Characteristics and Dynamics of Cyberstalking Victimization Among Juveniles and Young Adults

Using the nationally representative Ipsos online KnowledgePanel, the sample included three hundred thirty-six 18- to 28-year-olds who retrospectively reported first cyberstalking incidents as juveniles (9- to 17-year-olds) or adults. Half of the sample first experienced cyberstalking as juveniles and half first experienced it as adults. Juveniles were more likely to have more than two perpetrators in the same episode, to experience more violent threats, and to avoid people because of what happened. Few reported the incident to the police, with juveniles less likely to report it to the police. Cyberstalking of juveniles appears just as or more serious than cyberstalking of adults.

Factors Affecting Telemedicine Implementation in Emergency Departments and Nurses' Perceptions of Virtual Sexual Assault Nurse Examiner Consultation for Sexual Assault Survivors

INTRODUCTION

Emergency department (ED) nurses play a critical role in caring for sexual assault patients, but many have not received training on how to conduct a proper sexual assault forensic medical examination. Live or real-time sexual assault nurse examiner (SANE) consultation provided via telemedicine (known as "teleSANE") during sexual assault examinations is a promising new practice to address this issue.

PURPOSE

The purpose of this study was to assess ED nurses' perceptions of influences on telemedicine use, as well as the utility and feasibility of teleSANE, and identify potential influences on teleSANE implementation in EDs.

METHODS

Guided by the Consolidated Framework for Implementation Research, this developmental evaluation involved semistructured qualitative interviews with 15 ED nurses from 13 EDs.

RESULTS

Interviews revealed facilitators and barriers to current telemedicine use across Consolidated Framework for Implementation Research levels. Facilitators included state-level grant funding and technical assistance. Barriers included clinician discomfort being on video and access to ongoing training. Participants believed teleSANE consultation would improve patient care and forensic evidence collection but had concerns for patient privacy and acceptability. Most participants worked in EDs that have the information technology support and telemedicine equipment needed to support teleSANE implementation, although many requested ongoing education and trainings on teleSANE and sexual assault care to improve clinician confidence and account for high staff turnover.

DISCUSSION

Findings highlight the unique needs of sexual assault survivors receiving telemedicine services in EDs, particularly those in rural communities with heightened privacy concerns and limited access to specialty care.

Statutory Rape: Case Characteristics When Offenders are Younger Than 21 Years of Age Versus Older

Statutory rape laws are intended to protect adolescents from harm as a result of sexual activity with older individuals. In this pursuit, many, but far from all, states' statutory rape laws differentiate younger and older offenders. In effect, many of these states differentiate offenders who are 21 and older from those who are under 21. It is unknown, however, whether and how the dynamics of statutory rape vary depending on the age of the offender. To explore the contribution of offender age to the dynamics of statutory rape, data were collected from the records of 105 statutory rape cases referred to a child abuse assessment center over a 63-month period. Records included detailed reports on case history and victims' family history, mental health and health-risking behaviors, medical examination results, and forensic interview summaries. Cases of offenders¹1.Because these cases are under investigation, "offenders" here refers to "suspects." For ease of reading, we use "offenders" to be consistent with prior research terminology. under 21 were compared to the cases of offenders 21 years and older. Compared to cases of younger offenders, cases of offenders 21 years and older more often involved slightly older adolescent victims. Independent of age, victims with offenders 21 and over compared with offenders under 21 were over six times as likely to have a prior history of a high, versus low, number of psychosocial problems and were seven times more likely to experience multiple forms of coercion versus no coercion by the offender. Findings suggest that statutory rape prevention, policy and response strategies should consider the critical ways that case characteristics and victims differ according to this key offender attribute.

