The hydrocarbon phenanthrene is an organic compound commonly found in the environment. In aquatic ecosystems, it is highly toxic to organisms, although little is known about its effects on sediment-dwelling organisms. The purpose of this study was to evaluate phenanthrene effects on biochemical, histological, and ontogenetic levels in larvae of the sediment-dwelling invertebrate Chironomus sancticaroli at acute and chronic exposure. Lethal concentrations were estimated and toxicity (acute-96 h and chronic- 8 d) tests were performed at phenanthrene concentrations from 0.12 to 1.2 mg L⁻¹. At acute and chronic exposure, we evaluated acetylcholinesterase (AChE), alpha esterase (EST-α), and beta esterase (EST-β) activities as well as histological alterations. In the assays with chronic exposure, effects on larval development were estimated using antennae length (instar estimative) and body length (growth estimative). The EST-α showed a significantly increased activity after 48 h at acute exposure to high concentrations of phenanthrene, while EST-β activity was increased after 48 and 72 h at acute exposure at higher concentrations and at 0.12 mg L⁻¹ at chronic exposure. At acute exposure, the midgut showed alterations such as brush border disruption, gastric caeca regression, and lumen area reduction; the fat body showed nuclear alteration in the trophocytes, while the Malpighian tubules showed brush border reduction and the salivary glands were subject to cytoplasm vacuolation. At chronic exposure, the same alterations were observed, in addition to vacuolar coalescence in the trophocytes of the fat body. Regarding larval development, a reduction of body length was observed with increasing phenanthrene concentrations. Similarly, molting was delayed; in the control group, all larvae were in the fourth instar, while at higher phenanthrene concentrations, larvae were predominantly in the third instar. Phenanthrene had toxic effects on this chironomid, indicating risks for natural populations.

The area of agriculturally used land and following to that the use of pesticides are steadily increasing. Insecticides do not only reduce pest organisms on crops but can also affect non-target organisms when present in sublethal concentrations in the environment. We investigated the effects of an exposure to sublethal pyrethroid (lambda-cyhalothrin) concentrations, at doses 20 and 60 times lower than the LC50, respectively, on reproductive traits and adult cuticular hydrocarbon (CHC) profiles of a leaf beetle (Phaedon cochleariae Fabricius). Furthermore, we tested for effects on growth and antennae symmetry of the offspring generation that was not exposed to the insecticide. Sublethal insecticide concentrations decreased the egg number produced by the adults and the hatching rate. Moreover, the chemical phenotype (CHC profile) of adults was altered in dependence of the insecticide treatment, with sex-specific effects. In the unexposed offspring of insecticide-exposed parents, a prolonged development time and a fluctuating asymmetry of the females' antennae were detected, revealing transgenerational effects. The insecticide effects on the CHC profiles of the parental generation might have been caused by changes in CHC precursors, which were potentially induced by the insecticide treatment of the insect diet. Such altered CHC pattern may have implications for intraspecific communication, e.g., in mate choice, as well as in an interspecific way, e.g., in interactions with other arthropod species. The observed detrimental transgenerational effects might be explainable by a reduced investment in the offspring, maternal transfer or epigenetic processes. An asymmetry of the antennae may lead to defects in the reception of chemical signals. In conclusion, the results disclose that, besides detrimental (transgenerational) effects on reproduction and development, an exposure to sublethal insecticide concentrations can impair the chemical communication between individuals, with impacts on the sender (i.e., the CHC profile) and the receiver (i.e., caused by asymmetry of the antennae).