Description of the fourth instar larva of Lutzomyia longipalpis, under scanning electron microscopy

The fourth instar larva of Lutzomyia (Lutzomyia) longipalpis (Phlebotomidae: Phlebotominae) was studied by scanning electron microscope. Based on three-dimensional observations, the fine structure and setal position (using of setal numeration) of the larva are presented.

The First Instar Larva of Lutzomyia longipalpis (Diptera: Phlebotomidae)

The morphology and chaetotaxy of the first instar larva of Lutzomyia (Lutzomyia) longipalpis are described based on observations made under scanning electron microscope. Because three-dimensional images were studied, some terminological changes are proposed to give a more realistic description of the positions of the setae. On the larval body, the pairs of setae have the following number: 9 on the head, 12 on the prothorax, 8 on the meso- and metathorax, 6 on the first to eighth abdominal segments, and 8 on the ninth abdominal segment

Physical Factors Influencing the Oviposition of Lutzomyia migonei (Diptera: Psychodidae) in Laboratory Conditions

To determine the influence of physical factors on oviposition of Lutzomyia migonei (Diptera: Psychodidae) under laboratory conditions, two sets of experiments were performed. The first test was to determine the influence of the size of pots on oviposition. Gravid flies were placed individually or in groups in different oviposition pots. The number of eggs laid, oviposition time and survival of gravid females were observed. In the second experiment, the influence of irregular surfaces on oviposition was studied. The results suggested that physical space was not an important factor in the oviposition behavior of L. migonei and that the flies showed a preference to oviposit on irregular horizontal surfaces in response to thigmotropic behavior

Notes on the Phlebotomine Sand Flies from the Peruvian Southeast: I. Description of Lutzomyia (Helcocyrtomyia) adamsi n. sp. (Diptera: Psychodidae)

A new species of phlebotomine sand fly, Lutzomyia adamsi n. sp., is described and illustrated from specimens collected during August 1994, in Sandia, Department of Puno-Peru. According to the Oficina Nacional de Evaluacion de Recursos Naturales(ONERN 1976), this locality is situated in the life zone known as humid, mountain, low tropical forest (bh-MBT). Many areas in the northern part of Puno, mainly in the Inambari and Tambopata basins, are endemic to leishmaniasis. These areas are the continuation of others, largely known as "leishmaniasic" in the departments of Cusco and Madre de Dios. The morphological characteristics indicated that this species belongs to the genus Lutzomyia, subgenus Helcocyrtomyia Barretto, 1962

Genetic Variation among Natural and Laboratory Colony Populations of Lutzomyia longipalpis (Lutz & Neiva, 1912)(Diptera:Psychodidae) from Colombia

Genetic diversity among three field populations of Lutzomyia longipalpis in Colombia was studied using isozyme analysis. Study sites were as much as 598 km apart and included populations separated by the eastern Cordillera of the Andes. Genetic variability among populations, estimated by heterozygosity, was within values typical for insects in general (8.1%). Heterozygosity for field populations were compared with a laboratory colony from Colombia (Melgar colony) and were only slightly lower. These results suggest that establishment and long term maintenance of the Melgar colony has had little effect on the level of isozyme variability it carries. Genetic divergences between populations was evaluated using estimates of genetic distance. Genetic divergence among the three field populations was low (D=0.021), suggesting they represent local populations within a single species. Genetic distance between field populations and the Melgar colony was also low (D=0.016), suggesting that this colony population does not depart significantly from natural populations. Finally, comparisons were made between Colombian populations and colonies from Brazil and Costa Rica. Genetic distance values were high between Colombian and both Brazil and Costa Rica colony populations (D=0.199 and 0.098 respectively) providing additional support for our earlier report that populations from the three countries represent distinct species

Morphological Study of the Larval Spiracular System in Eight Lutzomyia Species (Diptera: Psychodidae)

The morphology of the spiracles of fourth instar larva in eight sandfly species were examined by light and scanning electron microscopy. Species studied were: Lutzomyia longipalpis (Lutz & Neiva), L. ovallesi (Ortiz), L. youngi Feliciangeli & Murillo, L. evansi (Nuñez-Tovar), L. trinidadensis (Newstead), L. migonei (França), L. absonodonta Feliciangeli, and L. venezuelensis (Floch & Abonnenc). In larvae of all eight species both thoracic and abdominal spiracles are located at the top of a globular bulge. Their structure consists of a spiracular plate with a sclerotized central portion and a rose-like peripheral portion. The latter has circularly arranged papillae, separated from each other by elongated septa. Each papilla is longitudinally crossed by a fine cleft dividing it into two identical parts. The taxonomic and adaptative value of spiracular morphology is discussed

Life Cycle and Fecundity Analysis of Lutzomyia shannoni (Dyar) (Diptera: Psychodidae)

The life cycle of Lutzomyia shannoni (Dyar), was described for laboratory conditions with maximum daily temperatures of 27-30°C, minimum daily temperatures of 22-27°C and relative humidity between 87-99 %. Life cycle in each stage was as follows: egg 6-12 days (ave. 8.5 days); first stage larva 5-13 days (ave. 9.6 days); second stage larva 4-13 days (ave. 9.2 days ); third stage larva 5-19 days (ave. 11.8 days); fourth stage larva 7-37 days (ave. 19.9 days); pupa 7-32 days (ave. 15.2 days). The life expectancy of adults ranged from 4 to 15 days (ave. 8.6 days). The entire egg to adult period ranged from 36 to 74 days (ave. 54.6 days). On average, each female oviposited 22.7 eggs; the average egg retention per female was 24.3 eggs.

