The Effect of Ammonia on the Host–Parasite System Tenebrio molitor at Different Temperatures

Ammonia (NH₃) is an environmental pollutant that enters ecosystems as a result of agricultural activities, industrial accidents, leaks of ammonia-based rocket fuel, and explosions at chemical plants. Temperature changes can alter the toxicity of ammonia to invertebrates. This study investigated the effect of ammonia on the relationship between <i>Tenebrio molitor</i> Linnaeus, 1758 (Coleoptera: Tenebrionidae) and its parasites at temperatures of 21-23 °C and 26-28 °C. We used 150 <i>T. molitor</i> larvae, which were divided into five groups of ammonia concentrations (0-4000 mg NH₃/kg of substrate) at two temperatures (21-23 °C, 26-28 °C). During a 10-day exposure, mortality, body weight changes, and the intensity of parasitic invasion by three species of <i>Gregarina</i> were assessed. The results showed a concentration-dependent effect of ammonia on the physiological state and parasitic systems of <i>T. molitor</i> (body weight changes: <i>p</i> = 2 × 10^-16; intensity of parasitic invasion: R² = 0.13-0.87), while mortality increased from 0% in the control groups to 40-60% at maximum concentration. Contrary to expectations, temperature did not alter the toxicity of ammonia in the studied range of 21-28 °C (all <i>p</i> > 0.18). Parasitological parameters showed higher sensitivity to ammonia stress compared to physiological indicators, forming 4-5 concentration groups versus 2 groups for body weight changes. The observed absence of temperature-dependent changes in ammonia toxicity in the range of 21-28 °C contrasts with the known effects in aquatic invertebrates and may reflect the physiological characteristics of terrestrial insects. The higher sensitivity of parasitological parameters confirms their suitability as indicators of sublethal toxicity for monitoring ammonia pollution in industrial insect breeding systems.