RESUMO
Lutzomyia longipalpis is the main vector of visceral Leishmaniasis in the Americas and is composed of a species complex. Males of this sand-fly produce acoustic signals during copulation and different patterns are observed among Brazilian populations. Such acoustic signals are commonly involved in species recognition. However, since the song is only produced during copulation it is not clear how it affects mating success or contributes to sexual isolation. Another aspect that may affect reproductive success is the presence of food. Since hematophagy is such an important aspect of L. longipalpis biology, we wanted to test if blood-feeding can influence the reproductive behaviour of this insect. We performed crossing experiments removing males' wings (silencing them) and playing back either the homo-specific or the hetero-specific song to either unfed or blood-fed females. Our results showed that both songs and blood-feeding affect insemination success, but not the frequency of copulation. In trials where females were not blood-fed song clearly affected insemination; males with wings, and males with homo-specific song playback had a higher insemination success than wingless males (no song) and trials with hetero-specific song. Blood-feeding females prior to the trials increased insemination in all groups including the control group which suggests that mating happens simultaneously with, or immediately after, the blood meal. Blood-fed females also seemed to discriminate less against the wrong song or the lack of song (wingless) one day after feeding, however trials with the correct song still had higher insemination rates. Altogether, our results show that both the male copulatory courtship songs and female blood-feeding are important for reproductive success and as such are important components of the sexual behaviour of L. longipalpis.
Assuntos
Copulação/fisiologia , Corte , Vetores de Doenças , Leishmaniose Visceral/transmissão , Psychodidae/fisiologia , Reprodução/fisiologia , Comportamento Sexual Animal/fisiologia , Animais , Brasil , Feminino , MasculinoRESUMO
Acoustic communication in the form of courtship and mating songs are often involved in reproductive isolation between species of Diptera, such as Drosophila, mosquitoes and sand flies. The patterns of courtship songs in New World sand fly species evolve quickly under sexual selection; and therefore, represent an important trait that can be used as a marker to study the evolution of species complexes and may aid identification of sibling species with a complex. The ability to identify vector species within species complexes is of critical importance for effective and efficient vector control programs. Species-specific song patterns seems to contribute to reproductive isolation in New World sand fly species, suggesting that auditory communication signals may be widespread among these important vectors of leishmaniasis. The main goal of the present study was to characterize the copulatory courtship song of Phlebotomus argentipes, an important vector of visceral leishmaniasis in the Old World. Ph. argentipes males produce acoustic signals during copulation and two types of songs were observed. The one we called primary song is a 'pulse song' with similar length and amplitude to the previously observed 'P1' pattern recorded in Brazilian populations of Lu. longipalpis s.l. The secondary song has 'sine song' characteristics and is quite different from any song produced by New World species. The discovery of this copulation courtship songs in Ph. argentipes supports the possibility that acoustic communication in sandflies might be more widespread than previously thought, including Old World species. Our results highlight the importance of further research on acoustic communication in the Ph. argentipes species complex and other Old World vectors of leishmaniasis.
Assuntos
Corte , Phlebotomus/fisiologia , Isolamento Reprodutivo , Comportamento Sexual Animal/fisiologia , Vocalização Animal/fisiologia , Animais , Drosophila/fisiologia , Feminino , Insetos Vetores/parasitologia , Insetos Vetores/fisiologia , Masculino , Phlebotomus/parasitologiaRESUMO
Lutzomyia longipalpis s.l. is a complex of sibling species and is the principal vector of American visceral leishmaniasis. The present review summarises the diversity of efforts that have been undertaken to elucidate the number of unnamed species in this species complex and the phylogenetic relationships among them. A wide variety of evidence, including chemical, behavioral and molecular traits, suggests very recent speciation events and complex population structure in this group. Although significant advances have been achieved to date, differential vector capacity and the correlation between structure of parasite and vector populations have yet to be elucidated. Furthermore, increased knowledge about recent epidemiological changes, such as urbanisation, is essential for pursuing effective strategies for sandfly control in the New World.
