Host feeding preference of Phlebotomus guggisbergi,a vector of Leishmania tropica in Kenya

Abstract. Recently the sandfly Phlebotomus guggisbergi was found to be a vector of Leishmania tropica causing cutaneous leishmaniasis in the Laikipia focus, Kenya, but extensive searches have shed no light on the identity of the rural reservoir host(s). In order to discover more about the biology of the vector, a host feeding preference study was conducted on wild sandflies in their natural cave environment over a 6-month period. Solid state Army miniature (SSAM) traps, without light bulb, were suspended over cages with potential hosts or an empty cage control. The animals tested included sheep, goat, dog, cat, hamster, rabbit, giant rat (Cricetomys gambianus), crested rat (Lophiomys imhausi) and rock hyrax (Procavia capensis), all of which (except hamsters) are normally found in the vicinity of the study site. Sandfly collections from traps baited with goat, sheep, cat, dog, rabbit, or wild rodent species were significantly higher than the control, whereas trap collections with hamster and rock hyrax were not significantly different from the control. Numbers of sandflies collected from the goat, sheep and cat were significantly greater than from the rabbit and rodents. The sex ratio also varied between collections: larger animals attracted a higher proportion of female P.guggisbergi than did the smaller animals (P>0.05). Therefore greater emphasis should be placed on surveying larger animals to assess their status as reservoir hosts for L.tropica in Kenya.     

Correlations between the temperature dependence of chlorophyll fluorescence and the fluidity of thylakoid membranes

To monitor changes in membrane fluidity in Arabidopsis leaves and thylakoid membranes, we investigated the temperature dependence of a chlorophyll fluorescence parameter, minimum fluorescence (Fo), and calculated the threshold temperature [T(Fo)] at which the rise of the fluorescence level Fo was considered to be started. For the modification of membrane fluidity we took three different approaches: (1) an examination of wild‐type leaves initially cultured at room temperature (22°C), then exposed to either a lower (4°C) or higher (35°C) temperature for 5 days; (2) measurements of the shift in T(Fo) by two mutants deficient in fatty acid desaturase genes – fad7 and fad7fad8 and (3) an evaluation of the performance of wild‐type plants when leaves were infiltrated with chemicals that modify fluidity. When wild‐type plants were grown at 22°C, the T(Fo) was 48.3 ± 0.3°C. Plants that were then transferred to a chamber set at 4 or 35°C showed a shift in their T(Fo) to 42.7 ± 0.9°C or 48.9 ± 0.1°C, respectively. Under low‐temperature acclimation, the decline in this putative transition temperature was significantly less in fad7 and fad7fad8 mutants compared with the wild‐type. In both leaf and thylakoid samples, values for T(Fo) were reduced in samples treated with benzyl alcohol, a membrane fluidizer, whereas T(Fo) rose in samples treated with dimethylsulfoxide, a membrane rigidifier. These results indicate that the heat‐induced rise of chlorophyll fluorescence is strongly correlated with the fluidity of thylakoid membranes.     

Sugars in the alimentary canal of Lutzomyia youngi (Diptera: Phlebotominae)

Abstract. Gas chromatography (GC) analysis of 159 specimens (144 females and 15 males) of Lutzomyia youngi collected in Shannon traps in a coffee plantation in the Andean region of western Venezuela, where leishmaniasis is endemic, revealed the presence of fructose, sucrose, glucose and maltose in the gut and crop of the wild sandflies. The identification of the sugars was confirmed by comparing retention times with those observed for standard sugars and those obtained from sandflies experimentally fed on known sugar solutions. Although the sandflies in nature may ingest each of the four sugars, the results suggest that it is more probable there is an invertase enzyme (glycosidase?) in the gut or crop of the sandfly which hydrolyses ingested disaccharides (e.g. sucrose) to the constituent monosaccharides (i.e. fructose and glucose). Ecological and altitudinal distributions of sandfly species may be related to the availability of specific sugar sources, with epidemiological implications. Identification of the preferred sugar could make breeding easier and would facilitate further research on Leishmania–wector relationships.     

