Activity of Syzygium aromaticum essential oil and its main constituent eugenol in the inhibition of the development of Ctenocephalides felis felis and the control of adults

Highlights

• The major constituent of Syzygium aromaticum essential oil is eugenol.

• Syzygium aromaticum essential oil and eugenol are effective for control of C. felis.

• Positive results point to the development of natural insecticides for flea control.

Abstract

The aim of this study was to evaluate the in vitro activity of Syzygium aromaticum essential oil (SAEO) and its main constituent eugenol (EG) against adult fleas and their action in the maturation of eggs into adults of Ctenocephalides felis felis. In order to evaluate the pulicidal activity, 10 adult fleas were exposed to a filter paper impregnated with SAEO and EG at increasing concentrations of 0.047; 0.094; 0.188; 0.375; 0.750; 1.50; 3.00; 6.00; 12.00 and 24.00 μg cm⁻². Flea mortality was evaluated 24 and 48 h after exposure. In order to evaluate the inhibition of the maturation of eggs into adults, 10 eggs were exposed to filter paper impregnated with SAEO and EG at the same concentrations used in the pulicidal test, and the evaluation was performed 30 days after incubation. Untreated repetitions were maintained in both studies (control group). The lethal concentration 50 (LC₅₀) of pulicidal activity to SAEO was 5.70 μg cm⁻² in 24 h and 3.91 μg cm⁻² in 48 h. The LC₉₀ was 16.10 μg cm⁻² and 15.80 μg cm⁻² in 24 and 48 h, respectively. The LC₅₀ of inhibition of the maturation of eggs into adults was 0.30 μg cm⁻² and the LC₉₀ 3.44 μg cm⁻². The LC₅₀ of pulicidal activity to EG was 2.40 μg cm⁻² in 24 h and 1.40 μg cm⁻² in 48 h; the LC₉₀ was 8.10 μg cm⁻² and 3.70 μg cm⁻² in 24 h and 48 h, respectively. The LC₅₀ of inhibition of the maturation of eggs into adults was 0.10 μg cm⁻² and the LC₉₀ 0.68 μg cm⁻². Based on the results obtained, it is possible to conclude that the both SAEO and EG have in vitro pulicidal activity as well as acting as inhibitors of the maturation of eggs into adults of the flea C. felis felis.

Introduction

Fleas of Ctenocephalides genus (Siphonaptera: Pulicidae) are the most prevalent parasitic insects infesting dogs and cats in the world (Rust, 2017). They are considered vectors of several pathogens for pets and for humans. Among them it can be highlighted: Rickettsia typhi (Adams et al., 1990; Brown and Macaluso, 2016), Bartonella henselae (Chomel et al., 1996; Higgins et al., 1996), Mycoplasma spp. (Shaw et al., 2004; Woods et al., 2005), Yersinia pestis (Eisen et al., 2008; Wilder and Vetter, 2008) and Coxiella burnetii (Psaroulaki et al., 2017). They also act as intermediate helminths hosts to Dipylidium caninum (Pugh, 1987; Beugnet et al., 2014) and Acanthocheilonema reconditum (Dipetalonema reconditum) (Nelson, 1962; Napoli et al., 2014). The two main species that are included in this genus are C. canis and C. felis (MéNier and Beaucournu, 1998; Linardi and Guimarães, 2000).

Historically, plant substances have been used in arthropod control due to their possible pesticide effect (Chagas, 2004; Karunamoorthi et al., 2009). Alternative medicine therapies including natural or plant-derived herbal products for animal healthcare have recently gained importance (Genovese et al., 2012). Some medicinal plants (Artemisia vulgaris, Citrus limon, Juniperus communis, Lavundula officinalis, Melissa officinalis and Thuja plicata) had their uses reported as natural insecticides against fleas in cats and dogs (Lans et al., 2008). Essential oils (EO), products of plant’s secondary metabolism, are a complex mixture of chemical compounds, volatile, fat soluble and rarely colorful (Bakkali et al., 2008; Baser and Buchbauer, 2015). EO have shown to be very promising due to their insecticidal potential (Benelli and Pavella, 2018) including the control of veterinary ectoparasites (Ellse and Wall, 2014).

Syzygium aromaticum (sin. Eugenia caryophyllus) species, belonging to the Myrtaceae Family, is popularly known as clove-of-India. It is a native plant to the Maluku islands in eastern Indonesia. Eugenol is the main component, composing 95% of the oil extracted from this plant (Pramod et al., 2010; Cortés-Rojas et al., 2014; Affonso et al., 2012).

SAEO and EG had already been evaluated for their inseticidal activity against mosquitoes Aedes aegypti, Culex quinquefasciatus and Anopheles dirus (Phasomkusolsil and Soonwera, 2011). Besides that, they also have shown activity against Musca domestica (Sinthusiri et al., 2013; Soonwera and Sinthusiri, 2014) and Pediculus humanus (Bagavan et al., 2011). Their insecticidal properties have also been demonstrated for the control of insects that can cause damage to the agriculture such as: Tribolium castaneum and Sitophilus zeamais (Ho et al., 1994; Huang et al., 2002); Anastrepha (Vargas et al., 2010) and Oriza sativa (Xu et al., 2015).

To the best of our knowledge, there are no scientific reports about the use of SAEO and EG against fleas in the literature, however the pulicidal activity of other EO containing Eugenol as a majority has already been described (Dos Santos et al., 2020). Therefore, the purpose of this study was to evaluate the in vitro activity of SAEO and EG against adult fleas and their inhibition of the maturation of eggs into adults of C. felis felis.