"If you don't send me five other pictures I am going to post the photo online": A qualitative analysis of experiences of survivors of sextortion

In this study, we explored survivors' experience with sextortion (threats to expose sexual images to coerce victims to provide additional pictures, sex, or other favors). We conducted in-depth telephone interviews with 48 adults aged 18 to 25 who had been targets of sextortion. Nearly half of participants were minors at the time of the sextortion incident. Data were analyzed using thematic analysis, which resulted in four major dimensions. The dimensions identified were the emotional connections between victims and perpetrators, the nature of the threats, societal responses, and integrating the sextortion into their life stories. The findings emphasized the multidimensional nature of this phenomenon. There was a wide range of emotional connections, from brief connections to close intimate relationships or strong friendships. Some threats remained unfulfilled, while other were carried out. Some threats were one-time and some lasted for years. Societal responses were central in participants' narratives, with most participants actually turning to their peers and parents for support. Many expressed thankfulness for the opportunity to tell their story during the interviews. For the majority of participants sextortion was perceived as a central event in their lives, one that changed them forever. Listening to the voices of survivors helps professionals understand these harmful situations.

Academic Correlates of Unwanted Sexual Contact, Intercourse, Stalking, and Intimate Partner Violence: An Understudied but Important Consequence for College Students

Sexual assault, partner abuse, and stalking are major problems on college campuses. Past research has demonstrated a host of physiological and psychological outcomes associated with victimization; however, there has been little research conducted on the potential academic outcomes associated with victimization. The purpose of this study was to measure the relation between academic outcomes and experiences of sexual violence, intimate partner violence, and stalking victimization among college students. A sample of 6,482 undergraduate students currently enrolled at one of eight universities in New England was surveyed using items from the subscales of the College Persistence Questionnaire (Academic Efficacy, Collegiate Stress, Institutional Commitment, and Scholastic Conscientiousness). All four types of victimization were associated with significant differences on academic outcomes after controlling for sex and year in school, with victimized students reporting lower academic efficacy, higher college-related stress, lower institutional commitment, and lower scholastic conscientiousness. Polyvictimization was also significantly correlated with outcomes, with the greater number of types of victimization experienced by students being associated with more negative academic outcomes. Implications for future research and campus response were discussed.

Using Telehealth for Pediatric, Adolescent, and Adult Sexual Assault Forensic Medical Examinations: An Integrative Review

OBJECTIVE

Improved access to qualified nurse examiners to perform sexual assault forensic examinations is needed. This integrative review examines the current research literature on synchronous "real-time or live" telehealth support and guidance during pediatric, adolescent, and adult sexual abuse/assault forensic examinations.

METHODS

Informational databases (CINAHL, Health Source: Nursing/Academic Edition, Medline, PsychInfo, and Violence & Abuse Abstracts) were searched, and research articles including live telehealth for sexual assault survivors were reviewed (n = 98).

RESULTS

Review of the articles resulted in the inclusion of seven studies that utilized live video telehealth during the sexual assault forensic examination.

CONCLUSION

The current research literature supports the premise that synchronous telehealth is a promising modality for this patient population. However, the lack of large comprehensive studies warrants additional research to understand outcomes and develop best practices. Additional research studies are needed to evaluate the effectiveness, cost, and criminal justice impact of this intervention.

Using Telehealth for Sexual Assault Forensic Examinations: A Process Evaluation of a National Pilot Project

INTRODUCTION

This project describes the first time live sexual assault nurse examiner (SANE) services were provided via telehealth to support site clinicians conducting sexual assault forensic medical examinations for adult and adolescent patients. It involved six sites in three states, including rural, tribal, military, and community hospitals. The purpose of this process evaluation was to determine the extent to which patients consent to telehealth technology, examine how the technology worked, and explore the types of assistance.

METHODS

We reviewed information for sexual assault patients who presented at emergency departments (N = 215) and conducted telephone and online surveys with 178 clinicians who provided or received telehealth services.

RESULTS

Between May 1, 2015, and March 31, 2018, 129 patients and site clinicians received services via telehealth and an additional 86 site clinicians received consultation advice via telehealth. Most patients consented and accepted SANE services via telehealth (86% overall and 97% in non-U.S. Navy sites). No significant technology problems were experienced for most interactions (92%). The assistance provided remotely by SANEs to site clinicians included guiding clinicians through history taking and documentation, forensic examination and evidence collection techniques, identifying and documenting injuries, and guiding clinical practice. Site clinicians reported, on average, a positive impact of the assistance on their confidence in providing an effective examination, their ability to provide their patient with the best care, and their sense of feeling supported.

