Ultrastructural Comparison of External Morphology of Immature Stages of <I>Lutzomyia</I> (<I>Nyssomyia</I>) <I>intermedia</I> and <I>Lutzomyia</I> (<I>Nyssomyia</I>) <I>whitmani</I> (Diptera: Psychodidae), Vectors of Cutaneous Leishmaniasis, by Scanning Electron Microscopy

Abstract

Lutzomyia (Nyssomyia) intermedia (Lutz & Neiva 1912) and Lutzomyia (Nyssomyia) whitmani (Antunes & Coutinho 1939) (Diptera: Psychodidae) are vectors of American cutaneous leishmaniasis in several endemic regions of Brazil. We analyzed the external morphological aspects of the immature stages of these two vectors by using scanning electron microscopy. In general, the larval stages of the two species are morphologically similar, although some differences were noted. Detailed examination of the eggs of both species revealed similar exchorionic ornamentations of unconnected parallel ridges. The larval head capsules are well defined, heavily sclerotized, and bear prominent chewing mouthparts. The abdominal segments are easily recognized by the presence of prolegs on their ventral surfaces. The morphology of the anal lobe on the terminal abdominal segment differs between the two species. We found the following three types of sensillae inserted on the antennae: (1) clavate basiconic; (2) small, blunt coeloconic; and (3) multipourous clavate coleoconic. In addition; five subtypes of trichoid sensillae were found on the larval body: (1) long, (2) short, (3) curved long, (4) brush-like, and (5) weakly brush-like. The caudal filaments located on the last abdominal segment were recognized as long trichoid sensillae. We observed pores on the surface of the clavate coelonic sensillae and on the caudal filaments that presumably function as chemoreceptors. The larvae of the two species show similarities in the lobular-form antennae of L1 larvae, which changes to digitiform in second instar (L2), L3, and L4. This study demonstrated that the external surface of the eggs and larvae of Lu. intermedia and Lu. whitmani are morphologically similar, but they can be distinguished by details in the microanatomy observed by scanning electron microscopy.

Ultrastructural comparison and distribution of sensilla on male and female antennae of the sand fly Phlebotomus papatasi (Diptera: Psychodidae): the vector of cutaneous leishmaniasis in Egypt

“…Five subtypes of trichoid sensilla were observed, namely long blunttipped, short sharp-tipped, short blunt-tipped, medium pointed-tipped, and apical. Bahia et al (2007) observed the trichoid sensilla in the larvae of Ny. whitmani and Ny.…”

Significance of eggshell morphology as an additional tool to distinguish species of sand flies (Diptera: Psychodidae: Phlebotominae)

“…The chorionic sculpturing of sand fly eggs was first studied and described by Ward and Ready in thirteen species of New World sand flies [4]. The ultrastructure of sand fly eggshells was investigated in many New World species (approximately 50 species) [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] but only in a limited number of species of Old World sand flies [20][21][22][23][24][25]. Chorionic patterns reflect phylogenetic relationships among certain Lutzomyia sand fly species in the New World [6][7][8]10].…”

“…whitmani (Antunes and Coutinho) revealed that chorionic patterns of both species are similar. However, details in the microanatomy of the external surface of the eggs observed by SEM can be used to differentiate the two species [14]. Alencar and Scarpassa [19] examined the chorionic sculpturing of ten Brazilian sand fly species using SEM: Ny.…”