Assuntos
Animais , Psychodidae/classificação , Psychodidae/genética , Especificidade da Espécie , Genes de Insetos , Biodiversidade , Insetos Vetores/classificação , Insetos Vetores/genética , Leishmaniose Visceral/transmissão , Filogenia , Polimorfismo Genético , Polimorfismo de Fragmento de Restrição , BrasilRESUMO
Lutzomyia longipalpis s.l. is a complex of sibling species and is the principal vector of American visceral leishmaniasis. The present review summarises the diversity of efforts that have been undertaken to elucidate the number of unnamed species in this species complex and the phylogenetic relationships among them. A wide variety of evidence, including chemical, behavioral and molecular traits, suggests very recent speciation events and complex population structure in this group. Although significant advances have been achieved to date, differential vector capacity and the correlation between structure of parasite and vector populations have yet to be elucidated. Furthermore, increased knowledge about recent epidemiological changes, such as urbanisation, is essential for pursuing effective strategies for sandfly control in the New World.
Assuntos
Biodiversidade , Insetos Vetores/classificação , Insetos Vetores/genética , Psychodidae/classificação , Psychodidae/genética , Animais , Brasil , Genes de Insetos , Leishmaniose Visceral/transmissão , Filogenia , Polimorfismo de Fragmento de Restrição , Especificidade da EspécieRESUMO
In this paper we review the natural history of pheromone communication and the current diversity of aggregation-sex pheromones in the sand fly Lutzomyia longipalpis. This species complex is the main vector of Leishmania infantum, the agent of visceral leishmaniasis in the Americas. The identification of variation in pheromone chemotypes combined with molecular and sound analyses have all contributed to our understanding of the extent of divergence among cryptic members of this complex. The importance of chemical signals as pre-mating barriers and drivers of speciation is discussed. Moreover, the importance of aggregation-sex pheromones as sexually selected signals is highlighted with evidence from the literature suggesting their potential role in species and mate recognition as well as mate assessment. The distinct evolutionary forces possibly involved are briefly reviewed and discussed in the context of this intriguing insect.
Assuntos
Psychodidae/fisiologia , Atrativos Sexuais/metabolismo , Comportamento Sexual Animal , Animais , Insetos Vetores/fisiologia , Atrativos Sexuais/químicaRESUMO
BACKGROUND: Lutzomyia longipalpis, the main vector of visceral leishmaniasis in Latin America, is a complex of sibling species. In Brazil, a number of very closely related sibling species have been revealed by the analyses of copulation songs, sex pheromones and molecular markers. However, the level of divergence and gene flow between the sibling species remains unclear. Brazilian populations of this vector can be divided in two main groups: one producing Burst-type songs and the Cembrene-1 pheromone and a second more diverse group producing various Pulse song subtypes and different pheromones. METHODOLOGY/PRINCIPAL FINDINGS: We analyzed 21 nuclear loci in two pairs of Brazilian populations: two sympatric populations from the Sobral locality (1S and 2S) in northeastern Brazil and two allopatric populations from the Lapinha and Pancas localities in southeastern Brazil. Pancas and Sobral 2S are populations of the Burst/Cembrene-1 species while Lapinha and Sobral 1S are two putative incipient species producing the same pheromone and similar Pulse song subtypes. The multilocus analysis strongly suggests the occurrence of gene flow during the divergence between the sibling species, with different levels of introgression between loci. Moreover, this differential introgression is asymmetrical, with estimated gene flow being higher in the direction of the Burst/Cembrene-1 species. CONCLUSIONS/SIGNIFICANCE: The results indicate that introgressive hybridization has been a crucial phenomenon in shaping the genome of the L. longipalpis complex. This has possible epidemiological implications and is particularly interesting considering the potential for increased introgression caused by man-made environmental changes and the current trend of leishmaniasis urbanization in Brazil.
