Toxicity of Rocket Fuel Derivatives to the Tenebrio molitor–Gregarina spp. Host–Parasite System at Different Temperatures

Hydrazine (N2H4) is a component of rocket fuel, and its dinitroaromatic relatives are feedstocks for explosives and pesticides. Both classes contaminate soils around aerospace facilities and in areas of armed conflict. The toxicity of hydrazine hydrate, 2,4-dinitrophenylhydrazine (DNPH) and 2,4-dinitroaniline to terrestrial invertebrates remains unexplored. This study examined the effects of these substances on the mortality, body mass, pupation, and intensity of Gregarina spp. infestation in larvae of Tenebrio molitor Linnaeus, 1758 (Coleoptera, Tenebrionidae). Mortality rose with dose for all three compounds and at 90 mg/kg reached 26.7%. Pupation responded to the fact of exposure itself: none was recorded in the control (0.0%), whereas 59.6% of the exposed larvae pupated, already at the lowest concentration of 10 mg/kg, where no deaths occurred. The proportion pupating was similar across the three compounds (55.0–62.2%) but declined with increasing concentration, from 67.2% at 10 mg/kg to 52.2% at 90 mg/kg. Within the 21–28 °C range, no main effect of temperature on mortality, pupation, or body mass was found. All three compounds reduced the intensity of Gregarina spp. infestation with increasing concentration. Under acute 5-day exposure, therefore, the studied compounds cause little larval mortality but alter pupation, body mass and the intensity of parasitic infestation.