Reproductive isolation between sympatric and allopatric Brazilian populations of Lutzomyia longipalpis s.l. (Diptera: Psychodidae)

Abstract

Lutzomyia longipalpis s.l. occurs from Argentina to Mexico (Young & Duncan 1994) and because of its wide distribution there have been doubts expressed that this taxon is a single species. Mangabeira (1969) commented on morphological variation seen in males. He observed that specimens captured in the state of Pará, North Brazil, bore a single pair of pale tergal spots on abdominal segment IV (1S males) and those captured from the Northeastern state of Ceará (CE) showed an additional pair of spots on segment III (2S males). Mangabeira commented that the two forms were found in different ecological conditions and speculated that they might represent two species. The existence of a complex was confirmed by Ward et al. (1983Ward et al. ( , 1988 and Lanzaro et al. (1993) in crossing experiments, although the male spot phenotype turned out to be only useful as a morphological marker of different species in some localities such as Sobral, CE (see below) (reviewed in Bauzer et al. 2007).In Brazil, Lutzomyia longipalpis s. l. (Lutz & Neiva, 1912) is without any doubt the principal vector of American visceral leishmaniasis (AVL). It is present in nearly all of the foci of visceral leishmaniasis, is highly anthropophilic as well as readily feeding on dogs and foxes which act as reservoirs of Leishamania chagasi which are frequently found infected (reviewed in Lainson & Rangel 2005).Analysis of male copulatory courtship songs (Souza et al. 2002 and pheromones (Ward et al. 1988, Hamilton et al. 1996a,b, 2005 The best studied populations in Brazil, from an evolutionary point of view, are located in Jacobina (state of Bahía), Lapinha Cave in Lagoa Santa (state of Minas Gerais), Natal (state of Rio Grande do Norte) and Sobral (CE) (Bauzer et al. 2007). The first three localities represent different allopatric siblings (Bauzer et al. 2002b, Bottecchia et al. 2004, Watts et al. 2005) while in Sobral two species coexist in sympatry (Bauzer et al. 2002a, Maingon et al. 2003, Bottecchia et al. 2004. In the present study we compared the reproductive isolation among the three allopatric populations and between the Sobral sympatric siblings.Initially samples of the populations of Jacobina, Lapinha and Natal were obtained using CDC traps (4 to 9 traps in each locality). All males collected in Lapinha had a single pair of spots (1S) in segment IV and all males from Jacobina were 2S (two pairs in segments III and IV, with similar sizes). The majority of males from Natal had the intermediate phenotype, with the extra pair in segment III with less than 3/4 of the size of the spots in segment IV (see Ward et al. 1988). The population from Natal is highly polymorphic for the male spot phenotype but in this locality there is no evidence for the existence of sympatric sibling species (Mukhopadhyay et al. 1998, Bauzer et al. 2002b, Bottecchia et al. 2004, Watts et al. 2005. Eggs from 100 to 200 wild-caught females from each of the three localities were used to establish laboratory colonies following the methodologies 217 Reproductive isolation...

The Lutzomyia longipalpis complex: a brief natural history of aggregation-sex pheromone communication

“…Specifically, males were described as producing either a “farnesene/homofarnesene-like” molecule (C 16 H 26 ) or “diterpenoid-like” molecule (C 20 H 32 ). The reproductive compatibility of these populations correlated with the type of terpenoid compounds present was not associated with the spot phenotype [37–39], insects could share the same number of pale spots but the main component of the pheromone could vary. However, the reproductive incompatibility [37] between different populations was not fully explained by the presence of only 2 chemotypes.…”

Acoustic communication in insect disease vectors

“…longipalpis s.l. are likely to be involved in reproductive isolation since mating experiments show a high level of insemination failure in copulations between sibling species that produce different songs (Ward et al 1988, Souza et al 2008 ). Why female choice should be based on copulatory courtship is not well understood, but it may suggest that cryptic female choice ( Eberhard 1996 ) possibly related to sperm competition ( Hoikkala & Crossley 2000 ), is important during mating in this insect vector.…”

Copulatory courtship song in Lutzomyia migonei (Diptera: Psychodidae)

“…One important marker that has been used to differentiate the cryptic sibling species of this complex occurring in Brazil is the song produced by males during copulation (Souza et al 2004, Araki et al 2009). Differences in this copulatory courtship song probably contribute to the insemination failure observed in crosses between some Brazilian populations of this vector (Ward et al 1983, 1988, Souza et al 2008). Indeed, acoustic signals in insects are often involved in sexual selection and reproductive isolation of closely related species (Ewing 1989).…”