A long-lasting topical deltamethrin treatment to protect dogs against visceral leishmaniasis

To develop long‐lasting, topical pour‐on insecticides for dogs to control zoonotic visceral leishmaniasis, two deltamethrin‐based formulations (emulsifiable concentrate [EC] and suspension concentrate [SC]) were tested for their efficacy against the phlebotomine sandfly Lutzomyia longipalpis Lutz & Neiva (Diptera: Psychodidae), vector of Leishmania infantum Nicolle (Kinetoplastida: Trypanosomatidae). The entomological outcomes tested were anti‐feeding effect (proportion of female sandflies unfed), lethal effect (24‐h female sandfly mortality) and these two effects combined, and the insecticide persistence time at 50% (residual activity, RA₅₀) and 80% (RA₈₀) efficacy. On initial application, the proportions of female flies that demonstrated anti‐feeding activity or were killed were similar for both formulations, at 0.93 (95% confidence interval [CI] 0.856–0.977) vs. 0.81 (95% CI 0.763–0.858) (anti‐feeding) and 0.86 (95% CI 0.787–0.920) vs. 0.76 (95% CI 0.698–0.817) (24‐h mortality) for EC and SC, respectively. The RA₅₀ rates for anti‐feeding and mortality caused by the EC formulation were 4.7 months (95% CI 4.18–5.84) and 2.5 months (95% CI 2.25–2.90), respectively, compared with 1.1 months (95% CI 0.96–1.15) and 0.6 months (95% CI 0.50–0.61), respectively, for the SC formulation. The RA₅₀ for the combined anti‐feeding and mortality effects of EC was 5.2 months (95% CI 4.73–5.96), compared with only 0.9 months (95% CI 0.85–1.00) for the SC formulation. The four‐ to six‐fold superior residual activity of the EC formulation was attributed to the addition of a solvent‐soluble resin in the formulation which improved fur adhesion and acted as a reservoir for the slow release of the active ingredient. These results identify the potential of such a low‐cost formulation to reduce the inter‐intervention interval to 5–6 months, similar to that recommended for deltamethrin‐impregnated dog collars or for re‐impregnation of conventional bednets, both of which are currently used to combat Leishmania transmission. Finally, a novel bioassay was developed in which sandflies were exposed to fur from treated dogs, revealing no detectable tolerance (24‐h mortality) in wild‐caught sandflies to the insecticide formulations up to 8 months after the initiation of communitywide application of the insecticides to dogs.     

Molecular detection of Wolbachia pipientis in natural populations of sandfly vectors of Leishmania infantum in endemic areas: first detection in Lutzomyia longipalpis

A polymerase chain reaction‐based method was used to screen sandflies for infection with Wolbachia (Rickettsiales: Rickettsiaceae), an intracellular bacterial endosymbiont found in many arthropods and filarial hosts. Positive results were obtained in five of 200 field‐collected sandflies and were confirmed by sequencing. All sandflies were Lutzomyia longipalpis (Diptera: Psychodidae) captured in a region endemic for visceral leishmaniasis in Brazil. This is the first study to identify Wolbachia infection in this Lutzomyia species, which is the main vector of leishmaniasis in the study area. The low infection rate found in this study (2.5%), together with the lack of detection of Wolbachia in previous studies and the diversity found in the sequences analysed, suggests horizontal transmission to these sandflies.     

Trypanosoma thecadactyli sp. n. from Forest Geckoes in Panama,and its Development in the Sandfly Lutzomyia trinidadensis (Newstead) (Diptera,Psychodidae)*

SYNOPSIS. Trypanosoma thecadactyli sp. n. is described from the forest gecko Thecadactylus rapicaudus in Panama. Blood smears from 18 of 25 (72%) geckoes sampled were positive for the new trypanosome. The flagellate, ～22 μm long, is ovoid or roughly triangular in shape and has a posterior cytoplasmic projection. Tree buttresses, rock crevices, and caves are microhabitats shared by T. rapicaudus and the phlebotomine sandfly Lutzomyia trinidadensis. Approximately 20% of the wild-caught and dissected L. trinidadensis were infected with flagellates. Twenty-four of 45 (53%) laboratory-reared L. trinidadensis allowed to feed on parasitized geckoes developed heavy infections of the mid- and hindgut which persisted up to 2 weeks, the longest postprandial period before dissection. Transmission probably occurs as a result of geckoes feeding on infected sandflies in nature. The distribution of L. trinidadensis, from Mexico to Brazil, approximates that of the gecko. Laboratory results and ecologic observations implicate L. trinidadensis as a potential vector of T. thecadactyli.     

