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K R ASCHER

Publications and source records attributed to K R ASCHER.

18 recordsLinked to original sources
PubMed1961

Prof. G. G. MER.

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PubMed1959

Studies on insecticide-resistant anophelines. 2. Chromosome arrangements in laboratory-developed DDT-resistant strains of Anopheles atroparvus.

The development of several DDT-resistant strains of Anopheles atroparvus is described. They were selected by larval treatment only (RL), selection of larval and adult females (RLAF), and selection of adult females and males (RAFM). Their rate of DDT-resistance was measured in the larval and adult states (mainly in the 32nd generation). The results were compared with those of a dieldrin-selected strain (R/dieldrin) and several normal and semi-normal reference strains. In the larval assay DDT-resistance was of the following order: RL>RLAF>RAFM>R/dieldrin. Topical application to adults gave: RLAF>(RL?)>RAFM>R/dieldrin; while adult tarsal contact gave: RAFM>RLAF>RL>R/dieldrin These different orders of resistance are discussed.The strains were subjected to cytological examination by the method of Frizzi. The percentages of heterozygous inversions found were as follows: R/dieldrin, 77.4%; RL, 55.3%; RLAF, 54.0%; RAFM, 24.4%; all normal and semi-normal strains about 12%-21%.The rate of DDT-resistance could not be correlated with the percentages of heterozygous inversions found in the various strains.

Animals↗
PubMed1958

Studies on insecticide-resistant anophelines. I. Chromosome arrangements in a dieldrin-selected strain of Anopheles atroparvus.

The authors present the results of a cytological examination, carried out by the technique developed by Frizzi, of the larvae of a normally susceptible and a dieldrin-selected strain of Anopheles atroparvus, both laboratory-reared. A very high percentage (77.4) of heterozygous inversions was observed in the larvae of the 28th generation of the dieldrin-resistant strain, whereas only 20.8% occurred in the normally susceptible strain, in which the standard chromosomal arrangement predominated (74.2%). These results are similar to those obtained recently by other workers in the case of larvae of the 12th generation of a DDT-selected strain of A. atroparvus (74.8% heterozygous inversions observed).

Animals↗