Wolbachia-induced cytoplasmic incompatibility as a means for insect pest population control

Biological control is the purposeful introduction of parasites, predators, and pathogens to reduce or suppress pest populations. Wolbachia are inherited bacteria of arthropods that have recently attracted attention for their potential as new biocontrol agents. Wolbachia manipulate host reproduction by using several strategies, one of which is cytoplasmic incompatibility (CI) [Stouthamer, R., Breeuwer, J. A. J. & Hurst, G. D. D. (1999) Annu. Rev. Microbiol. 53,71-102]. We established Wolbachia-infected lines of the medfly Ceratitis capitata using the infected cherry fruit fly Rhagoletis cerasi as donor. Wolbachia induced complete CI in the novel host. Laboratory cage populations were completely suppressed by single releases of infected males, suggesting that Wolbachia-induced CI could be used as a novel environmentally friendly tool for the control of medfly populations. The results also encourage the introduction of Wolbachia into pest and vector species of economic and hygenic relevance to suppress or modify natural populations.

Wolbachia transfer from Rhagoletis cerasi to Drosophila simulans: Investigating the outcomes of host-symbiont coevolution

Wolbachia is an endosymbiont of diverse arthropod lineages that can induce various alterations of host reproduction for its own benefice. Cytoplasmic incompatibility (CI) is the most common phenomenon, which results in embryonic lethality when males that bear Wolbachia are mated with females that do not. In the cherry fruit fly, Rhagoletis cerasi, Wolbachia seems to be responsible for previously reported patterns of incompatibility between populations. Here we report on the artificial transfer of two Wolbachia variants (wCer1 and wCer2) from R. cerasi into Drosophila simulans, which was performed with two major goals in mind: first, to isolate wCer1 from wCer2 in order to individually test their respective abilities to induce Cl in the new host; and, second, to test the theoretical prediction that recent Wolbachia-host associations should be characterized by high levels of CI, fitness costs to the new host, and inefficient transmission from mothers to offspring. wCer1 was unable to develop in the new host, resulting in its rapid loss after successful injection, while wCer2 was established in the new host. Transmission rates of wCer2 were low, and the infection showed negative fitness effects, consistent with our prediction, but CI levels were unexpectedly lower in the new host. Based on these parameter estimates, neither wCer1 nor wCer2 could be naturally maintained in D. simulans. The experiment thus suggests that natural Wolbachia transfer between species might be restricted by many factors, should the ecological barriers be bypassed.

General practitioner, specialist providers case conferences in palliative care: Lessons learned from 56 case conferences

OBJECTIVE: To describe the utility and acceptability to general practitioners and palliative care staff of case conferences in palliative care. METHOD: Research focussed on case conferences conducted between GPs and staff of three specialist palliative care units (in an inner urban, outer metropolitan and regional setting), at the time of referral of patients to the service. Telephone interviews were conducted with all GPs who participated in a case conference, and focus groups were conducted with palliative care staff. RESULTS: For most GPs, case conferences by teleconference were a time effective and immediate means of information transfer. The best instances for a conference were at time of patient referral, time of discharge to the community, or where the case was complex. General practitioners appreciated access to multiple professionals simultaneously. Workload pressures were a drawback of participation for both GPs and specialists. Palliative care team members thought case conferences gave GPs an appreciation of a team approach, and reduced professional isolation. The usefulness of the case conferences depended on the willingness of the GP to participate. General practitioners would participate again provided they did not have to organise the case conference. Specialist staff were concerned by the financial cost of organising case conferences. DISCUSSION: Case conferences provide useful information exchange between GPs and specialist staff, and are acceptable to both parties. Much depends on the individual GPs attitude toward participation, as well as the timing of the conferences in the course of the patient's illness. Organisation needs to be a task of the specialist units, who would need administrative support to organise them. (author abstract)