Protection of dogs from bites of phlebotomine sandflies by deltamethrin collars for control of canine leishmaniasis

Abstract. Dog collars made of PVC plastic impregnated with the pyrethroid insecticide deltamethrin at 40 mg/g were investigated for their protective efficacy against phlebotomine sandflies. Collared dogs were kept separately (two untreated control dogs lived together) in outdoor enclosures, each with a kennel, in the Cevennes, southern France. To measure sandfly mortality and anti-feeding effects due to the deltamethrin-impregnated collars worn continuously by the dogs for up to 8 months, each dog was periodically sedated and exposed for 2h to 150–200 laboratory-reared Phlebotomus perniciosus females (plus c. 25 males) inside a net (1.2m square, 1.8 m high) indoors. After dogs were removed from the nets, allowed to recover and returned to their kennels, any dead sandflies were collected from inside the net and counted. Surviving flies were kept overnight, then scored according to whether they were still alive or dead, unfed or blood-fed. From tests 2, 3, 4, 13, 20, 26 and 34 weeks after the dogs began wearing collars, the overall numbers of blood-fed female sandflies recaptured were 75 from two dogs with collars, compared with 1911 from two collarless dogs. Thus, for every 100 flies which fed on collarless dogs, only 4 fed on collared dogs, i.e. the collars protected dogs from 96% of the bites and this activity was maintained for up to 34 weeks. During the same period, the percentage of recaptured female sandflies that had fed on collared dogs was 0–12% compared to 55–95% on collarless dogs. Immediately after dogs were taken out of the nets, 21–60% of flies confined with the collared dogs were found dead, compared to 0–12% with the controls. It is concluded that, at least in the Mediterranean subregion, this insecticidal collar would protect a dog from the majority of sandfly bites and retain a killing effect for a complete sandfly season. Moreover, it seems likely that the use of collars on all dogs in a focus of Leishmania infantum would reduce contact between sandfly vectors and canine reservoir hosts sufficiently to diminish the risk of infection for humans as well as dogs.     

Trypanosoma gerrhonoti n. sp., and Extrinsic Development of Lizard Trypanosomes in California Sandflies

Trypanosoma gerrhonoti n. sp. is described from southern alligator lizards Gerrhonotus multicarinatus of central California. It is the 2nd trypanosome species described from western North America. Extrinsic development of T. gerrhonoti and T. scelopori of western fence lizards was observed in phlebotomine sandflies Lutzomyia vexatrix occidentis, the probable natural vector. Both trypanosomes establish dense anterior midgut infections composed of long, thin epimastigotes.     

Sphaceloma poinsettiae as a potential biological control agent for wild poinsettia (Euphorbia heterophylla)

Sphaceloma poinsettiae, a scab-causing fungus that attacks wild poinsettia (Euphorbia heterophylla) was evaluated as a mycoherbicide. Plants representing nine different E. heterophylla accessions were tested and variable resistance levels to 10 different isolates of S. poinsettiae were observed. One isolate was selected based on its high aggressiveness; it caused scab that led to stem-girdling in the majority of plants belonging to most wild poinsettia accessions. Plants inoculated with conidial suspension developed low disease severity; suspensions of mycelial fragments caused higher disease severity. Viability of mycelium declined rapidly either in storage under room temperature or at 4 °C. After 25 days, 60% of mycelial fragments kept in distilled water at 4 °C or in 35% sterile sucrose solution germinated. Cultures of S. poinsettiae were capable of growing at temperatures ranging from 10 to 30 °C (maximum growth at 25 °C) whereas the mycelial fragments germinated at 20–30 °C. The highest mycelial yield occurred in potato-dextrose broth after culturing for 12 days at 168 rpm at room temperature. A host-range test involving 37 plant species in addition to wild poinsettia indicated that S. poinsettiae is highly specific to E. heterophylla. The viability of S. poinsettiae as a mycoherbicide depends on the development of suitable mass production, formulation, and inoculum preservation methods. On several occasions, this fungus has been observed to cause devastating epidemics in the field on this host; therefore, it should be considered a potential biocontrol agent of wild poinsettia.     

