Volume 49, Issue 3
March 1959, pages 149-206
pp 149-155 March 1959
Labelling of the adults ofBracon gelechiæ Ashmead by allowing them to feed on 10 per cent. glucose solution containing phosphoric acid (H3PO4) with P32 is not practicable as the adult parasites are unable to pick up enough radioactivity. On the other hand labelling of the adults by rearing them on host caterpillars ofCorcyra cephalonica Stainton, the latter being fed on crushed maize mixed with radioactive phosphoric acid is quite a convenient and satisfactory method for the purpose of mass release of the parasite under the natural conditions, as such individuals show tolerably high degree of radioactivity and are therefore easy to detect. Moreover, the developmental period of the parasite by rearing it on radioactive host caterpillars is not adversely affected and the adults remain alive for a considerable period.
pp 156-160 March 1959
pp 161-166 March 1959
pp 167-182 March 1959
pp 183-193 March 1959
The oxygen consumption ofMegascolex mauritii was measured at 15, 20, 25, 30 and 35° C. during summer with worms varying in weight from 0·15 to 1·5 gm. They were kept immersed under water at the laboratory temperature (at 28±1° C).
The size-temperature relationship for oxygen consumption revealed a proportionate rise in oxygen consumption at higher temperatures. But the relative rate of increase is greatest in smaller worms.
Q10 is discussed in relation to size and sudden changes in temperature and it was shown that it increases with decreasing weight. No systematic variation in Q10 with temperature was noticed.
The regression coefficient for oxygen consumption in relation to weight shows a consistent decrease with increasing temperature over the range 15 to 35° C. But at 25 and 30° C. which approximate the habitat temperature, the oxygen consumption ofMegascolex mauritii shows surface proportionality.
The changes in theb-values (regression coefficient) are explained on the basis of observed Q10 values.
pp 194-206 March 1959
Normal somatic complement inA. indica consists of 32 chromosomes in female and 16 in male. Karyo-typic analysis of haploid males shows eight homomorphic pairs indicating distinct somatic association (2m.c.+2s.m.c.+4s.t.c.).
Excepting the gonial and epithelial layers of blastoderm, other tissues show polysomatic increase in euploid or aneuploid numbers through repeated endomitosis.
In view of occurrence of eight homomorphic pairs in the male showing somatic association, it is inferred that the male, thoughj numerically haploid is genetically diploid thus the famale being a tetraploid. This is supported by control of certain characters by multiple genes without linkage and diploid, constitution ofA. florea having 16 chromosomes in female and 8 in male.
It is suggested thatA. indica originated from primitive diploid by (1) polyploidy combined with adaptive mutations for multiple enclosed comb habits or (2) hybridization at diploid level among closely relatedApis andTrigona followed by polyploidy during pleistocene glaciation in the Indo-Malayan region.
PrimitiveA. indica gradually evolved intoA. mellifera which differentiated further into a number of African, Eurasian and Sino-Japanese races during the course of the passage through the three main northern migratory routes of the Himalayas.
Bearings of these observations on the practical problems of breeding better strains of Indian bees are discussed.
Investigations on comparative cyto-genetics of Indian species ofApis, Trigona and related genera are in progress.