In the cattlesheds of Solmarah, a sylvan village in Sonitpur district, Assam, India, a collection of 31, 853 specimens of 33 species of mosquitoes was obtained by using C.D.C. light traps with five different coloured bulbs. It was found that mosquitoes were attracted more towards the white colour of a clear glass bulb and blue light followed in descending order by yellow, green and red. Anopheles crawfordi and Aedes (B) lineatopennis were highly attracted towards white lights; Culex bitaeniorhynchus towards blue while Mansonia uniformis and M. indiana were attracted by both, blue and white lights.

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KEY WORDS : CDC light trap; relative attractiveness of colours; visual stimuli; Anopheles spp.; Mansonia spp.; Culex spp.; Aedes spp.; Armigeres spp.; Coquillettidia spp.; Ficalbia spp.; ‘F’ test; Sonitpur; Solmarah, Assam, India

1. Accepted on 9.9.1993.

2. Medical Entomology Section, Defence Research Laboratory, Tezpur, Assam 784001, India.

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Four different kinds of traps, viz., Communicable Disease Centre, USA (CDC) miniature light trap; New Jersey light trap, Monkswood light trap and cattle baited Magoon trap were evaluated for collection of vector mosquitoes in six villages located in sub-Himalayan bordering areas of Assam - Arunachal Pradesh in India. A total of 19,186 mosquitoes belonging to 30 species was collected in 40 trap nights (10 trap nights’ collection with each trap). Statistical analysis revealed significantly high collections of both mosquitoes and species in CDC light trap followed by New Jersey, Magoon and Monkswood traps. Anopheles aconitus, Culex gelidus and Culex vishnui group of mosquitoes were attracted more towards CDC than Monkswood and Magoon traps. Similarly, New Jersey light trap yielded more specimens of C. vishnui group of mosquitoes than Monkswood and Magoon traps.

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KEY WORDS : CDC light trap, Monkswood light trap, New Jersey light trap, Magoon trap, biotope, Micro-habitat, ‘t’ and ‘f’ test, surveillance.

1. Accepted on 9. 9. 1993.

2. Medical Entomology Section, Defence Research Laboratory, Tezpur, Assam 784001, India.

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Focal index is a new parameter for the evaluation of malaria control in any area. It is dealing with the relationship between the quantum of malaria parasitic reservoir, its distribution and the transmission. This parameter can easily be calculated from the basic data of epidemiological information collected at different levels of anti epidemic and sanitary stations. The product of total nos. of cases in a district divided by the nos. of villages which are positive for malaria gives the focal index of that area. The probability of a mosquito infected by malaria parasites depend on the volume of the population and the total nos. of malaria cases in the total population of the village. For calculation of focal index in a group of villages with different nos. of reported malaria cases a varying coefficient factor is applied which is the square of the nos. of malaria cases in the given village. An equation for calculation of basic focal index in complex situation is given. These indices were applied on the results obtained in the Napo county of Guangxi Zhuang region of China. It was demonstrated that the effect of foci eradication in these areas with bednets impregnated with deltamethrin was better than DDT residual spraying. It is expected that for testing the validity, these indices will be applied on the results obtained in other parts of the world also.

KEY WORDS : Focal index; malaria transmission; vector biology; epidemiological data; varying coefficient; correction factor; basic focal index; corrected varying focal index; Napo county; Guangxi Zhuang region, China.

1. Accepted on 27. 9. 1993.

2.Guangxi Institute form Parasitic Diseases Control, 80, Tao Yuan Road, Nanning Guangxi 530021, P. R. of China

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(With one text figure)

In two highly malarious villages of Badkhal and Anangpur of Kheri Kalan primary health centre of Faridabad, environmental restraints viz., deweeding, filling of pits and release of larvivorous fishes Poecilia reticulata, radical & preventive treatment and 25 per cent water dispersible malathion spraying at the rate of 2 gm/m reduced significantly annual parasite incidence from 22.3 to 6.6 per thousand in Badkhal village while from 34.6 to 21.8 per thousand in Anangpur village and a decline in Anopheles culicifacies densities in these villages.

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KEY WORDS : Susceptibility, malathion, bio-environmental restraints, DDT resistant Anopheles culicifacies, larvivorous fishes Poecilia spp., Badkhal, Anangpur, Faridabad, Haryana, India.

1. Accepted on 9. 10. 1993.

2. Regional Office (Health & F. W.), K. No. 3281, Sec. 21D, Chandigarh, India.

3. National Malaria Eradication Programme, 22, Shamnath Marg, Delhi, India.

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(With five text figures.)

In 1206 man-hours 341 specimens of Anopheles tessellatus were collected in 19 villages of Bastar district, Madhya Pradesh. This mosquito was not found resting in the cattlesheds during the day time. A uniform feeding pattern was not seen all round the year. This species appeared to be more numerous in early winter season. This insect seemed to be more abundant in the North-eastern Plateau with hot-moist climate and elevation range from 609 to 761 m. This Anopheles was not captured on human bait. In precipitin tests females fed on human blood were detected. None of the females dissected showed gut or gland infection of malarial parasites.

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KEY WORDS : Bionomics, Anopheles (Cellia) tessellatus Theobald, 1901, distribution, diurnal resting sites, feeding times, seasonal prevalence, malaria, precipitin test, abundance. epidemiological significance, Bastar district, India.

1. Accepted on 17. 10. 1993.

2. Assistant Entomologist, National Malaria Eradication Programme, Jagdalpur, Bastar district, (M.P.), India.