Studies on biological attributes of laboratory and field populations of Chilo partellus (Swinhoe) on maize
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Date
2013
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Punjab Agricultural University
Abstract
The studies on biological attributes of laboratory and field populations of Chilo partellus (Swinhoe) on maize were conducted during kharif season, 2012 in the Punjab. The variation, in important biological characters of 3 different populations i.e. P1 (laboratory population reared for 8 generations under laboratory conditions), P2 (field collected population reared for 3 generations under laboratory conditions) and P3 (field collected population reared only for 1 generation under laboratory conditions); and their response to different maize cultivars (i.e. PMH 1, JH 3459 and CML 67) was studied under laboratory; and field conditions, respectively. The relative susceptibility of these populations to insecticides (i.e. Decis 2.8 EC and Dipel 8L) was also studied under laboratory conditions. The mean incubation, larval and pupal periods (male and female) were highest in P1, intermediate in P2 and lowest in P3 while, the mean per cent hatchability of eggs, per cent pupation, pupal weight (male and female), adult longevity (male and female) and fecundity was highest in P3, intermediate in P2 and lowest in P1. Similarly host plant reaction was also influenced by these populations which showed significant differences in leaf injury rating (LIR). At 20 and 25 days after egg release (DAER), the mean LIR was significantly more for P3 (6.0 and 7.2, respectively) than that for P2 (5.5 and 6.5, respectively) and P1 (4.6 and 5.4, respectively). However at 10 DAER it was 4.3, 4.5 and 3.7, respectively. The P3 also formed more (39.99 %) dead-hearts than that of P2 (26.66 %) and P1 (9.99 %). The interaction between test genotypes and populations varied non-significantly with respect to LIR, and it ranged from 3.5 to 4.9, 4.1 to 6.8 and 4.4 to 7.6 at 10, 20 and 25 DAER, respectively; and the dead-heart formation at 25 DAER ranged from 3.33 to 53.33 per cent. The order of susceptibility of the test populations to Decis 2.8 EC (deltamethrin) and Dipel 8L (Bacillus thuringiensis var. kurstaki strain HD-1) was P1 > P2> P3. The adverse effect on biological attributes of C. partellus showed an increasing trend when it was reared from 1 to 8 generations under laboratory conditions which might have influenced the response of these populations to maize genotypes and their susceptibility to insecticides.
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Keywords
insecticides, maize