Seasonal incidence and weather-based population dynamics of yellow stem borer (Scirpophaga incertulas Walker) in rice ecosystems of western Uttar Pradesh

Introduction

Rice (Oryza sativa L.) is the principal cereal crop in Asia and serves as a staple food for more than half of the world's population, contributing significantly to food security and rural livelihoods (Bhandari et al., 2023; Tagliapietra et al., 2024) [2,16] . However, rice productivity is severely affected by several insect pests, among which stem borers are considered one of the most destructive groups causing substantial yield losses (Savary et al., 2000; Chintalapati et al., 2023) [3,11] . Among the stem borer species, the yellow stem borer, Scirpophaga incertulas (Walker) (Lepidoptera: Crambidae), is the most economically important pest in irrigated and rainfed lowland rice ecosystems across South and Southeast Asia (Dale, 1994; Newton and Dixon, 1990) [4,7] . The larval stage feeds internally within the rice stem, making it difficult to control because the larvae remain protected from natural enemies and contact insecticides. Infestation during the vegetative stage results in the formation of dead hearts, whereas attack during the reproductive stage produces white ear heads, both of which considerably reduce grain yield and productive tillers (Dale, 1994; Savary et al., 2000) [4,11] . The importance of yellow stem borer has increased with the adoption of high-yielding rice cultivars, intensive fertilizer application and continuous rice cultivation (Heong et al., 2015) [6] . In addition, favourable climatic conditions, particularly higher temperatures and humidity, enhance pest survival, development and population build-up, leading to increased infestation. Although chemical insecticides have been widely used for its management, their indiscriminate application has resulted in insecticide resistance, pest resurgence and ecological imbalance (Heong et al., 2015) [6] . Consequently, integrated pest management (IPM) approaches combining cultural practices, host-plant resistance, biological control, pheromone-based monitoring and judicious use of selective insecticides have gained considerable importance. A thorough understanding of the seasonal occurrence and ecological relationship of S. incertulas with weather parameters is essential for developing effective forecasting systems and sustainable management strategies. Therefore, the present study was undertaken to investigate the seasonal incidence of yellow stem borer in relation to abiotic factors under the agroclimatic conditions of the Western Plain Zone of Uttar Pradesh.

Materials and Methods

Experimental Site

The experiment was conducted during the Kharif 2025 season at the Crop Research Centre (CRC), Sardar Vallabhbhai Patel University of Agriculture and Technology (SVPUAT), Modipuram, Meerut, Uttar Pradesh, India. The experimental farm is located at 29°01′ N latitude and 77°45′ E longitude, with an altitude of 237 m above mean sea level, representing the Western Plain Zone of Uttar Pradesh. The experiment was conducted in an untreated field under natural infestation conditions.

Crop Establishment

The experiment was conducted using the basmati rice variety Pusa Basmati-1509. Twenty-five-day-old seedlings were transplanted during the third week of July 2025 (transplanting date: 25 July 2025) at a spacing of 20 × 15 cm. The crop was raised following the recommended agronomic practices of SVPUAT, Meerut. A fertilizer dose of 120:60:40 kg N:P₂O₅: K₂O ha⁻¹ was applied according to the university recommendations. No insecticidal treatments were applied throughout the crop season to permit natural infestation of yellow stem borer.

Sampling Method and Recording of Yellow Stem Borer Incidence

Seasonal incidence of the yellow stem borer, Scirpophaga incertulas (Walker), was recorded at weekly intervals from the 29 th to the 44 th Standard Meteorological Week (SMW). Five hills were selected randomly from the untreated observation area during each observation. During the vegetative stage, infestation was assessed by recording dead hearts (DH), whereas during the reproductive stage, infestation was recorded as white ear heads (WEH). Previously recorded damaged tillers were removed after each observation to avoid repeated counting of the same infestation. The percentage infestation was calculated using the following formulae:

Statistical Analysis

The relationship between yellow stem borer incidence and weather parameters was analysed using Pearson's correlation coefficient (r). Weekly pest incidence data were correlated with the corresponding meteorological variables to determine the influence of abiotic factors on seasonal population dynamics. Statistical analyses were performed using OPSTAT statistical software (Version 16.0, CCS Haryana Agricultural University, Hisar, India) and the significance of correlation coefficients was tested at the 5% probability level (P ≤ 0.05).

Result

The Correlation analysis indicated that yellow stem borer infestation was significantly and positively associated with maximum temperature (r = 0.521). However, minimum temperature (r = 0.108NS) exhibited a non-significant positive correlation, while morning relative humidity (r = -0.281NS), evening relative humidity (r = -0.143NS), and rainfall (r = -0.400NS) showed non-significant negative correlations with pest infestation. The present findings are in agreement with Pal et al. (2023) [8] , Hatwar et al. (2021) [5] , Sharma et al. (2018) [12] and Samrit et al. (2019) [10] , who also reported similar seasonal occurrence and weather-dependent population dynamics of yellow stem borer under different rice-growing regions.