IMPLICATION

Results of this pilot suggest that using live telehealth services for sexual assault forensic examinations is a promising practice.

Lessons Learned: Conducting Research With Victims Portrayed in Sexual Abuse Images and Their Parents

Victims portrayed in sexual abuse images may be resistant to participate in research because of embarrassment or shame due to the sensitive nature and potential permanency of images. No studies we are aware of explore reactions to participating in research after this type of crime. Telephone interviews were conducted with convenience samples of parents ( n = 46) and adolescents who were victims of child sexual abuse ( n = 11; some of whom were portrayed in sexual abuse images), and online surveys were completed by adult survivors depicted in abuse images ( N = 133). The first lesson was that few agencies tracked this type of crime. This lack of tracking raises the question as to what types of data should be collected and tracked as part of an investigation. The second lesson was that few victims at the two participating agencies had been portrayed in sexual abuse images (4%-5%). The third lesson was that once possible cases were identified, we found relatively high percentages of consent to contact and interview completions. This implies that researchers and service providers should not be hesitant about conducting research after an investigation of child sexual abuse. The fourth lesson was that the vast majority of participants reported not being upset by the questions. We hope that the data presented here will encourage agencies to reconsider the types of data being tracked and will encourage researchers to conduct in-depth research with populations that are often difficult to reach to continue improving the professional response to child victimization.

Physical dating violence, sexual violence, and unwanted pursuit victimization: a comparison of incidence rates among sexual-minority and heterosexual college students

The purpose of this study was to estimate the 6-month incidence rates of sexual assault, physical dating violence (DV), and unwanted pursuit (e.g., stalking) victimization among sexual-minority (i.e., individuals with any same-sex sexual experiences) college students with comparison data from non-sexual-minority (i.e., individuals with only heterosexual sexual experiences) college students. Participants (N = 6,030) were primarily Caucasian (92.7%) and non-sexual-minority (82.3%). Compared with non-sexual-minority students (N-SMS; n = 4,961), sexual-minority students (SMS; n = 1,069) reported significantly higher 6-month incidence rates of physical DV (SMS: 30.3%; N-SMS: 18.5%), sexual assault (SMS: 24.3%; N-SMS: 11.0%), and unwanted pursuit (SMS: 53.1%; N-SMS: 36.0%) victimization. We also explored the moderating role of gender and found that female SMS reported significantly higher rates of physical DV than female N-SMS, whereas male SMS and male N-SMS reported similar rates of physical DV. Gender did not moderate the relationship between sexual-minority status and victimization experiences for either unwanted pursuit or sexual victimization. These findings underscore the alarmingly high rates of interpersonal victimization among SMS and the critical need for research to better understand the explanatory factors that place SMS at increased risk for interpersonal victimization.

Using child advocacy center tracking data to examine criminal disposition times

Given the difficulty of obtaining criminal justice data on child abuse cases, information from child advocacy centers could be an important resource for answering questions about criminal justice outcomes for child abuse cases. In this exploratory study, we use data from one child advocacy center (N = 632) to examine the feasibility of using NCAtrak, a national computerized, Web-based case tracking system, to examine criminal disposition timeframes in child abuse cases. The system data indicated that the time frame for the cases to be criminally resolved varied widely. About one in four child physical and sexual abuse cases with adult offenders took more than one year to reach a final disposition. About 11% of child sexual abuse cases with juvenile offenders took more than one year to reach a criminal disposition. We encourage child advocacy centers using computer-based data systems to think of additional ways they might use this potentially rich source of data.

