Phlebotomine sand flies (Diptera: Psychodidae) of the Palestinian West Bank: potential vectors of leishmaniasis

Two forms of leishmaniasis are endemic to the Jenin district in the northern region of the West Bank. Visceral leishmaniasis (VL), caused by Leishmania infantum, mainly affects infants. Cutaneous leishmaniasis (CL) affects a broader age group and is probably caused by L. tropica. Although the Jenin district is the most important focus of leishmaniasis in the West Bank, the sand fly fauna of the area has never been studied in a systematic manner. We collected base-line data on sand fly species, their distribution, and their feeding preferences to facilitate risk assessments for contracting leishmaniasis. Light traps, sticky traps, insecticide knockdown collections, aspirator, and human-landing collections were used. A total of 4,082 sand flies was collected in foci of confidence limits and/or VL between June and December 1998. Nine Phlebotomus species representing seven subgenera were identified: P. (Larroussius) perfiliewi transcaucasicus Perfil'ev, P. (La.) tobbi Adler & Theodor, P. (La.) mascitti canaaniticus Adler & Theodor, P. (La.) mascitti mascitti Grassi, P. (La.) syriacus Adler & Theodor, P. (Phlebotomus) papatasi Scopoli, P. (Synphlebotomus) s.p., P. (Paraphlebotomus) sergenti Parrot, P. (Par.) jacusieli Theodor, P. (Adlerius) halepensis Theodor. Two other Phlebotomus subspecies, P. (La.) major major Annandale, P. (La .) neglectus Tonnoir, require confirmation. In addition, four species of the closely related genus, Sergentomyia were also found: S. (Sergentomyia) theodori Parrot, S. (S.) fallax Parrot, S. (Sintonitus) tiberiadis Adler, Theodor & Lourie, S. (Sin.) christophersi Sinton. Among five species of sand flies collected on human bait, P. papatasi constituted approximately 90% followed by P. major syriacus (8%) and P. mascitti (2%). Sand fly human-biting activity occurred through the night and it was highest between 2400 and 0300 hours. P. papatasi. P. perfiliewi, P. major and P. tobbi were the more endophilic species constituting 93% of all flies caught indoors. Seven Phlebotomus spp. constitute potential vectors of leishmaniasis but the most probable ones are as follows: P. papatasi the main human-biting species, a recognized vector of L. major (CL), P. sergenti, L. tropica (CL) and P. syriacus, L. infantum (VL).     

Distribution of phlebotomine sand flies (Diptera: Psychodidae) in a primary forest-crop interface, Salta, Argentina

Disordered urbanization and deforestation are the main activities proposed as causal factors of re-emergence of American cutaneous leishmaniasis caused by Leishmania braziliensis. The purpose of this work was to investigate, in the hyperendemic area of Argentina, the distribution of Phlebotomine sand flies at the modified primary vegetation-crop interface, as one of the potential sites where the effects of changing landscape on sand fly populations may be manifested. Twenty samplings were made between June 2004 and August 2005. The traps to catch sand flies were set on two consecutive nights every month (except in 5 mo, where it became every 15 d). The relationship between sand fly abundance and meteorological and landscape variables was analyzed using non-metric multidimensional scaling and Kendall's correlation coefficients. Lutzomyia neivai (Pinto) was the most abundant species, followed by Lutzomyia migonei (Fran?a), Lutzomyia cortelezzii (Brèthes), Lutzomyia shannoni (Dyar), and Lutzomyia punctigeniculata (Floch and Abonnenc). Traps located close to modified areas collected the greatest numbers of sand flies, whereas traps located in the least modified area (adjacent to the primary vegetation) collected the fewest. There was a strong negative correlation between the abundance of sand flies and precipitation. This study shows that even small modifications in the landscape led to an increase in sand fly abundance, mainly Lu. neivai, a Leishmania braziliensis vector. This underscores the need for recommendations about the risk of American cutaneous leishmaniasis before any environmental intervention is done in an endemic area, as well as for the monitoring of sand fly population dynamics at the site of intervention, before, during, and after the process.     

