Chickpea (Cicer arietinum L.) commonly known as Bengal gram, gram or Chana belongs to Leguminosae family. Globally, chickpea as the third most important pulse crop in term of production, following the common bean (Phaseolus vulgaris L.) and field pea (Pisum sativum L.) (Jukanti et al., 2012). India accounts for 75 per cent of the world chickpea production and consumption (Das et al., 2017). Chickpea is a rich source of carbohydrates (60.7%), protein (21.5%), fat (6.0%) and contains essential nutrients such as niacin (B3), riboflavin (B2), pantothenic acid (B5) and vitamin C (Ahlawat and Om Prakash 1996; Jukanti et al., 2012). Additionally, chickpea contains significantly higher levels of calcium and phosphorus compared to other legumes. In India, chickpea is cultivated over an area of 10.91 million hectares with an annual production of 13.75 million tonnes and a productivity of 1260 kg/hectare (Anonymous, 2022a). The major chickpea growing states are Madhya Pradesh, Rajasthan, Maharashtra, Uttar Pradesh, Andhra Pradesh, Karnataka, Chhattisgarh, Bihar and Jharkhand, contributing over 95% of the total production. In Rajasthan, chickpea is cultivated on 2.25 million hectares area, produced 2.65 million tonnes annually with productivity of 1177 kg/hectare (Anonymous, 2022b). Major chickpea growing districts in Rajasthan includes Kota, Sriganganagar, Chittorgarh, Alwar, Tonk, Jhalawar, Pali, Jaipur, Sawai Madhopur, Bikaner, Churu, Sikar and Hanumangarh contributing approximately 14 per cent of the total production. Despite its significance, the per availability of pulses is only 52.9 grams per capita per day or 19.3 kg per capita per year (Anonymous, 2017), far below the Indian Council of Medical Research (ICMR) recommended daily requirement of 104 grams (Anonymous, 2010). This shortfall is primarily due to various production constraints, including abiotic and biotic factors. 

To study the seasonal incidence of H. armigera on chickpea, the variety RSG-902 was sown on 28th October during Rabi 2022-23 and on 1st November during Rabi 2023-24 five plots of 2.4 × 2.0 m² size keeping row to row and plant to plant distance of 30 cm and 10 cm, respectively. All the recommended practices for raising the crop will be followed except for plant protection measures.

For this purpose the crop was left for natural infestation. The larval population of pod borer was recorded at weekly interval on one-meter row length at five spots selected randomly in each plot from the first appearance till harvesting of the crop in the early morning hours without disturbing the flora and fauna.  The data recorded on larval population and meteorological parameters used for statistical analysis.

The simple correlation computed between the larval population of gram pod borer and weather parameters, viz., maximum and minimum temperatures, relative humidity and rainfall, as per Karl Pearson’s coefficient of correlation formula (Steel and Torry 1980).

Where,  

rxy = Simple correlation coefficient  

x = Variable, i.e. abiotic component.  

(Maximum temperature, minimum temperature, relative humidity and total rainfall)  

 y = Variable, i.e. mean number of insect pests 

 n = Number of observations. 

The data recorded on larval population of gram pod borer, H. armigera in chickpea crop during Rabi, 2022-23 and 2023-24 have been presented in Table 1 & 2 and Fig. 1 & 2. The study of Seasonal incidence of Helicoverpa armigera and their correlation with abiotic factors is help to know the most susceptible stage of pests which, suitable control measures should be adopted to manage the pests. Further the study is also helpful to minimize the population of regular pests through changing the cropping pattern.

In the present investigation the incidence of larval population of gram pod borer, H. armigera in chickpea crop was commenced from the first and second week of December i.e. 50th and 49th SMW, which gradually increased and reached to peak (6.52 & 7.32 larvae/MRL) in the third week of February (8th SMW) and second week of February (7th SMW) in Rabi, 2022-23 & 2023-24 respectively.

The present study are conformity with that of Choudhary et al. (2024) conducted the population dynamics of H. armigera on chickpea. The incidence commenced from first and second week of December i.e. 49th and 50th SMW. Which, increased gradually and reached peak (6.4 and 5.2 larvae/ m row) in the third and second week of February (8th and 9th SMW).