"It all depends on the guy and the girl": a qualitative study of youth experiences with statutory victimization relationships

The purpose of this exploratory study was to examine youths' perceptions of statutory victimization relationships and youths' experience interacting with professionals. In-person qualitative interviews were conducted with 22 youths identified as statutory rape victims by two child advocacy centers. Using grounded theory, interviews were coded thematically using constant comparison analysis. The discussion of the relationship dynamics suggested a great deal of variation. Some youths described the relationships in exploitive terms. However, more typically, the interviewed youth described the relationship as reciprocal, even some time after it had ended. The professional intervention often resulted in feelings of helplessness for the youth. The results suggest creative and flexible protocols are needed for handling these cases that recognize adolescents' developing autonomy.

Do parents blame or doubt their child more when sexually abused by adolescents versus adults?

Although the importance of parental support for child sexual abuse victims is well documented, the nature of parental support for victims sexually abused by adolescents is less understood. In this exploratory study, we examine whether parents differ in their levels of blame or doubt for their child when sexually abused by adolescents versus adults. Data included 161 reports of child sexual abuse. Parental blame toward their child was higher when sexually abused by an adolescent versus an adult suspect. In the bivariate and multivariate analysis, parental blame was significantly higher as victim age increased, for Black, non-Hispanic children, and when there was an adolescent suspect. Practitioners need to recognize that high levels of blame and doubt could exist for adolescent victims of sexual abuse and when children are sexually abused by adolescents.

Mental health professionals in children's advocacy centers: is there role conflict?

Two recent chapters in professional books have criticized children's advocacy centers for creating role conflict for mental health professionals because of their work with criminal justice and child protection professionals in children's advocacy centers as part of a coordinated response to child abuse. This article argues that these critiques misunderstand children's advocacy center practice and overestimate the risk of role conflict. Children's advocacy center standards set a boundary between forensic interviewing and therapy, which in most children's advocacy centers are done by separate professionals and never by the same professional for a given child. Many mental health professionals serve children's advocacy centers as consultants with no treatment role. Children's advocacy center therapists are rarely involved in investigation, and their participation in multidisciplinary teams focuses on children's interests and well-being.

Nonoffending caregiver and youth experiences with child sexual abuse investigations

Qualitative responses by caregivers (n = 203) and youth (aged 8 and older; n = 65) about their experiences with sexual abuse investigations were analyzed in conjunction with quantitative ratings of satisfaction. Respondents described mostly high levels of satisfaction, although dissatisfaction was reported with some key aspects of investigations. The features cited as worse than expected by caregivers were the investigators' commitment to prosecuting the alleged offender and the absence of clear and regular communication about the status of the case. The features mentioned most often by caregivers as better than expected were the emotional support and interviewing skills of investigators. Youth focused both praise and criticism on investigators' interviewing skills. There were relatively few complaints by either caregivers or youth about the duration of the investigation, medical exams, lack of services, or failures of interagency communication, areas of considerable reform in the past several decades. Implications for investigator training and reform initiatives are discussed.

Friends of survivors: the community impact of unwanted sexual experiences

Since sexual assault survivors are most likely to disclose their experiences to a friend; prevention efforts increasingly focus on friends as informal helpers. The current study examined friends' perceptions of the disclosure experience. Undergraduates (N=1,241) at the University of New Hampshire completed a shortened version of the Ahrens and Campbell (2000) Impact on Friends measure. Results found that about 1 in 3 female undergraduates and 1 in 5 male students were told by a friend that they were a victim of an unwanted sexual experience. Gender differences were found in friends' responses to disclosure. Women reported greater emotional distress in response to a friend's disclosure, greater positive responses and lesser-perceived confusion/ineffectiveness as compared to men. Implications include the need to develop specific and clear educational material to help the community cope with and effectively respond to unwanted sexual experiences on college campuses.

Disclosure and service use on a college campus after an unwanted sexual experience

In order to continue to facilitate the disclosure of sexual assault to professional support services, the current study examined the extent to which survivors report using campus services and whether friends who had disclosed to participants used the services. We also compared knowledge of a campus sexual assault center and likelihood of using the center among college men and women. Surveys were completed by 1,230 students, including victims of unwanted contact (n = 127), victims of unwanted intercourse (n = 26), and friends of victims (n = 253). Students who reported being victims of unwanted sexual experiences were reluctant to use services, expressing concerns that they would not be believed and that they would be blamed for what had happened to them. College men were significantly less likely to know where the sexual assault center was located, to report that they would use the center, and to report that unwanted sexual experiences were a problem on campus. Results indicate that much needs to be done to educate the campus community about the value of using professional support services after a sexual assault.

