A constant flow valve for hand-compression hydraulic sprayers.

A commercial inline constant flow valve for hand-compression hydraulic sprayers was tested to evaluate its capability to maintain constant pressure to the nozzle down to a preset cut-out pressure. The flow-control valve provided consistent flow rates when used with the H.D. Hudson X-Pert 9.5-liter hand-compression sprayers. This flow valve may have potential for use in vector control operations.

Operational note indoor low-volume spray trials: handheld equipment evaluation.

Four handheld aerosol-mist generators and 1 thermal fog generator were evaluated initially for their ability to deliver low flow rates (< or = 5 ml/min) of resmethrin insecticide. Two generators, the London Fog Eliminator and Clarke Pl, were then selected from that group to conduct a treatment of a block of 16 residences (4 x 4 grid) vs. direct treatment of individual residences to determine the most efficacious method of treating a group of small dwellings or a village. Data are presented on droplet density, volume median diameter, and mortality of caged mosquitoes treated with the P1 and Eliminator in residences treated as a group; and mortality for caged Aedes aegypti L. in residences treated individually with the P1 at various flow control settings and spray-on times.

Susceptibility of sand flies to selected insecticides in North Africa and the Middle East.

The purpose of this study was to determine the baseline susceptibility of 4 species of phlebotomine sand flies from North Africa and the Middle East to various insecticides. Susceptibility was determined using the World Health Organization test kits for measuring resistance in mosquitoes exposed to insecticide-impregnated papers. Fifty, 90, and 99% lethal doses were calculated for bendiocarb, cyfluthrin, DDT, malathion, permethrin, and resmethrin on Phlebotomus bergeroti, P. langeroni, P. papatasi. and P. sergenti. The least toxic insecticide to all species was DDT, followed by malathion and permethrin in order of increasing toxicity. Cyfluthrin was the most toxic to P. langeroni and P. papatasi, followed by resmethrin and bendiocarb in order of decreasing toxicity. Resmethrin exhibited the highest toxicity to P. bergeroti followed by cyfluthrin and bendiocarb, whereas bendiocarb was most toxic to P. sergenti, followed by cyfluthrin and resmethrin in order of decreasing toxicity. An attempt was made to obtain data for deltamethrin, but close response data were insufficient to determine regression lines for this insecticide on these species. However, analysis of preliminary data indicated that deltamethrin is highly toxic to these sand flies.

New record of Phlebotomus sergenti, the vector of Leishmania tropica, in the southern Nile valley of Egypt.

We report the 1st collection of Phlebotomus sergenti, a vector of the cutaneous and visceralizing forms of Leishmania tropica, from southern Egypt. Four female and 1 male P. sergenti were collected from unlit Centers for Disease Control light traps placed in a village on the Nile River, 6 km north of Aswan, Egypt, during studies conducted from 1998 to 1999. This extends the known distribution of this species farther south in Egypt than previously recorded.

Effects of permethrin on the salivary glands and neuroendocrine organs of unfed female Hyalomma (Hyalomma) dromedarii (Ixodoidea: Ixodidae).

Permethrin-impregnated fabric has been shown to be an effective repellent against various tick species. However, some tick species are not repelled by this chemical. In Hyalomma dromedarii (Koch), permethrin exposure is reported to actually enhance the tick's attachment behavior. This study evaluated the histological effects of permethrin exposure on the salivary glands and neuroendocrine organs of unfed, virgin H. dromedarii ticks of uniform age. Three fabric treatments consisting of unwashed-untreated (control), washed after treatment (0.125 mg [AI] / cm2) and unwashed-treated were used after 5- and 10-min exposure times for unfed, unmated females. For all of the organs examined, the cellular structure of treated ticks differed from controls as evidenced by increases in cellular activity, as well as significant increases in the size of the cells of the organs under study (P < 0.05). These data conclusively demonstrate that an unexpected enhanced attachment response observed in this tick species after permethrin exposure is the direct result of increased neurosecretory and salivary gland activity induced by that exposure.

The effect of Leishmania major on some biological parameters of Phlebotomus papatasi (Diptera: Psychodidae) from endemic and non-endemic areas in Egypt.

