SPATIO-TEMPORAL TRENDS AND INTEGRATED MANAGEMENT OF SUGARCANE WHITEFLY, ALEUROLOBUS BARODENSIS (Mask.), (ALEYRODIDAE:HOMOPTERA)

Abstract

The experiments were conducted to study the spatio temporal trend and integrated management of whitefly, Aleurolobus barodensis (Mask.) (Aleyrodidae: Homoptera) during 2008 to 2009 in sugarcane growing areas of various districts of the Punjab. The results are abstracted under the following sub headings: Spatio-Temporal Trend of Whitefly Three farmer’s fields surrounding each of the Chinar Sugar Mills, Tandlianwala, Faisalabad; Ashraf Sugar Mills, Bahawalpur and Jamal Din Wali Sugar mills, Raheem Yar Khan were selected. The population of whitefly (nymphs and adults) were recorded at fortnight interval during the crop season 2008. The data were also correlated with the ambient weather factors. The results revealed that population of whitefly (nymphs + pupae) differed significantly among dates of observation, districts and in interaction between dates of observation and districts. The population was appeared during 2 nd fortnight of June in district Faisalabad and Bahawalpur while in district Rahim Yar Khan it was appeared during 1 st fortnight of July. The maximum peak population was recorded on 1 st fortnight of November each in district Faisalabad (7.96/leaf) and Rahim Yar Khan (14.94/leaf) while on 2nd fortnight of October in district Bahawalpur (15.81/leaf). On an average basis, the district Rahim Yar Khan showed maximum population of whitefly (4.61/leaf) while district Faisalabad possessed minimum population (2.48/leaf). All the weather factors viz. Maximum temperature, minimum temperature, average temperature, relative humidity and rainfall showed non-significant correlation with the population of whitefly in all the districts. On an average basis relative humidity had positive and significant (P ≤ 0.05) correlation with the whitefly population. Relative humidity was found to be the most important factor that contributed maximum in population fluctuation of the pest in all the districts as well as on cumulative basis by exerting 42.3%, 43.8%, 35.9% and 18.3% role in population fluctuation of the pest, respectively. Host Plant Resistance Twenty (20) genotypes of sugarcane viz. BF-16, BF-129, BF-162, CMP-13, CO- 132, COJ-84, COJ-1148, CP-43/33, CP-72/2086, CP-77/400, CPF-237, I-62-96, NIA-98, CPF-243, HSF-240, HSF-242, SPF-213, SPF-234, SPF-245 and SPSG-26 sown in the farmer’s Jhang following RCBD with three replications were tested for their resistancesusceptibility against whitefly during 2008 as a preliminary screening experiment. From these studies, three varieties showing comparatively susceptible trend (HSF-242, COJ-84 and SPSG-26), three intermediate (CO-132, NIA-98 and CP-72/2086) and three showing resistant response (CPF-237, CPF-243 and CPM-13) were selected for final screening trial during 2009. The selected varieties of sugarcane were sown under the same ecological conditions following RCBD with three replications. The data on whitefly population were recorded at fortnightly interval at the appearance of the pest. The results revealed that in the preliminary screening trial during 2008, significant variations were found to exist among dates of observation, varieties and interactions between dates of observation and varieties. The variety HSF-242 was found to be comparatively susceptible showing maximum population of whitefly (nymphs + pupae) per leaf (15.48) while CPF-243 appeared to be comparatively resistant with minimum population of whitefly (5.63/leaf). In the final screening trial during 2009, the trend was found to be almost similar as that of observed in the preliminary screening experiment. The variety CPF-243 was found to be relatively resistant showing minimum population of whitefly (4.01/leaf) while HSF-242 appeared as susceptible with maximum population of the pest (11.09/leaf). The descending order of other genotypes based on population density count per leaf are COJ-84 (9.68), SPSG-26 (8.76), CO-132 (7.29), NIA-98 (6.70), CP-72/2086 (6.12), CMP-13 (5.43) and CPF-237 (4.82). The 1 st fortnight of the month of October during 2008 showed maximum abundance of the pest i.e. 22.85/leaf and there was only one peak in the season. Similarly during 2009 the 1 st week of October showed 16.75/leaf population of whitefly followed by 2 nd week of October i.e. 14.40/leaf. Thus it was concluded that the 1 st fortnight of October is the most suitable period for the development of the pest. Relative humidity during 2009 showed positive and significant correlation (P < 0.01) with r-value of 0.754 while maximum temperature on cumulative basis exerted negative and significant correlation with r-values of 0.419 at P < 0.05. The impact of relative humidity during 2008 and during 2009 was maximum on the fluctuation of the pest and showed 10.5 and 47.3% contribution. On cumulative basis minimum temperature was found to be an important factor and contributed maximum role i.e. 16.01% in population fluctuation of the pest.Role of Morpho-physical and chemical Plant Characters towards Resistance against Whitefly on Sugarcane Various morpho-physical (plant height, cane girth, leaf area, hair density, thickness of leaf seed and moisture in leaves) and chemical plant characters ( total minerals. nitrogen, phosphorus, potassium, calcium, magnesium, carbohydrates, fat, ferrous, manganese, copper and zinc) were studied in various selected genotypes of sugarcane and correlated with the population density of whitefly. POL, brix, CCS and fiber contents in the samples of sugar from each selected genotype were also determined. The selected genotypes differed significantly in all plant characters except moisture percentage, total minerals and magnesium in the leaves. Cane girth, leaf area and hair density on leaf sheath resulted negative and significant correlation with the pest population whereas, plant height and thickness of leaf sheath showed positive and significant correlation. Cane girth had negative and significant impact on the pest population fluctuation and contributed maximum role i.e. 35.2 percent. nd plant height were the 2 Leaf area and most important factors and showed 19.2 and 18.9% role in population fluctuation of the pest. All the regression equation was found to be fitted the best. Nitrogen, potassium, magnesium and zinc contents had positive and significant correlation with the pest population while phosphorus showed negative and significant correlation. Nitrogen percentage in the leaves of sugarcane plants showed positive and significant impact with maximum role i.e. 96.3% in population fluctuation of the pest. CCS in sugar samples had positive and significant correlation while fiber percentage showed negative and significant correlation with the pest population. CCS showed positive and significant role with 49.2% impact while fiber contents in the samples of sugar had negative and significant role with 25.8% impact on the population fluctuation of whitefly. Integrated Pest Management Studies Various control methods such as cultural (de-trashing during July and September) biological (release of 2 nd instars larva per plant, chemical (application of imidachloprid 200 SL @ 568 ml/ha and botanical (application of neem seed kernel extract 5% @ 6.17 litre/ha twice in the season on August 26 and September 27, 2009) were applied singly and in their possible combinations for the control of whitefly on a resistant and asusceptible genotypes of sugarcane. There were sixteen treatments in total including control. The experiment was sown in two sets (one for resistant genotype and the other for susceptible) at three localities viz. in the farmer’s field near Shakarganj Sugar Mills, Jhang, Kamalia Sugar Mills Toba Tek Singh and Chinar Sugar Mills Tandlianwala, Faisalabad, following randomized complete block design with three replications. The data on the population of whitefly (pupae + nymphs) were recorded at fortnightly interval from each locality. The results revealed that the population of whitefly in the farmer’s field near Shakarganj Sugar Mills, Jhang and Kamalia Sugar Mills did not reach to a desired level, therefore, no plant protection measure were taken. The results obtained from the farmer’s field near Chinar Sugar Mills, Tandlianwala, Faisalabad revealed significant variation among dates of observation, treatments and between genotypes. The maximum control of whitefly was recorded to be 1.57 per leaf and 3.49 per leaf with maximum population reduction of 72.45 and 65.68% in susceptible (HSF-242) and resistant (CPF-243) genotypes of sugarcane, respectively in those plots where all the control methods were applied in combinations. The release of 2 nd instars larva per leaf of Chrysoperla carnea showed minimum control of whitefly with 4.40 and 8.22 individuals per leaf with minimum reduction in population of whitefly i.e. 22.80 and 19.17% in resistant and susceptible genotypes of sugarcane, respectively. The population of whitefly was higher in susceptible genotype of sugarcane as compared to resistant genotype in all the treatments including control. Cane yield also showed significant difference between genotypes, among treatments and between the interaction of genotypes and treatments. The application of all the control methods in combination resulted in maximum cane yield i.e. 2857.79 and 3061.15 maund/ha in susceptible and resistant genotypes of sugarcane with maximum increase in yield over control i.e. 24.27 and 20.17%, respectively. The release of C. carnea showed discouraging results with minimum cane yield i.e. 2310.27 and 2674.19 maund/ha with minimum increase over control i.e. 0.46 and 4.97% in susceptible and resistant genotypes, respectively. The application of imidachloprid 200 SL @ 568 ml/ha twice in the season when applied alone showed maximum cost benefit ratio i.e. 1: 50.80 and 1: 59.63 in susceptible and resistant genotypes of sugarcane, respectively. De-trashing of older leaves twice in the season showing CBR of 1: 37.09 and 1: 40.98 in susceptible and resistant genotypes ofsugarcane, respectively. The minimum CBRs were recorded to be 1: 8.26 and 1: 8.85 in those treatments where all the control methods were combined together in susceptible and resistant genotypes of sugarcane, respectively