Biomedical subjects

R Brightwell

Publications and source records attributed to R Brightwell.

13 recordsLinked to original sources

PubMed1991

Development of a low-cost tsetse trap and odour baits for Glossina pallidipes and G. longipennis in Kenya.

Experiments were carried out to improve the NG2B tsetse trap (Brightwell et al., 1987), baited with acetone and cow urine, for use by rural communities to control G.pallidipes Austen and G.longipennis Corti. Modifications included a lower dose rate of acetone, a new cage design and raising the trap about 15-20 cm. Research on different trap cone materials showed that the degree of light transmission of the netting, rather than its colour, was the crucial factor affecting the catch of G.pallidipes. Adding an additional metre of blue cloth to one side of the trap increased catches of females of both species by about 60%. Traps baited with synthetic phenols yielded similar numbers of G.pallidipes and significantly more G.longipennis than those baited with natural cow urine. The latter difference was not apparent when octenol was also used, so cow urine was retained as one of the odour baits in preference to the imported phenols. Although octenol increased catches of G.pallidipes by only about 30%, catches of G.longipennis were increased 2-4-fold, making it a very useful attractant for the latter species. The cost of the trap/odour-bait system was estimated to be US$8.5 per unit per annum. The economics of this method of tsetse control are discussed.

Acetone↗

PubMed1990

Monitoring tsetse fly populations. I. The intrinsic variability of trap catches of Glossina pallidipes at Nguruman, Kenya.

During 1986 the tsetse fly Glossina pallidipes Austen was monitored daily at Nguruman, southwestern Kenya, using three unbaited biconical traps. This was done to investigate the nature and causes of daily variation in trap catches. The variability of the observed catches was compared to a model which includes the trapping probability and the stochastic variation in the sex-ratio. By comparing the catches of male and female flies we are able to establish the sampling distribution of the trap catches. In addition to seasonal changes in the trap catches, day-to-day variations are observed and these are considered greater than the variation arising from the stochastic nature of the sampling process. Recommendations are made in relation to sampling tsetse fly populations.

Animals↗

PubMed1990

Monitoring tsetse fly populations. II. The effect of climate on trap catches of Glossina pallidipes.

In Part I it was shown that the sampling distribution of trap catches of tsetse flies, Glossina pallidipes Austen, at Nguruman, Kenya, using unbaited biconical traps follows a Poisson distribution. In this paper we examine the effect of humidity and temperature on day-to-day and seasonal variations in the trap catches. It is shown that the seasonal variation is significantly correlated with maximum daily temperature, the catches increasing with temperature when the maximum temperature is below 34 degrees C and decreasing with temperature when it is above 34 degrees C. The correlation between trap catches and relative humidity is not as good as the correlation with the maximum temperature, and the two together do not improve the fit to the trap catches. The day-to-day variation is significantly greater than the intrinsic variation due to the stochastic nature of the sampling process and for some traps it is correlated with temperature and humidity. An autoregressive model gives a half-life for the decay of departures from the mean of about 1 day and it is suggested that this indicates the movement of flies in response to animal movement or to climatic factors other than temperature or humidity. After removing the temperature dependent part of the seasonal variation and the autoregressive component of the data, the male and female catches are still significantly correlated.

Animals↗

PubMed1989

Size and mortality rates of Glossina pallidipes in the semi-arid zone of southwestern Kenya.

Seasonal changes in the mean size of tsetse, Glossina pallidipes Austen, as indicated by wing vein length, were monitored during 1983-86 at Nguruman, southwestern Kenya. Changes in size of nulliparous females and wing fray category 1 males were shown to be correlated with the relative humidity 2 months before they were captured. Soil temperature when flies were in the pupal stage had much less effect. Size dependent mortality was demonstrated, with the mean size of flies emerging from pupae significantly less than that of field-caught flies. This mortality must occur at emergence, since there was no evidence of size-dependent mortality once the flies became available to the trap. Size was correlated with density-independent mortality acting on the parent population 2 months previously. It might therefore be possible to use size as an index of the intensity of such mortality. This could be useful when assessing the level of additional mortality required to suppress tsetse populations.

Animals↗

PubMed1989

Problems of field testing theoretical models: a case study.

The problems of field-testing models are discussed with reference to a population simulation model for the tsetse fly glossina pallidipes Austen developed by us at Nguruman in southwestern Kenya. Model predictions showed a reasonable fit to the changes in the biconical trap index of population size, but tended to overestimate some changes and underestimate others. A more rigorous test for the model is to manipulate one of the population parameters and compare model predictions with the observed population trends. This revealed that some changes in population size resulted more from fly movement than from changes in mortality rates. Fly movement must therefore be incorporated in the model for it to be a useful tool in the development of appropriate control strategies.

Algorithms↗

PubMed1981

Levamisole and other diamine oxidase inhibitors as inhibitors of sperm motility.

Levamisole, an anthelmintic drug and inhibitor of sperm motility, is a potent inhibitor of seminal diamine oxidase. Many other diamine oxidase inhibitors also inhibit sperm motility. The most active class of these sperm motility inhibitors is the group for isothiuronium compounds, some of which are much more potent than many other metabolic inhibitors tested. They also possess the property of inducing sperm to be motile in closed circles becoming immotile with a characteristically curled shape, and are active against mouse epididymal, rabbit, and human spermatozoa.

Amine Oxidase (Copper-Containing)↗

PubMed1971