Signals from predators, injured conspecifics, and pesticide modify the swimming behavior of the gregarious tadpole of the Dorbigny’s Toad, Rhinella dorbignyi (Anura: Bufonidae)

Abstract

Tadpoles detect chemical signals released from predators and conspecifics, and those present in the environment, and adjust their behavioral responses. This study evaluated the swimming activity of Rhinella dorbignyi (Duméril and Bibron, 1941) tadpoles exposed to chemical signals, including cues from a predator fish Synbranchus marmoratus Bloch, 1975 and an injured conspecific; sublethal concentration of insecticide cypermethrin; and their combination. Swimming behavior (total distance moved, average speed, global activity, number of contacts between tadpoles) was evaluated in an individual (1) and groups of different size (3, 5, 7 and 10 tadpoles) using a video-tracking software tool. Predator exposure modified behavioral parameters, reducing encounters with predators and, therefore, mortality. Total distance moved and average speed increased in trials involving 1 tadpole and 3 interacting tadpoles exposed to injured conspecifics, whereas global activity increased in all group sizes, showing that gregarious tadpoles may be affected by alarm cues and their behavior may be disrupted. The insecticide treatments (alone and combined) increased parameters in all group sizes, causing hyperactivity due to its neurotoxic effect. The different responses observed after exposure to alarm cues and environmental signals in the different group sizes modified the normal behavior and the ecological dynamics of gregarious tadpoles.

The integrated biomarker response in three anuran species larvae at sublethal concentrations of cypermethrin, chlorpyrifos, glyphosate, and glufosinate-ammonium

“…The findings of the present study, agrees with many other studies, which showed that pyrethroid affects the swimming behavior of amphibian larvae such as twisting, writhing, and not coordinated swimming. [39][40][41] Noticeably, similar behavioral changes were described for fish species such as Poecilia reticulata, presenting loss of general activity and equilibrium [42] ; in Oncohrhynchus mykiss [43] presented loss of coordination thus, showing that CYP similarly affects the behavior of phylogenetically distant organisms from communities in aquatic ecosystems.…”

“…Consequently, GLY sublethal effects include accelerated [54] or delayed development, [55] reduced size at metamorphosis, [54,55] developmental malformations, [56] and symptoms of oxidative stress. [57] Remarkably, the most active species R. arenarum [58] , seemed more sensitive to behavioral biomarkers than R. dorbignyi [41] and O. americanus [59] , considering that these species showed behavioral effects by CYP, GLY, and CP (Table 1).…”