Conservation and Augmentation of Natural Enemies against Cotton Diseases and Pests

Throughout the cotton growth cycle, critical emphasis must be placed on utilizing natural enemies to maximize their predatory and parasitic biocontrol efficacy. For instance, in crop rotation systems involving cotton and wheat, leaving wheat straw in the field for two days post-harvest can effectively stimulate the migration of natural enemies, such as ladybugs (Coccinellidae), into adjacent cotton fields, thereby achieving efficient control over pests like aphids. Concurrently, rigorous efforts must be dedicated to the conservation of these natural enemies. Minimizing the application of highly toxic or acutely hazardous chemical pesticides is essential to foster suitable habitats, augment natural enemy populations, and sustainably suppress cotton diseases and insect pests.

Artificial Release of Trichogramma Wasps

Trichogramma wasps play a pivotal role in the management of cotton pests, demonstrating exceptional efficacy particularly against the cotton bollworm (Helicoverpa armigera). Farmers should artificially release Trichogramma chilonis during the initial peak period of adult cotton bollworm emergence to suppress field populations. For optimal control outcomes, the recommended release rate is 10,000 wasps per 667 m² per release, with 2 to 3 releases conducted per pest generation at 5-day intervals.

Microbial- and Plant-Derived Biopesticides

The application of biopesticides to manage cotton diseases and pests offers significant advantages, including high safety profiles, zero chemical toxicity, and zero environmental pollution; thus, their integration warrants substantial priority. For example, Empedobacter brevis (formerly Brevibacterium frigidotolerans) and Helicoverpa armigera nucleopolyhedrovirus (HaNPV) exhibit pronounced control efficacy against the cotton bollworm. Beauveria bassiana provides excellent suppression of the tobacco cutworm (Spodoptera litura) without posing a threat to natural enemies. Bacillus subtilis and ethylicin are highly effective in preventing and treating cotton Fusarium wilt and Verticillium wilt. Veratrine can be deployed against both cotton bollworms and cotton aphids, while polyoxin delivers satisfactory control performance against cotton boll diseases.

Insect Pheromone Mass Trapping

Insect pheromones can be highly leveraged for the mass trapping and eradication of various cotton pests. For the cotton bollworm, sex pheromone attractants should be deployed using one rubber septum (lure) and one dry moth trap per 667 m². For the tobacco cutworm, one sex pheromone lure combined with a dedicated noctuid trap per mu (667 m²) can successfully capture adult moths and drastically reduce subsequent egg densities in the field. Alternatively, biological food attractants (biomimetic baits) can be implemented via the strip-spraying method. By uniformly trickling the bait onto the top leaves of a single row of cotton plants every 60 meters, multiple adult pest species, including cotton bollworms and cutworms (Agrotis spp.), can be efficiently lured and eradicated.