Establishing ex ante public construction supply chain guidelines in the public procurement of Schools' estate

Purpose – The purpose of this study is to explore the formative development of construction supply chain guidelines or proposals in a UK region’s schools’ estates procurement process to more effectively address a forthcoming increase in investment.

Design/methodology/approach – The research approach is interpretive. Using an action research approach, repeated semi-structured interviews and focus groups with a range of stakeholders are conducted.

Findings – The current construction supply chain in schools’ estate procurement has many difficulties, not least given the highly fragmented and disconnected nature of the projects. Synergies are being missed and there is little or no continuous improvement. Drawing on these findings, the research iteratively develops a range of proposals and guidelines to address this situation.

Research limitations/implications – This research adds weight to the current focus on pressing for change in the construction industry. It presents potentially valuable insights into the benefits of partnering arrangements and how these might usefully be incorporated into schools’ estate supply chain.

Practical implications – A set of guidelines is developed to guide the public procurement of schools’ estate in a UK region. These guidelines are set within the context of the Modernising and Rethinking Construction agenda.

Originality/value – The action research approach enabled the researchers to gain a unique insight into how public procurement and contractor personnel interact and to establish effective practical guidelines.

Selection for cuticular melanism reveals immune function and life-history trade-offs in Spodoptera littoralis

Several insect species show an increase in cuticular melanism in response to high densities. In some species, there is evidence that this melanism is correlated with an up-regulation of certain immune system components, particularly phenoloxidase (PO) activity, and with the down-regulation of lysozyme activity, suggesting a trade-off between the two traits. As melanism has a genetic component, we selected both melanic and nonmelanic lines of the phase-polyphenic lepidopteran, Spodoptera littoralis, in order to test for a causative genetic link between melanism, PO activity and lysozyme activity, and to establish if there are any life-history costs associated with the melanic response. We found that, in fact, melanic lines had lower PO activity and higher lysozyme activity than nonmelanic lines, confirming a genetic trade-off between the two immune responses, but also indicating a genetic trade-off between melanism and PO activity. In addition, we found that lines with high PO activity had slower development rates suggesting that investment in PO, rather than in melanism, is costly.

Costs of resistance: genetic correlations and potential trade-offs in an insect immune system

Theory predicts that natural selection will erode additive genetic variation in fitness-related traits. However, numerous studies have found considerable heritable variation in traits related to immune function, which should be closely linked to fitness. This could be due to trade-offs maintaining variation in these traits. We used the Egyptian cotton leafworm, Spodoptera littoralis, as a model system to examine the quantitative genetics of insect immune function. We estimated the heritabilities of several different measures of innate immunity and the genetic correlations between these immune traits and a number of life history traits. Our results provide the first evidence for a potential genetic trade-off within the insect immune system, with antibacterial activity (lysozyme-like) exhibiting a significant negative genetic correlation with haemocyte density, which itself is positively genetically correlated with both haemolymph phenoloxidase activity and cuticular melanization. We speculate on a potential trade-off between defence against parasites and predators, mediated by larval colour, and its role in maintaining genetic variation in traits under natural selection.