Lal et al. (2013) noticed two peaks of the larval population of gram pod borer, (H. armigera) on chickpea. First peak during 49th meteorological week (SMW) with a maximum of 1.73 and 2.13 larvae per meter row length and second peak with 8.93 and 7.93 larvae per meter row during 8th and 9th SMW in 2003-04 and 2004-05, respectively which decreased sharply with maturity of the crop. 

Likewise, Awasthi et al. (2003); Chatar et al. (2010); Shinde et al. (2013); Patel et al. (2015); Patidar et al. (2020); Bajya et al. (2022); Yadav et al. (2024); Kumawat et al. (2024) reported the incidence of H. armigera throughout the crop growth stages. The population appeared from second fortnight of November being minimum in second fortnight of December to first fortnight of January and peak during second fortnight of February to first fortnight of April depending on the climatic conditions.

The correlation studies revealed that the larval population had positive significant correlation with maximum and minimum temperatures (r = 0.528 and 0.572; p<.05) while, non-significant negative correlation with morning and evening relative humidity (r = -0.278: p<.05, r = -0.314; p<.05) and non-significant positive correlation with rainfall during Rabi, 2022-23. Likewise, the population of H. armigera had significant positive correlation with maximum and minimum temperatures (r = 0.539 and 0.562; p<.05) and significant negative correlation with morning (r = -0.578; p<.05) relative humidity while, non-significant negative correlation with evening relative humidity and non-significant positive correlation with rainfall during Rabi, 2023-24.

The multiple linear regression analysis explained 41.0 and 59.0 percent variation in H. armigera population due to combined contribution of abiotic factors during Rabi, 2022-23 and 2023-24, respectively. The step wise regression analysis explained 29.0 per cent significant variation in H. armigera population due to maximum temperature during Rabi, 2022-23 and 28.0 per cent significant variation in H. armigera population due to evening relative humidity during Rabi, 2023-24. 

The present findings are conformity with that of Pandey et al. (2012) the larval population showed a significant positive correlation with minimum and maximum temperature (r = 0.621 and r = 0.643). In contrast, morning relative humidity exhibited a strong negative correlation (r = -0.760).

Shinde et al. (2013) reported positive correlation with both minimum and maximum temperatures and negative correlation with morning fully support the finding. Singh and Ali (2006); Yadav and Jat (2009); Malik et al. (2015) reported positive correlation of larval population with both maximum and minimum temperatures. Bajya et al. (2010); Meena and Bhatia (2014) reported positive correlation of larval population H. armigera with relative humidity. 

Fig. 1. Seasonal incidence of H. armigera  on chickpea in relation to abiotic factors during Rabi, 2022-23.

Table 1 : Seasonal incidence of H. armigera  on chickpea in relation to abiotic factors during Rabi, 2022-23.

#SMW – Standard Meteorological Weeks;    **MRL- meter row length

Table 2 : Seasonal incidence of H. armigera  on chickpea in relation to abiotic factors during Rabi 2023-24.

#SMW – Standard Meteorological Meeks;   **MRL- meter row length

Fig. 2. Seasonal incidence of H. armigera  on chickpea in relation to abiotic factors during Rabi 2023-24.

Table 3: Correlation coefficient between larval population of H. armigera   on chickpea in relation to abiotic factors during Rabi, 2022-23 and 2023-24.

* Significant at 5 per cent of significance 

Table 4:  Multiple regression models developed for larval population of H.armigera on chickpea during Rabi, 2022-23 and 2023-24.

          a = constant

Table 5: Step wise regression models developed for larval population of H. armigera on chickpea during Rabi, 22-2023 and 23-2024.

The findings of the current investigation on the seasonal occurrence of Helicoverpa armigera can significantly contribute to the development of targeted pest control strategies. By pinpointing the most vulnerable stages of these pests, it becomes possible to minimize the reliance on chemical pesticides. This approach helps create a safer environment that supports the growth of natural predators. Reducing pesticide use not only aids in the conservation of biological control agents but also enhances the effectiveness of natural pest management, particularly in controlling the larval populations of H. armigera.