Small-scale land-use variability affects Anopheles spp. distribution and concomitant Plasmodium infection in humans and mosquito vectors in southeastern Madagascar

Additional file 1. Individual health assessment form

Field evaluation of synthetic lure (3-methyl-1-butanol) when compared to non odor-baited control in capturing Anopheles mosquitoes in varying land-use sites in Madagascar

Abstract Background Malaria is the 4th largest cause of mortality in Madagascar. To better understand malaria transmission dynamics, it is crucial to map the distribution of the malaria vectors, mosquitoes belonging to the genus Anopheles. To do so, it is important to have a strong Anopheles-specific lure to ensure the maximum number of captures. Previous studies have isolated volatiles from the human skin microbiota and found the compound 3-methyl-1-butanol to be the most attractive to the malaria mosquito, Anopheles gambiae, in a laboratory setting; and recommended 3-methyl-1-butanol as a compound to increase An. gambiae captures in the field. To date, this compound’s ability to lure wild mosquitoes in differing land-use settings has not been tested. In this study, we evaluate the role of the synthetic compound, 3-methyl-1-butanol in combination with field produced CO2 in attracting Anopheles mosquitoes in varying land-use sites in Madagascar. Methods CDC miniature light traps in combination with field produced CO2 were deployed in and around six villages near Ranomafana National Park, Madagascar. To test the role of 3-methyl-1-butanol in luring Anopheles mosquitoes, two traps were set in each land-use site (village, agricultural sites, and forested habitats affiliated with each village). One was baited with the synthetic odor and the other was kept as a non-baited control. Results While 3-methyl-1-butanol baited traps did capture An. gambiae s.l. in this study, we did not find traps baited with synthetic 3-methyl-1-butanol to be more successful in capturing Anopheles mosquitoes, (including Anopheles gambiae s.l.) than the non odor-baited control traps in any of the land-use sites examined; however, regardless of odor bait, trapping near livestock pens resulted in the capture of significantly more Anopheles specimens. Conclusions A strong synthetic lure in combination with insecticide has great potential as a mosquito control. Our findings suggest that trapping mosquitoes near livestock in malaria endemic regions, such as Madagascar, may be more successful at capturing Anopheles mosquitoes than the proposed 3-1-methyl-butanol lure

Comparative study on the amphiphilicity, emulsifying and foaming properties of saponins extracted from Furcraea foetida

International audienceA sustainable surfactant was obtained as a by-product of waste from the production of fibers from Furcraea foetida (FF). The extraction process is described and the chemical constituents (flavonoids, saponins and others) in the hemp of Mauritius in Madagascar were determined using ultra-performance liquid chromatography coupled to high resolution hybrid mass spectrometer. The hypothesis of surface-active behavior of this crude mixture was corroborated by surface tension measurements and these results were compared with 2 commercial Quillaja saponaria (QS) samples: S0019 (TCI) and Q-Naturale 200 V. The critical micellar concentration of the FF saponins is 0.025 wt%. The hydrophilicity-lipophilicity radius was determined by the PIT-slope method and all saponins are more hydrophilic than the C10E4, the polyethoxylated reference surfactant. The hydrophilicity decreasing order is as follows: Q-Naturale 200 V > FF> S0019. Oil in water (O/W) emulsions were formulated with isopropyl myristate as oil and their size distribution and stability during 7 days are equivalents for the three saponins. There is no coalescence, and creaming phenomena can be reduced increasing the oil fraction. Nanoemulsions were obtained with FF using ultrasounds and reducing the oil content. Foaming properties were also studied and the stability of foams is similar between the 3 saponins (higher than the foam formulated with sodium laureth sulfate). These findings show that FF is a new source of saponins that can be used as promising emulsifier and foam agent with properties equivalent to those quantified for available commercial saponins and equal or better than typical benchmark surfactants as Tween 40 (emulsifier) or sodium laureth sulfate (foaming agent)

Chirality Effects on Repellent Properties of 4-Alkoxycoumarins Against Asian Tiger Mosquito (Diptera: Culicidae)

International audienceThe use of semiochemicals as repellents and attractants has been proposed to complement insecticides used for the control of vector mosquito populations. In several studies, the optical purities of the molecules tested have been described as having little or no effect on repellent activity. However, these observations seem difficult to explain because of the chirality effect of molecules on the olfactory system of insects and humans. Thus, the purpose of this study is to assess the effects of chirality on the repellent properties of 4-alcoxycoumarins against Aedes albopictus Skuse, mosquito vector of arboviruses. We report here that the racemic (R/S)-4sec-butoxycoumarin had the highest repellent effect (Repellent Index = 49.9%) followed by (R) enantiomer (Repellent Index = 24.2%) for the dose of 5 mg/mL. Contrary, no significant repellent activity was recorded for S-(+)-4-sec-butoxycoumarin. This experiment demonstrates the close relationship between the molecules' optical purities and the behavioral response of mosquitoes

Development of Sustainable Chemistry in Madagascar: Example of the Valuation of CNSL and the Use of Chromones as an Attractant for Mosquitoes

This article describes a part of the results obtained from the cooperation between the University of Lyon1 (France) and the University of Antananarivo (Madagascar). It shows (among others) that useful research can be carried out in developing countries of the tropics if their social, technical, and economic conditions are taken into account. The concepts and methods associated with so-called “green chemistry” are particularly appropriated for this purpose. To illustrate this approach, two examples are shown. The first deals with industrial ecology and concerns waste transformation from the production of cashew nut into an amphiphilic product, oxyacetic derivatives. This product was obtained with a high yield and in a single step reaction. It exhibited an important surfactant property similar to those of the main fossil-based ones but with a much lower ecological impact. The second talks about chemical ecology as an alternative to insecticides and used to control dangerous mosquito populations. New substituted chromones were synthesized and showed biological activities toward Aedes albopictus mosquito species. Strong repellent properties were recorded for some alkoxylated products if others had a significant attractant effect (Kairomone) depending on their stereochemistry and the length of the alkyl chain