Evaluation of eco-friendly management strategies against Helicoverpa armigera in tomato under the agro-ecological conditions of Jamtara district (Jharkhand)
Abstract
Tomato (Solanum lycopersicum L.) is one of the most economically important vegetable crops of Jharkhand, but its productivity is heavily constrained by the fruit borer Helicoverpa armigera. The present investigation was conducted during 2023–24 and 2024–25 at farmers fields of the Jamtara district to evaluate the efficacy of bio-insecticides and their combinations against H. armigera under field conditions. Eight treatments comprising NSKE, Ha. NPV, Bacillus thuringiensis (Bt), their combinations, alternated sprays, and water control were evaluated in a Randomized Block Design with three replications. Four sprays were applied at 15-day intervals beginning 15 days after transplanting (DAT). Observations on larval population were recorded at 24 h before spray and 3, 7, 10, 15 days after spraying. Results revealed that Bt (T6) consistently recorded the lowest larval population across spray schedules, followed by alternate spraying of Ha. NPV and Bt (T7). NSKE in combination with Ha. NPV + Bt (T3) also exhibited superior suppression compared to NSKE alone. Control plots (T8) recorded the highest larval infestation. The study concludes that Bt alone or its alternate application with Ha. NPV provides effective eco-friendly management of H. armigera in tomato under Jamtara conditions.
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Introduction
Tomato (Solanum lycopersicum L.) is a highly valued solanaceous vegetable in India and plays a significant role in the livelihood of small and marginal farmers in Jharkhand. However, its productivity is severely affected by insect pests, of which the tomato fruit borer, Helicoverpa armigera (Hubner), is the most destructive. The larvae feed voraciously on flowers and fruits, leading to yield losses up to 55% (Singh et al, 2017) [1] . Sometimes losses in yield may reach 60-70% also (Ghosal et al., 2016) [2] Indiscriminate use of synthetic insecticides has resulted in resistance development, resurgence, residue hazards, and negative impacts on beneficial insects (Kranthi et al., 2002 & Rahman et al.,2014) [3] . Therefore, biological control agents such as Neem Seed Kernel Extract (NSKE), Helicoverpa armigera Nucleopolyhedrosis Virus (Ha.NPV), and Bacillus thuringiensis (Bt) have emerged as environmentally safe and sustainable alternatives. However, the efficacy of these agents varies with local climatic conditions, application schedule, and pest load. Hence, location-specific validation is essential. The present study was conducted to evaluate the effectiveness of bio-pesticides and their combinations under the agro-climatic conditions of Jamtara district.
Materials and Methods
Field experiments were conducted at farmers' fields in Jamtara district, Jharkhand, during 2023-24 and 2024-25 to evaluate the efficacy of various biopesticides and their combinations against Helicoverpa armigera on tomato. The tomato variety Swarn Baibhav was transplanted on 4 September 2023 and 1 September 2024. The experiment was laid out in a Randomized Block Design (RBD) consisting of eight treatments replicated three times, with a total of four insecticidal sprays applied at 15-day intervals, beginning 15 days after transplanting. Observations on larval population were recorded at 24 hours before spray and at 3, 7, 10, and 15 days after each spray. The treatments included: T₁-NSKE (5%) × four sprays + Ha.NPV × last two sprays; T₂-NSKE× four sprays + Bt × last two sprays; T₃-NSKE × four sprays + Ha.NPV (3rd spray) + Bt (4th spray); T₄-NSKE× four sprays; T₅-Ha.NPV × four sprays; T₆-Bt× four sprays; T₇alternate sprays of Ha.NPV and Bt; and T₈control (water spray). Data recorded over both years were pooled and subjected to √((x α +α) 0.5) transformation whenever required, and the analysis of variance (ANOVA) was performed at the 5% level of significance, with critical difference (CD) values used to compare treatment
Results and Discussion
The pooled results from both years revealed that after the first spray, Bt alone (T6) recorded the lowest larval population of H. armigera (0.33 larvae per plant), followed by alternate sprays of Ha.NPV and Bt (T7) and Ha.NPV alone (T5), while NSKEbased combinations produced a moderate reduction and the control showed 0.63 larvae per plant, indicating that Bt was the most effective treatment at the initial stage (Table .1). [4] , who reported the high efficacy of Bacillus thuringiensis against Helicoverpa armigera and highlighted enhanced larval mortality when Bt was combined with neem-based biopesticides; Rabindra and Jayaraj (1988) [5] , who emphasized the effectiveness of Ha.NPV as a biological control agent; Rahman et al. (2014) [6] , who demonstrated that alternating applications of Ha.NPV and Bt effectively reduced fruit infestation and increased tomato yield, and Reddy and Chowdary (2021) [7] , who highlighted that integrating botanical and microbial biopesticides in IPM helps improve pest suppression while minimizing the risk of resistance development. Neem (NSKE) showed moderate suppression but performed better when used in combination with Bt or Ha.NPV, and the alternate spraying of Ha.NPV and Bt (T7) proved particularly beneficial for maintaining long-term suppression and preventing resurgence of the pest population.
Conclusion
The results from two consecutive years clearly indicate that:
• Bt (T6) at 2 g/litre applied at 15-day intervals was the most effective and consistent treatment for suppressing H. armigera larval populations. • Alternate sprays of Ha.NPV and Bt (T7) also provided significantly effective and ecofriendly control. • NSKE-based combinations offered moderate protection but were inferior to Bt. • Control plots showed heavy infestation, proving the necessity of interventions.
Therefore, Bt alone or in alternation with Ha.NPV is recommended as an eco-friendly and effective strategy for tomato fruit borer management under the agro-climatic conditions of Jamtara, Jharkhand.
References
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