Sustainable management of black thrips (Thrips parvispinus Karny) in chilli through integrated pest management

Introduction

Chilli (Capsicum annuum L.) is one of the most important spice and vegetable crops cultivated globally, owing to its high economic value, diverse uses, and export potential. India is the largest producer, consumer, and exporter of chillies in the world, contributing significantly to global production (FAO, 2022). According to national horticultural statistics, chilli is cultivated over a substantial area in India with consistently increasing production. Among Indian states, Andhra Pradesh and Telangana are major chilliproducing states, together accounting for a significant share of national production. Andhra Pradesh ranks first in chilli production with high productivity levels, while Telangana is an important contributor with expanding area under irrigated conditions (DES-AP, 2023; DES-Telangana, 2023). However, productivity remains highly variable across regions due to biotic and abiotic constraints (NHB, 2023; Horticulture Statistics at a Glance, 2024). Chilli productivity in these states is frequently reduced by severe pest pressure, particularly from sucking insect pests. In recent years, black thrips (Thrips parvispinus Karny), an invasive species of Southeast Asian origin, has emerged as a serious and economically destructive pest of chilli in southern India. The pest was first reported in India during 2015-16, initially on papaya and subsequently expanded its host range to several horticultural crops, including chilli (Tyagi et al., 2015; Kumar et al., 2019) [9,20] . Since its introduction, T. parvispinus has rapidly established and frequent outbreaks and resurgence have been reported under intensive cultivation systems (Reddy et al., 2020; Seal et al., 2020) [15,16] . In Andhra Pradesh its establishment in chilli ecosystems was first documented in January 2021 in Guntur district, followed by widespread outbreaks across chilligrowing areas of Andhra Pradesh and Telangana during the 2021-22 season due to largely depend on repeated and unselective application of insecticides. Moreover, an indiscriminate use of synthetic pyrethroids and organophosphates, which has led to reduced field efficacy, pest resurgence, resistance development, and adverse environmental effects (Reddy et al., 2018; Gupta and Dikshit, 2021) [6,14] . Such practices increase production costs while compromising ecological sustainability. Integrated Pest Management (IPM) is globally recognized as a sustainable and eco-friendly, approach that integrates cultural, mechanical, biological, and judicious chemical methods to maintain pest populations below economic threshold levels (Kogan, 1998; FAO, 2019) [8] . IPM components such as sticky traps, neem-based botanicals, entomopathogenic fungi, balanced nutrient management, and rotation of selective insecticides have been reported to effectively manage thrips in chilli while improving yield and profitability (Sundar et al., 2020; Lakshmi et al., 2022) [10, 18] . In this context, an investigation was undertaken to evaluate and demonstrate an IPM module for the www.extensionjournal.com management of black thrips in chilli through On-Farm Trials (OFT) during 2023-24 and Front-Line Demonstrations (FLD) during 2024-25 under irrigated medium black soil conditions of Telangana. The study aimed to assess the impact of IPM practices over farmers' conventional practices in terms of pest incidence, yield, and economic returns, thereby supporting sustainable chilli production in major chilli-growing regions.

Materials and Methods

Experimental Site

The present study was conducted during the Rabi seasons of 2023-24 and 2024-25 in different locations of the different farmer fields under irrigated medium black soil (Vertisols) conditions of Bhadradri Kothagudem district, Telangana, India. The area receives an average annual rainfall of 1100 to 1200 mm and the climate is semi-arid, suitable for chilli cultivation.

Experimental Design

The experiments evaluated four treatments for the management of black thrips (Thrips parvispinus Karny) under different farmers' fields of Kothagudem district. A Randomized Block Design (RBD) with three replications were planned. Each plot measured 10 m × 10 m, with recommended crop spacing and agronomic practices maintained uniformly across all plots.

