Behavioural responses ofPhlebotomus duboscqito plant-derived volatile organic compounds

Abstract

Phlebotomine sand flies are vectors ofLeishmaniaparasites that causeleishmaniases. Both sexes of sand flies feed on plants primarily for sugars, althoughthe chemical cues that mediate attraction to host plants remain largely unknown.Previously, using coupled gas chromatography-mass spectrometry, the authors identifiedseveral volatile organic compounds (VOCs) common to preferred host plants forselected Afrotropical sand flies from the Fabaceae family. Of the identified volatiles,the significance of the monoterpenes linalool oxide, ocimene andp-cymene and thebenzenoidm-cresol,p-cresol in sand fly behaviour is unknown. In olfactometer assays,the authors tested these compounds singly and in blends for their attractiveness toPhlebotomus duboscqi, cutaneous leishmaniasis vector in Kenya. In dose–responseassays, single compounds increased the responses of males and females over controls,but their optimum attractive doses varied between the sexes. Two five-component blends,referred to as Blend-f and Blend-m for females and males respectively, were formulatedand tested in dose–response assays against 1-octen-3-ol (positive control). The resultsof the present study showed that males and females were significantly attracted tovarying levels of the two blends. In pairwise assays, the authors evaluated the mostattractive of these blends to each sex (i.e., Blend Am for male against Blend Bf forfemale), revealing that males were attracted to both blends at varying levels, whereasfemales were indifferent. The study’s results demonstrate that plant-derived VOCs canbe exploited for sand fly management.