Sand flies (Diptera: Phlebotominae) in Sanliurfa, Turkey: relationship of Phlebotomus sergenti with the epidemic of anthroponotic cutaneous leishmaniasis

Sand fly (Diptera: Phlebotominae) fauna were surveyed in various districts of Sanliurfa in southeast Turkey for 3 yr immediately after an epidemic of cutaneous leishmaniasis (Leishmania tropica). Sticky papers and CDC light traps collected a total of 10,937 sand flies, of which 10,919 (4,158 females and 6,761 males) were identified as Phlebotomus and 18 (11 females and seven males) as Sergentomyia (S. theodori Parrot; S. adleri Theodor). Eight Phlebotomus spp. were identified: P. sergenti Parrot (72.3%), P. papatasi (Scopoli) (27.2%), P. brevis Theodor & Mesghali (0.20%), P. neglectus Leger & Pesson (0.13%), P. perfiliewi Parrot (0.05%), P. mascitti Grassi, P. halepensisTheodor, and P. alexandri Sinton (0.01%). Phlebotomus mascitti and P. neglectus, along with both Sergentomyia sp., have not been previously described from the study area. Similar results were obtained when both trapping methods were applied in the same houses, indicating that local P. sergenti and P. papatasi populations were equally attracted to the light. P. sergenti was consistently abundant, agreeing with the general view that this species is the vector of leishmaniasis in the region. There was no apparent decrease in the relative abundance of this vector versus the other species, suggesting that factor (s) other than a change in the dynamics of sand fly populations precipitated the decline of the human leishmaniasis epidemic in Sanliurfa.     

Evaluation of novaluron as a feed-through insecticide for control of immature sand flies (Diptera: Psychodidae)

The development and survival of sand fly Phlebotomus papatasi Scopoli (Diptera: Psychodidae) larvae fed feces of Syrian hamsters, Mesocricetus auratus, that had been fed a diet containing novaluron were evaluated. In total, six larval diets were used in sand fly larval bioassays. Four groups of larvae were fed feces of hamsters that had been maintained on a diet containing either 0, 9.88, 98.8, or 988 ppm novaluron. Two additional groups were fed a larval diet composed of equal parts composted rabbit feces and rabbit chow containing either 0 or 988 ppm novaluron. No pupation, hence no adult emergence, occurred when larvae were fed feces of hamsters that were fed diets containing novaluron. The mortality of sand flies fed feces of treated hamsters occurred during larval molts. The results of this study suggest that a control strategy using rodent baits containing novaluron to control phlebotomine sand flies and zoonotic cutaneous leishmaniasis may be possible.     

Efficacy of commercial mosquito traps in capturing phlebotomine sand flies (Diptera: Psychodidae) in Egypt

Four types of commercial mosquito control traps, the Mosquito Magnet Pro (MMP), the Sentinel 360 (S360), the BG-Sentinel (BGS), and the Mega-Catch Ultra (MCU), were compared with a standard Centers for Disease Control and Prevention (CDC) light trap for efficacy in collecting phlebotomine sand flies (Diptera: Psychodidae) in a small farming village in the Nile River Valley 10 km north of Aswan, Egypt. Each trap was baited with either carbon dioxide (CO2) from combustion of butane gas (MMP), dry ice (CDC and BGS traps), light (MCU and S360), or dry ice and light (CDC). Traps were rotated through five sites in a5 x 5 Latin square design, repeated four times during the height of the sand fly season (June, August, and September 2007) at a site where 94% of sand flies in past collections were Phlebotomus papatasi (Scopoli). A total of 6,440 sand flies was collected, of which 6,037 (93.7%) were P. papatasi. Of the CO2-baited traps, the BGS trap collected twice as many P. papatasi as the MMP and CDC light traps, and at least three times more P. papatasi than the light-only MCU and S360 traps (P < 0.05). Mean numbers (+/- SE) of P. papatasi captured per trap night were as follows: BGS 142.1 (+/- 45.8) > MMP 56.8 (+/- 9.0) > CDC 52.3 (+/- 6.1) > MCU 38.2 (+/- 6.4) > S360 12.6 (+/- 1.8). Results indicate that several types of commercial traps are suitable substitutes for the CDC light trap in sand fly surveillance programs.     

