IJCRR - 12(3), February, 2020
Pages: 07-11
Date of Publication: 10-Feb-2020
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Long Term Studies on the Role of Parasitic Nematode Hexamermis Sp. in Controlling Brown Planthopper in Farmer's Rice Field of West Bengal, India
Author: Pinaki Acharjee, Chitta Ranjan Satpathi, Malay Kanti Modak
Category: Life Sciences
Abstract:On farm, trials were carried out at rainfed rice growing areas of West Bengal, India during Kharif(rainy) season 2003-04 and an average population of parasitic nematode Hexamermis sp. counted from the same field during 2003-04 to 2018-19 in Birbhum. A similar set of experiment was conducted during boro(summer) season 2008-09 in Bankura and average population of Hexamermis sp. was also calculated from the same field during 2008-09 to 2018-19. Each trial comprised three treatments viz (i) Natural Biological Control (NBC) with no pesticide application throughout the crop season (ii)Need based protection (NBP)- judged by periodic monitoring of brown planthopper population and (iii) Schedule treatment (ST)- involving application of insecticides following usual package of practices. The study revealed that NBC resulted in maintaining highest level of parasitism of Brown Plant hopper by this parasite Nematode as compared to NBP and ST. Identical results were also obtained from 15 years and 10 years average data from Birbhum and Bankura during kharif (rainy) and boro(summer) season rice respectively..
Keywords: Brown planthopper, Hexamermis sp., Natural Biological Control, Need Based protection, Scheduled treatment, Parasite, Pest
Full Text:
India is the second largest producer of rice in the world. Rice being the principal crop occupied 66% of the gross cropped area of eastern India particularly in West Bengal. Brown plant hopper Nilaparavata lugens Stål has been recognized as the major biotic stress responsible for significant reduction in yield of rice in west Bengal (Satpathi et al. 2005, Katti et al. 2006) and about 30% of the natural control of brown plant hopper in eastern India are due to parasitic nematode (Satpathi et al. 2008). Farmers of eastern India have been relying mostly on chemical pesticides for the management of brown plant hopper, however their indiscriminate use has led to the destruction of the natural parasites. Hence on farm trials were conducted by National Agricultural Technology Project (NATP) and National Agricultural Innovative project (NAIP) during kharif 2003 & 04 and Boro 2008 & 09 to generate the information on the effect of different treatment on Hexamermis sp population(Fig-1) in rain fed rice of west Bengal .
Fig 1 Hexamermis sp. emerged out from adult brown planthopper in Birbhum
Materials and Methods:
Field trials were conducted in 2 villages spread across Birbhum and Bankura districts of West Bengal during kharif (rainy)season of 2003 & 04 and boro (summer) seasons of 2008 & 09. In each village, 3 hectare field was selected in farmer’s field , where there were three treatment blocks viz (i) Natural Biological Control (NBC) with no pesticide application throughout the crop season (ii)Need based protection (NBP)- judged by periodic monitoring of brown planthopper population and (iii) Schedule treatment (ST)- involving application of insecticides where all the other agronomic Practices are common to three treatments and followed as per recommended package of practices. The population of brown planthoppers were recorded randomly from 50 hills in each sub plot at weekly interval. For estimation of parasitism the mummified adult and nymphs were collected at regular interval and released on potted plant for laboratory study. The infected hopper pests were split horizontally and kept in containers with small quantity of water and was collected and retained for examination. Maintaining the identical treatment procedure, the data were collected from one acre area at the same locality for last 15 years from 2004-2005 to 2018 -19 during Kharif (rainy) and 10 years from 2009-10 to 2018-19 during rabi (summer ) seasons to estimate the population level of Hexamermis sp. in farmer’s field of rain fed rice growing areas of West Bengal. The treatments are applied in each plot is given in Table-1.
