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CULTIVARS RESISTANCE AND CHEMICAL CONTROL OF TOMATO FRUITWORM, Heliothis armigera Hb. ON TOMATO Lycopersicon esculentum Mill.

Ahmad, Imtiaz (1994) CULTIVARS RESISTANCE AND CHEMICAL CONTROL OF TOMATO FRUITWORM, Heliothis armigera Hb. ON TOMATO Lycopersicon esculentum Mill. PhD thesis, Sindh Agriculture University, Tando Jam.

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Abstract

During present investigation experiments were conducted on the pest phenology on tomato crop for three years (1989-91), at Agricultural Research Institute, Tarnab, and Peshawar. Pest Pehnological studies comprised egg, larval population dynamics, spatial distribution analysis and development of larval time sequential sampling plan. On population dynamics, the regression equation for egg and/or larval population development showed feeble, negative B values during 1989 and 1991, and positive B values during the year 1990. All equations showed poor correlation coefficient. The sequentional sampling programme data showed two distinct population configurations i.e. outbreak and endemic. The differences in growth rates between types were small at first, reached to its peak and then declined. A total of ca. 6 samples (each week) would be adequate to detect type of configuration in anyone year. Spatial pattern of armigera Hb. egg distribution during the study revealed that index of dispersion (I.D.) values were more than 1 in 1990 and 1991. However, in 1989 the I.D. values oscillated around 1. Moreover, most of the green's index J (G.I.) values were positive which confirm the negative binomial distribution of H. armigera Hb. eggs. The I. D. values of the spatial pattern of H. armigera Hb. larval distribution were mostly higher than 1. Therefore, larval distribution also fits negative binomial distribution. The results of discriminating doses of potassium fertilizer on egg and larval population and the fruit infestation showed that there was no significant effect of fertilizer on the uptake of tomato plants, on egg and larval population, and on the infestation of tomato. To compare relative efficacy of nine insecticides, one application was done during the year (1989), and three during each remaining two years of study i.e. 1990 and 1991. All the insecticides were found successful in keeping the larval population below outbreak configuration level upto 15 days after spray. Consolidation of study data over a period of three years revealed that Thiodon was statistically the most effective with 77.88 percent larval mortality, followed by Followed M (75.96%), Sevin (69.32%), Thuricide (67.12%), Dimilin(66.38%), Edcidin (65.32%) and Atabron (59.85%). Permasect and Azodrin were significantly the least effective with 58.55% and 54.66% larval mortality respectively (cdii=17.03 at 0.05 level). The results also indicated a tendency in the reduction of effectiveness of Folidol M, Azodrin, Dimilin and Thuricide over a period of three years which might probably be due to enhancement in the degree of tolerance developing in H. armigera Hb. Cluster analysis on the interactions of eggs and larval per plant, percent fruit damage and yield in Kg per plant of 65 tomato cultivars gave five cluster groups. Frequency-wise cluster analysis showed two varieties in group A (3.08%), two in B (3.08%), f one in C (1.53%), fifty nine in D (90.78%) and one in E (1.53%). In the regression analysis of correlation between characteristics of 65 varieties and armigera Hb. infestation, step-wise model was fitted, the correlation between infestation gave negative dependence larval infestation (-0.3251) with poor correlation coefficient (-0.2558). Similar results were obtained for correlation between yield and number of larvae per plant (b=0.4804, r=0.0893). The step-wise model correlation between larval population and chemical/physical parameters gave negative dependence on trichome length (-0.0100) and iron content (-15494E-04) and positive dependence on zinc (0.0028) and vitamin C (0.0279). Cluster analysis on the interaction of larval duration, pupal duration, and adult longevity, duration of life cycle, larval and pupal weight and survival to adult stage also gave five cluster groups. Frequency-wise cluster analysis showed two varieties in group A (3.08%), four in B (6.15%), fifty two in C (84.62%), three in D (4.62%) and one in E (1.53%). Tiny Tim being moderately resistant cultivar was placed in group E. The results indicated that integration of resistant cultivar, Tiny Tim and Bacillus thuringiensis had maximum effect on larval mortality and minimum percent fruit infestation, it was followed by accession 87-11(1) also a resistant line, while the maximum infestation was recorded on the most susceptible cultivar, Big long. The host range and average number of larvae/plant of H.armigera Hb. were recorded on soybean (1.63), gram (4.80), tomato (0.31), tobacco (1.64), maize (0.81), sunfloYler (0.07), okra (0.67), potato (1.92) and burseem (0.90). Gram Was observed to be he most favourable host plant of this pest.

Item Type:Thesis (PhD)
Uncontrolled Keywords:Cultivar Resistance, Chemical Control, Tomato Fruitworm, Heliothis armigera Hb, Lycopersicon esulentum mill, Pest phenology, Egg, Larval population dynamics, Spatial distribution, Larval time, Sequential sampling, Thiodon, Folidol M, Sevin, Atabron, Pupal duration, Adutl longevity, Duration life cycle, Gram, Tobacco, Maize, Sunflower, Okra, Potato, Burseem.
Subjects:Agriculture & Veterinary Sciences(a) > Agriculture(a1)
ID Code:119
Deposited By:Mr. Abdul Qayoom Sohoo
Deposited On:17 Jun 2006
Last Modified:04 Oct 2007 20:59

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