Epicuticular chemistry reinforces the new taxonomic classification of the Bactrocera dorsalis species complex (Diptera: Tephritidae, Dacinae)

Abstract

Bactrocera invadens Drew, Tsuruta & White, Bactrocera papayae Drew & Hancock, and Bactrocera philippinensis Drew & Hancock, key pest species within the Bactrocera dorsalis species complex, have been recently synonymized under the name Bactrocera dorsalis (Hendel). The closely related Bactrocera carambolae Drew & Hancock remains as a discrete taxonomic entity. Although the synonymizations have been accepted by most researchers, debate about the species limits remains. Because of the economic importance of this group of taxa, any new information available to support or deny the synonymizations is valuable. We investigated the chemical epicuticle composition of males and females of B. dorsalis, B. invadens, B. papayae, B. philippinensis, and B. carambolae by means of one- and two-dimensional gas chromatography–mass spectrometry, followed by multiple factor analyses and principal component analysis. Clear segregation of complex cuticule profiles of both B. carambolae sexes from B. dorsalis (Hendel) was observed. In addition to cuticular hydrocarbons, abundant complex mixtures of sex-specific oxygenated lipids (three fatty acids and 22 fatty acid esters) with so far unknown function were identified in epicuticle extracts from females of all species. The data obtained supports both taxonomic synonymization of B. invadens, B. papayae, and B. philippinensis with B. dorsalis, as well as the exclusion of B. carambolae from B. dorsalis.

Allyl‐2,6‐dimethoxyphenol, a female‐biased compound, is robustly attractive to conspecific males of Bactrocera dorsalis at close range

“…Another potential target of insect sexual selection is the blend of CHCs, which often show intra‐ and interspecific variation, sexual dimorphism, and may act as pheromones (Ferveur, ; Thomas & Simmons, ; Jennings et al, ). In recent studies, CHC profiles were analysed mainly for taxonomic research in Tephritidae flies (Vaníčková et al, , , ). To explore the cues regulating the courtship and mating behaviour of female B. dorsalis , we extracted CHCs of both sexes with n‐hexane and compared the differences between male and female flies.…”

The Complete Mitochondrial Genome of Bactrocera carambolae (Diptera: Tephritidae): Genome Description and Phylogenetic Implications

“…invadens'). Their status has been verified by taxonomists and the insect materials have been used in several research projects [11,[17][18][19][20]69].…”

“…invadens') as B. dorsalis. The latter taxonomic revision was supported by multidisciplinary evidence from morphological, morphometric, molecular/genetic, cytogenetic, behavioral/sexual compatibility and chemo-ecological studies [8][9][10][11][12][13][14][15][16][17][18][19][20][21]. However, the synonymization by Schutze et al [8] was criticized [22] and debated [23].…”

“…The species status of B. carambolae in relation to B. dorsalis has also been explored by many researchers using multiple approaches. Data on morphology/morphometrics [1,24], certain genetic markers [12,14,21,[25][26][27][28][29], mating behavior [11] and chemoecology [20,[30][31][32] supported the identity of B. carambolae as a separate biological species and provided some diagnostic features for species discrimination. On the other hand, identification of morphological hybrids [33] and data from nuclear protein coding genes [14] and microsatellite analysis [34] suggest naturally occurring hybridization and gene flow between the two taxa.…”

Cuticular Chemistry of the Queensland Fruit Fly Bactrocera tryoni (Froggatt)

“…Some aspects of tephritid fruit fly semiochemistry have received significant attention, particularly the pheromones [ 34 , 35 ] they use to attract mates and for aggregation and the particular compounds found in fruit, food and certain flowers to which they are attracted [ 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 ]. Some work has also been performed on fruit fly cuticular chemistry because their cuticular chemical profiles tend to be highly species-specific [ 48 , 49 ] and have been used to resolve species, cryptic species and geographic variation in larvae [ 50 , 51 , 52 ] and adults [ 53 , 54 , 55 , 56 , 57 , 58 ]. Beyond their use as chemotaxonomic tools, however, relatively little work has been performed on tephritid cuticular compounds.…”