Field assessment of 4-hydroxycoumarin as an attractant for anthropophilic Anopheles spp. vectors of malaria in Madagascar

Abstract

Mosquito-borne diseases like malaria are a major public health problem in tropical countries, such as Madagascar. Female Anopheles mosquito vectors the human malaria parasites (Plasmodium spp.) and is important indicator in malaria surveillance activities. Among the various means of vector control in Madagascar, the use of attractants for mass trapping of target species could be an alternative to insecticides. The aim of this study is to evaluate whether 4-hydroxycoumarin can be used as an attractant for anthropophilic Anopheles spp. vectors of malaria. For this, a field study was conducted using CDC light traps in the village of Ambohidray, Madagascar. 16 days of trapping was conducted and four replicates nights were performed for each product tested. 4-hydroxycoumarin, octenol and two types of blend of these products were tested. The results showed that 4-hydroxycoumarin (2 mg) have a significant attractive effect on Anopheles spp. and significant selectivity towards Anopheles gambiae s.l, and Anopheles mascarensis which are both significant malaria vectors in Madagascar. A synergy of 4-hydroxycoumarin with octenol was found to attract these mosquito vectors. A significant decrease in vector populations was observed during this experiment. These results suggest that 4-hydroxycoumarin could be useful for malaria surveillance and the control of vector populations. Mosquito-borne diseases present a major public health threat in tropical and subtropical areas and disproportionately impact developing nations, such as Madagascar 1. Among numerous mosquito vectors existent in Madagascar several Anopheles species are responsible for the transmission of malaria parasites 2-4. Due to their distribution, malaria is endemic to 90% of the country 5 and is the fourth leading cause of death in Madagascar 6. In order to limit the transmission of malaria, several methods of control have been implemented such as the use of long lasting insecticide-treated mosquito nets (LLINs) 7 , and indoor residual spraying (IRS) 8 to protect populations in regions with a high potential for epidemics 9. These control methods have shown significant efficacy, but they are also insufficient in the long term due to the rapid amplification of insecticide resistance in vector populations 10,11. In addition, controlling mosquito populations through the use of larvicides and adulticides has found to have negative impacts on ecosystems 12-14. For these reasons, the explorations of other more sustainable and environmentally friendly alternatives are encouraged worldwide 15,16. The use of attractants for selective and mass trapping has been suggested as a promising complementary to insecticide for malaria vector surveillance, control and reduction 17-19. A recent study has shown that 4-hydroxycoumarin, a compound derived from coumarin, a natural substance of plant origin, has a significant attractiveness activity on the mosquito Aedes albopictus, a mosquito vector of Dengue and Chikungunya, in

Effect of the Stereoselectivity of para-Menthane-3,8-diol Isomers on Repulsion toward Aedes albopictus

“…The use of repellents is promising to fight against this scourge . Indeed, we have shown, in previous works, that several coumarin derivatives have excellent repellent properties. − Since the World War II, synthetic repellents such as N , N -diethyl- meta -toluamide (DEET), picaridin, and ethyl 3-[acetyl­(butyl)­amino]­propanoate (IR3535) were shown to be highly effective, − despite their negative effects. DEET causes skin irritation and is neurotoxic, − and picaridin is highly toxic to several reptiles .…”

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

“…Comparison of the repellent effect of R-(−)-7-sec-butoxychromone (14) with those of known repellents at equivalent quantities 5, 10, and 30 mg shows that this new repellent is more effective than picaridin and DEET, which are considered to be the most effective products on the market (Table 17). The mean activity of mosquitoes during testing of the three compounds, racemic 7-secpentoxychromone (11), R-(−)-7-sec-pentoxychromone (16), and S-(+)-7-sec-pentoxychromone (17), was >85%. Average numbers of mosquitoes recorded in the control zone were significantly lower than those of the treated zone (p-values < 0.05) except for the 30 mg of the two enantiomers R( 16) and S-(+)-7-sec-pentoxychromone (17) (p-values > 0.05) where the mean of mosquitoes in the control was statistically similar to that of treated (Table 18).…”

“…Four enantiomers were synthesized by the Mitsunobu reaction: R-(−)-7-sec-butoxychromone ( 14), S-(+)-7-sec-butoxychromone (15), R-(−)-7-sec-pentoxychromone (16), and S-(+)-7-sec-pentoxychromone (17). The results are presented in Table 15.…”

“…Table 18. T-test comparison of the average numbers of mosquitoes in the two zones: control and treated with racemic 7-sec-pentoxychromone (11), R-(−)-7-sec-pentoxychromone (16), and S-(+)-7-sec-pentoxychromone (17). Racemic 7-sec-pentoxychromone (11) and its enantiomers have attractive effects on Aedes albopictus.…”

“…We believe that finding new attractants, with high selectivity for dangerous species, could be an important tool for creating selective traps to limit populations of dangerous species without destroying useful ones. We have already shown that hydroxycoumarins are selective attractants for Aedes albopictus and Anopheles vectors of malaria [15,16]. We are currently working on a new family of semiochemicals: substituted chromones which have potential attractive and repellent properties.…”