Azoxystrobin, a strobilurin widely used to control rice diseases, has raised concerns about possible adverse effects on aquatic ecosystems. At present, very little is known about the effects of azoxystrobin on courtship and aggressive behavior and the potential underlying mechanisms. In the present study, after exposing adult male and female zebrafish to worst-case scenario concentrations of azoxystrobin (0, 2 μg/L, 20 μg/L, and 200 μg/L) for 42 d, we observed a decrease in courtship behavior and an increase in aggressive behavior in both male and female zebrafish. In addition, to elucidate the molecular mechanism of the behavioral effects of azoxystrobin, we quantified the changes in the concentrations of kisspeptin, 5-HT, GnIH, and their corresponding receptor mRNA expression in the brain. The results showed that 200 μg/L azoxystrobin decreased the concentrations of kisspeptin and increased the concentration of GnIH in both male and female zebrafish brain. In addition, azoxystrobin also significantly reduced 5-HT concentration in female zebrafish brain. Further investigation revealed that altered courtship and aggressive behavior were associated with the expression levels of genes (kiss1, kiss2, gnrh3, gnrhr3, 5ht1a, and 5ht2a) involved in kisspeptin-GnIH signaling pathway. In conclusion, our study suggested that azoxystrobin may impair courtship and aggressive behavior in zebrafish by interfering with the kisspeptin-GnIH signaling pathway, which may have more profound effects on natural zebrafish populations.
Simple SummaryThe butterflyByasa hedistusexhibits strong volatiles but shows no significant differences in color and shape. We analyzed the volatile organic compounds (VOCs) and tested the visual and olfactory behavioral responses ofB. hedistusduring foraging and courtship. The effects of colors and VOCs on the foraging and courtship ofB. hedistusare discussed. This study enhances our understanding of how male and female butterflies of similar coloration use different signals for foraging and courtship.AbstractColor and odor are crucial cues for butterflies during foraging and courtship. While most sexual dimorphic butterflies rely more on vision, our understanding of how butterflies with similar coloration use different signals remains limited. This study investigated the visual and olfactory behavioral responses of the similarly colored butterflyByasa hedistusduring foraging and courtship. While visiting artificial flowers of different colors, we found thatB. hedistusexhibits an innate color preference, with a sequence of preferences for red, purple, and blue. The frequency of flower visits byB. hedistussignificantly increased when honey water was sprayed on the artificial flowers, but it hardly visited apetalous branches with honey water. This proves that locating nectar sources by odor alone is difficult in the absence of floral color guides. During courtship, males are active while females hardly chase; only two models were observed: males chasing males and males chasing females. The courtship process includes four behaviors: slowing approach, straight chasing, hovering, and spinning.B. hedistuscannot distinguish between sexes based on color, as there is no significant difference in color and shape between them. Twenty-three VOCs (>1%) were identified inB. hedistus, with 21 shared by both sexes, while ketones are specific to males. These VOCs are principally represented by cineole, β-pinene, and linalool. When cineole was added to butterfly mimics, many butterflies were attracted to them, but the butterflies did not seem to distinguish between males and females. This suggests that cineole may be the feature VOC for identifying conspecific groups. Adding β-pinene and linalool to mimics induced numerous butterflies to chase, hover, spin around, and attempt to mate with them. This suggests that β-pinene and linalool are crucial cues indicating the presence of females.
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