Multi-function oxidases are responsible for the synergistic interactions occurring between repellents and insecticides in mosquitoes

Background: With the spread of pyrethroid resistance in mosquitoes, the combination of an insecticide (carbamate or organophosphate) with a repellent (DEET) is considered as a promising alternative strategy for the treatment of mosquito nets and other relevant materials. The efficacy of these mixtures comes from the fact that they reproduce pyrethroid features and that positive interactions occur between insecticides and repellent. To better understand the mechanisms involved and assess the impact of detoxifying enzymes (oxidases and esterases) in these interactions, bioassays were carried out in the laboratory against the main dengue vector Aedes aegypti. Methods: Topical applications of DEET and propoxur (carbamate), used alone or as a mixture, were carried out on female mosquitoes, using inhibitors of the two main detoxification pathways in the insect. PBO, an inhibitor of multi-function oxidases, and DEF, an inhibitor of esterases, were applied one hour prior to the main treatment. Results: Results showed that synergism between DEET and propoxur disappeared in the presence of PBO but not with DEF. This suggests that oxidases, contrary to esterases, play a key role in the interactions occurring between DEET and cholinesterase inhibitors in mosquitoes. Conclusion: These findings are of great interest for the implementation of "combination nets" in the field. They support the need to combine insecticide with repellent to overcome insecticide resistance in mosquitoes of public health importance.

Literature and the shaman: Jung, trauma stories and new origin stories in The Lion, the witch and the wardrobe by C.S. Lewis

The paper first considers the role of Jungian ideas in relation to academic disciplines and to literary studies in particular. Jung is a significant resource in negotiating developments in literary theory because of his characteristic treatment of the ‘other’. The paper then looks at The Lion, the Witch and the Wardrobe (1950) by C.S. Lewis whose own construction of archetypes is very close to Jung’s. By drawing upon new post-Jungian work from Jerome Bernstein’s Living in the Borderland (2005), the novel is revealed to be intimately concerned with narratives of trauma and of origin. Indeed, a Jungian and post-Jungian approach is able to situate the text both within nature and in the historical traumas of war as well as the personal traumas of subjectivity. Where Bernstein connects his work to the postcolonial ethos of the modern Navajo shaman, this new weaving of literary and cultural theory points to the residue of shamanism within the arts of the West. [From the Publisher]

Multiple attractors of host-parasitoid models with integrated pest management strategies: eradication, persistence and outbreak

Host-parasitoid models including integrated pest management (IPM) interventions with impulsive effects at both fixed and unfixed times were analyzed with regard to host-eradication, host-parasitoid persistence and host-outbreak solutions. The host-eradication periodic solution with fixed moments is globally stable if the host's intrinsic growth rate is less than the summation of the mean host-killing rate and the mean parasitization rate during the impulsive period. Solutions for all three categories can coexist, with switch-like transitions among their attractors showing that varying dosages and frequencies of insecticide applications and the numbers of parasitoids released are crucial. Periodic solutions also exist for models with unfixed moments for which the maximum amplitude of the host is less than the economic threshold. The dosages and frequencies of IPM interventions for these solutions are much reduced in comparison with the pest-eradication periodic solution. Our results, which are robust to inclusion of stochastic effects and with a wide range of parameter values, confirm that IPM is more effective than any single control tactic.