ABSTRACT
Visceral and cutaneous leishmaniases are endemic in some parts of Kenya, where they are transmitted by phlebobotomine sandflies of genus Phlebotomus. This review is a compilation of the currently known distribution of phlebotomine sandflies in the parts of Kenya that have been studied, from the time sandflies were first reported in the country. So far 48 species of sandflies have been identified falling in the genera Phlebotomus Rondani & Berte and Sergentomyia Franca & Parrot. Genus Phlebotomus in Kenya is represented in five subgenera, namely Phlebotomus, Larroussius, Synphlebotomus, Paraphlebotomus and Anaphlebotomus. Genus Sergentomyia has the largest number of sandflies, and is represented in four subgenera, namely Sergentomyia, Sintonius, Grassomyia and Parvidens.
ABSTRACT
Background & objectives: Biological control of sandflies using entomopathogenic fungi is a possible alternative to the expensive synthetic chemical control. It is potentially sustainable, less hazardous, and relatively inexpensive and merits further investigations. The objective of this study was to identify the most pathogenic fungal isolate(s) to sandflies in the laboratory. Methods: Isolates of entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana were screened for their pathogenicity against Phlebotomus duboscqi. Adult flies were contaminated using the technique described by Migiro et al (2010). Briefly, flies were exposed to 0.1 g of dry conidia evenly spread on a cotton velvet cloth covering the inner side of a cylindrical plastic tube (95 mm long × 48 mm diam). In all 25 sandflies were transferred into the cylindrical tube and allowed to walk on the velvet for one minute, after which they were transferred from the velvet into the cages in Perplex. Insects in the control treatments were exposed to fungusfree velvet cloth before being transferred into similar cages. The treatments were maintained at 25 ± 2°C, 60–70% RH and 12L: 12D photoperiod. The experiment was replicated 5 times. The most pathogenic isolates were selected for further studies. Results: A total of 19 isolates were screened against adult sandflies in the laboratory. Mortality in the controls was approximately 16.8 ± 1.7 %. All the isolates were found to be pathogenic to P. duboscqi. Mortality ranged between 76.8 and 100% on all the fungal isolates tested. The lethal time taken to 50% (LT50) and 90% (LT90) mortality ranged from 3.0–7.8 days and from 5.3–16.2 days, respectively. The virulent isolates, causing mortalities of 97.5–100%, were selected for further studies. Interpretation & conclusion: The high susceptibility of sandflies to entomopathogenic fungi suggests that fungi are potential alternatives to chemical control methods. We conclude that application of entomopathogenic fungi could result in acute mortalities of sandflies and reduction of parasite transmission and subsequently, reduction of leishmaniasis risk. This method of biological control has great potential as a new strategy for leishmaniasis control.
ABSTRACT
Background & objectives: Phlebotomine sandflies are vectors of leishmaniases and other diseases. Long-lasting insecticidal nets (LLINs) as possible tools for control have not been widely tested against them. The objective of this study was to determine the efficacy of Olyset® Net and PermaNet® LLINs alongside a local brand, K-O Tab® treated net (Supanet) against Phlebotomus duboscqi female sandflies. Methods: Four replicates of unwashed and 20x washed Olyset Nets and PermaNets, K-O Tabtreated and untreated Supanet and ‘no net’ treatments were evaluated against sandflies within the laboratory by tunnel tests and in semi-field conditions in the greenhouse model for their efficacy. Results: All bednets allowed entry of P. duboscqi sandflies and subsequent blood-feeding. Olyset net’s blood feeding inhibition was significantly higher than that of Supanet in the laboratory but not in semi-field condition. Of the LLINs, only Olyset net had sandflies that could not feed significantly more than those of Supanet. Additionally, no significant efficacy difference was observed between LLINs washed 20x and unwashed ones. The only significant difference noted in number of sandflies that were found dead or paralyzed within bednets in the semi-field condition was between Olyset and K-O Tab treated Supanet. In the laboratory, unwashed Olyset had a significantly higher number of sandflies killed than all other bednet treatments. Conclusion: Olyset net use in areas where sandflies are nuisance biters and/or disease vectors could be more beneficial in preventing sandfly bites than other tested bednets. It is recommended that mesh sizes of LLINs should be smaller for control of sandflies than those used for control of mosquitoes.
ABSTRACT
Background & objectives: In order to understand sandfly bionomics, vector species identification, and to develop methods for sandfly control, there is a need to sample sandflies in any particular habitat. This survey was aimed at determining the best method of sampling Phlebotomus (Phlebotomus) duboscqi (Diptera: Psychodidae) in the field. Methods: Different animal baits and CO2-baited CDC light traps were used to attract sandflies released in an insect-proof screen-house located in the sandfly’s natural habitat in Marigat, Baringo district of Kenya. Results: Attraction of hungry P. duboscqi female sandflies by the goat (Capra hircis) was significantly higher than that of hamster (Mesocricetus auretus), Nile grass rat (Arvicanthis niloticus), gerbil (Tatera robusta) and chicken (Gallus domestica). However, two rodent species, A. niloticus and T. robusta did not differ significantly. A linear regression analysis of weights of animal baits and number of sandflies attracted revealed an insignificant result. The fluorescent dyes used to distinguish sandflies of different day experiments seemed not to influence the sandfly numbers in relation to the studied sandfly behaviour. Interpretation & conclusion: The similar attraction pattern of P. duboscqi in semi-field environment by CO2-baited CDC light trap and the goat provides hope for solution to the problem of fast dissipating dry ice (CO2 source) in the field. Goats can, therefore, also be utilized as deflectors of vectors of cutaneous leishmaniasis from humans in zooprophylaxis in Leishmania major endemic areas where the sandfly is found.