Rearing and Colonization of Lutzomyia evansi (Diptera: Psychodidae), a Vector of Visceral Leishmaniasis in Colombia

The sandfly Lutzomyia evansi from a focus of visceral leishmaniasis in northern Colombia was reared and maintained under laboratory conditions for five generations. The average time for total development was 41.8 days (range = 35.1- 49.6) at 25 oC and 89-95% of relative humidity. The mean number of eggs laid was lower in laboratory bred females either in pots (13.2 eggs/female) or vials (29.9 eggs/female) than in wild caught females (33.4 eggs/female). Immature mortality, mainly due to fungal and mite contamination, was higher during the first two instars than in the remaining immature stages. Adults were robust and healthy although difficult to feed on hamster or chick skin membrane. In summary, Lu. evansi is a colonizable species but requires specific conditions.

Phlebotomine Sand Flies from São Gabriel da Cachoeira (State of Amazonas, Brazil) with a Description of Lutzomyia (Psychodopygus) douradoi n. sp. (Diptera: Psychodidae)

Thirty-five species of Lutzomyia and two species of Brumptomyia were identified among 795 phlebotomines taken in light-traps near the upper reaches of the middle Rio Negro. The subgenus Psychodopygus predominated in number of species (11) and relative abundance (74-81% in light trap samples from the forest and 99% on human bait). For many of the species these records help to fill large gaps on current maps of distribution, and for others (L. olmeca nociva, L. mangabeirana, L. triacantha) the findings represent a significant expansion of their known range. A new species in the subgenus Psychodopygus (L. douradoi) is described from both sexes, and L. bettinii is recorded for the first time in Brazil.

Field Monitoring of Cypermethrin Residual Effect on the Mortality Rates of the Phlebotomine Sand Fly Lutzomyia longipalpis in the State of Paraíba, Brazil

In a visceral leishmaniasis endemic locality of northeast of Brasil where all settlements were treated with cypermethrin, a follow-up of Lutzomyia longipalpis populations was carried out by regular collections. The residual effect of the insecticide was studied using biological assays on three different types of walls. The results showed that the insecticides had an effect on intradomiciliar Lu. longipalpis populations limited to two months, and had no significant effect on peridomiciliar vector populations. The mortality rates of the tested sandflies were variable according to the type of wall. The decreasing of the insecticide effect was marked since the 3rd month, and mortality rates were identical whatever the type of wall since the 4th month. Unsufficient residual effect was detected after the 4th month.

Lufaxin, a novel factor Xa inhibitor from the salivary gland of the sand fly Lutzomyia longipalpis blocks protease-activated receptor 2 activation and inhibits inflammation and thrombosis in vivo.

OBJECTIVE: Blood-sucking arthropods' salivary glands contain a remarkable diversity of antihemostatics. The aim of the present study was to identify the unique salivary anticoagulant of the sand fly Lutzomyia longipalpis, which remained elusive for decades. METHODS AND RESULTS: Several L. longipalpis salivary proteins were expressed in human embryonic kidney 293 cells and screened for inhibition of blood coagulation. A novel 32.4-kDa molecule, named Lufaxin, was identified as a slow, tight, noncompetitive, and reversible inhibitor of factor Xa (FXa). Notably, Lufaxin's primary sequence does not share similarity to any physiological or salivary inhibitors of coagulation reported to date. Lufaxin is specific for FXa and does not interact with FX, Dansyl-Glu-Gly-Arg-FXa, or 15 other enzymes. In addition, Lufaxin blocks prothrombinase and increases both prothrombin time and activated partial thromboplastin time. Surface plasmon resonance experiments revealed that FXa binds Lufaxin with an equilibrium constant ≈3 nM, and isothermal titration calorimetry determined a stoichiometry of 1:1. Lufaxin also prevents protease-activated receptor 2 activation by FXa in the MDA-MB-231 cell line and abrogates edema formation triggered by injection of FXa in the paw of mice. Moreover, Lufaxin prevents FeCl(3)-induced carotid artery thrombus formation and prolongs activated partial thromboplastin time ex vivo, implying that it works as an anticoagulant in vivo. Finally, salivary gland of sand flies was found to inhibit FXa and to interact with the enzyme. CONCLUSIONS: Lufaxin belongs to a novel family of slow-tight FXa inhibitors, which display antithrombotic and anti-inflammatory activities. It is a useful tool to understand FXa structural features and its role in prohemostatic and proinflammatory events.