Abstract Dragonflies and damselflies provide crucial insights into environmental health as bioindicators of aquatic and terrestrial ecosystems, making it essential to study eutrophication effects on their populations. These insects exhibit diverse reproductive and territorial behaviours, which may be the first response to environmental disturbances. We hypothesized that eutrophication disrupts physiology and alters energy investment, affecting nutritional status and time allocation to territorial and reproductive behaviours. We estimated flight capacity and body condition-related traits in two sympatric dragonfly species at 12 sites along an eutrophication gradient, and recorded their territorial and reproductive behaviours. We determined the effects of eutrophication, body condition, and flight capacity-related traits on reproductive and territorial behaviours and analysed them according to sex and species. We found that increased eutrophication reduced on males the time allocated to territoriality and interspecific interactions, but increased the time spent in copulation and guarding females during oviposition. However, time spent for females in reproduction (e.g. copulation and oviposition) was positively related to eutrophication in Erythrodiplax abjecta but negatively related in Sympetrum gilvum. These differential responses indicate species-specific adaptive responses; however, the general reduction in behavioural duration suggests that physiological constraints imposed by altered environments may limit energy allocation for key activities in odonates.
Palacino-Rodríguez et al. (Wed,) studied this question.