Pheromone trapping models for pest control: Effects of mating patterns and immigration

Summary Several models are presented which examine pest population behaviour with the release of female sex pheromones for the attraction and annihilation of males. These models include male polygamy and female monogamy, various mating frequencies, delayed mating of females, immigration of one or all individual types, and differential survivorship of males and females. In all the models there are two steady states, a stable s.s. at the origin and an unstable s.s. in the positive domain for a given value of pheromone release rate. In all the models, control relies on the reduced ability of males to fertilize virgin females following trapping and male annihilation. As such, control is very sensitive to mating frequency, being very difficult when males mate frequently. Control is also very difficult with the immigration of even a moderate number of fertilized females. Control is much easier when mating is delayed, especially if survivorship is low, or with density dependent population regulation.     

Power and identity in theory and practice

Power is often theorised in a way that equates its meaning with A's control over B. Alternatively, it is regarded as a universal transformative capacity. In which case, power is conceptualised in terms of its accomplishment of social order. The central objective of this paper is to expose the contribution and limitations of existing functionalist, action theoretic, radical and relational conceptions of power. This is done by attending to the significance of identity securing strategies in the reproduction of power relations. Highlighting the relevance of this identity dimension, we argue that individuals’ attempts to distance and protect themselves from their ‘powerlessness’ can have important, self-defeating consequences in respect of the reproduction of asymmetrical relations of power. Connecting the search for independence to the preoccupation with securing a stable and valued sense of identity, we explore how this preoccupation sustains the very structural conditions that promote insecurity. Our thesis on power and identity is then applied and illustrated through a critical discussion of relevant aspects of two recent labour ethnographies: Nichols and Beynon's Living with Capitalism and Willis's Learning to Labour.     

Modelling selection for resistance to methods of insect pest control in combination

The development of resistance to insecticides is now widespread among insects. Other methods of pest control are also potentially at risk of encountering resistance. A modelling approach is presented here to evaluate the effects of combining methods of insect pest control on the selection for resistance to the control methods. This analysis is based on partitioning the total mortality acting on a population into its constituent components from all known sources, and these are related to selection for resistance. When two control methods are used in combination, selection for resistance against the two is a linear function if the two don't interact, otherwise it may be sublinear or supralinear. A specific example is presented using a model of the Olive fruit fly (Dacus oleae Gmel.) and employing food-baited and pheromone-baited traps for control. The control methods that appear least likely to encounter resistance are natural enemies and the use of pheromone traps for male annihilation. These should be integrated into a control program where possible to minimize the development of resistance to other control methods being used.     

Rethinking Management and Managerial Work: Capitalism, Control, and Subjectivity

The paper presents an alternative understandingof managerial work based upon a reconstruction of laborprocess theory. Drawing upon contemporary studies ofmanagement practice, the paper explores the relevance of poststructuralism and an attentiveness tosubjectivity to articulate a view of managerial work asthe subject and object of the contradictory organizationand control of capitalist labor processes. This understanding is illustrated by reference toempirical studies of ICI and is supplemented byinterview material drawn from a study of changingmanagement practices in the U.K.     

Family Processes and Problem Behaviors in Middle‐Class African American Adolescents

This study examined the joint association between mothers’ and adolescents’ ratings of parental behavioral control and adolescents’ and observers’ ratings of mother – adolescent communication with adolescent problem behaviors in a sample of 86 middle‐class African American early adolescent boys and girls (age: M= 13.08 years, SD= 1.32) and their mothers. Consistent with hypotheses, greater adolescent‐rated parental behavioral control and better observer‐rated mother – adolescent communication were associated with lower levels of adolescent problem behavior, as examined using structural equation modeling. Furthermore, interrelationships between age and adolescent problem behavior were partially mediated by adolescents’ reports of parental behavioral control and observers’ ratings of positive mother – adolescent communication, which both decreased with adolescents’ age. Although the sample was primarily middle class, higher socioeconomic status was associated with more positive mother – adolescent communication, as rated by observers. Problem behavior was greater among boys than girls, but the hypothesized indirect effect of gender on problem behavior through associations with parenting was not observed. The findings demonstrate the utility of conceptually distinguishing between parenting and parent – adolescent relationships, and suggest that both have unique influences on middle‐class African American adolescents’ problem behavior.     

State-of-the-Art Developments in Expert Systems and Strategic Marketing Planning

This paper describes a case history of the development of an Expert System in Strategic Marketing Planning codenamed EXMAR. It traces the evolution of the system from the formation of the DTI club two years ago to the launch of the prototype model. The paper outlines the technical and domain–specific obstacles encountered en route and how these were overcome. A number of conclusions are drawn from the project. The principal one is that there is a bright future for expert systems in the field of strategic management. Professor Malcolm McDonald is the principal expert to the club. Hugh Wilson is a senior consultant with Artificial Intelligence Ltd. He was also the knowledge engineer and the project manager. For readers who would like a simple explanation of Expert Systems, please refer to Professor McDonald's paper ‘Marketing Planning and Expert Systems: an Epistemology of Practice’, Marketing Intelligence and Planning, 7, 7/8, 1989.