Life history and host range of Alagoasa extrema (Coleoptera: Chrysomelidae: Alticinae), a potential biological control agent of Lantana spp. (Verbenaceae) in Australia

The life history and host range of the lantana beetle, Alagoasa extrema, a potential biocontrol agent for Lantana spp. were investigated in a quarantine unit at the Alan Fletcher Research Station, Brisbane, Australia. Adults feed on leaves and females lay batches of about 17 eggs on the soil surface around the stems of plants. The eggs take 16 days to hatch and newly emerged larvae move up the stem to feed on young leaves. Larvae feed for about 23 days and there are three instars. There is a prepupal non-feeding stage that lasts about 12 days and the pupal stage, which occurs in a cocoon in the soil, lasts 16 days. Teneral adults remain in the cocoon for 3 days to harden prior to emergence. Males live for about 151 days while females live for about 127 days. The pre-oviposition period is 19 days. In no-choice larval feeding trials, nine plant species, representing three families, supported development to adult. Three species, Aloysia triphylla, Citharexylum spinosum and Pandorea pandorana were able to support at least two successive generations. These results confirm those reported in South Africa and suggest that A. extrema is not sufficiently specific for release in Australia. Furthermore, it is not recommended for release in any other country which is considering biological control of lantana.     

Introduction to placebo effects in medicine: mechanisms and clinical implications

The field of placebo research has made considerable progress in the last years and it has become a major focus of interest. We know now that the placebo effect is a real neurobiological phenomenon and that the brain's 'inner pharmacy' is a critical determinant for the occurrence of psychobiological and behavioural changes relevant to healing processes and well-being. However, harnessing the advantages of placebo effects in healthcare is still a challenge. The first part of the theme issue summarizes and discusses the various kinds of placebo mechanisms across medical fields, thereby not only focusing on two main explanatory models-expectation and conditioning theory-but also taking into account empathy and social learning, emotion and motivation, spirituality and the healing ritual. The second part of the issue focuses on questions related to transferring knowledge from placebo research into clinical practice and discusses implications for the design and interpretation of clinical trials, for the therapeutic settings in daily patient care, and for future translational placebo research.     

Tuberculosis vaccines: beyond bacille Calmette-Guerin

Tuberculosis (TB) disease caused by Mycobacterium tuberculosis (M. tb) remains one of the leading infectious causes of death and disease throughout the world. The only licensed vaccine, Mycobacterium bovis bacille Calmette-Guérin (BCG) confers highly variable protection against pulmonary disease. An effective vaccination regimen would be the most efficient way to control the epidemic. However, BCG does confer consistent and reliable protection against disseminated disease in childhood, and most TB vaccine strategies being developed incorporate BCG to retain this protection. Cellular immunity is necessary for protection against TB and all the new vaccines in development are focused on inducing a strong and durable cellular immune response. There are two main strategies being pursued in TB vaccine development. The first is to replace BCG with an improved whole organism mycobacterial priming vaccine, which is either a recombinant BCG or an attenuated strain of M. tb. The second is to develop a subunit boosting vaccine, which is designed to be administered after BCG vaccination, and to enhance the protective efficacy of BCG. This article reviews the leading candidate vaccines in development and considers the current challenges in the field with regard to efficacy testing.     

Discriminant analysis of Lepidopteran prey characteristics and their effects on the outcome of bird-feeding trials

Discriminant analysis was used to analyse the results of 348 bird-feeding trials conducted from 1982 to 1985 in Leverett, Massachusetts. Four size classes, seven appearance categories, and five larval host types, based on 163 species of moths and butterflies used as prey in two or more trials, were selected as predictor variables to discriminate between prey taken and not taken by birds. Discriminant analysis of individual feeding trials correctly classified 97.5 percent of prey taken or not-taken and ranked the predictor variables according to their relative importance in determining prey acceptability. Characteristics most acceptable to birds were: (1) large size, (2) bark-like appearance, (3) warning colouration, (4) woody generalist, (5) dead-leaf-like appearance, (6) woody specialist, and (7) medium size. Characteristics least acceptable to birds were: (1) small size, (2) mimetic appearance, (3) butterfly appearance, (4) herbaceous specialist food type, (5) black-and-white appearance, (6) extra large size, and (7) overall generalist feeder. A summary of the analyses includes a discriminant function based on lepidopteran characteristics that can be used to predict the prey acceptability of species not used in this study. A multiple regression analysis of prey taken revealed that size alone and larval host type combined with other prey characteristics were the most important variables in determining the selection of prey regardless of their abundance in the trials.     

