High-altitude grasslands face severe threats from Gynaephora qinghaiensis, a lepidopteran pest causing significant damage to key forage species like Kobresia humilis and Elymus nutans. Traditional control methods involving broad-spectrum chemicals pose environmental risks and operational challenges in these remote terrains. This study evaluated nine eco-friendly biopesticides applied via agricultural UAV technology for sustainable pest management.
Field trials were conducted in high-altitude pastures (3,500 m elevation) using DJI T60 agricultural drones with standardized parameters: flight altitude = 3 m, speed = 5 m/s, swath width = 7.5 m. The experimental design assessed nine insecticides at three dosage levels in 1-ha randomized plots:
| Insecticide Formulation | Dosage Levels (mL/hm²) | Mode of Action |
|---|---|---|
| Lambda-cyhalothrin 10% EC | 300, 375, 450 | Sodium channel modulator |
| Nicotine·matrine 1.2% EC | 225, 300, 375 | Acetylcholine receptor disruption |
| Abamectin 5% EC | 150, 225, 300 | GABA agonist |
| Osthole 1% SL | 225, 300, 375 | AChE inhibitor |
| Metarhizium anisopliae WP | 600, 900, 1200 g/hm² | Entomopathogenic fungus |
Efficacy was calculated using standard entomological formulas where population density (PD) was measured in larvae/m²:
Population reduction:
$$PR = \frac{PD_{pre} – PD_{post}}{PD_{pre}} \times 100$$
Corrected efficacy:
$$CE = \frac{PR_{treatment} – PR_{control}}{1 – PR_{control}} \times 100$$
Agricultural UAV applications demonstrated exceptional precision in high-altitude conditions. Three days post-application, lambda-cyhalothrin and nicotine·matrine showed rapid knockdown effects:
| Treatment | Dosage | Corrected Efficacy (%) |
|---|---|---|
| Lambda-cyhalothrin 10% EC | 450 mL/hm² | 96.1 ± 0.01 |
| Nicotine·matrine 1.2% EC | 375 mL/hm² | 92.7 ± 0.02 |
Time-efficacy relationships revealed critical performance differences. Fungal agents showed delayed but sustained activity, with Metarhizium anisopliae achieving 82.4% efficacy by day 7. The agricultural drone platform enabled uniform coverage despite complex topography, with efficacy variations between formulations following the kinetic model:
Efficacy progression:
$$E_t = E_{max} (1 – e^{-kt})$$
Where \(E_t\) = efficacy at time t, \(E_{max}\) = maximum efficacy, k = efficacy rate constant.
Dosage-response analysis demonstrated that agricultural UAV applications could maintain efficacy at reduced chemical loads. Abamectin showed no significant efficacy difference between 150 mL/hm² (92.2%) and 300 mL/hm² (94.8%) at day 7, indicating potential for input optimization. Similarly, nicotine·matrine at 300 mL/hm² achieved 90.8% efficacy comparable to higher dosages.
The operational advantages of agricultural UAV technology were particularly evident in high-altitude conditions. The aerial platform delivered precise droplet distribution (VMD 150-250 μm) at application rates of 15-20 L/ha, with treatment efficiency exceeding 5 ha/hour. This represented a 10-fold increase over manual methods while eliminating operator exposure risks.
Economic analysis revealed that agricultural drone applications reduced control costs by 30-40% compared to ground-based systems, primarily through labor savings and optimized chemical use. The integration of biological agents like entomopathogenic fungi offers particular promise for sustainable management programs, though their slower action necessitates strategic timing.
Based on multi-parameter optimization, we recommend: 1) Emergency response: Lambda-cyhalothrin or nicotine·matrine (300 mL/hm²) applied via agricultural UAV 2) Routine management: Rotation of abamectin (150 mL/hm²), osthole (300 mL/hm²), and fungal agents (900 g/hm²). This integrated approach leverages the precision of agricultural UAV technology to minimize environmental impact while maintaining control efficacy above 90% against this challenging high-altitude pest.