Durant leur cycle de vie, les insectes doivent faire face à différents perturbateurs pour réussir à survivre et à se reproduire. L’utilisation de plus en plus répandue des insecticides néonicotinoïdes, en raison de leur grande efficacité, a conduit à l’accumulation de résidus dans l’environnement. Ceux-ci ont certainement un effet additif toxique sur les insectes cibles. Cependant il a été montré que ces résidus peuvent aussi avoir un effet positif non désiré sur certains traits de vie des insectes ravageurs.Dans ma thèse, j’ai étudié les effets d’un insecticide néonicotinoïde sur le système olfactif d’un insecte ravageur, la noctuelle Agrotis ipsilon. Nos résultats montrent que l’exposition aigüe des mâles à des faibles doses de clothianidine modifie leurs réponses comportementales à la phéromone sexuelle: une baisse est observée à la dose 0,25 ng/insecte (<DL0) alors que la doses de 10 ng (DL20) induit une augmentation de la réponse chez les adultes naïfs ou pré-exposés à la phéromone. Cet effet biphasique à faible et très faible dose s’apparente à un effet hormétique et les modifications observées sont corrélées avec des changements de sensibilité du système olfactif central et non périphérique. Nous émettons l’hypothèse que la clothianidine agirait sur l’expression des sous-unités des récepteurs nicotiniques pour lesquels elle joue le rôle d’agoniste, changeant leur affinité pour l’acétylcholine et perturbant ou améliorant la transmission synaptique des signaux sensoriels selon la dose. Nos résultats montrent que la prise en compte d’effets de doses sublétales d’insecticides est essentielle non seulement pour les insectes non cibles, mais aussi des insectes cibles. / Insects face a multitude of environmental stresses, which they have to bypass in order to survive and reproduce. The extensive use of neonicotinoid insecticides, because of their high efficiency, leads to the accumulation of residues in the environment, which can have an additive toxic effect on target insects. However, such residues can also have unwanted positive effects on certain life traits of pest insects. In my thesis I studied the effects of a neonicotinoid insecticide on the olfactory system of the pest insect Agrotis ipsilon. Our results show that acute oral treatments of males with low doses of clothianidin modify their behavioural responses to the sex pheromone: a treatment with 0.25 ng/moth (<LD0) induces a decrease of pheromone responses whereas intoxication with 10 ng/moth (LD20) leads to an increase in the capacity of naive and pre-exposed males to locate a pheromone source as compared to controls. We propose that this biphasic effect, with low dose stimulation and very low dose inhibition is an hormeticlike effect, that is correlated with sensitivity changes within the central, but not the peripheral olfactory system. We hypothesize that the observed modifications might be due to a differential effect of clothianidin on the expression of different subunits of nicotinic acetylcholine receptors, which might change the affinity of the receptors for acetylcholine, and thus disturb or improve synaptic transmission of sensory signals as a function of the insecticide dose. Our results show that effects of sublethal doses of insecticides need to be taken into account not only for non-target, but also for target insects when evaluating pest management strategies.

<p>This study aims to compare the sexual behaviour patterns of male elite student athletes, male student recreational sports (RSP) and male student non-athletes at the University of Botswana in relation to high-risk sexual behaviours. High-risk behaviors in the domain of sexual behaviour were investigated in relation to the determinants of risk behaviour such as multiple partnerships, condom use, and history of sexually transmitted infections, the partners past sex life, current sexual life, casual sexual partners and age of first exual experience. The purpose was to establish which group of the male students is more at risk of HIV infection due to its engagement in high-risk sexual behaviour. Data was collected by means of an anonymous self-report questionnaire. Participants included 235 male students (94 non-athletes, 92 athletes and 50 elite athletes) at the University of Botswana. Selfreport questionnaires were administered, which included items from the 2005 Youth Risk Surveillance System (YRBSS), Student Life Style questionnaire, as well as items from a questionnaire assessing knowledge and practice of safe sex amongst Rhodes University students (Simpson, 1996).</p>