How are we measuring resilience following childhood maltreatment? Is the research adequate and consistent? What is the impact on research, practice, and policy?

The authors review the literature on resilience following childhood maltreatment and describe how variation in the measurement of outcomes at various developmental stages affects research findings, practice implications, and policy recommendations. Although the 21 studies reviewed considered competent functioning in similar domains as evidence of resilience following maltreatment, few provided prevalence estimates for specific indicators or across domains of functioning. Using the National Survey of Child and Adolescent Well-Being (NSCAW), the authors explored different ways of operationalizing resilience. The number of children demonstrating competence following maltreatment varied greatly by the indicators used; furthermore, competence in one domain (behavioral, emotional, or educational) did not guarantee competence in another. About one in five children were functioning poorly in all three domains. Because findings vary according to the operational definition of resilience, researchers must use caution in conceptualizing their analytic variables and interpreting findings. Furthermore, given the lack of cross-domain competence, services to maltreated children and their families should be comprehensive.

How long to prosecute child sexual abuse for a community using a Children's Advocacy Center and two comparison communities?

This article explores the length of time between key events in the criminal prosecution of child sexual abuse cases (charging decision, case resolution process, and total case-processing time), which previous research suggests is related to victims' recovery. The sample included 160 cases in three communities served by the Dallas County District Attorney. Most cases (69%) took at least 60 days for the charging decision, with cases investigated at the Children's Advocacy Center having a quicker time than either comparison community. Only 20% of cases had a case resolution time within the 180-day target suggested by the American Bar Association standard for felonies. Controlling for case characteristics, one of the three communities and cases with an initial arrest had a significantly quicker case resolution time. Total case processing generally took more than 2 years. Implications include the need to better monitor and shorten case resolution time.

Child forensic interviewing in Children's Advocacy Centers: empirical data on a practice model

OBJECTIVE

Children's Advocacy Centers (CACs) aim to improve child forensic interviewing following allegations of child abuse by coordinating multiple investigations, providing child-friendly interviewing locations, and limiting redundant interviewing. This analysis presents one of the first rigorous evaluations of CACs' implementation of these methods.

METHODS

This analysis is part of a quasi-experimental study, the Multi-Site Evaluation of Children's Advocacy Centers, which evaluated four CACs relative to within-state non-CAC comparison communities. Case abstractors collected data on investigation methods in 1,069 child sexual abuse cases with forensic interviews by reviewing case records from multiple agencies.

RESULTS

CAC cases were more likely than comparison cases to feature police involvement in CPS cases (41% vs. 15%), multidisciplinary team (MDT) interviews (28% vs. 6%), case reviews (56% vs. 7%), joint police/child protective services (CPS) investigations (81% vs. 52%) and video/audiotaping of interviews (52% vs. 17%, all these comparisons p<.001). CACs varied in which coordination methods they used, and some comparison communities also used certain coordination methods more than the CAC with which they were paired. Eighty-five percent of CAC interviews took place in child-friendly CAC facilities, while notable proportions of comparison interviews took place at CPS offices (22%), police facilities (18%), home (16%), or school (19%). Ninety-five percent of children had no more than two forensic interviews, and CAC and comparison differences on number of interviews were mostly non-significant.

CONCLUSIONS

Relative to the comparison communities, these CACs appear to have increased coordination on investigations and child forensic interviewing. The CAC setting was the location for the vast majority of CAC child interviews, while comparison communities often used settings that many consider undesirable. CACs showed no advantage on reducing the number of forensic interviews, which was consistently small across the sample.

Do Children's Advocacy Centers improve families' experiences of child sexual abuse investigations?

