Abstract

Simple Summary Epigenetic molecular mechanisms (EMMs) are capable of regulating and stabilizing a wide range of living cell processes without altering its DNA sequence. EMMs can be triggered by environmental inputs. In insects, EMMs contribute to explaining both negative effects as well as adaptive responses towards environmental cues. Among these stimuli are chemical stressors, such as pesticides. We review the link between EMMs and pesticides in insects. We suggest that pesticide chemical behavior promotes both lethal and sublethal exposure of both target and non-target insects. As a consequence, for several native and beneficial insect (e.g., pollinators), EMMs are involved in diseases and disruptive responses due to pesticides, while in the case of pest species, EMMs are linked in the development of pesticide resistance and hormesis. We discuss the consequences of these in the context of insect global decline and biotic homogenization. Currently, the human species has been recognized as the primary species responsible for Earth's biodiversity decline. Contamination by different chemical compounds, such as pesticides, is among the main causes of population decreases and species extinction. Insects are key for ecosystem maintenance; unfortunately, their populations are being drastically affected by human-derived disturbances. Pesticides, applied in agricultural and urban environments, are capable of polluting soil and water sources, reaching non-target organisms (native and introduced). Pesticides alter insect's development, physiology, and inheritance. Recently, a link between pesticide effects on insects and their epigenetic molecular mechanisms (EMMs) has been demonstrated. EMMs are capable of regulating gene expression without modifying genetic sequences, resulting in the expression of different stress responses as well as compensatory mechanisms. In this work, we review the main anthropogenic contaminants capable of affecting insect biology and of triggering EMMs. EMMs are involved in the development of several diseases in native insects affected by pesticides (e.g., anomalous teratogenic reactions). Additionally, EMMs also may allow for the survival of some species (mainly pests) under contamination-derived habitats; this may lead to biodiversity decline and further biotic homogenization. We illustrate these patterns by reviewing the effect of neonicotinoid insecticides, insect EMMs, and their ecological consequences.