Assuntos
Variação Genética , Psychodidae/classificação , Psychodidae/genética , Animais , Brasil , Quimera , Genoma de Inseto , Masculino , Dados de Sequência Molecular , Tipagem de Sequências Multilocus , IrmãosRESUMO
Lutzomyia longipalpis s.l. is the primary vector of Leishmania (L.) infantum in the New World. In this study, male Lutzomyia longipalpis specimens from Posadas, Argentina were characterized for two polymorphic markers: the male sex pheromone and the period (per) gene. The male sex pheromone was identified as (S)-9-methylgermacrene-B, the same compound produced by Lu. longipalpis from Paraguay and many populations from Brazil. The analysis of per gene sequences revealed that the population from Argentina is significantly differentiated from previously studied Brazilian populations. Marker studies could contribute to the understanding of the distribution and spread of urban American visceral leishmaniasis, thus aiding in the design of regional surveillance and control strategies.
Assuntos
Insetos Vetores/química , Psychodidae/química , Sesquiterpenos de Germacrano/genética , Atrativos Sexuais/genética , Animais , Argentina , MasculinoRESUMO
Lutzomyia longipalpis s.l. is the primary vector of Leishmania (L.) infantum in the New World. In this study, male Lutzomyia longipalpis specimens from Posadas, Argentina were characterized for two polymorphic markers: the male sex pheromone and the period (per) gene. The male sex pheromone was identified as (S)-9-methylgermacrene-B, the same compound produced by Lu. longipalpis from Paraguay and many populations from Brazil. The analysis of per gene sequences revealed that the population from Argentina is significantly differentiated from previously studied Brazilian populations. Marker studies could contribute to the understanding of the distribution and spread of urban American visceral leishmaniasis, thus aiding in the design of regional surveillance and control strategies.
Assuntos
Animais , Masculino , Insetos Vetores , Psychodidae , Sesquiterpenos de Germacrano , Atrativos Sexuais , ArgentinaRESUMO
The sand fly Lutzomyia cruzi (Mangabeira, 1938) is implicated as a vector of American visceral leishmaniasis (AVL) in some areas of Brazil. Lutzomyia cruzi is closely related to Lutzomyia longipalpis s.l. (Lutz and Neiva, 1912) the main Latin American vector of AVL and a species complex. Although females of the two species are identical, the males can be distinguished by differences in the genitalia. Nevertheless, pheromone analysis shows that Lu. cruzi males produce 9-methyl-germacrene-B, which has also been found in a number of Latin American populations of Lu. longipalpis s.l. In addition, analysis of microsatellite loci shows that the level of divergence between Lu. cruzi and Lu. longipalpis s.l. is similar to that observed among the Lu. longipalpis s.l. sibling species. Here we present the lovesongs of Lu. cruzi males which are similar to the Burst-type songs produced by one of the Lu. longipalpis s.l. sibling species. We also present data on the molecular polymorphisms of the period gene of Lu. cruzi that indicate this species as another sibling within the Lu. longipalpis complex. The results highlight the importance of an integrative approach to understand the patterns of genetic and phenotypic divergence among very closely related vector species.