<p>The aim of the study was to explore the socio-cultural influences in decision making involving sexual behaviour among adolescents in Khayelitsha, Cape Town. Cultural beliefs associated with adolescents&rsquo / decision to become sexually active were explored, as well as the social norms influences involved in adolescents&rsquo / sexual behaviour. The theoretical framework used for the study was Bronfenbrenner&rsquo / s ecological systems theory of development. The results indicated that adolescent pregnancy was perceived as unacceptable behaviour although found widespread in communities. Social influences such as peer influence, low socioeconomic status, alcohol use and lack of parental supervision were found to play a role in adolescents&rsquo / risky sexual behaviour. Cultural beliefs, cultural myths and social norms were identified as socio-cultural influences that endorsed issues such as gender disparities, which made adolescent mothers vulnerable. Findings from this study suggest that female adolescents are faced with sexual behaviour complexities.</p>

No description available.

Dabar vis daugiau mokslininkų bando identifikuotus gyvūnų feromonus sintetinti ir panaudoti praktinėms reikmėms, pavyzdžiui, vabzdžių sintetinių feromonų analogus naudoti kovai su žemės ūkio kenkėjais. Tačiau tik XX amžiaus pabaigoje pradėta domėtis ir žinduolių feromonais. Viena iš naujų tiriamų sričių yra: lytinių feromonų įtaka gyvūnų lytinei elgsenai. Lytinė elgsena yra vienas iš svarbiausių šunų kaip ir, bet kurios kitos gyvosios sistemos egzistavimo garantas, todėl tai paskatino mus išsamiau paanalizuoti šunų lytinės elgsenos modelį (asistavimą). Taip pat mūsų tikslas buvo sumodeliuoti tokį biotestavimo modelį kaip materiali informacija paveikia individo (šuns) elgesį ir nustatyti bei apibūdinti kas tai yra ta informacija, šiuo atveju – cheminė medžiaga. Tyrimai buvo atlikti 2005 – 2007 metais. Buvo surinkti šlapimo ėminiai iš skirtingų šunų veislių devynių kalių nerujos ir rujos metu. Ėminių rinkimo metodika buvo specialiai sukurta įgyvendinti mūsų užduotis ir yra originali. Viena dalis rinkimo metu surinktos medžiagos buvo išsiusta į Karališkąjį Technologijų Institutą Stokholme (Royal Institute of Technologies). Atlikus pirminius ėminių tyrimus, nustatyta jog tik rujojančių kalių šlapime yra TC medžiaga. Antra dalis rinkimo metu surinktos medžiagos buvo naudota biotestui. Po to buvo atlikti du biotestavimai lauko sąlygomis Pietų Rusijos aviganių veislyne „Balandis“. Šiuose tyrimuose buvo atlikti testavimai su šios veislės patinais pagal 7 mūsų sukurtus testavimo... [toliau žr. visą tekstą] / More and more scientists nowadays are trying to syntetic animals‘ pheromones and use them for practical purposes. Analogues of syntetic pheromones, for instance, are used in agriculture against pests. It was only in the end of the 20th century, however, that mammals‘ pheromones, too, started arousing interest. One of the new fields of resaerch is the animals‘ sexual behaviour. Sexual behaviour is one of the guarantees of dogs‘, as well as any other living systems‘ existence. Then an idea suggested itself to us to analyze more deeply the model of this type of behaviour amoung dogs. Our aim was also to set up a model of biotesting in what way material information is reflected on an individual‘s (dog‘s) behaviour and to establish what that information is. In this case – a chemical substance. The research was carried out between 2005 and 2007. Urine samples were gathered from bitches of different dogs‘ breeds then they were on the heat and when they were not on the heat. The method of taking the samples was specially created to satisfy our requirements and is original. One part of the samples gathered was sent to the Royal Institute of Technologies in Stockholm. The research conducted on the primary samples showed that the substance TC was to be found only in the urinie of bitches (females) that were on the heat. The rest of material gathered was used for examination. Then two biotests (in outside)was conducted at the South Russian Sheep – dog kennel “Balandis“. Researched... [to full text]