Result and Discussions
The fifteen years average(2004-18) data presented in Table-2 showed that at Birbhum district the percent of parasitisation was low 0.8 to 5.7 during the Kharif season 2008 at 60 DAT and the significant differences were there among the treatments. However the percentage of parasitism was recorded up to 32.60% in NBC treatment showed significantly higher in the range of 18.60-32.60% compared to 1.44 to 4.66% in schedule treatment (ST) and 4.00 to 13.57% in Need Based Protection (NBP) during 70 to 130 DAT. The data confirmed the results of Satpathi et al. 2011 as given in Table-2.
Although the percentage of parasitism of last 15 years (2005-19) was low at 60 DAT during kharif season in another study but the higher parasitism in the range of 16.00 to 34.00%, 2.00to5.50%,4.20 to 14.00 % were recorded in NBC, ST and NBP during 70 to130 DAT respectively. Identical results were also obtained in the same field in 2003 which indicated that the parasitic nematode population drastically reduced due to the indiscriminate use of pesticides as given inTable-3.
At Bankura the ten years average data (2009-10 to 2018-19) on percentage of parasitism was very low in the range of 1.80 to 3.2 % in NBC treatment during boro(summer) season significantly higher as compare 0.32 to 0.35 % in ST and 0.5 to 1.00 in NBP during 90 to 110 DAT. The observation on average population on Hexamermis sp. also confirmed the result of 2003 in the same field where the nematode population appeared for short period as given in Table-4.
The result corroborated the study of previous workers from most of the rice growing areas round the world. Mention may be made of the natural incidence of parasitism by Hexamermis sp on BPH was first reported in south India by Manjunath (1978) and in eastern india by Satpathi (1999). In addition to this Grewal et al. (2006) recorded it in Asia and Pena & Shepared (1985) recorded 50% parasitisation of BHP by Hexamermis sp. in Phillippines. Heong (1983) also reported that an entomopathogenic nematode Amphimermis unka K&I caused high mortality of hoppers pest in China. Ramani, (2003) also reported that mermathrid Hexamermis sp. was most important nymphal /adult parasitoid from India . Satpathi et al. (2008) studied in detail about the factor affecting abundance of parasitic nematode Hexamermis sp. in eastern India where the nematode started to build up its population in the month of September starting with very low number of 3 to4 per 100 brown plathopper and two distinct population peaks were observed with population level of 18.52 and 35.00 per 100 BPH. During first and last week of October respectively. From behavioral study with respect to the ecological niche of the host and parasite a relationship was drawn between Hexamermis sp . and Nilaparvata lugens Stål in rice crop in Eastern India where it was recorded that peak population of this parasitic nematode was usually found a week after peak appearance of BPH in rice field but the temperature range of 25 to30ºC and relative humidity of 60 to80% were conducive for population build up of both this host as well as parasite in the rice field ( Satpathi 2009) .The quantification of role of Hexamermis sp in controlling brown planthopper was first initiated with respect to the different plant protection measured was fist initiated in West Bengal during 2003 to 2009 (Satpathi et al.2011) and this long term data may also taken as consideration for one of the component of biological control in most of the rice growing areas of West Bengal.
Conclusion:
From the intensive study of last fifteen years during kharif(rainy) season and ten years during boro(summer) season in rainfed rice growing areas of West Bengal, it is to be concluded that Natural Biological control (NBC) had shown the optimum result by exhibiting higher parasitism as compare with that of Schedule Treatment (ST) and Need Based Protection (NBP) due to the considerable reduction the number of application of insecticide. Both the Need Based Protection (NBP) and scheduled protection (ST)resulted in optimum build up of Hexamermis sp population akin to that natural biological control (NBC) making it more environment friendly.
Acknowledgement
The authors are thankful to the Director of Research, Bidhan Chandra Krshi Viswavidyalaya, Kalayani, Nadia, West Bengal for providing the facilities to carry out the experiment. We gratefully acknowledge the financial support received from ICAR under the World Bank aided National Agricultural Technology Project (NATP)and National Agricultural Innovative Project(NAIP) during the course of study.
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