Table1: Treatment details and pest management components evaluated against Thrips parvispinus in chilli

Statistical Analysis

All graphical representations were generated using the ggploT2 package in R software to visualize treatment effects on thrips population, yield, and economic returns. Data were subjected to ANOVA, and mean comparisons were performed using Duncan's Multiple Range Test (DMRT) at p < 0.05. [16] . The botanical and trap-based treatment (T2) significantly reduced thrips population compared to T1. Installation of yellow and blue sticky traps combined with azadirachtin sprays effectively suppressed early-stage infestations. Botanical insecticides are known to deter feeding and oviposition while conserving natural enemies, thereby contributing to reduced pest pressure (Kumar et al., 2019) [9] . Treatment T3 (biocontrol with minimal chemical intervention) recorded further reduction in thrips incidence.

Results and Discussion

Regular application of Beauveria bassiana and

Lecanicillium lecanii, supplemented with selective insecticides applied on need basis, effectively controlled thrips populations. Entomopathogenic fungi infect thrips through cuticular penetration and are particularly effective under humid conditions prevalent during the chilli-growing season (Lalitha Priya et al., 2022) [11] . The lowest thrips population was consistently recorded under the full IPM module (T4). The combined use of sticky traps, botanicals, biocontrol agents, selective insecticides, and balanced nutrient and cultural practices resulted in synergistic pest suppression. Similar findings have been reported where integration of multiple IPM components minimized pest outbreaks and delayed resistance development.

Effect on Fruit Yield: Significant differences in fruit yield were observed among treatments. The lowest yields were recorded under T1, likely due to sustained pest damage, flower drop, and fruit deformation caused by high thrips infestation. Repeated chemical sprays without monitoring failed to provide long-term protection. Treatment T2 showed moderate yield improvement over farmers' practice, indicating the role of botanicals and traps in reducing pest pressure during early crop stages. However, botanical-only approaches may not be sufficient under high pest pressure conditions. T3 recorded substantially higher yields due to effective suppression of thrips by biocontrol agents and judicious chemical use. These results confirm earlier reports that selective insecticides combined with biological agents improve crop productivity while reducing pesticide load www.extensionjournal.com (Thakur et al., 2021) [19] . The highest fruit yield was obtained under T4 (full IPM), demonstrating the importance of integrating pest, nutrient, and cultural management practices. Balanced fertilization and micronutrient sprays improved plant vigor, enabling plants to tolerate minor pest injury and recover faster. Similar yield advantages under IPM modules have been reported in chilli and other vegetable crops (Devare et al., 2024) [3] .

Table 2: IPM (T4) produced higher fruit yields than T1 Year T1 (q/ha) T2 (q/ha) T3 (q/ha) T4 (q/ha) 2023 Although the cost of cultivation was slightly higher under T3 and T4 due to additional inputs, net returns were significantly higher, owing to increased yield and better fruit quality. Farmers' practice recorded comparatively lower net returns despite frequent pesticide sprays, highlighting inefficiency and higher input wastage. The full IPM module (T4) recorded the highest net returns and favourable benefitcost ratio, confirming its economic viability. These findings align with previous studies emphasizing that IPM not only improves yield but also enhances profitability by optimizing input use (Kogan, 1998; Reddy et al., 2020) [8,15] . [17] .

Conclusion

The study demonstrates that IPM strategies are superior to conventional chemical-based practices for managing Thrips parvispinus in chilli. Among treatments, the full IPM module (T4) was most effective at suppressing thrips, increasing yield and economic returns. Reliance on indiscriminate chemical use fails to provide sustainable control and promotes pest resurgence. In contrast, integrating botanicals, biocontrol agents, selective insecticides and agronomic practices offers a sustainable, economically viable, and eco-friendly approach. Adoption of IPM modules is strongly recommended for chilli cultivation in Andhra Pradesh, Telangana and similar agroecological regions. Large-scale promotion through extension programs and field demonstrations will be essential for long-term pest management and sustainable production.

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