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: The study was undertaken to characterize factors influencing differential productivity of Anopheles gambiae complex mosquitoes at larval habitats in a rural village in western Kenya. Methods: Longitudinal larval sampling was done using an area sampler for 3 months. Emerged adults were identified to species level morphologically using taxonomic keys and to sub-species by polymerase chain reaction (PCR). Nutrient content was analyzed using persulphate oxidation method. Water pH was measured using an Orion pH/conductivity meter. Turbidity was measured using a Hach 2100A turbidity meter. Algal count density was estimated using a sedge-wick rafter cell. Results: A total 3367 larvae were harvested. Out of 500 adults subjected to PCR analysis 358 (71.6%) were Anopheles gambiae s.s., 127 (25.4%) An. arabiensis while PCR amplification failed for 15 (3%) specimens. Rainwater pools were the most productive habitat type. There was a positive association between algal density and larval density (p<0). Total nitrogen, water pH and turbidity were positively correlated with larval density (p<0.01) and pH was negatively associated with larval density. Conclusion: Results indicate water nutrient and algal content in larval habitats of An. gambiae play crucial, dual roles in the resource ecology of these mosquitoes. Overall, the findings of this study support the notion that anti-larval source reduction measures aimed at manipulating physicochemical variables in larval habitats to eliminate larval production have a chance of succeeding in an integrated vector control program.
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.