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20102
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Subject: Entomology × End date: 2010 × Start date: 2010 ×
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    ThesisItemOpen Access
    TOXICITY OF DIFFERENT INSECTICIDES AGAINST COTTON MEALY BUG, Phenacoccus solenopsis Tinsley
    (PAU Ludhiana, 2010) Amit Punj; A. K., Dhawan
    The studies on the evaluation of LC50 of insecticides against mealy bug, Phenacoccus solenopsis population collected from cotton belt during vegetative, flowering and maturity phase were conducted at Entomological Farm, PAU, Ludhiana. The new molecule, spirotetramat was found to be most toxic to first instar, third instar nymphs and adult females. Among the conventional insecticides, profenophos and thiodicarb was proved to be the most toxic. The order of toxicity was spirotetramat > clothianidin > profenophos > thiodicarb > buprofezin > chlorpyriphos > acephate. In another experiment, the persistence of different insecticides at recommended concentrations against first instar, third instar nymphs and adult females was estimated. Based on the index of persistence toxicity, the order of effectiveness for the first instar nymphs of mealy bug was profenophos (645.40) > thiodicarb (619.60) > buprofezin (572.52) > spirotetramat (430.00) > acephate (400.17) > clothianidin (376.83) > chlorpyriphos (330.17). Similarly, for third instar nymphs the order of effectiveness was profenophos (589.18) > thiodicarb (562.93) > buprofezin (548.76) > spirotetramat (395.01) > acephate (384.18) > clothianidin (359.24) > chlorpyriphos (314.53). Similarly, for the adult females the order of effectiveness was profenophos (523.23) > buprofezin (478.77) > thiodicarb (435.13) > spirotetramat (330.10) > acephate (305.00) > clothianidin (290.34) > chlorpyriphos (260.19). The third experiment was conducted to study the effect of host of mealy bug like bitterweed, cocklebur and carpet weed on the efficacy of promising insecticides. Based on LC50 values, profenophos was found to be extremely toxic to first instar, third instar nymphs and adult females of mealy bug on the above mentioned weed hosts in comparison to thiodicarb.
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    ThesisItemOpen Access
    EVALUATION OF NAPIER GRASS (Pennisetum sp.) AS A TRAP CROP IN THE MANAGEMENT OF Chilo partellus (Swinhoe) ON MAIZE
    (PAU Ludhiana, 2010) Bhupinder Singh Sidhu; Uma, Kanta
    The first experiment on the differential development and survival of Chilo partellus on different genotypes of Napier grass viz; Copricon, K-56351, K-56379 and M-285303, conditions at 27.08 ± 2.35 °C and 75.91 ± 5.83 per cent relative humidity. After 4 days of larval release on different genotypes of Napier grass, Napier millet and PMH 1, the larval survival of C. partellus among different treatments was maximum(73.33%) on PBN-342. The larvae could not survive on M-285303, K-56351 and K-56379 after 19 days of their release. After 21 days, the larvae could survive only on Copricon and maize (PMH 1). The developmental period from hatching to adult formation on Copricon and maize was 32.48 and 36.01 days, respectively and survival was 4.0 and 34.0 per cent, respectively. From these studies, it was inferred that different genotypes of Napier grass and Napier millet were not suitable for the development and survival of C.partellus. The second experiment was conducted on the ovipositional preference of female moth of C. partellus for different genotypes of Napier grass, Napier millet and PMH 1. The female moths laid significantly more number of egg clusters per plant in all the treatments in comparison to maize. The genotypes of Napier grass viz; Copricon, M-285303, K-56379, K-56351 and Napier millet, i.e. PBN-233 and PBN-342 received more number of eggs than maize showing that these genotypes were preferred than maize for oviposition. The third experiment was conducted to evaluate different genotypes of Napier grass and Napier millet as trap crop against C. partellus. The maize plots with two rows of all the different genotypes of Napier grass and Napier millet as trap crop on either side of plot suffered significantly less leaf injury and mean damage grade (range- 14.63 to 17.56% and 3.0 to 4.0) than the plots (37.85 to 45.33% and 5.0 to 7.0 m.d.g) having treated maize and maize without any treatment and resulted in obtaining more maize yield in plots having two border rows of genotypes of Napier grass and Napier millet over the treatments with treated maize and maize without any border row or treatment.