Natural Products against Sand Fly Vectors of Leishmaniosis: A Systematic Review

Abstract

Leishmaniosis is a vector-borne disease transmitted to animals and humans by the bite of blood-sucking phlebotomine sand flies. These small insects play a crucial role in the diffusion of the disease. To date, the sole strategy recognized for the prevention of leishmaniosis is the use of topical repellent compounds against sand fly bites. Several synthetic insecticides and repellents have been developed; however, the wide and unprejudiced use of these formulations have led to the loss of their effectiveness and the development of resistance phenomena. Moreover, some of these synthetic repellents have severe detrimental effects on the environment and could represent a serious threat to both animal and human health. Recently, an increased interest in the research on alternative approaches to sand fly control has been expressed. In this study, we systematically reviewed the efforts of the scientific community to individuate a phytochemical alternative for the control of sand fly species recognized as vectors of Leishmania spp. Based on literature research using different electronic databases, a total of 527 potentially relevant studies were screened and narrowed down to a final 14 eligible scientific reports. Our analysis suggests that although there is a rapidly growing body of literature dedicated to botanical insecticides and repellents against sand fly vectors of Leishmania spp., much of this literature is limited to in vitro studies conducted in laboratory conditions, and only a few of them investigated the repellency of plant-based products. These studies highlighted that natural compounds display a really short period of action and this significantly limits the use of these products as an alternative to chemical-based repellents.

Repellent and insecticidal activities of vegetal material against sand fly populations (Diptera: Psychodidae): Systematic review and Metaanalysis.

“…Furthermore, 58 plants were studied in total, with 303 studies on insecticidal impact and only 115 studies on sand y repelling activity of medicinal plants. With the revelation that there had been little investigation into the repellant effects of plant-based products (23). Although there is a signi cant difference (p = 0.000) in the high mortality and repellency of botanical products across the research papers, effect analysis of natural products on sand ies revealed signi cant heterogeneity (I Squared ≥ 75%), necessitating the task of determining the source of this difference using subgroup analysis.…”

“…Therefore, the possibility of sand y sensitivity to laboratory conditions was supported by our nding. Furthermore, there was no signi cant difference between population and botanical effects, although the majority of studies were based on grown sand ies in adult stage, which explains minimal studies owing to the di culty of maintaining sand y colonies up to adult stage (23). The breeding places of young sand ies are mostly unknown and inaccessible.…”

In Vitro Evaluation of Essential Oils and Saturated Fatty Acids for Repellency against the Old-World Sand Fly, Phlebotomus papatasi (Scopoli) (Diptera: Psychodidae)

“…Additionally, the number of flies in each quadrant of the chamber was also recorded at 15, 30, 60, 90, 120, and 180 min, with flies on the filter papers at the ends of the chamber included in the number of flies for the appropriate end quadrant. DEET (97% pure, technical grade, Sigma-Aldrich, St. Louis, MO, USA) was used as a reference standard for comparison of relative repellent or avoidant activity [ 29 ]). Repellency (spatial repellency), avoidance (contact repellency), and insecticidal activities were calculated for each time point, as described by Paluch et al [ 16 , 64 ].…”

“…Essential oils are generally regarded as safe relative to synthetic compounds with insecticidal or repellent activities [ 21 , 22 , 23 , 24 , 25 ]. Although the insecticidal and repellent effects of essential oils or fatty acids against mosquitoes and ticks were documented repeatedly [ 26 , 27 ], reports of similar investigations concerning P. papatasi and other old-world sand fly species are limited [ 14 , 28 , 29 ]. Yaghoobi-Ershadi et al [ 30 ] reported that the essential oil of myrtle, Myrtus communis , and DEET were effective repellents to P. papatasi ; however, DEET exhibited higher repellent efficacy.…”

“…Laboratory studies on the repellency of natural products against sand flies need to include DEET because this synthetic compound is considered the gold standard, enabling comparison of repellent activity among different studies [ 7 , 29 , 38 ]. DEET appears to act by targeting octopaminergic synapses, producing neuroexcitation and toxicity to insects [ 39 ].…”