Mini-plot field experiments on slug control using biological and chemical control agents

In three field experiments, the rhabditid nematode Phasmarhabditis hermaphrodita was applied one or more times at the standard rate (3 × 10⁹ ha^?1) or half the standard rate to protect crops from slug damage under experimental conditions. Expt 1 was done in a field planted with the ornamental Polygonatum japonica. The treatments were: infective juveniles of the nematode at the standard field rate, metaldehyde pellets at the recommended field rate, and ioxynil (a herbicide with molluscicidal properties) at 90 mg m^?2. The treatments were repeated every 2 wk. Arion ater agg. caused most of the damage to P. japonica. There were no significant differences in damage between treatments during the 3 wk after first application, but plants on plots treated with metaldehyde or nematodes had significantly less damage than plants on untreated plots in the fourth and fifth weeks. Expts 2 and 3 were done on the same site, the first with leaf beet and the second with lettuce. The treatments in these experiments were: nematodes applied to the planted area at the standard field rate 3 days prior to planting, with or without previous application of cow manure; nematodes at half standard rate applied twice, 6 days apart, to the planted area or to the surrounding area; metaldehyde pellets and iron phosphate pellets, both applied at the recommended rate to the planted area immediately after planting. In both experiments, the two chemical molluscicides and nematodes applied once to the planted area at the standard field rate without previous application of cow manure, or twice at half standard rate, were able to reduce slug damage. Nematodes applied after manure did not reduce slug damage. None of the treatments reduced the numbers of slugs contaminating the harvested plants. Slug populations were assessed by means of soil sampling before and after Expts 2 and 3. Only after Expt 3 was there a significant effect of treatment on slug numbers, with significantly fewer in metaldehyde treated plots than in untreated plots.     

Adaptive two-stage designs for single-arm phase IIA cancer clinical trials

The main purpose of a phase IIA trial of a new anticancer therapy is to determine whether the therapy has sufficient promise against a specific type of tumor to warrant its further development. The therapy will be rejected for further investigation if the true response rate is less than some uninteresting level and the test of hypothesis is powered at a specific target response rate. Two-stage designs are commonly used for this situation. However, in many situations investigators often express concern about uncertainty in targeting the alternative hypothesis to study power at the planning stage. In this article, motivated by a real example, we propose a strategy for adaptive two-stage designs that will use the information at the first stage of the study to either reject the therapy or continue testing with either an optimistic or a skeptic target response rate, while the type I error rate is controlled. We also introduce new optimal criteria to reduce the expected total sample size.     

Methods for the statistical analysis of binary data in split-cluster designs

Split-cluster designs are frequently used in the health sciences when naturally occurring clusters such as multiple sites or organs in the same subject are assigned to different treatments. However, statistical methods for the analysis of binary data arising from such designs are not well developed. The purpose of this article is to propose and evaluate a new procedure for testing the equality of event rates in a design dividing each of k clusters into two segments having multiple sites (e.g., teeth, lesions). The test statistic proposed is a generalization of a previously published procedure based on adjusting the standard Pearson chi-square statistic, but can also be derived as a score test using the approach of generalized estimating equations.     

Restricted treatments, inducements, and research participation

In this paper, I support the claim that placing certain restrictions on public access to possible new treatments is morally problematic under some exceptional circumstances. Very ill patients may find that all available standard treatments are unacceptable, either because they are ineffective or have serious adverse effects, and these patients may understandably be desperate to try something new even if this means stepping into the unknown. Faced with certain death, it is rational to want to try something new and to chance a dire outcome. Restricting possible new treatments to research trials may put these treatments scientifically, geographically or economically out of reach of these patients. For those who can get access, research restrictions could weaken, though not necessarily eliminate, the value of consent participants of such trials are able to give. Some participants may therefore be exploited for scientific purposes in the name of public interest. There are nonetheless compelling reasons for keeping some restrictive regulation in this area.