OBJECTIVE

The Children's Advocacy Center (CAC) model of child abuse investigation is designed to be more child and family-friendly than traditional methods, but there have been no rigorous studies of their effect on children's and caregivers' experience. Data collected as part of the Multi-Site Evaluation of Children's Advocacy Centers were used to examine whether CACs improve caregivers' and children's satisfaction with investigations.

METHODS

Nonoffending caregiver and child satisfaction were assessed during research interviews, including the administration of a 14-item Investigation Satisfaction Scale (ISS) for caregivers. Two hundred and twenty-nine sexual abuse cases investigated through a CAC were compared to 55 cases investigated in communities with no CAC.

RESULTS

Hierarchical linear regression results indicated that caregivers in CAC cases were more satisfied with the investigation than those from comparison sites, even after controlling for a number of relevant variables. There were few differences between CAC and comparison samples on children's satisfaction. Children described moderate to high satisfaction with the investigation, while a minority expressed concerns about their experience.

CONCLUSIONS

The CAC model shows promise for improving families' experiences, but to build upon this promise, agencies will need to systematize procedures for refining and adapting the model as new research becomes available.

Which sexual abuse victims receive a forensic medical examination? The impact of Children's Advocacy Centers

OBJECTIVE

This study examines the impact of Children's Advocacy Centers (CAC) and other factors, such as the child's age, alleged penetration, and injury on the use of forensic medical examinations as part of the response to reported child sexual abuse.

METHODS

This analysis is part of a quasi-experimental study, the Multi-Site Evaluation of Children's Advocacy Centers, which evaluated four CACs relative to within-state non-CAC comparison communities. Case abstractors collected data on forensic medical exams in 1,220 child sexual abuse cases through review of case records.

RESULTS

Suspected sexual abuse victims at CACs were two times more likely to have forensic medical examinations than those seen at comparison communities, controlling for other variables. Girls, children with reported penetration, victims who were physically injured while being abused, White victims, and younger children were more likely to have exams, controlling for other variables. Non-penetration cases at CACs were four times more likely to receive exams as compared to those in comparison communities. About half of exams were conducted the same day as the reported abuse in both CAC and comparison communities. The majority of caregivers were very satisfied with the medical professional. Receipt of a medical exam was not associated with offenders being charged.

CONCLUSIONS

Results of this study suggest that CACs are an effective tool for furthering access to forensic medical examinations for child sexual abuse victims.

Nonforcible Internet-related sex crimes with adolescent victims: prosecution issues and outcomes

Law enforcement officials and the public are said to hold the stereotype that it is difficult to prosecute cases involving nonforcible sex crimes with willing adolescent victims. The authors examine prosecution outcomes in nonforcible Internet-related sex crimes with adolescent victims and extra-familial adult defendants. Data are from a national sample of law enforcement officers and prosecutors (N = 77). Most (91%) of the defendants are convicted, usually via a guilty plea (77%). Results show that even when victim cooperation is lacking or victims willingly engage in sexual activity, defendants are convicted. A small group of defendants are not convicted, and certain conditions appear to contribute to this, including victims' untruthfulness, defendants giving victims illegal drugs or alcohol, and lack of a confession from the defendant. Most defendants, however, are sentenced to incarceration and required to register as sex offenders. The findings show promise for holding defendants accountable for this type of crime.

Criminal investigations of child abuse: the research behind "best practices"

This article reviews the research relevant to seven practices considered by many to be among the most progressive approaches to criminal child abuse investigations: multidisciplinary team investigations, trained child forensic interviewers, videotaped interviews, specialized forensic medical examiners, victim advocacy programs, improved access to mental health treatment for victims, and Children's Advocacy Centers (CACs). The review finds that despite the popularity of these practices, little outcome research is currently available documenting their success. However, preliminary research supports many of these practices or has influenced their development. Knowledge of this research can assist investigators and policy makers who want to improve the response to victims, understand the effectiveness of particular programs, or identify where assumptions about effectiveness are not empirically supported.

