Exploring climate-resilient sorghum varieties and their defense mechanisms against destructive pests in semi-arid regions
Shoot fly, stem borer, and grain mold
Cultural, biological & chemical controls
3-year varietal screening study
In the semi-arid fields of Vidarbha, where rainfall is unpredictable and temperatures frequently soar, farmers have long relied on a remarkable crop—grain sorghum. Known as jowar in local communities, this hardy cereal has earned its reputation as the "camel of crops" for its exceptional ability to thrive where other grains would fail.
With deep roots that tap into hidden soil moisture and leaves that curl to conserve water, sorghum represents food security for millions. Yet, despite these formidable defenses, this resilient crop faces relentless attacks from invisible enemies—insect pests and diseases that can decimate yields and threaten livelihoods.
Sorghum is the fifth most important cereal crop worldwide after rice, wheat, maize, and barley, and serves as a dietary staple for more than 200 million people, particularly in arid regions of Asia and Africa 3 .
In India alone, sorghum occupies 13.6% of the global sorghum cultivation area, though productivity remains concerningly low at approximately 1,250 kg/ha compared to the global average 8 . Nearly one-third of India's sorghum crop is lost to insect pests during the rainy season, with an additional 26% damage occurring post-rainy 8 .
The sorghum shoot fly (Atherigona soccata) represents one of the most destructive early-season pests, particularly devastating during the crop's vulnerable seedling stage.
Female flies lay eggs on the undersides of young leaves, and upon hatching, the maggots migrate to the plant's upper regions where they bore into the main stem. This attack severs the growing point from the base, resulting in the characteristic "dead heart" symptom—a central shoot that withers and dies while surrounding leaves remain temporarily green.
Early shoot fly damage doesn't just kill individual plants; it reduces overall stand density, compromises crop uniformity, and creates entry points for secondary infections.
The spotted stem borer (Chilo partellus) presents a more insidious threat throughout sorghum's growth cycle. Under the warm, humid conditions typical of Vidarbha, stem borer populations flourish.
Female moths lay eggs on sorghum stems, and the emerging larvae burrow into the plant, feeding on internal tissues while creating extensive tunnels 2 . Unlike external feeders, stem borers inflict damage from within, remaining protected from contact insecticides and natural predators.
Initial symptoms include "shot holes" on young leaves as early-stage larvae feed, progressing to stem tunneling, impaired nutrient transport, and eventual yield loss. In severe infestations, the peduncle (the stem supporting the grain head) may be damaged, leading to complete yield loss through the production of chaffy panicles or stem breakage 2 .
While insects represent visible foes, fungal diseases like grain mold pose an equally significant threat, particularly during Vidarbha's humid harvesting periods.
Grain mold encompasses several fungal pathogens that discolor and degrade developing grains, reducing both yield and market value. The problem intensifies when rainy weather coincides with flowering or harvest, creating ideal conditions for fungal proliferation.
Beyond yield reduction, grain molds produce mycotoxins that render grain unsafe for consumption and affect seed viability. Certain sorghum varieties with compact panicles and poor husk coverage prove particularly susceptible as they retain moisture longer, creating microenvironments where fungi thrive.
Modern sorghum pest management employs an integrated approach that combines cultural, biological, and chemical strategies tailored to Vidarbha's specific conditions.
Using resistant varieties, optimal planting dates, and field sanitation to prevent pest establishment
Harnessing natural enemies and biopesticides for sustainable pest suppression
Targeted insecticide application when pest thresholds exceed economic injury levels
Natural enemies provide sustainable pest suppression without chemical residues. The egg parasitoid Trichogramma chilonis and larval parasitoids Bracon chinensis and Apanteles flavipes effectively reduce stem borer populations 2 .
Additionally, neem-based biopesticides containing azadirachtin (0.4-0.7ml/liter) and fungal formulations of Beauveria bassiana (2-3ml/liter) provide effective control while preserving beneficial insects 2 .