Xanthomonas campestris, a novel stress tolerant, phosphate-solubilizing bacterial strain from saline–alkali soils

A total of 198 bacterial strains were isolated from various niches of saline–alkali soils, out of which 85 strains were able to solubilize phosphate on plates at 30 °C. The strain RMLU-26, identified as Xanthomonas campestris, was the most efficient with its ability to solubilize P, subjected to N-methyl-N′-nitro-N-nitrosoguanidine (NTG) for development of mutants. The P solubilizing ability of X. campestris is reported for the first time. The wild type and mutant strains of X. campestris revealed a differential response to various stress factors (high pH, temperature, and salt concentration). The mutant strain revealed maximum P solubilization (67.1%) at 30 °C and pH 8.0 while the wild type strain showed maximum solubilization (41.9%) at 35 °C and pH 7.0. Percent P₂O₅ solubilization by both strains revealed a steep decline in tricalcium phosphate solubilization with an increase in NaCl concentration from 0.5 to 10% along with a concomitant drop in pH of the medium from 8.0 to 4.5 in wild type and 4.0 in mutant strain. However, a 1.5- to 2-fold increase in ‘P’ solubilization was observed in the mutant strain when compared to the wild type strain in the presence of NaCl. The overall improved tolerance of the strains to alkalinity and salinity could be due to accumulation and/or secretion of specific solute (xanthan).     

The role of the hexose transporter in the chloroplasts of Arabidopsis thaliana L.

The metabolism of wild-type Arabidopsis thaliana L. and its mutant TC265 were compared in order to reveal the role of the chloroplast glucose transporter. Plants were grown in a 12-h photoperiod. From 20 to 40 days after germination, starch per gram fresh weight of shoot in the mutant was four times that in the wild type. The extent of this difference did not alter during this period. Stereological analysis showed that the chloroplasts in the mutant were larger than those in the wild type; the thylakoids appeared to be distorted by the high starch content. [U-¹⁴C]Glucose and [U-¹⁴C]glycerol were supplied, separately, to excised leaves in the dark. [U-¹⁴C]Glucose was a good precursor of sucrose in the wild type and mutant; [U-¹⁴C]glycerol was a poor precursor of sucrose in both. The distribution of ¹⁴C in the wild type was used to calculate that the net flux was from hexose monophosphates to triose phosphates, not vice versa. During the first 4 h of the night the sugar content (75% sucrose, 20% glucose) of the leaves of the mutant dropped sharply, and at all times during the night it was less than that of the wild-type leaves. This drop in sugar coincided with a decrease in the rate of respiration. The growth rate of the mutant was less than that of the wild type. Addition of sucrose restored the rate of respiration at night and increased the rate of growth. It is argued that a major function of the glucose transporter in Arabidopsis chloroplasts is export of the products of starch breakdown that are destined for sucrose synthesis at night.We thank Professor C.R. Somerville for his generous gift of seed of the Arabidopsis mutant TC265. We are also grateful to Mr B. Chapman for assistance with the preparation of the sections for electron microscopy. R.N.T. thanks the Science and Engineering Research Council for a studentship.     

Species composition and seasonal abundance of sandflies (Diptera: Psychodidae: Phlebotominae) in coffee agroecosystems

The composition and seasonal occurrence of sandflies were investigated in coffee agroecosystems in the Soconusco region of Chiapas, Mexico. Insect sampling was performed on three plantations located at different altitudes: Finca Guadalupe Zajú [1,000 m above sea level (a.s.l.)], Finca Argovia (613 m a.s.l.) and Teotihuacán del Valle (429 m a.s.l.). Sandflies were sampled monthly from August 2007-July 2008 using three sampling methods: Shannon traps, CDC miniature light traps and Disney traps. Sampling was conducted for 3 h during three consecutive nights, beginning at sunset. A total of 4,387 sandflies were collected during the course of the study: 2,718 individuals in Finca Guadalupe Zajú, 605 in Finca Argovia and 1,064 in Teotihuacán del Valle. The Shannon traps captured 94.3% of the total sandflies, while the CDC light traps and Disney traps captured 4.9% and 0.8%, respectively. More females than males were collected at all sites. While the number of sandflies captured was positively correlated with temperature and relative humidity, a negative correlation was observed between sandfly numbers and rainfall. Five species of sandflies were captured: Lutzomyia cruciata , Lutzomyia texana , Lutzomyia ovallesi , Lutzomyia cratifer / undulata and Brumptomyia sp. Lu. cruciata , constituting 98.8% of the total, was the most abundant species. None of the captured sandflies was infected with Leishmania spp.     

