W. W. Macdonald

A light and electron microscope study of rickettsia-like organisms in the ovaries of mosquitoes of the Aedes scutellaris group.

The ovaries from some members of the Aedes scutellaris group were examined by light and electron microscopy to locate rickettsia-like organisms, and Culex pipiens fatigans was used as a control. It was found that light microscopy was unsatisfactory for this purpose since none of the available staining techniques demonstrates the organisms clearly and diagnostically. With the electron microscope it was shown that the organisms were by no means as common in the mosquitoes of the A. scutellaris group as in C.p. fatigans; they were quite frequently seen in A. polynesiensis, of sporadic occurrence in A. malayensis, rare in A. tabu and have not yet been identified with certainty in A. cooki.

A mark-release-recapture experiment with Anopheles lesteri paraliae in northwest Peninsular Malaysia

In a coastal village in northwest Malaysia, 3231 fed Anopheles females of eight to 10 species were collected, marked with fluorescent dust, and released on three consecutive nights. In collections made on the 10 nights after the first release, 58 mosquitoes of three species, An. lesteri paraliae, An. subpictus and An. vagus, were recaptured; the recapture rates were 3.42%, 1.19% and 0.97%, respectively. The data for An. subpictus and An. vagus were insufficient for further analysis. Those for An. l. paraliae were plotted against time of recapture and, from the regression coefficient, an estimate of 0.68 was obtained for the daily survival rate. An independent estimate based on the parous rate during the previous year was 0.55. The temporal distribution of the recaptures strongly suggested a gonotrophic cycle and oviposition cycle of two days.

Control of Culex quinquefasciatus in Myanmar (Burma) and India: 1960–1990

During the past 30 years three major programmes of research have been carried out in Myanmar (Burma) and India on the ecology and control of Culex quinquefasciatus. To differing degrees the programmes have employed environmental, chemical, biological and genetic control strategies, but none has been an unqualified success. Results have been good when well-trained staff with substantial resources were employed, but much poorer when less-well-equipped general health workers took over the programmes. Overall, it would seem most cost-effective for health workers to concentrate their efforts on the elimination of the limited number of larval habitat categories which commonly contribute a large fraction of the adult population. Insecticides and biological control agents should serve as supplements, not as alternatives, to environmental management. Genetic control strategies have currently no place in C. quinquefasciatus programmes.