Discussion

The present study revealed that the incidence of yellow stem borer (Scirpophaga incertulas Walker) commenced during the vegetative stage of the rice crop, gradually increased with crop growth, reached its peak during the middle of the season and declined towards crop maturity. Similar seasonal trends have been reported by Samrit et al. (2019) [10] , Sharma et al. (2018) [12] and Sulagitti et al. (2018) [15] who observed maximum yellow stem borer infestation during September-October. Correlation analysis indicated that yellow stem borer incidence was positively associated with maximum temperature, whereas minimum temperature, morning relative humidity and rainfall exhibited negative associations. Evening relative humidity showed a positive relationship with pest incidence. These findings are in agreement with Hatwar et al. (2021) [5] , Singh et al. (2020) [14] and Pallavi et al. (2018) [9] , who also reported that higher temperatures favoured yellow stem borer activity, while rainfall and lower temperatures generally suppressed pest incidence. Similar observations were reported by Balaji and Vijaykumar (2025) [1] under different transplanting conditions.

Conclusion

The present study demonstrated that the incidence of yellow stem borer (Scirpophaga incertulas Walker) in basmati rice commenced during the early vegetative stage, gradually increased with crop growth, reached its peak during the middle of the crop season and declined towards maturity. The seasonal incidence of the pest was influenced by prevailing weather conditions. Correlation analysis indicated that maximum temperature favoured yellow stem borer incidence, whereas minimum temperature, morning relative humidity and rainfall exhibited negative associations, while evening relative humidity showed a positive association. The findings suggest that abiotic factors play an important role in determining the seasonal abundance of yellow stem borer. Therefore, regular pest surveillance together with weather-based forecasting can facilitate timely implementation of integrated pest management (IPM) practices, thereby minimize yield losses and improve sustainable rice production under the Western Plain Zone of Uttar Pradesh.

References

1. Balaji BN, Vijaykumar L. Assessing yellow stem borer (Scirpophaga incertulas) incidence patterns in paddy (Oryza sativa) cultivation: Implications for climate change adaptation strategies. The Indian Journal of Agricultural Sciences. 2025;95(4):389-394.
2. Bhandari U, Gajurel A, Khadka B, Thapa I, Chand I, Bhatta D, et al. Morpho-physiological and biochemical response of rice (Oryza sativa L.) to drought stress: A review. Heliyon. 2023;9(3):e13744.
3. Chintalapati P, Rathod S, Repalle N, Varma NRG, Karthikeyan K, Sharma S, et al. Insect pest incidence with the system of rice intensification: Results of a multi-location study and a meta-analysis. Agronomy. 2023;13(4):1100.
4. Dale D. Insect pests of the rice plant: Their biology and ecology. In: Heinrichs EA, editor. Biology and Management of Rice Insects. New York: Wiley Eastern Ltd./IRRI; 1994. p. 363-485.
5. Hatwar NK, Jalgaonkar VN, Wade PS, Naik KV, Thantharate SH, Kinjale RS. Seasonal incidence of yellow stem borer, Scirpophaga incertulas (Walker) infesting rice and its correlation with weather parameters. Journal of Entomology and Zoology Studies. 2021;9(1):263-266.
6. Heong KL, Cheng JA, Escalada MM. Rice pest management: Issues and opportunities. In: Heong KL, Cheng JA, Escalada MM, editors. Rice Planthoppers: Ecology, Management, Socio Economics and Policy. Cham: Springer; 2015. p. 1-20.
7. Newton C, Dixon AFG. Pattern of growth in weight of alate and apterous nymphs of the English grain aphid, Sitobion avenae. Entomologia Experimentalis et Applicata. 1990;55(3):231-238.
8. Pal R, Chandra U, Kumar D, Kumar S. Investigation on the abiotic influences on amplitude fluctuation in the incidence of major pests of rice in Eastern Uttar Pradesh, India. International Journal of Environment and Climate Change. 2023;13(11):20-28.
9. Pallavi D, Sharanabasappa, Megaladevi P. Seasonal fluctuation of yellow stem borer, Scirpophaga incertulas (Walker) on paddy and its relationship between trap catches with weather parameters. International Journal of Current Microbiology and Applied Sciences. 2018;7(9):3575-3584.
10. Samrit RM, Chaudhari BN, Gahane KD. Seasonal incidence of rice yellow stem borer, Scirpophaga incertulas (Walk.) and its correlation with weather parameters and natural enemies. Journal of Pharmacognosy and Phytochemistry. 2019;8(5):740742.
11. Savary S, Willocquet L, Elazegui FA, Castilla NP, Teng PS. Rice pest constraints in tropical Asia: Quantification of yield losses due to rice pests in a range of production situations. Plant Disease. 2000;84(3):357-369.
12. Sharma KR, Raju SVS, Roshan DR, Jaiswal DK. Effect of abiotic factors on yellow stem borer, Scirpophaga incertulas (Walker) and rice leaf folder, Cnaphalocrocis medinalis (Guenée) population. Journal of Experimental Zoology. 2018;21(1):233-236.
13. Sharma RK, Sharma KK. Population dynamics of rice yellow stem borer and sheath blight. Indian Journal of Entomology. 2023;85(3):234-237.
14. Singh D, Umrao RS, Verma K, Kumar A, Vikrant. Population dynamics of major insect-pests of rice and their natural enemies and its correlation with weather parameters in Central Uttar Pradesh. International Journal of Current Microbiology and Applied Sciences. 2020;9(2):1517-1531.
15. Sulagitti A, Raghuraman M, Reddy MS, Sathua SK. Impact of abiotic factors on population fluctuation of major insect pests of rice under Varanasi conditions. Journal of Experimental Zoology, India. 2018;21(2):709-712.
16. Tagliapietra BL, Soares CF, Clerici MTPS. Rice (Oryza sativa L.) and its products for human consumption: General characteristics, nutritional properties and types of processing. Food Science and Technology. 2024;44:e00000.