When pest thresholds exceed economic injury levels, targeted insecticide application becomes necessary.
| Product Name | Technical Content | Dosage | Target Pests |
|---|---|---|---|
| Coragen Insecticide | Chlorantraniliprole 18.5% SC | 0.4 ml/liter | Stem borer, leaf roller |
| Alika Insecticide | Thiamethoxam 12.6% + Lambda-cyhalothrin 9.5% ZC | 0.5 ml/liter | Multiple pests |
| Tafgor Insecticide | Dimethoate 30% EC | 1.5 ml/liter | Shoot fly, stem borer |
| Reeva 5 Insecticide | Lambda Cyhalothrin 5% EC | 2 ml/liter | Stem borer, leaf feeder |
To objectively identify sorghum varieties with enhanced pest resistance, researchers conducted a comprehensive three-year study (2018-2020) evaluating 24 sorghum varieties across multiple locations with similar agro-climatic conditions to Vidarbha 8 .
The experiment employed a Randomized Complete Block Design with three replications to ensure statistical reliability. Each variety was assessed under natural pest infestation conditions without protective insecticide applications, allowing researchers to observe inherent resistance mechanisms.
Initial screening of 24 sorghum varieties under natural infestation conditions
Replicated trials with focus on shoot fly and stem borer resistance
Comprehensive evaluation including grain mold assessment and yield analysis
The study evaluated 24 sorghum varieties across 3 years with 3 replications each, providing robust data on varietal performance under pest pressure.
The multi-year study revealed significant differences in varietal responses to major pests, enabling researchers to identify lines with superior combined resistance.
| Variety | Grain Yield (kg/ha) | Shoot Fly Tolerance (1-9 scale) | Grain Mold Tolerance (1-9 scale) | Stem Borer Damage (1-9 scale) | Protein Content (%) |
|---|---|---|---|---|---|
| SPV 2579 | 4069 | 6 | 8 | 7 | 10.2 |
| SPV 2678 | 3985 | 5 | 7 | 6 | 9.8 |
| PYPS 2 | 3850 | 8 | 8 | 6 | 12.5 |
| PYPS 8 | 3620 | 9 | 9 | 7 | 13.1 |
| CSV 15 (Check) | 2658 | 3 | 4 | 3 | 9.5 |
The adoption of pest-resistant varieties translates to direct economic benefits for Vidarbha's farmers. The research revealed that resistant varieties require 2-3 fewer insecticide applications per season, reducing production costs by approximately 15-20%.
When combined with yield preservation, this approach increases net returns by 25-30% compared to susceptible varieties under high pest pressure. Furthermore, the integrated genetic resistance approach helps delay development of pesticide resistance in pest populations, extending the effectiveness of available chemical tools.
Reduction in production costs
Increase in net returns
Fewer insecticide applications
The future of sorghum pest management in Vidarbha lies in integrating traditional wisdom with cutting-edge science. Genomic tools now allow breeders to identify and incorporate specific resistance genes with greater precision and efficiency.
Marker-assisted selection enables the development of varieties with multiple disease and pest resistance without compromising yield or grain quality. Research initiatives are increasingly focusing on pyramiding resistance genes to create more durable protection against the complex of pests that challenge sorghum production.
The absolute genetic gain for grain yield calculated from this research showed an increase of 44.93 kg/ha/year since 1990, demonstrating steady breeding progress 8 .
Emerging technologies like semiochemical-based trapping systems, which use pest attractants for monitoring and mass trapping, offer environmentally sustainable management options.
Additionally, precision agriculture tools including remote sensing and drone-based imaging allow early detection of pest hotspots, enabling targeted interventions before significant damage occurs 6 .
As climate patterns shift, creating greater uncertainty for Vidarbha's farmers, these climate-resilient sorghum varieties coupled with integrated pest management will become increasingly vital for regional food security.
The development of drought-tolerant varieties with built-in pest resistance represents a crucial strategy for maintaining productivity under changing environmental conditions.
The battle between sorghum varieties and their pests represents a fascinating evolutionary arms race, with farmers and researchers as keen observers and active participants.
The comprehensive research conducted on sorghum varieties reveals a clear path forward: through the intelligent selection of resistant varieties adapted to local conditions, combined with ecological management practices that enhance natural control mechanisms, Vidarbha's farmers can effectively manage major pests while minimizing environmental impact.
The steady genetic gains achieved through systematic breeding efforts demonstrate that sustained investment in agricultural research delivers tangible returns 8 .
As public breeding programs continue to develop and distribute improved genetic material, and as farmers gain access to knowledge about integrated management approaches, sorghum will continue to fulfill its historical role as a reliable crop for Vidarbha's challenging environments. In this ancient grain, we find not just sustenance for the present, but promise for a more food-secure future.