Application of pesticides can affect earthworms in three ways: They can affect their gene-expression and physiology (intra individual level), ii change life history traits, population density and behaviour (individual and population level or iii) modify biomass and density of earthworm populations (community level). Pesticides may disrupt enzymatic processes, increase individual mortality, decrease fecundity and growth, or they may change individual behaviour such as feeding rate and decrease overall community biomass and density.