Releases of Trichogramma platneri (Hymenoptera: Trichogrammatidae) in Apple Orchards under a Sterile Codling Moth Release Program

Based on the premise that augmented host numbers may help multiply and support parasitoid populations, the egg parasitoid Trichogramma platneri Nargarkatti was released in apple orchards which were participating in a sterile codling moth, Cydia pomonella (L.), release program. Nonviable eggs resulting from matings involving at least one sterile codling moth partner can be successfully parasitized by T. platneri. Grain moth-reared, as well as codling moth-reared, T. platneri were released either in the spring or in the spring and summer oviposition period(s) of wild codling moth. Sentinel codling moth eggs were hung weekly, for 3-day periods, from May until September to determine fluctuations in T. platneri populations both during and between releases. Low numbers of wild or nonviable codling moth eggs or other susceptible host eggs resulted in sufficient eggs to maintain low spring- or summer-introduced T. platneri populations. T. platneri reduced codling moth damage in trees in which the Trichogramma were released.     

Replication in Drosophila chromosomes

Prolongation of larval life in Drosophila melanogaster, by growing wild type larvae at lower temperature, or in animals carrying the X-linked mutation giant is known to result in a greater proportion of nuclei in salivary glands showing the highest level of polyteny. We have examined by autoradiography the patterns of ³H-thymidine incorporation during 10 min or 1 min pulses in salivary gland polytene chromosomes of older giant larvae and of wild type late third instar larvae of D. melanogaster grown since hatching either at 24 ° C or at 10 ° C. The various patterns of labelling and their relative frequencies are generally similar in glands from the warm-(24 ° C) or cold (10 ° C)-reared wild type larvae, except the interband (IB) labelling patterns which are very frequent in the later group but rare in the former. The IB type labelled nuclei in cold-reared wild type larvae show labelling ranging from only a few puffs/interbands labelled to nearly all puffs/interbands labelled. In warm-reared wild type larvae, very low labelled IB patterns are not seen. In older giant larvae, the ³H-thymidine labelling patterns are in most respects similar to those seen in cold-reared wild type larvae. In 1 min pulsed preparations from all larvae, the IB patterns are relatively more frequent than in corresponding 10 min pulsed preparations. No nuclei with the continuous (2C or 3C) type of labelling pattern, with all bands and interbands/puffs labelled, were seen in 1 min pulsed preparations from cold-reared wild type or in giant larvae, and only a few nuclei in 1 min pulsed preparations from warm-reared wild type larvae exhibited the 2C labelling pattern. Analysis of silver grain density on specific late replicating sites in late discontinuous (1D) type labelled nuclei suggests that the rate of DNA synthesis per chromosomal site is not different at the two developmental temperatures. It is suggested that correlated with the prolongation of larval life under cold-rearing conditions or in giant larvae, the polytene replication cycles are also prolonged. It is further suggested that the polytene S-period in these larvae is longer due to a considerable asynchrony in the initiation and termination of replication of different sites during a replication cycle.     

Development of a field‐friendly technique for fecal steroid extraction and storage using the African wild dog (Lycaon pictus)

Hormonal analysis provides information about wildlife populations, but is difficult to conduct in the field. Our goal was to develop a rapid and effective field method for fecal steroid analysis by comparing: (1) three extraction methods (laboratory (LAB), homogenize (HO) and handshake (HS)) and (2) two storage methods (solid‐phase extraction (SPE) tubes vs. plastic tubes (PT)). Samples (n=23) from captive African wild dogs (Lycaon pictus) were thoroughly mixed, three aliquots of each were weighed (～0.5 g) and 5 ml of 90% ethanol was added. For LAB, samples were agitated (mixer setting 60; 30 min), centrifuged (1,500 rpm; 20 min) and poured into glass tubes. Or aliquots were HO (1 min) or HS (1 min) and poured through filter paper into glass tubes. Samples were split, analyzed for corticosterone (C) and testosterone (T) metabolites using enzyme immunoassays or stored in SPE or PT. Samples were stored (room temperature) for 30, 60 or 180 days, reconstituted in buffer and analyzed. Mean C and T recoveries of HO were greater (P=0.03) than HS compared with LAB, which was similar to HO (P>0.05). After 30 days <21% of C and T was recovered from SPE, but ～100% of each was recovered from HO‐PT and HS‐PT. Similarly, after 60 and 180 days, ～100% of C and T was recovered from HO‐PT and HS‐PT. Results demonstrated that, for C and T, HO was more comparable (P<0.001) to LAB than HS and PT storage was more efficient than SPE (P<0.001). Zoo Biol 29:289–302, 2010. © 2009 Wiley‐Liss, Inc.     

