RELATIVE ABUNDANCE OF STEM BORER SPECIES INFESTING RICE AND MANAGEMENT OF RICE YELLOW STEM BORER, Scirpophaga incertulas (WALKER) (CRAMBIDAE: LEPIDOPTERA)
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Date
2019
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ACHARYA N G RANGA AGRICULTURAL UNIVERSITY, GUNTUR
Abstract
The studies on relative abundance of stem borer species infesting rice and management of rice yellow stem borer, Scirpophaga incertulas (Walker) (Crambidae : Lepidoptera) were carried out at farmers fields of Krishna district and at Agricultural Research Station, Garikapadu, Krishna district, Andhra Pradesh for four consecutive seasons viz., kharif 2016, rabi 2016-17, kharif 2017 and rabi 2017-18.
A total of 215 rice germplasm lines from IIRR, Hyderabad were screened for resistance/ susceptibility against rice yellow stem borer, S. incertulas in augmented block design for two seasons i.e., kharif, 2016 and kharif, 2017. Only seven entries exhibited moderate resistance/ resistance with regards to both dead hearts and white ears symptoms and these seven promising genotypes (IC No. 381538, 450535, 463380, 464140, 464186, 574807 and 578388) were selected for further biochemical analysis. The analysis revealed that rice genotypes with low sugars, low free amino acids and high total phenols, proteins, proline and silica content conferred resistance to rice yellow stem borer and these genotypes can be utlilised in the breeding programme to develop resistant varieties against S. incertulas.
Survey was conducted to assess the relative abundance and distribution of various stem borer species and predators in rice ecosystem through stratified random sampling procedure. The survey was carried out for four consecutive seasons i.e., kharif 2016, rabi 2016-17, kharif 2017 and rabi 2017-18 in ten mandals of Krishna district. The results inferred that yellow stem borer was the predominant stem borer species in rice ecosystem of Krishna district with 82.0 and 78.88 per cent abundance during kharif and rabi seasons, respectively. Next to yellow stem borer, pink stem borer was more abundant than white stem borer and dark headed stem borer during kharif season, whereas white stem borer was more dominant compared to pink stem borer and dark
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headed stem borer in rabi season. The predatory fauna prevalent in rice ecosystem of Krishna district exhibited uniform distribution throughout the crop season. The cluster analysis indicated a relationship between stem borer species abundance and predatory guild prevalence in rice ecosystem of Krishna district and the highest species divergence was witnessed in Jaggayapeta mandal (20.88%) followed by Penuganchiprolu mandal (17.58%) whereas, in Mopidevi mandal the least divergence (0.01%) was noticed.
The influence of various planting methods viz., manual transplantation (random), manual transplantation (straight row), direct seeding, drum seeder and machine transplantation (8 row) on incidence of rice yellow stem borer was assessed for four consecutive seasons (kharif 2016, rabi 2016-17, kharif 2017 and rabi 2017-18). The cumulative mean incidence of yellow stem borer in ascending order among various planting methods was machine planting (3.80 & 3.41% DH; 3.65 & 4.55% WE) > straight row planting (4.99 & 4.29% DH; 5.93 & 7.08% WE) > random planting (9.84 & 10.66% DH; 9.62 &13.25%WE) > drum seeded (15.31 & 14.31% DH; 17.12 &15.11 %WE) > direct sown (12.28 & 10.93% DH; 18.38 &19.52%WE) during kharif and rabi seasons, respectively.
The efficacy of five pest management modules against rice yellow stem borer were evaluated for four successive seasons viz., kharif 2016, rabi 2016-17, kharif 2017 and rabi 2017-18 and it was evident from the pooled mean data that among various modules, the least per cent dead heart and white ears were registered in IPM module (2.68 & 2.56% DH; 2.79 & 2.31% WE), farmers practice (2.31 & 2.32% DH; 3.92 & 4.77%WE) and chemical based module (2.90 & 4.24% DH; 5.59 & 5.18% WE) and were statistically on par with each other as against highest incidence in non chemical (13.78 & 13.7% DH; 18.24 & 17.94% WE) and non chemical + bio rational (11.40 & 9.88% DH; 13.09 & 11.25% WE ) based modules. However, the average highest C: B ratio (1: 2.75 & 1: 2.49) and net profits (Rs. 151587 ha-1 & Rs. 150115 ha-1) were realized with IPM based management module in both kharif and rabi seasons, respectively.
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D5889
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