Antiparasitic activity of the essential oil of Lippia alba on ectoparasites of Colossoma macropomum (tambaqui) and its physiological and histopathological effects

Abstract

This study investigated the in vivo and in vitro antiparasitic effects of the essential oil of Lippia alba and the bloodrelated and histopathological alterations that it causes in Colossoma macropomum. In the in vitro trial, the anthelminthic effects of 160, 320, 640, 1280 and 2560 mg/L of the essential oil were tested against monogenoideans (Anacanthorus spathulatus, Notozothecium janauachensis and Mymarothecium boegeri) of the gills of this fish, which are its natural parasites. The concentrations of 1280 mg/L and 2560 mg/L showed 100% efficacy after 20 min of exposure to the essential oil, while at lower concentrations this efficacy against the gill monogenoideans only occurred after 2-3 h of in vitro exposure. However, in the controls, mortality of all of these monogenoideans only occurred after 9 h. A total of 240 fry were distributed into four treatments (20 fish per repetition) and three repetitions were used in the in vivo trial for baths with 100 and 150 mg/L of the essential oil of L. alba, for 30 min. The efficacy in this trial against Ichthyophthirius multifiliis in fish exposed to 100 and 150 mg/L of the essential oil was 40.7% and 50.3%, respectively. However, for monogenoideans, there was efficacy of 14.0% only in the fish exposed to 100 mg/L of the essential oil used. Moreover, the fish exposed to these concentrations of the essential oil presented increased plasma glucose levels, thus denoting signs of stress. Severe lesions such as hyperplasia, fusion of the lamellar epithelium, capillary dilatation, epithelial detachment, lamellar aneurysm, epithelial rupture with hemorrhage, congestion, edema, necrosis, mucous cell proliferation, chloride cells and lamellar hypertrophy were observed in the gills of the fish exposed to 100 and 150 mg/L of the essential oil of L. alba. Alterations to total protein levels, hemoglobin, hematocrit, red blood cell number, thrombocytes number, white blood cell number, lymphocytes, eosinophils and blood neutrophil number was also observed in these fish. The essential oil of L. alba showed great potential for antiparasitic treatment, given that it had high in vitro efficacy against monogenoideans and in vivo efficacy against the protozoon I. multifiliis. Because of the low concentrations of the essential oil (100 and 150 mg/L) that were tolerated by the fish and thus could be used in the therapeutic baths, the efficacy against monogenoideans was low. This indicates that there is a need for additional strategies for using this essential oil in antiparasitic treatments, since the concentrations that eliminate these ectoparasites are toxic for the hosts. Lastly, this was the first study on the antiparasitic activity of L. alba. Statement of Relevance The manuscript entitled "Antiparasitic activity of the essential oil of Lippia alba on ectoparasites of Colossoma macropomum (tambaqui) and its physiological and histopathological effects", represents original article on use of the essential oil of Lippia alba on ectoparasites of tambaqui, an important finfish of Amazon regio...

Physiological responses of Rhamdia quelen (Siluriformes: Heptapteridae) to anesthesia with essential oils from two different chemotypes of Lippia alba

“…Lippia alba occurs in all regions of Brazil (Zétola et al, 2002;Oliveira et al, 2006;Neto et al, 2009;Cunha et al, 2010;Teles et al, 2012;Vale et al, 2012;Soares et al, 2016). Due to its genetic variation, wide geographical distribution and exposure to different soil and weather conditions, and distinct seasons of collection, L. alba can produce EOs with different chemical composition, which expresses the occurrence of distinct chemotypes (Pascual et al, 2001;Hennebelle et al, 2008;Maffei et al, 2011;Teles et al, 2012).…”

Current knowledge on use of essential oils as alternative treatment against fish parasites

“…However, their use can cause problems such as selection of resistant organisms, aggression to the environment and to humans because of the accumulation of chemical residues. Thus, consumption of farmed fish that have been treated may present risks to health (Ling et al, 2015;Hashimoto et al, 2016;Soares et al, 2016;Soares et al, 2017a, b). Therefore, use of chemical pesticides to control fish diseases is often restricted in many countries (Ling et al, 2015).…”

“…Herbal therapy is a potentially beneficial alternative for fish farming, since it may be cheaper and more effective than chemotherapy (Soares and Tavares-Dias, 2013;Soares et al, 2016;Soares et al, 2017a, b). Globally, advances in disease management may result in increased economic sustainability, improved livelihoods for producers and greater contribution of fish farming to the local, regional and national economies (Engle et al, 2017), as well as providing natural treatment that is more efficient.…”

β-Cyclodextrins as Encapsulating Agents of Essential Oils

“…Essential oils or their components not only have antibacterial properties [22,23,25,32,33] but also have antiparasitic [34,35], antiviral [36,37], antifungal [38][39][40], and antioxidant properties [32,41,42].…”