Base editing with high efficiency in allotetraploid oilseed rape by A3A‐PBE system

CRISPR/Cas‐base editing is an emerging technology that could convert a nucleotide to another type at the target site. In this study, A3A‐PBE system consisting of human A3A cytidine deaminase fused with a Cas9 nickase and uracil glycosylase inhibitor was established and developed in allotetraploid Brassica napus. We designed three sgRNAs to target ALS, RGA and IAA7 genes, respectively. Base‐editing efficiency was demonstrated to be more than 20% for all the three target genes. Target sequencing results revealed that the editing window ranged from C1 to C10 of the PAM sequence. Base‐edited plants of ALS conferred high herbicide resistance, while base‐edited plants of RGA or IAA7 exhibited decreased plant height. All the base editing could be genetically inherited from T₀ to T₁ generation. Several Indel mutations were confirmed at the target sites for all the three sgRNAs. Furthermore, though no C to T substitution was detected at the most potential off‐target sites, large‐scale SNP variations were determined through whole‐genome sequencing between some base‐edited and wild‐type plants. These results revealed that A3A‐PBE base‐editing system could effectively convert C to T substitution with high‐editing efficiency and broadened editing window in oilseed rape. Mutants for ALS, IAA7 and RGA genes could be potentially applied to confer herbicide resistance for weed control or with better plant architecture suitable for mechanic harvesting.     

Intraspecific differentiation of sandflies specimens by optical spectroscopy and multivariate analysis

Lutzomyia longipalpis and Lutzomyia cruzi are the main sandflies species involved in the transmission of Leishmania infantum protozoan in Brazil. The morphological characteristics can be used for species identification of males specimens, while females are indistinguishable. Although, sandflies identification is essential to understand vectorial capacity, and susceptibility to infectious agents or insecticides, there is a lack of new strategies for specimen identification. In this study, Fourier transform infrared photoacoustic spectroscopy combined with multivariate analysis identified intraspecific differences between Lutzomyia populations. Successfully group clustering was achieved by principal component analysis. The main differences observed can be related to the protein content of the specimens. A classification with 100% accuracy was obtained using machine learning approach, allowing the identification of sandflies specimens.     

Within-population variation in hybridisation and transgene transfer between wild Brassica rapa and Brassica napus in the UK

Several studies in Europe and North America have shown that cultivated Brassica napus will readily hybridise with wild Brassica rapa but at widely different frequencies. To understand the implications of this phenomenon with regard to transgene flow, we examined the rate at which cultivated B. napus cv. Westar containing a capsid (coat protein, CP)‐coding sequence from Turnip mosaic virus (Potyvirus) hybridised under glasshouse conditions with wild B. rapa from Culham, in Oxfordshire, UK. We found that the hybridisation rate, as judged using simple sequence repeat (SSR)‐PCR and primer oligonucleotides specific for either the C or the A genomes in progeny from individual crosses varied from 5% to 100%. In hybrids (F₁ progeny), transgene transfer was always observed (inferred by SSR‐PCR) when hybrids were detected. Our observations revealed a hitherto unrecorded source of variability in transgene flow to wild UK B. rapa.     

Response of female Lutzomyia longipalpis to host odour kairomones from human skin

Lutzomyia longipalpis Lutz & Neiva (Diptera: Psychodidae) is the vector of Leishmania chagasi, the aetiologic agent of visceral leishmaniasis in the New World. In the present study, the response of female sandflies from Jacobina, Brazil, to human odours from six different volunteers was investigated. Glass Petri dishes were handled by different volunteers and then exposed to female sandflies. There was a significant difference between subjects in that some individuals were more attractive or less repellent to sandflies. Response of flies to handled Petri dishes was higher during the first minutes of observation, suggesting the presence of volatile compounds in hand odours. Extracts of glass Petri dishes that had been handled by the volunteers were made with organic solvents such as acetone, methanol, pentane and ether. These were then concentrated and tested for sandfly response. Only extracts carried out with non-polar solvents such as pentane and ether were able to transfer odours from handled glass Petri dishes onto clean dishes. The attractivity of male and female human subjects was monitored for 80 days, and minor fluctuations in attractiveness were observed.