Repellent efficacy of a combination containing imidacloprid and permethrin against sand flies (Phlebotomus papatasi) in dogs

Infection in dogs and humans with the protozoan parasite Leishmania are widespread in tropical and subtropical countries around the globe. Sand flies of the order Phlebotomus in the Old World and Lutzomyia in the New World function as the vector of this disease. In dogs, skin lesions are the most prominent signs of canine leishmaniasis, besides other complex underlying manifestations. To prevent dogs from sand fly bites and thus transmission of Leishmania, an imidacloprid 10% w/v / permethrin 50% w/v combination was evaluated for its insecticidal and repellent efficacy. Treated and untreated control dogs were exposed weekly to about 200 female Phlebotomus papatasi for a period of four weeks. Dead and alive sand flies were counted for surviving rate evaluation and feeding rate was determined for repellency evaluation. The repellent efficacy was 94.6% (day 1), 93.3% (day 8), 80.0% (day 15), 72.8% (day 22) and 55.9% (day 29).The insecticidal efficacy was 60.0% (day 1), 46.2% (day 8), 42.6% (day 15), 35.2% (day 22) and 29.3% (day 29). The study demonstrated the high repellent potential of the imidacloprid / permethrin combination, thus protecting dogs from sand fly bites.     

Distribution of sand fly (Diptera: Psychodidae) species and efficiency of capturing methods in Sanliurfa province, Turkey

The population dynamics of sand flies (Diptera: Psychodidae) were studied in Sanliurfa province in southeastern Turkey, in the country's largest focus of typical anthroponotic cutaneous leishmaniasis, during 2000-2002. Sand flies were collected at nine different sampling stations, located throughout the city, representing a cross section of urban and rural habitats. In total, 29,771 sand flies were collected, 45.35% of which were Phlebotomus papatasi Scopoli. In this study, the overall sand fly species diversity, relative abundance of each species, biodiversity, and similarity indices among sampling stations and efficiency of trapping methods were evaluated. Among the sampling stations, Sanliurfa city center and Suru? were shown to have the highest number of sand fly species; Harran-Akcakale and Hilvan habitats produced the largest number of individuals. The greatest similarity rates (80%) in terms of sand fly species were observed between Hilvan and city center, Harran-Akcakale and city center, Harran-Akcakale and Yenice, and Siverek and Viransehir. The lowest similarity rate (16%) was observed between Bozova-Birecik and city center. Comparison of biodiversity and similarity indices between the various sampling stations reveals the distribution of the suspected vector species and provides basic knowledge required to develop logical and effective control strategies. Among the trapping methods used, light traps showed the highest capture efficiency, above aspirators and sticky papers. It was concluded that light traps alone were sufficient to determine the sand fly fauna of the study area. It is recommended that the spatial and temporal dynamics of sand fly populations be monitored throughout the southeastern Anatolia Project (GAP) construction period, considering the potential impact the project may have on mean temperature, humidity, and human population movements.     

Laboratory evaluation of diflubenzuron as a feed-through for control of immature sand flies (Diptera: Psychodidae)

The benzoylurea chitin synthesis inhibitor diflubenzuron was evaluated as a rodent feed-through for the control of immature stages of Phlebotomus papatasi Scopoli (Diptera: Psychodidae). The development and survival of second instars of P. papatasi larvae that were fed feces from Syrian hamsters, Mesocricetus auratus, that had been fed a diet containing 0, 8.97, 89.7, or 897 ppm diflubenzuron was evaluated. No pupation or adult emergence occurred when larvae were fed feces from hamsters that were fed diets containing diflubenzuron. The mortality of sand flies fed feces from treated hamsters was coincident with pupation of the controls, suggesting a specific effect on the larval-to-pupal molt. The results of this study suggest that a control strategy using rodent baits containing diflubenzuron for phlebotomine sand flies and zoonotic cutaneous leishmaniasis may be possible.     

