Kolhe, Dr. A. V.LONAGRE, SWATI GAJANAN.2021-04-132021-04-132021-01-22LONAGRE, SWATI GAJANAN. (2020). Assessment of Sampling units and Distribution Pattern of major pests of okra. Department of Agricultural Entomology, Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola. Ph. D. 2020. Print. xxiii, 267p. (Unpublished).https://krishikosh.egranth.ac.in/handle/1/5810163459The present study was conducted during kharif season for the year 2015-16 and 2016-17 at Experimental Farm of Department of Entomology, Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola. Laboratory observations were taken at laboratory of Agril. Entomology, PGI, Dr. P.D.K.V., Akola.The present investigation entitled “Assessment of sampling units and distribution pattern of major pests of okra.” conducted during kharif season for the year 2015-16 and 2016-17 at Experimental Farm of Department of Entomology, Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola. An experiment was laid in Randomized block design. Sampling units viz., number of leaves, shoots and fruiting bodies according to strata i. e. top, middle and bottom canopy of selected plants were evaluated to determine best sampling unit for sucking pests, fruit borer eggs and larvae, respectively. The size of plant samples for these pests was also optimized on okra. In the present investigation the predatory response of ladybird beetles and chrysopa under different densities of aphids and leafhopper was also determined. The result revealed that for counting of sucking pests, selection one each leaf from top, middle and bottom stratum of the plant gave highest population of sucking pests during both the season. Hence, this stratified sampling is appropriate and should be uses for counting of sucking pests on okra. The highest count of sucking pests (aphid, leafhopper and whitefly) was noted (No/leaf) in middle stratum of the okra crop as compared to top and bottom stratum of plant during morning hrs. Whereas, counts of Helicoverpa armigera Hubner eggs, selection of one each lateral shoot from top, middle and bottom stratum of the plant was found appropriate sampling method as it gives highest number of eggs count. However, for H. armigera larval count selection of all flowers and fruits on whole plant gave highest count. Hence, this method can be used for recording of fruit borer larvae on okra. The population of Helicoverpa armigera eggs and larva was significantly higher at top than middle and bottom stratum of plant. During kharif, 2015 the optimum sample size of 10.91, 4.90, 6.72, 3.93 and 5.49 plants was estimated for aphid, leafhopper, whitefly, Helicoverpa armigera eggs and larva respectively at their ETL, whereas, during kharif, 2016 such plant size was 10.19, 4.52, 5.17, 4.94 and 5.42 respectively estimated by N= (tS /Dx) 2 formula ( level one). The optimum sample size (33.58, 15.72, 20.89, 12.34 and 16.53) in 2015 and (31.36, 13.90, 16.13, 15.55 and 16.92) in 2016 at their ETL estimated by Nt=(Ss2/ns)+ Sp2/(D*x)2(level two) formula. For estimating the population of (sucking pests and fruit borer) at lower and higher plant density and at ETL the higher number of plant sampling is required at ETL than population at lower and higher density. The Comparison of the two different formulae i.e. N=((ts)/(dx))2(Level one) and Nt=(Ss2/ns)+Sp2/(D*x)2(level two) used for calculating the optimum sampling unit and sample size for major pest of okra. For sucking pests and fruit borer the actual sample units were 20 units. Estimated sample units can be calculated by using level one formula for sucking pest and for fruit borer was less. i.e.(10.91, 4.90, 6.72, 3.93 and 5.49) in 2015 and (10.19, 4.52, 5.17, 4.94 and 5.42) in 2016 than level two formula i.e.(33.58,15.72, 20.89, 12.34 and 16.53) in 2015 and (31.36, 13.90, 16.13, 15.55 and 16.92) in 2016.at their ETL. Hence, estimated more précised sampling unit and sample size by using N= (tS/Dx) 2 level one formula than Nt= (Ss2/ns) +Sp2/(D*x)2 level two formula. A study on the spatial distribution pattern (inter and intra plant) of sucking pests and fruit borer of okra revealed aggregated or clump type of distribution invariably on plant, various strata and growth stages of the crop. Various indices of dispersion were used to study the distribution pattern. In both seasons, the variance to mean ratios(s2/ x), were found to be less than unity, dispersion parameter ‘k’ was less than 8, the morisita index of aggregation (Iδ) were less than unity and David and Moore’s indices of clumping were negative. The number of prey consumed increases, the percentage of consumption decreases towards higher prey density which confirms type II response of prey predator relationship confirmed by this study conducted on C. sexmaculata and Chrysoperla carnae over their prey i.e. aphids and leafhopper. The highest prey consumption potential of C. sexmaculata (168.6 aphid and 66.2 leafhopper) and Chrysoperla carnae (145.3 aphids and 74.1 leafhoppers) was recorded at 24 hrs of prey offered. Similarly, the highest consumption rate of C. sexmaculata and Chrysoperla carnae for aphid 455.40% and 572.79%and for leafhopper 117.70% and 115.21% respectively was recorded at 24 hrs of prey offered. Whereas, highest predation efficiency of each C. sexmaculata and Chrysoperla carnae was recorded at prey density of 5 aphids and 10 leafhoppers.EnglishThesis