This study investigates the conceptualisation of child-on-child sexual offenders from the perspective of a group of isiZulu educators. Although a number of studies focusing on child-on-child sexual offenders have been conducted internationally, this is not the case in South Africa. The lack of literature regarding this issue, particularly in the school environment, and the increasing number of child-on-child sexual offenders provided the motivation for the research. Three focus groups were conducted with educators representing three educational environments, namely: educators teaching at a school for mentally retarded children, educators from a rural school and finally educators from township schools. The focus groups were transcribed and then analysed on two levels. Firstly, the data was examined in terms of explicit concepts and were based on concepts previously identified in the literature. The concepts were, quantified by way of a content analysis. In relation to this, four major conceptualisations emerged, each of which were further subdivided. The four major concepts included: 1) child-on-child sexual offending as "abnormal"; 2) childon-child sexual offending as "normal"; 3) the role of acculturation in child-on-child sexual offending; and, 4) the role of educators and the educational system in relation to child-onchild sexual offending. This analysis was useful in that it highlighted common and significant themes among the three focus groups. Secondly, the data was analysed qualitatively and emerging implicit themes examined in greater depth. During this phase a number of strategies that were used by the educators to normalise, relativise and justify the issue of child-on-child sexual offending were identified. The function of these strategies was considered to be a defensive strategy to make the issue of child-on-child sexual offending more tolerable and thus easier to talk about. / Thesis (M.A.)-University of Natal, Pietermaritzburg, 2001.

Sexual and reproductive health care have become key priorities both within developing and developed nations. Young people have been identified as particularly vulnerable to negative health outcomes. South Africa is one such example of a country that presently faces significant challenges in addressing the unmet sexual and reproductive health needs of young people. With the enormous burden of reproductive health problems and the accelerating HIV epidemic, the provision of sexual and reproductive health services remains a challenge. Though various studies highlight the importance of comprehensive services targeted at youth, there is a lack of adequate research in evaluating the extent to which health services are addressing the health needs of clients. This study aimed to address this gap by examining a health care facility for students at one of the largest tertiary institutions in KwaZulu-Natal. The core objective was to determine the extent to which the health services are responding to the sexual and reproductive needs of young people by, exploring the experiences and perspectives of service providers and young men and women in relation to comprehensive, youth-friendly sexual and reproductive health care. This was assessed using a revised version of the Bruce-Jain quality of care framework. Information for this study was obtained using quantitative and qualitative data collection methods including: an inventory of the facility and services, in-depth interviews with staff and exit interviews with 200 clients aged 18 to 24 years. The findings of the study reveal that logistical constraints hindered effective implementation of comprehensive, youth-friendly services by providers. Providers missed opportunities to provide clients with much needed information and services due to staff shortage, client overload, lack of infrastructure, and poor continuity mechanisms. HIV, STIs and unwanted pregnancies were some of the most important health issues among young people visiting the health facility. Very few young men utilised the services. Some of the key findings were that clients continue to experience barriers in interpersonal relations while many expressed the need for more information from providers. In addition, many young women still have an unmet need for contraception. Policy makers need to incorporate the needs of young clients within sexual and reproductive health initiatives. Ideally young people should be involved in the design and implementation process of comprehensive, youth-friendly health initiatives. This would form a platform for addressing the barriers that hinder health service provision. / Thesis (M.A.)-University of KwaZulu-Natal, Durban, 2011.

Unintended pregnancy has been the subject of considerable research in Lesotho. Lack of priority placed on young people’s sexuality and reproductive health was found to be a major factor exacerbating the rate of unintended pregnancy in the country. The study draws on qualitative data collected from in-depth interviews with university students in Lesotho. In total, 15 in-depth interviews were conducted with 10 women and 5 men. The findings of the study show that unsafe sex coupled with low contraceptive use are the leading causes of unintended pregnancy among young women in Lesotho. Evidence suggests that even though contraceptive prevalence is noticeably low, modern contraceptive methods have a greater potential than other means for reducing the prevalence of unintended pregnancy. The findings of the study also suggest that there is a considerable gender differences in sexual behaviour; males are more likely than females to experience earlier sexual onset, have more sexual partners and to practise unsafe sex. This study recommends that increasing contraceptive prevalence among young people will lead to better reproductive health outcomes. The study also suggests that family planning services should be more male friendly because men play a major role in decision making, and have a great influence on their partners’ decisions to use contraceptives. / Thesis (M.A.)-University of KwaZulu-Natal, Durban, 2011.

