Repellency of DEET, picaridin, and three essential oils to Triatoma rubida (Hemiptera: Reduviidae: Triatominae).

The kissing bug, Triatoma rubida (Uhler) is a common hematophagous bug in Tucson, AZ, and is responsible for causing severe allergic reactions in some bitten individuals. DEET, picaridin, tea tree oil, peppermint oil, and citronella oil were tested for repellency to T. rubida and its ability to probe and feed on a small restrained rat. No long range repellency was observed with any of the test materials. The lowest repellent concentrations observed were: 10% DEET, 7% picaridin; 30% tea tree oil, 3.3% peppermint oil, and 0.165% citronella oil. Only citronella oil was able to stop all probing and feeding by T. rubida. Citronella oil appears to be a promising potential repellent to prevent sleeping people from being bitten by kissing bugs.

Evaluation of control measures for black carpenter ant (Hymenoptera: Formicidae).

Current control methods for the black carpenter ant, Camponotus pennsylvanicus (De Geer), include the use of remedial and preventative residual sprays as well as toxic baits. We evaluated the acceptance of three baits (Maxforce, Niban, and Baygon) to field colonies of the black carpenter ant in the spring and fall. Maxforce bait granules were more readily accepted than either Niban or Baygon bait granules in the spring. A change in food preference from protein to sugar by the black carpenter ant appeared to reduce the number of Maxforce bait granules removed in the fall, resulting in no differences in bait acceptability. The longevity of Dursban 50W and Tempo 20WP were evaluated in the summer and fall on painted wood panels. Panels aged outside for 15 d under prevailing weather conditions exhibited increased LT50 values. For each sampling period, panels aged on the south face (in the sun) exhibited less insecticidal activity (i.e., large LT50 values) than panels on the north face (shaded; small LT50 values). At each sampling period, Tempo 20WP provided smaller LT50 values than Dursban 50W. Because of changing dietary preferences, our data highlight the importance of using various bait types for carpenter ant control. Moreover, the application of residual spays should be made to locations protected from direct sunlight.

Toxicity and repellency of borate-sucrose water baits to Argentine ants (Hymenoptera: Formicidae).

The oral toxicity of boron compounds to the Argentine ant, Linepithema humile (Mayr), was evaluated in laboratory tests. The ants were provided 25% sucrose water containing 0.5 and 1% boric acid, disodium octaborate tetrahydrate, and borax. Lethal times of these solutions were a function of the concentration of boron. In field tests, the ants showed no discrimination between disodium octaborate tetrahydrate and boric acid. There was a significant reduction in consumption of sucrose water with > 1% boric acid.

Argentine ant (Hymenoptera: Formicidae) trail pheromone enhances consumption of liquid sucrose solution.

We investigated whether the Argentine ant, Linepithema humile (Mayr), trail pheromone, Z9-16:Ald, could enhance recruitment to and consumption of liquid sucrose solutions. All tests were done as paired comparisons with a 10% sucrose solution as food. In the laboratory, mixing 20 microl of a 10-microg/ml solution of the pheromone with 50 microl of the 10% sucrose solution increased the number of ants feeding by >150%. In a field test, we combined the trail pheromone with a 10% sucrose solution in 50-ml vials. These vials were covered with a plastic membrane that has 1.5-mm-diameter holes punched uniformly across its surface. Ants could drink from the holes after the vials were inverted. For half of the vials, 1 microg of the pheromone was put onto the plastic membrane before the vials were filled with a 10% sucrose solution. The remaining vials had no pheromone on the plastic membrane. After 4 h we measured the consumption in each vial. Bait consumption with the pheromone was enhanced by 29%. In a 2nd series of tests, vials were left outside for 24 h. The consumption rate was 33% higher with the pheromone compared with the controls that didn't have pheromone.

Oral toxicity of boric acid and other boron compounds to immature cat fleas (Siphonaptera: Pulicidae).