The potential distribution of Phlebotomus papatasi (Diptera: Psychodidae) in Libya based on ecological niche model

The increased cases of cutaneous leishmaniasis vectored by Phlebotomus papatasi (Scopoli) in Libya have driven considerable effort to develop a predictive model for the potential geographical distribution of this disease. We collected adult P. papatasi from 17 sites in Musrata and Yefern regions of Libya using four different attraction traps. Our trap results and literature records describing the distribution of P. papatasi were incorporated into a MaxEnt algorithm prediction model that used 22 environmental variables. The model showed a high performance (AUC = 0.992 and 0.990 for training and test data, respectively). High suitability for P. papatasi was predicted to be largely confined to the coast at altitudes <600 m. Regions south of 300 degrees N latitude were calculated as unsuitable for this species. Jackknife analysis identified precipitation as having the most significant predictive power, while temperature and elevation variables were less influential. The National Leishmaniasis Control Program in Libya may find this information useful in their efforts to control zoonotic cutaneous leishmaniasis. Existing records are strongly biased toward a few geographical regions, and therefore, further sand fly collections are warranted that should include documentation of such factors as soil texture and humidity, land cover, and normalized difference vegetation index (NDVI) data to increase the model's predictive power.     

Phenology of Phlebotomus papatasi (Diptera: Psychodidae) relative to the seasonal prevalence of zoonotic cutaneous leishmaniasis in central Tunisia

The population density of Phlebotomus papatasi Scopoli (Diptera: Psychodidae), vector of Leishmania major Yakimoff & Schokhor (Kinetoplastida: Trypanosomatidae), the etiologic agent of zoonotic cutaneous leishmaniasis (ZCL), was assessed May-November 2005 in central Tunisia by using sticky traps. The densities of P. papatasi were found to peak in early spring and again in the autumn. The lowest densities were observed in August. Prevalence of ZCL in the governorate of Sidi Bouzid peaks in December, 3 to 3.5 mo after the fall sand fly population peak, suggesting a close temporal association with the abundance of P. papatasi.     

Photosynthesis modulates the plant feeding of Phlebotomus papatasi (Diptera: Psychodidae)

Phlebotomus papatasi (Scopoli), the vector of Leishmania major (Yakimoff & Schokhor), feeds on plants in desert habitats in the Jordan Valley. At the end of the dry summer, the life span of sand flies is short and the amount of sugars in their guts is small. In this season the plants are under the stress of heat and dehydration. This stress arrests the photosynthesis and decreases the amounts of the main end products, sucrose and starch. We presumed that the paucity of sugars in the sand fly plant tissue diet resulted from the arrest of photosynthesis. To test this assumption, we compared the feeding of sand flies on branches of Capparis spinosa (L.) that had been kept for 24 h in darkness and on branches cut after a normal day of photosynthesis. In darkness, the branches had lost more than half of their sugar content. Afterward they were fed upon overnight by 45.2% of female and 14.3% of male sand flies. A higher proportion of 81.0% females and 38.7% males fed on branches from natural conditions and these fed flies were significantly heavier. Laboratory experiments also showed that plant tissue meals of P. papatasi often include starch grains. Such grains were found also in 50% of field-caught males and females. The nutritive potential of plant tissues was demonstrated by the 33-d median survival of P. papatasi series that had been maintained on fresh C. spinosa branches and water.     