The study examined correlates of HIV perceived risks and protective strategies among adolescents in rural Malawi i.e. whether there was an association between socio demographic characteristics of adolescents and subsequent HIV perceived risks and protective strategies. Age at sexual debut is a variable of interest in this study. The objectives were to investigate whether age at first sexual intercourse does influence adolescents’ individual’s risk perceptions of HIV and protective strategies, i.e. does age at first sex set a precedence in the thinking of adolescentswith regards HIV risks and protective strategies such as condom use. Data: This study uses cross sectional data from Wave 3 of a wider study, the Malawi Diffusion and Ideational Change Project (MDICP).The MDICP is a joint collaboration between researchers from the Population Studies Centre at the University of Pennsylvania and the University of Malawi‘s College of Medicine and Chancellor College. In this study, a multiple regression analysis on the cross sectional data from the 2004 wave 3of the Malawi Diffusion and Ideational Change Project was done. The focus of this study is on the relationship between age at first sexual intercourse and the individual‘s perception of risk of HIV/AIDS and protective strategies, it examines if there is an association between the two factors. Descriptive analysis: Descriptive statistics to obtain the frequencies of the main variables of interest such as the background characteristics of respondents (gender, marital status, mean age at sexual debut, education, economic status of household) were computed in order to better understand the population under study. Multivariate Analysis: Three separate models were employed; two multinomial regression analysis measuring worry and likelihood of infection against socio demographic variables and a binary logistic regression measuring condom use and the socio demographic variables. Relative Risk Ratios were used to interpret the multinomial logistic regression output while odds ratios were used to interpret the logistic output. Results: Consistent with existing literature, results indicate that early age at first sex is a predictor of HIV risk perceptions and protective strategies. Age at first sex does set a precedence in the future thinking of adolescents with regards to how they perceive HIV risks, as well as how they perceive protective strategies against HIV-particularly condom use. This study confirms that age at first sex alongside with other socio demographic variables are significantly associated with HIV risk perceptions HIV and condom use, while other factors may matter, such as gender, region, HIV knowledge, religion or educational level. Limitations: The information on age at first sexual encounter was based exclusively on respondent’s self–reports. This data collection method often has limitations that are attributed to the tendency for people to under-report socially unacceptable behaviours (e.g. having multiple sex partners) and to over-report socially acceptable behavior. The other limitation is that the study lacks longitudinal data to allow a more in-depth analysis of trends in HIV/AIDS-related indicators. / Thesis (M.A.)-University of KwaZulu-Natal, Durban, 2011.

This study investigates the conceptualisation of child-on-child sexual offenders from the perspective of a group of isiZulu educators. Although a number of studies focusing on child-on-child sexual offenders have been conducted internationally, this is not the case in South Africa. The lack of literature regarding this issue, particularly in the school environment, and the increasing number of child-on-child sexual offenders provided the motivation for the research. Three focus groups were conducted with educators representing three educational environments, namely: educators teaching at a school for mentally retarded children, educators from a rural school and finally educators from township schools. The focus groups were transcribed and then analysed on two levels. Firstly, the data was examined in terms of explicit concepts and were based on concepts previously identified in the literature. The concepts were, quantified by way of a content analysis. In relation to this, four major conceptualisations emerged, each of which were further subdivided. The four major concepts included: 1) child-on-child sexual offending as "abnormal"; 2) child- on-child sexual offending as "normal"; 3) the role of acculturation in child-on-child sexual offending; and, 4) the role of educators and the educational system in relation to child-on- child sexual offending. This analysis was useful in that it highlighted common and significant themes among the three focus groups. Secondly, the data was analysed qualitatively and emerging implicit themes examined in greater depth. During this phase a number of strategies that were used by the educators to normalise, relativise and justify the issue of child-on-child sexual offending were identified. The function of these strategies was considered to be a defensive strategy to make the issue of child-on-child sexual offending more tolerable and thus easier to talk about. / Thesis (M.A.)-University of Natal, Pietermaritzburg, 2001.