks by both stinkbugs and parasitoids. However, increased body size decreased the success rate of attacks by all three natural enemies and increased handling time for both predators. Larger group sizes did not influence the number of attacks from predators but increased the number of attacks and the number of successful attacks from parasitoids. In all cases, individual risk was lower in larger groups. Caterpillars showed collective defenses against parasitoids but not against the walking predators. These results show that caterpillars use different tactics against different natural enemies. Overall, these tactics are both more diverse and more effective in fourth instar than in second instar caterpillars, confirming that growth reduces predation risk. We also show that grouping benefits caterpillars through dilution of risk, and, in the case of parasitoids, through group defenses. The decreased tendency to aggregate in the last larval instar may therefore be linked to decreasing predation risk

Romanian Suburban Housing : Home Improvement through Owner-building

The new suburban housing developments in post-socialist cities have been ubiquitous icons of socioeconomic and physical change. This paper examines suburban owner-built housing as a long-term strategy of home improvement in Romania. It analyses residents’ motivations and financial strategies to move up the housing ladder through owner-building and their responses to key neighbourhood problems, in particular poor public infrastructure and non-existent public facilities. I argue that owner-builders generally benefitted from the economic informality, the relaxed legal culture and the unregulated housing context of the Romanian post-socialist transition; but the absence of public actors has weakened their achievements, which is most apparent at neighbourhood level. The paper draws attention to a context of politico-economic reforms and a set of socio-cultural values of housing privatism in which resident responses may frequently generate consequential (collective) problems localised at the level of streets, neighbourhoods or even the whole society.PostprintPeer reviewe

Overcrowding and ‘under-occupancy’ in Romania : a case study of housing inequality

This paper examines aspects of space consumption in two very different housing types, the communist mid-rise estates and post-communist suburban self-built housing. Examining residents’ perceptions in order to categorize space as overcrowded or under-occupied, the paper engages critically with the issue of the inefficient distribution of Romanian housing, that is a considerable mismatch between dwelling and household size. The analysis documents the continued salience of overcrowding in the communist estates and conversely, self-builders’ satisfaction with the generous size of their new homes. Market forces permit various modes of residential mobility but their likely outcome is growing housing inequality while any redistributive impact will remain insignificant unless policy incentives could facilitate conversion of under-occupied space into (social) renting housing. However, only a sustained delivery of larger and affordable new dwellings could alleviate overcrowding.PostprintPeer reviewe

Strategies for In Situ Home Improvement in Romanian Large Housing Estates

Socio-economic and physical change have visibly affected post-socialist cities, yet the state of decay of their inherited large housing estates has only deepened throughout the 1990s, despite the change in tenure through policies of large-scale privatisation. Housing disrepair has now reached a critical stage that requires rapid private and public intervention. This paper examines the extent to which Romanian block residents have been able to improve in situ their housing conditions since 2000, the strategies they employed and the challenges they faced. It focuses on the often ignored private domain of housing, flats and blocks, where changes are also likely to be less visible. By analysing the process of individual utility metering and the practice of collective block management, I argue that besides economics, the unregulated housing context and a relaxed legal culture have challenged individual and collective action and have generated a framework of housing privatism.PostprintPeer reviewe