Prosecution of child abuse: a meta-analysis of rates of criminal justice decisions

This study meta-analyzed rates of criminal justice decisions in 21 studies of prosecution of child abuse. Rates of referral to prosecution, filing charges, and incarceration varied considerably. Rates of carrying cases forward without dismissal were consistently 72% or greater. For cases carried forward, plea rates averaged 82% and conviction rates 94%. Compared to national data, child abuse was less likely to lead to filing charges and incarceration than most other felonies but more likely to be carried forward without dismissal. Diversion, guilty plea, and trial and conviction rates were about the same for child abuse and all violent crimes. Thus, prosecuting child abuse is generally neither feckless nor reckless. Rates can be misleading and cannot be the sole measure of prosecution success.

Temporal snychrony and patterns in an exotic host-parasitoid community

We studied an imported host-parasitoid community in Hawaii, asking to what extent the species covaried in a systematic fashion even though all species were exotic to Hawaii, and occurred in an artificial agroecosystem (a commercial guava, Psidium guajava L., orchard). Using knock-down pyrethrin sprays we were able to accurately quantify numbers of the host, [oriental fruit fly, Bactrocera dorsalis (Hendel)] and its four major parasitoid species [Biosteres arisanus (Sonan), Diachasmimorpha longicaudata (Ashmead), Psyttalia incisi (Silvestri), and Bi. vandenboschi (Fullaway)] at hourly intervals. We found that the parasitoids' activity and abundance was well correlated with the activity and abundance of their host, and that all four parasitoid species covaried in concert with one another. In fact, the magnitude of correlation between the different species in this system was greater than the correlation with temperature. This show clearly that an entirely exotic community, reassembled piecemeal as a result of biocontrol efforts, can end up with patterns of temporal covariation that are highly coincident. One other interesting result concerns the speed with which sprayed trees were recolonized by the fruit fly and its parasitoids. The time that it took each species to reach its mean density prior to removal by the first pyrethrin spray at 0600 hours varied. It took 2 h for female B. dorsalis to recolonize guava trees to pre-spray levels. It took 3 h for Bi. arisanus, 4 h for D. longicaudata, 7 h for Bi. vandenboschi and 14 h for P. incisi to reach pre-spray levels. The fact that Bi. arisanus recolonized vacant trees almost as rapidly as did the fruit fly pest suggest that there is little opportunity for the fruit fly to escape in space and time by "staying one step ahead of its enemies".

Warfarin inhibition of vitamin K 2,3-epoxide reductase in rat liver microsomes

Warfarin is a potent inhibitor of vitamin K 2,3-epoxide reduction to vitamin K in vitro and in vivo. Dithiothreitol, an in vitro reductant for the vitamin K 2,3-epoxide reductase, antagonizes inhibition of the reductase by warfarin via mechanisms that have not been determined [Zimmermann, A., & Matschiner, J. T. (1974) Biochem. Pharmacol. 23, 1033-1040]. Experiments with rat hepatic microsomes were undertaken to characterize the interactions that exist between vitamin K 2,3-epoxide, warfarin, and dithiothreitol. Increasing concentrations of dithiothreitol decreased inhibition of the reductase by warfarin. When dithiothreitol was present prior to exposure of the reductase to warfarin, there was less inhibition than when the same concentration of dithiothreitol was present after its exposure to warfarin. Moreover, maximum inhibition of the reductase by warfarin occurred at a much slower rate when dithiothreitol was present initially. Inhibition of the reductase by warfarin was greater when the substrate concentration was 100 microM vitamin K 2,3-epoxide than when it was 10 microM epoxide. On the basis of these data, we conclude that (i) dithiothreitol reduces either directly or indirectly a critical disulfide within the reductase that it reoxidized during reduction of the epoxide substrate, (ii) warfarin and vitamin K 2,3-epoxide are not competitive with respect to one another, and (iii) warfarin binding, which produces inhibition, occurs solely to the disulfide form of the reductase. Once it is bound, warfarin inhibits further reduction of the critical disulfide by dithiothreitol. Dithiothreitol therefore antagonizes warfarin by maintaining the reductase in the reduced state.