Oral toxicity was characterized in first-instar cat fleas, Ctenocephalides felis felis (Bouché), feeding on dried blood treated with boric acid. LC50 values ranged from 2.11% after 24 h to 0.21% after 7 d. In carpet tests with five different boron compounds and a number of different formulations, significant mortality for first instars was observed in all cases. In similar tests with prepupae and cocoons, there was no significant effect on mortality. The importance of these results is discussed in light of current application procedures for boron compounds, and suggestions are made for future research.

A biological marker model for predicting disease transitions.

For patients with chronic myelogenous leukemia (CML), the effect of elevated blood levels of adenosine deaminase (ADA) is studied as a marker for transitions from stable disease to blast crisis and then to death. Data in the form of snapshots over time, with day, state of disease, and ADA level, are analyzed for 55 patients. A simple three-state Markov model with one-way transition probabilities dependent on ADA is used to determine if the marker has a significant effect on the prediction of changes from stable disease to blast crisis.

Statistical methods for the analysis of tumor multiplicity data.

The fit of tumor multiplicity data from 93 mouse skin, lung, and liver carcinogenicity experiments to Poisson, negative binomial, and normal distributions was studied. The data were fitted well by the negative binomial distribution. This distribution has two parameters, the mean tumor multiplicity and an exponent determined by the interanimal homogeneity of tumor response. The value of the latter parameter was related to animal strain and the target tissue studied in the carcinogenicity experiments. The null distribution of the two-sample likelihood ratio test based on the negative binomial with common exponent model for tumor multiplicity data was shown by simulation studies to be approximately chi 2 with 1 d.f. Simulation also indicated that the likelihood ratio test has sufficiently better performance when the negative binomial model is valid to make its use more attractive than the more commonly used Wilcoxon test or Student t test. Charts for estimating the number of animals per group that are required to detect specified differences in tumor multiplicities are provided for several commonly used assays.

5-FU versus combination therapy with tubercidin, streptozotocin, and 5-FU in the treatment of pancreatic carcinomas: COG protocol 7230.

From May 1972 until May 1976, 105 patients were entered on Central Oncology Group protocol 7230 to compare the combination of streptozotocin, tubercidin, and 5-fluorouracil (5-FU) versus 5-FU alone in the treatment of adenocarcinoma and islet cell carcinoma of the pancreas. Twenty-nine were not evaluable. Thirty-six evaluable cases received 5-FU, and 40 received the combination, with no significant difference in time to progression or survival. Toxicity in the two regimens was somewhat different but was essentially similar in magnitude. Results indicate no benefit in the treatment of adenocarcinoma of the pancreas with the three-drug combination over 5-FU alone. All of the islet cell tumor patients benefited from the combination by response or arrest of progression of disease. Further study should be directed toward the use of this combination in the treatment of functioning and non-functioning islet cell tumors of the pancreas.

Maximum entropy constrained balance randomization for clinical trials.

A specialization of the biased coin clinical trial randomization schemes of Pocock and Simon (1975) and Efron (1971) is proposed which gives guidelines for the coin biasing probabilities of assignment to treatment. The scheme parameterizes the often conflicting goals of random treatment assignment and allocation for stratum balance in terms of a single trade-off parameter specifying a desired degree of determinism. Treatment radomization probabilities are obtained iteratively in an exponential form which maximizes randomization entropy subject to a specified balance constraint.

Microcomputer voice-response telephone entry for balanced clinical trial randomization.

Simple randomization of patients to treatment regimens in clinical trials can result in inbalance among stratum categories. Procedures that produce balance may lack randomness. Systems that are not deterministic yet produce balance are often extremely complex and are not easily performed by randomization clerks. A microcomputer-based voice-response system has been implemented that permits clinic staff to easily randomize patients in clinical trials despite the complexity of the algorithm. Data entry is accomplished by the use of Touch-Tone keys. Input prompts and regimen assignment are spoken by a commercially available voice synthesizer.