(With five text figures)

In 81 villages out of 105 of Bastar district, Madhya Pradesh, India, 5542 specimens of Anopheles culicifacies Giles, 1901 were collected in 1206 man/hours. This insect seemed to be an indoor resting species. The peak feeding times varied in different seasons. This mosquito appeared to more numerous in the rainy season in the Indravati plains with hot-wet climate and elevation range from 457 to 609 m. Females of this Anopheles were captured on human bait. The precipitin analysis indicated an anthropophilic index in samples from all biotopes. None of the females dissected showed gut or gland infected with malaria parasites.

Key Words : Bionomics, epidemiology, malaria, Anopheles culicifacies Giles, 1901, distribution, diurnal resting sites, feeding times, seasonal prevalence, precipitin test, abundance, Bastar district

1. Accepted on 30.8.1997

2. This paper forms part of a thesis on which Indore University, Indore, Madhya Pradesh, India awarded a doctorate degree.

3. Assistant Entomologist, National Malaria Eradication Programme, Jagdalpur, Bastar district, Madhya Pradesh, India.

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For controlling Culex populations, preparations of Bacillus sphaericus Neide was introduced in the late 1980's. However in 1992 and 1994 resistance to this pathogen was noticed in the laboratory colonies of Cx. quiquefasciatus Say. Subsequently, the development of resistance in the field population of Cx. pipiens complex was revealed in France, India and Brazil, where B. sphaericus formulations was applied on large scale. Till date no cross resistance to other pathogenic species like Bacillus thuringiensis var. israelensis de Barjac (B.t.i.) have been reported in B. sphaericus resistant mosquitoes yet. It seems that resistance against B. sphaericus binary toxins is inherited recessively. It also appeared that more than one mechanism were involved in the development of resistance, such as the absence of specific receptors of B. sphaericus binary toxins on the brush border membrane fractions (BBMFs), and, the reduced feeding rate on B. sphaericus preparations. A rotation in the usage of B. sphaericus with another larvicide B.t.i coupled with genetic manipulation for producing diversified mosquitocidal toxins in these pathogens could be the feasible strategies to prevent or suppress the development of absolute resistance against B. sphaericus formulations.

Key Words : Bacillus sphaericus Neide, Bacillus thuringiensis var. israelensis de Barjac, binary toxins, brush border membrane fractions, Culex quinquefasciatus Say, Culex pipiens complex

1. Accepted on 30.8.1997.

2. Department of Biology, Shangqiu Normal College, Shangqiu 476000, P. Republic of China.

3. Department of Parasitology, Henan Medical University, Zhengzhou 450052, P. Republic of China.

4. Department of Entomology, University of California, Riverside, CA 92521 - 0314, U.S.A.

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