Behavioral evidence for the presence of a sex pheromone in male Phlebotomus papatasi scopoli (Diptera: Psychodidae)

Phlebotomus papatasi (Diptera: Psychodidae) is the Old World sand fly vector of zoonotic cutaneous leishmaniasis caused by Leishmania major (Trypanosomatidae: Kinetoplastida), a debilitating and disfiguring protist parasitic disease prevalent throughout southern Mediterranean countries, the Middle East, as well as southern and eastern European countries, where it is regarded as a serious public health problem. Little is known of the mating ecology of P. papatasi, and, in particular, the role (if any) of pheromones is not known. In this laboratory- and field-based study, we have shown that a male-produced sex pheromone exists in P. papatasi. Young female P. papatasi are attracted to the headspace volatiles of small groups of males, males and females together, but not females alone. Males were not attracted to males, females, or mixed groups of males and females in the laboratory. Larger groups of males or males and females together were repellent in the laboratory study. Field experiments showed that Centers for Disease Control (CDC) light traps baited with small groups of males and females together were attractive to females, but not males. CDC traps baited with large groups of males and females together caught significantly fewer females and males than the control traps; however, the proportion of females caught compared with males overall was much higher than with CDC traps baited with small numbers of males and females. These results suggest that females may be attracted in preference to males to the vicinity of the baited traps and are highly sensitive to the concentration of male pheromone. It also suggests that P. papatasi mating behavior is fundamentally different from that of Lutzomyia longipalpis, where large mating aggregations of males and females occur.     

Laboratory evaluation of rubidium as a long-lasting marker for bloodfeeding sand flies (Diptera: Psychodidae)

The objective of this study was to evaluate the use of the trace element rubidium (Rb) as a long-lasting systemic biomarker for bloodfeeding females of the sand fly Phlebotomus papatasi Scopoli. Baits containing Rb chloride were found to be palatable to hamsters in this study. We were able to detect Rb using a portable X-ray fluorescence analyzer in all sand flies that fed on Rb-treated hamsters for at least 14 d postbloodmeal. We also detected Rb in sand flies that took a bloodmeal from hamsters up to 10 d after the hamsters were withdrawn from a Rb-treated diet. Results of this study constitute proof of concept for the incorporation of Rb chloride into rodent baits for marking bloodfeeding sand flies, and suggest that Rb marking could be used as a technique for evaluating rodent-targeted sand fly control methods and in ecological studies on sand flies.     

Attractiveness of vertebrate hosts to Culex pipiens (Diptera: Culicidae) and other mosquitoes in Israel.

Host preferences of mosquitoes, mainly Culex pipiens L. and Aedes caspius (Pallas), were studied in Israel using live baits, chemical attractants, light, and suction traps. The feeding habits of Cx. pipiens were opportunistic. This species used a wide range of mammalian and avian hosts; a calf, chickens, turkeys, and sheep were the most attractive baits. A. caspius fed mainly on large mammals and was most attracted to calf and sheep baits. Although sheep were attractive, few Cx. pipiens and no Ae. caspius engorged after entering the traps. In addition to defensive behavior and the mechanical protection afforded by the wool, sheep may possess a close-acting repellent that deters mosquitoes from biting. CO2 was the best attractant for host-seeking Cx. pipiens and Ae. caspius, Aedes detritus (Haliday), Culiseta annulata (Schrank), Culiseta longiareolata (Macquart), and Uranotaenia unguiculata Edwards were caught in small numbers, and their bloodmeal hosts were recorded.     

Identification and frequency distribution of Leishmania (L.) major infections in sand flies from a new endemic ZCL focus in southeast Iran

Zoonotic cutaneous leishmaniasis (ZCL) is an important public health challenge in Iran. It is often caused by the protozoan parasite, Leishmania major. This pathogen is principally transmitted by the infectious bites of adult female phlebotomine sand flies which belong to the subgenus Phlebotomus (Phlebotomus) Rondani and Berte (Diptera: Psychodidae). A recent outbreak of clinical ZCL cases in the rural district of Jask, Hormozgan province, southern Iran prompted the identification of sand flies naturally infected with L. major using polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA). A total of 8,123 wild sand flies were caught using sticky paper traps indoors and outdoors in seven villages of Jask from March 2007 to February 2008. About 120 trap-nights per month were carried out during peak seasonal density. Eight sand fly species of two distinct genera were morphologically identified. The most abundant species, Phlebotomus papatasi (≈60?%) and Phlebotomus salehi (17?%), had simultaneous population peaks in May and October. The anthropophilic index of P. papatasi was approximately twice that of P. salehi. PCR reactivity of L. major infections in P. salehi was weaker than those in P. papatasi. This is discussed with regard to their role in the natural transmission cycle of ZCL. This study provided the first PCR and ELISA evidence on P. salehi as a vector of L. major parasites in a new endemic region of ZCL in southeast Iran.     

