Pathogenicity of Metarhizium anisopliae (Metch) Sorok and Beauveria bassiana (Bals) Vuill to adult Phlebotomus duboscqi (Neveu-Lemaire) in the laboratory

Background & objectives: Biological control of sandflies using entomopathogenic fungi is a possible alternativeto the expensive synthetic chemical control. It is potentially sustainable, less hazardous, and relatively inexpensiveand 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 screenedfor their pathogenicity against Phlebotomus duboscqi. Adult flies were contaminated using the technique describedby Migiro et al (2010). Briefly, flies were exposed to 0.1 g of dry conidia evenly spread on a cotton velvet clothcovering the inner side of a cylindrical plastic tube (95 mm long × 48 mm diam). In all 25 sandflies weretransferred into the cylindrical tube and allowed to walk on the velvet for one minute, after which they weretransferred 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 isolateswere selected for further studies.Results: A total of 19 isolates were screened against adult sandflies in the laboratory. Mortality in the controlswas approximately 16.8 ± 1.7 %. All the isolates were found to be pathogenic to P. duboscqi. Mortality rangedbetween 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 mortalitiesof 97.5–100%, were selected for further studies.Interpretation & conclusion: The high susceptibility of sandflies to entomopathogenic fungi suggests that fungiare potential alternatives to chemical control methods. We conclude that application of entomopathogenic fungicould result in acute mortalities of sandflies and reduction of parasite transmission and subsequently, reductionof leishmaniasis risk. This method of biological control has great potential as a new strategy for leishmaniasiscontro