Assuntos
Especiação Genética , Proteínas Circadianas Period/genética , Polimorfismo Genético , Psychodidae/genética , Vocalização Animal/fisiologia , Animais , Brasil , Corte , Feminino , Genes de Insetos/genética , Masculino , Filogenia , Polimorfismo Genético/fisiologia , Psychodidae/classificaçãoRESUMO
BACKGROUND: Lutzomyia longipalpis is the primary vector of American visceral leishmaniasis. There is strong evidence that L. longipalpis is a species complex, but until recently the existence of sibling species among Brazilian populations was considered a controversial issue. In addition, there is still no consensus regarding the number of species occurring in this complex. METHODOLOGY/PRINCIPAL FINDINGS: Using period, a gene that controls circadian rhythms and affects interpulse interval periodicity of the male courtship songs in Drosophila melanogaster and close relatives, we analyzed the molecular polymorphism in a number of L. longipalpis samples from different regions in Brazil and compared the results with our previously published data using the same marker. We also studied the male copulation songs and pheromones from some of these populations. The results obtained so far suggest the existence of two main groups of populations in Brazil, one group representing a single species with males producing Burst-type copulation songs and cembrene-1 pheromones; and a second group that is more heterogeneous and probably represents a number of incipient species producing different combinations of Pulse-type songs and pheromones. CONCLUSIONS/SIGNIFICANCE: Our results reveal a high level of complexity in the divergence and gene-flow among Brazilian populations of the L. longipalpis species complex. This raises important questions concerning the epidemiological consequences of this incipient speciation process.
Assuntos
Insetos Vetores/fisiologia , Leishmaniose Visceral/epidemiologia , Psychodidae/fisiologia , Animais , Brasil/epidemiologia , Ritmo Circadiano/genética , Genes de Insetos , Variação Genética , Insetos Vetores/genética , Insetos Vetores/metabolismo , Leishmaniose Visceral/transmissão , Masculino , Psychodidae/genética , Psychodidae/metabolismo , Atrativos Sexuais/análise , Comportamento Sexual AnimalRESUMO
BACKGROUND: The phlebotomine sand flies (Diptera:Psychodidae) Lutzomyia (Nyssomyia) intermedia Lutz & Neiva 1912 and Lutzomyia (Nyssomyia) whitmani Antunes & Coutinho 1932 are two very closely related species and important vectors of American cutaneous leishmaniasis. Two single-locus studies have revealed evidence for introgression between the two species in both mitochondrial and nuclear genomes. These findings have prompted the development of a multilocus approach to investigate in more detail the genetic exchanges between the two species. RESULTS: We analyzed ten nuclear loci using the "isolation with migration" model implemented in the IM program, finding evidence for introgression from L. intermedia towards L. whitmani in three loci. These results confirm that introgression is occurring between the two species and suggest variation in the effects of gene flow among the different regions of the genome. CONCLUSION: The demonstration that these two vectors are not fully reproductively isolated might have important epidemiological consequences as these species could be exchanging genes controlling aspects of their vectorial capacity.
Assuntos
Transferência Genética Horizontal , Insetos Vetores/genética , Psychodidae/genética , Migração Animal , Animais , Fluxo Gênico , Marcadores Genéticos , Genoma de Inseto , Leishmaniose Cutânea/transmissão , Filogenia , Polimorfismo Genético , Psychodidae/classificação , Especificidade da EspécieRESUMO
The sand fly Lutzomyia longipalpis Lutz & Neiva (Diptera: Psychodidae: Phlebotominae), the main vector of Leishmania infantum in the Americas, is believed to be a species complex, although the status of different Brazilian populations is still somewhat unclear. Preliminary analysis of the acoustic signals that are produced during copulation by L. longipalpis males has suggested the existence of three sibling species in Brazil. In the current report, we analyze in more detail a number of parameters of the copulatory courtship songs of L. longipalpis males from four allopatric populations from different parts of the country (Marajó Island, Natal, Jacobina, and Lapinha Cave) and from two sympatric populations from the locality of Sobral, where two types of males can be differentiated by the number of pale spots (one or two pairs) found on the abdomen. We show that males from the localities of Natal, Marajó, and Sobral (two-spot morph) have very similar songs composed of successive bursts, which are modulated in frequency and amplitude. No significant differences were found in the song parameters of these three populations. In contrast, one-spot males from Sobral and males from Jacobina and Lapinha produce songs that are made of pulses but with distinct patterns for each population and significant differences in all song parameters studied. The results suggest that the L. longipalpis complex in Brazil is composed of four sibling species and that the differences in song patterns between the populations are consistent with the level of divergence found in the period gene.