How does ammonia affect spider mites? - briefly
Ammonia acts as a contact toxin for spider mites, disrupting their respiratory system and causing rapid mortality. Concentrations above 1 % (v/v) are typically lethal, while lower levels may impair reproduction and feeding.
How does ammonia affect spider mites? - in detail
Ammonia acts as a contact toxin to spider mite populations. When a solution containing dissolved ammonia contacts the arthropod’s cuticle, the high pH disrupts the protective wax layer, causing rapid desiccation. The chemical also interferes with respiratory enzymes, leading to metabolic failure within minutes for adult mites and faster mortality for eggs and larvae.
The efficacy of ammonia depends on concentration, exposure time, and environmental conditions. Field trials have shown that solutions ranging from 5 % to 15 % ammonia (by volume) applied as a fine spray achieve 70–95 % mortality after a 30‑minute wet period. Lower concentrations (2‑4 %) may suppress reproduction without causing immediate death, reducing egg laying rates by up to 50 % over a week. Temperatures above 20 °C accelerate the toxic effect, while high humidity prolongs the wet film, enhancing contact time.
Key physiological impacts include:
- Disruption of the cuticular lipid barrier, leading to water loss.
- Inhibition of cytochrome c oxidase, impairing cellular respiration.
- Damage to chemosensory receptors, reducing host‑finding ability.
- Interference with molting hormones, causing developmental arrest.
Ammonia does not persist in soil or plant tissue; it volatilizes within hours, limiting residual activity. This rapid dissipation reduces the risk of phytotoxicity when applied correctly, but excessive concentrations (above 20 %) can scorch foliage, especially on young or sensitive cultivars. Protective measures such as early‑morning applications and immediate irrigation of non‑target plants mitigate this risk.
Integration into an integrated pest management (IPM) program involves:
- Monitoring mite density with leaf‑sampling thresholds.
- Applying ammonia only when populations exceed economic injury levels.
- Rotating with other control agents (e.g., predatory mites, neem oil) to prevent tolerance development.
- Using calibrated sprayers to maintain uniform coverage and avoid runoff.
Safety considerations require personal protective equipment (gloves, goggles, respirator) due to ammonia’s irritant properties. Workers should avoid inhalation and skin contact, and treated areas must be ventilated before re‑entry.
In summary, ammonia provides a rapid, short‑acting control option for spider mite infestations, effective across all life stages when applied at appropriate concentrations and combined with complementary IPM tactics.