Biological activities of two populations of Phlebotomus papatasi collected from two different areas in Egypt (Sinai and Aswan) and the effect of Leishmania major on such activities were investigated under insectary conditions. A significant reduction (P < 0.05) was observed in the number of eggs laid by the infected females when compared to the non-infected females of the tested populations. The immatures of the Aswan population required a longer period (P < 0.05) to complete larval development. Life expectancy at emergence for infected and non-infected females was almost 13 days for the two populations. No significant difference was observed for the effect of L. major on the survivorship of tested populations. The mean generation time for the non-infected and infected females of Sinai and Aswan were 47.5, 49.8, 50.8, 49.5 days, respectively. Mean productivity (the number of females produced by one female) of the non-infected females of the Sinai population (18.1 female female/female) was significantly higher (P < 0.05) than the Aswan population (12.3 female female/female) while the productivity for infected females for both Sinai and Aswan populations (10.8 and 7.3 female female/female) was significantly reduced (P < 0.05). These results show Leishmania infection affects the fertility and productivity of both populations and may be a factor in controlling the insect population size in nature.

Colonization and bionomics of the sandfly Phlebotomus kazeruni from Sinai, Egypt.

Phlebotomuius kazeruni (Diptera: Psychodidae) females were collected by light-trap in southern Sinai, Egypt, and this sandfly species was colonized for the first time as a laboratory strain, maintained by the procedures of Modi & Tesh (1983). Laboratory-reared females did not lay eggs autogenously; they blood-fed more readily (P=0.02) on a hamster (37%) than a human (22%) during 1 h exposure. Fecundity of hamster-fed females was significantly greater than for those fed on human blood: 69.4 +/- 5.8 vs. 45.2 +/- 8.1 eggs/female from the first gonotrophic cycle. Pre-oviposition and egg incubation periods were significantly less for females fed on hamster compared with human blood, but the larval development and pupation periods were not affected by this difference in bloodmeal source. Egg to adult survival was equivalent (38%) for progeny of females blood-fed on hamster or human. The mean generation time of progeny from females fed on hamster (51.9 +/- 1.0 days) or human (53.3 +/- 1.7 days) was not significantly different. The sex ratio of adult male:female progeny was similar (P=0.2) for both hosts: 42:58% from hamster, 46:54% from human blood-fed female parents. Evidently P. kazeruni from Sinai is sufficiently anthropophagic to be a potential vector of Leishmania from rodents to humans.

Response of mosquitoes (Diptera: Culicidae) to carbon dioxide and octenol in Egypt.

Carbon dioxide and 1-octen-3-ol (octenol were evaluated individually, and in combination, as adult mosquito attractants at two sites in Qara, Matruh Governorate, Egypt. Four mosquito species were collected during the study: Aedes caspius, Anopheles multicolor, An. sergenti and Culex pipiens. Anopheles multicolor and Cx. pipiens were collected in insufficient numbers to allow statistical analysis. Significantly greater numbers of Ae. caspius and An sergenti were collected in CO2 and CO2 + octenol traps than octenol alone or the control at both locations (P < 0.05). Traps baited with octenol + CO2 resulted in greater capture of these two species at both locations; but results were not significant when compared with CO2 alone. There were no significant differences in number of mosquitoes collected between the octenol alone and control traps at both locations. At the release rate tested (0.5 mg/h at 21 degrees C), octenol was not an effective attractant for the mosquito species collected during the course of this study.

Susceptibility to Leishmania major of different populations of Phlebotomus papatasi (Diptera: Psychodidae) from endemic and non-endemic regions of Egypt.

The ability of three populations of Phlebotomus papatasi collected from different areas of Egypt (Sinai, Aswan and Delta regions) to acquire successfully and transmit Leishmania major (Sinai sandfly isolate IPAP/EG/89/SI-177) was evaluated in the laboratory. Flies from each population were fed artificially on infected blood suspensions, using a chick-skin-membrane feeding apparatus, and naturally on infected mice. Samples of fed flies were dissected and examined microscopically to determine the infection rate and intensity of parasite infection. The Aswan population had a significantly lower feeding rate (16.2%) than the Sinai (51.2%) and Delta (69.7%) populations (P < 0.0001). The infection rate for the Sinai population was significantly higher (65.9%) than the rate for the Delta (52.3%; P < 0.05) and slightly higher than that for the Aswan (62.5%). No differences were observed in the intensity of L. major infection in the midguts of the sandflies examined from any of the three populations. When flies from each population were fed naturally on BALB/c mice infected with L. major, the feeding rates of the three populations showed a similar pattern to that seen in the membrane feeds, with the Aswan population having the lowest rate. In each of two separate trials for each population, a group of artificially infected flies was refed on uninfected BALB/c mice. Thirty-six days following exposure to the infected sandflies in the Sinai population, a leishmanial lesion was observed on the corner of one animal's mouth. These observations provide the final piece of evidence that P. papatasi is a vector of L. major in Egypt.