Pterodon emarginatus oleoresin-based nanoemulsion as a promising tool for Culex quinquefasciatus (Diptera: Culicidae) control

Abstract

BackgroundPreparation of nanoformulations using natural products as bioactive substances is considered very promising for innovative larvicidal agents. On this context, oil in water nanoemulsions develop a main role, since they satisfactorily disperse poor-water soluble substances, such as herbal oils, in aqueous media. Pterodon emarginatus, popularly known as sucupira, has a promising bioactive oleoresin. However, to our knowledge, no previous studies were carried out to evaluate its potential against Culex quinquefasciatus, the main vector of the tropical neglected disease called lymphatic filariasis or elephantiasis. Thus, we aimed to investigate influence of different pairs of surfactants in nanoemulsion formation and investigate if a sucupira oleoresin-based nanoemulsion has promising larvicidal activity against this C. quinquefasciatus. We also evaluated morphological alteration, possible mechanism of insecticidal action and ecotoxicity of the nanoemulsion against a non-target organism.ResultsAmong the different pairs of surfactants that were tested, nanoemulsions obtained with polysorbate 80/sorbitan monooleate and polysorbate 80/sorbitan trioleate presented smallest mean droplet size just afterwards preparation, respectively 151.0 ± 2.252 and 160.7 ± 1.493 nm. They presented high negative zeta potential values, low polydispersity index (<0.300) and did not present great alteration in mean droplet size and polydispersity index after 1 day of preparation. Overall, nanoemulsion prepared with polysorbate 80/sorbitan monooleate was considered more stable and was chosen for biological assays. It presented low LC50 value against larvae (34.75; 7.31–51.86 mg/L) after 48 h of treatment and some morphological alteration was observed. The nanoemulsion did not inhibit acetylcholinesterase of C. quinquefasciatus larvae. It was not toxic to green algae Chlorella vulgaris at low concentration (25 mg/L).ConclusionsOur results suggest that optimal nanoemulsions may be prepared with different surfactants using a low cost and low energy simple method. Moreover, this prototype proved to be effective against C. quinquefasciatus, being considered an ecofriendly novel nanoproduct that can be useful in integrated control programs of vector control.

Larvicidal effect of hydroethanolic extract from the leaves of Acmella oleracea L. R. K. Jansen in Aedes aegypti and Culex quinquefasciatus

“…Morphological studies in the larvae of Cx. quinquefasciatus also demonstrated alterations caused by a nanoemulsion of Pterodon emarginatus in the abdomen, thorax, and anal papillae (Oliveira et al, 2017); however, this effect was not observed in our results, suggesting that the mortality of Cx. quinquefasciatus is not related to external damage of the integument.…”

Preparation of a Nanoemulsion with Carapa guianensis Aublet (Meliaceae) Oil by a Low-Energy/Solvent-Free Method and Evaluation of Its Preliminary Residual Larvicidal Activity

“…It is well established that the film formed by nonionic surfactants around the droplets develops a main role in the stabilization of the disperse system [ 25 ]. This is highlighted by the fact that using different single surfactants or surfactant pair at a fixed HLB value and differences in the mean droplet size and stability may occur [ 26 ]. Considering that we used a different hydrophilic surfactant in the required HLB value determination, this fact should also be considered.…”

Developing a Highly Stable Carlina acaulis Essential Oil Nanoemulsion for Managing Lobesia botrana

“…As defined by Nikam et al [ 39 ], NEs are kinetically stable “biphasic dispersions of two immiscible liquids: either water-in-oil (W/O) or oil-in-water (O/W) droplets stabilized by an amphiphilic surfactant”; in this way, protection from the surrounding environment, suitable spreading, and penetration of the bioactive molecules are guaranteed by the matrix and low surface and interfacial tension [ 40 ]. Toxicity of EO-based NEs was tested on several insects of agricultural and medical interest such as aphids [ 41 , 42 , 43 ], mosquitoes [ 44 , 45 , 46 ], stored-product beetles [ 47 , 48 ], and some Lepidoptera [ 49 , 50 , 51 ]. Furthermore, it was also highlighted that the bioactivity of EO-based NEs was often higher compared to the EOs themselves [ 52 , 53 , 54 ].…”