Field evaluation of deet and a piperidine repellent against Aedes communis (Diptera: Culicidae) and Simulium venustum (Diptera: Simuliidae) in the Adirondack Mountains of New York

Repellent efficacy of N,N-diethyl-3-methyl-benzamide (deet), the piperidine, 1-[3-cyclohexen-1-ylcarbonyl]-2-methylpiperidine (AI3-37220), and a 1:1 ratio of deet + AI3-37220 were evaluated topically (0.25 mg/cm2 applied in ethanol solution) on human volunteers against the mosquito Aedes communis (DeGeer) and the black fly Simulium venustum Say. The average repellency of all three formulations was > 95% at 4 h. For both mosquitoes and black flies, deet alone provided < 90% protection at 6 h, whereas AI3-37220 provided > 95% protection. Although repellent treatments were not significantly different overall, the contrasts between AI3-3720 versus deet were significant at 6 and 8 h. The 95% confidence interval on percent repellency at 6 h ranged from 90.1 to 98.9% for AI3-37220 versus 64.3 to 82.2% for deet, and at 8 h ranged 76.1 to 88.5% for AI3-37220 versus 47.8 to 64.0% for deet. Similarly, the confidence interval for protection against black flies at 6 h by (AI3-37220 ranged from 86.3 to 99.5% and did not overlap with the confidence interval provided by deet alone (51.2 to 78.8%). There was no evidence of synergistic repellency from a combination of the two compounds; i.e., protection from combined compounds was no better than either repellent used alone.     

Impact of phlebotomine sand flies on U.S. Military operations at Tallil Air Base, Iraq: 2. Temporal and geographic distribution of sand flies

CDC miniature light traps were used to evaluate the general biology of phlebotomine sand flies from April 2003 to November 2004 at Tallil Air Base, Iraq. Factors evaluated include species diversity and temporal (daily and seasonal) and geographic distribution of the sand flies. In addition, the abundance of sand flies inside and outside tents and buildings was observed. In total, 61,630 sand flies were collected during 1,174 trap nights (mean 52 per trap, range 0-1,161), with 90% of traps containing sand flies. Sand fly numbers were low in April, rose through May, were highest from mid-June to early September, and dropped rapidly in late September and October. More than 70% of the sand flies were female, and of these sand flies, 8% contained visible blood. Phlebotomus alexandri Sinton, Phlebotomus papatasi Scopoli, Phlebotomus sergenti Parrot, and Sergentomyia spp. accounted for 30, 24, 1, and 45% of the sand flies that were identified, respectively. P. alexandri was more abundant earlier in the season (April and May) than P. papatasi, whereas P. papatasi predominated later in the season (August and September). Studies on the nocturnal activity of sand flies indicated that they were most active early in the evening during the cooler months, whereas they were more active in the middle of the night during the hotter months. Light traps placed inside tents with and without air conditioners collected 83 and 70% fewer sand flies, respectively, than did light traps placed outside the tents. The implications of these findings to Leishmania transmission in the vicinity of Tallil Air Base are discussed.     

First detection of Leishmania infantum in Phlebotomus (Larroussius) major (Diptera: Psychodidae) from Iran

Ghir-Karzin district is one of the most important endemic foci of visceral leishmaniaisis (VL) in Fars province of southern Iran. To identify the vector(s) of Leishmania in this focus, a total of 2,539 sand flies were collected during June to September 2005. Eleven species (six Phlebotomus and five Sergentomyia) were identified, of which Phlebotomus papatasi Scopoli and Phlebotomus major Annandale were the first (37.4%) and third (11.2%) most common species, respectively. Natural leptomonad infections were observed in two P. papatasi (4.25%) and three P. major (6.65%) specimens on dissection and microscopic examination. Using a Leishmania genus-specific standard polymerase chain reaction (PCR; primers RV1-RV2) and a species-specific nested-PCR (primers LINR4, LIN17, and LIN 19), Leishmania infantum and Leishmania major kinetoplast minicircle DNA was detected in 6 of 72 P. major (8.3%) and 4 of 65 P. papatasi (6.1%), respectively. This is the first detection of L. infantum in P. major, implicating this sand fly as a probable vector of VL in Iran.     

