Fungicide tests on adult alfalfa leafcutting bees (Hymenoptera: Megachilidae).

Chalkbrood is a serious disease of alfalfa leafcutting bee Megachile rotundata (F.) (Hymenoptera: Megachilidae) larvae, causing upward of 20% infection in the field. The causative agent is the fungus Ascosphaera aggregata. This bee is used extensively for alfalfa seed pollination in the United States. Using laboratory bioassays, we previously demonstrated that fungicides can reduce chalkbrood levels in the larvae. Here, we evaluate the toxicity of four fungicides, Benlate, Captan, Orbit, and Rovral, to adult bees by using three different bioassays. In the first test, fungicides were applied to bees' thoraces. In the second test, mimicking foliage residue, a piece of filter paper soaked in fungicide was placed on the bottom of a container of bees. The third test evaluated oral toxicity by incorporating fungicides into a sugar-water solution that was fed to the bees. The filter paper test did not discriminate among the fungicides well, and the oral test resulted in the greatest mortality. Toxicity to males was greater than to females. The use of fungicides for chalkbrood control is a logical choice, but caution should be used in how they are applied in the presence of bees.

Laboratory bioassays to evaluate fungicides for chalkbrood control in larvae of the alfalfa leafcutting bee (Hymenoptera: Megachilidae).

Chalkbrood, a fungal disease in bees, is caused by several species of Ascosphaera. A. aggregata is a major mortality factor in populations of the alfalfa leafcutting bee, Megachile rotundata (F.) (Hymenoptera: Megachilidae) used in commercial alfalfa seed production. Four formulated fungicides, Benlate 50 WP, Captan, Orbit, and Rovral 50 WP were tested in the laboratory for efficacy against hyphal growth of A. aggregata cultures. The same fungicides, with the addition of Rovral 4 F, were tested for their effects on incidence of chalkbrood disease, and toxicity to M. rotundata larvae. Benlate, Rovral 50 WP, and Rovral 4 F reduced incidence of chalkbrood with minimal mortality on larval bees. Benlate and Rovral 50 WP also reduced hyphal growth. Orbit was effective in reducing hyphal growth, but it did not reduce incidence of chalkbrood and was toxic to bee larvae. Captan was not effective in reducing hyphal growth or chalkbrood incidence, and it was toxic to bee larvae. Fungicides that reduce incidence of chalkbrood and larval mortality in this laboratory study are candidates for further study for chalkbrood control.

Randomized controlled trial of the use of compensatory strategies to enhance adaptive functioning in outpatients with schizophrenia.

OBJECTIVE: Cognitive adaptation training is a novel psychosocial treatment approach designed to improve adaptive functioning by using compensatory strategies in the home or work environment to bypass the cognitive deficits associated with schizophrenia. The authors tested the effect of cognitive adaptation training on level of adaptive functioning in outpatients with schizophrenia. METHOD: Forty-five patients with DSM-IV schizophrenia or schizoaffective disorder were randomly assigned for 9 months to one of three treatment conditions: 1) standard medication follow-up, 2) standard medication follow-up plus cognitive adaptation training, and 3) standard medication follow-up plus a condition designed to control for therapist time and provide environmental changes unrelated to cognitive deficits. Comprehensive assessments were conducted every 3 months by raters who were blind to treatment condition. RESULTS: Significant differences were found between the three treatment groups in levels of psychotic symptoms, motivation, and global functioning at the end of the 9-month study period. Patients in the cognitive adaptation training group overall had higher levels of improvement, compared with those in the remaining treatment conditions. In addition, the three groups had significantly different relapse rates over the 9-month study: 13% for the cognitive adaptation training group, 69% for the group in which therapist time and environmental changes were controlled, and 33% for the group who received standard follow-up only. CONCLUSIONS: Compensatory strategies may improve outcomes for patients with schizophrenia.

Dynamic collimator and dose rate control: enabling technology for enhanced dynamic wedge.

The key features that make dynamic dose delivery possible in the Enhanced Dynamic Wedge application are computerized position and control of the independent collimating jaws and computerized dynamic control of the linear accelerator dose rate. These features will be described and related to the current implementation of Enhanced Dynamic Wedge.

Clinical dosimetry for implementation of a multileaf collimator.

In order to initiate the use of a multileaf collimator (MLC) in the clinic, a set of technical procedures needs to be available sufficient to create MLC leaf settings and to deliver an accurate dose of radiation through the MLC-shaped field. Dosimetry data for clinical use of the MLC were measured. Dosimetric characteristics included central axis percent depth dose, output factors, and penumbra. In this paper, it has been concluded that a dose control monitor unit calculation procedure that has been applied to the use of conventional secondary field-shaping blocks can be applied to the multileaf collimator dosimetry. The multileaf collimator penumbra (20% to 80%) is only slightly wider (1-3 mm) than the penumbra of the conventional collimator jaws. Beam's-eye-view comparisons made between the isodose curves in fields shaped by conventional Cerrobend blocks and isodose curves in fields shaped by the multileaf collimator demonstrated that the 50% isodose line at 10-cm depth exhibited the discrete steps of the multileaf collimator leaves, but that the 90% and 10% isodose curves of the multileaf were close to those shaped by Cerrobend blocks.

Evaluation of multileaf collimator design for a photon beam.

Various aspects of multileaf collimator (MLC) design are examined relative to clinical requirements. The characteristics studied included: (a) irregular field edge definition or "effective" penumbra, (b) optimum field coverage for the multileaf portion of the field, and (c) leaf velocity. A film dosimetry technique was developed to measure the rapid 2-dimensional change in dose at an edge defined by a multileaf collimator with the segments staggered. The method applies a correction factor which allows for the changing ratio of scattered to primary photons at the field edge so that the energy dependence of the film is corrected. Stepped lead alloy blocks were irradiated with 6 MV photons to obtain films simulating a double-focused multileaf collimator, and the results were compared to films of fields shaped with standard divergent blocks. The effect of the shape of the leaf face (the end of the leaf) on penumbra was also studied. Proper shaping of the leaf ends may eliminate the need to exactly match beam divergence so that the mechanical of the collimator system is simplified. Leaves having several different end shapes and moving horizontally to intercept a vertical beam were compared to the divergent design where a straight face moves along an arc. The measurements showed that the "effective" penumbra (measured as the distance from the 80 to 20% isodose lines) for the multileaf collimator is a function of the angle between the direction of leaf motion and the edge defined by the leaves. In addition, all leaf end shapes showed some increase in penumbra compared to standard divergent blocking and also had increasing penumbra width as they moved over or back from the field center line. A total of 459 treatment fields and six disease sites were examined to determine the percentage of fields potentially shaped by multileaf segments of specified length. This study showed 93% of the fields had lengths of 30 cm or less and 99% had widths of 25 cm or less. A study conducted to determine the required leaf velocity to shape various target volume configurations during complete rotation (at 1 RPM) showed that a leaf speed of at least 1.5 cm/sec at isocenter is needed for dynamic conformal treatment.