Zoophilic feeding behaviour of phlebotomine sand flies in the endemic areas of cutaneous leishmaniasis of Sindh Province, Pakistan

Leishmania (Leishmania) major has been identified as the major causative agent of cutaneous leishmaniasis in Sindh Province of southern Pakistan. To make a rational approach for understanding the pathogen transmission cycles, the sand fly species and their natural blood meals in the endemic areas were examined. Total DNA was individually extracted from sand flies collected in four villages in Sindh Province. PCR-RFLP (restriction fragment length polymorphism) and sequence analysis of the 18S ribosomal RNA gene revealed that female sand flies identified were Sergentomyia clydei/Sergentomyia ghesquierei/Sergentomyia magna (68.6%), Sergentomyia dubia (17.1%), Phlebotomus papatasi (7.4%), Phlebotomus alexandri-like sand flies (3.4%) and Sergentomyia dentata (3.4%). PCR amplification of leishmanial kinetoplast DNA did not result in positive signals, suggesting that all 175 tested female sand flies were not infected with leishmanial parasites or contained undetectable levels of leishmanial DNA. Amplification and sequencing of the vertebrate cytochrome b gene in 28 blood-fed sand flies revealed that P. papatasi fed on cattle and wild rat whereas P. alexandri-like specimens fed on human, cattle, goat and dog. Although Sergentomyia sand flies are generally known to feed on cold-blooded animals, S. clydei, S. dubia and S. ghesquierei preferred humans, cattle, goat, sheep, buffalo, dog, donkey, wild rat and Indian gerbil. The epidemiological significance of the zoophilic feeding on various host species by Phlebotomus and Sergentomyia sand flies in Pakistan is further required to study for better understanding the zoonotic transmission of sand-fly-borne pathogens and for appropriate management of the vectors.     

Repellent and deterrent effects of SS220, Picaridin, and Deet suppress human blood feeding by Aedes aegypti, Anopheles stephensi, and Phlebotomus papatasi

A series of behavioral tests with Aedes aegypti (L.), Anopheles stephensi Liston, mosquitoes, and the sand fly Phlebotomus papatasi Scopoli in the presence of Deet, SS220, and Picaridin topically applied to the skin of human volunteers showed that the insects were deterred from feeding on and repelled from surfaces emanating the compounds. When offered a 12- or 24-cm2 area of skin, one-half treated with compound and one-half untreated, the insects fed almost exclusively on untreated skin. The sand flies and mosquitoes did not at any time physically contact chemically treated surfaces. When treated and untreated skin areas were covered with cloth, insects contacted, landed, and bit only through cloth covering untreated skin. These observations provided evidence that the compounds deterred feeding and repelled insects from treated surfaces primarily as a result of olfactory sensing. When cloth, one-half untreated and one-half treated with chemical, was placed over untreated skin, insects only touched and specifically bit through the untreated cloth. This showed that the activity of the chemicals does not involve a chemical x skin interaction. In the presence of any of the three chemicals, no matter how they were presented to the insects, overall population biting activity was reduced by about one-half relative to controls. This reduction showed a true repellent effect for the compounds. Results clearly showed that Deet, SS220, and Picaridin exert repellent and deterrent effects upon the behavior of mosquitoes and sand flies. Heretofore, the combined behavioral effects of these compounds upon mosquito and sand fly behavior were unknown. Moreover, protection afforded by Deet, SS220, and Picaridin against the feeding of these three disease vectors on humans is mechanistically a consequence of the two chemical effects.