An inexpensive culture medium based on sunflower seed extract (SSE) for production of L. chapmanii was developed. Vegetative growth on solid and liquid SSE was compared with two culture media used routinely (PYG and Emerson YPss). Results indicate that the oomycete is able to grow on SSE medium, producing more zoospores at a faster rate as well as inducing higher mortality rates in Ae. aegypti larvae.
Keywords:Mosquito control, diseases-borne vector, entomopathogen, Straminipila, Oomycete culture.Leptolegnia chapmanii (Seymour) (Straminipila: Peronosporomycetes) is an aquatic pathogen of mosquito larvae (McInnis & Schimmel, 1985;López Lastra et al., 2004). Its virulence and pathogenicity against Aedes aegypti larvae has been studied (McInnis & Zattau, 1982;López Lastra et al., 2004). It persists enabling it to reduce mosquito population for weeks after a single application (Rueda et al., 2015). It grows readily on culture media as PYG and Emerson YPss (Pelizza et al., 2011). However, the use of such culture media for its mass production could be expensive. A culture medium based on sunflower extract (SSE) was reported as an alternative for culture of the Downloaded by [Gazi University] at 05:44 18 December 2015A c c e p t e d M a n u s c r i p t 2 entomopathogen Lagenidium giganteum (Couch) (Guzman & Axtell, 1986). The mass production of zoospores from L. giganteum maintained on in vitro culture media by its immersion in water was used by Jaronski & Axtell, (1983) and a medium-scale production of L. giganteum and its application in laboratory and field was reported by Kerwin et al., (1994).Consequently we developed and evaluated a culture medium based on sunflower seeds as an inexpensive alternative for the mass production of L. chapmanii. SSE medium was prepared following the protocol proposed by Jaronski & Axtell (1984). To prepare one liter of medium, ten grams of sunflower seeds were blended with 100 ml distilled water for one minute, filtered through 2-4 layers of cheesecloth and the residue was blended again with 100 ml of distilled water for one minute. Suspensions were filtered, mixed and the final volume was increased with distilled water to one liter. The PYG (Peptone 1.25 g, Yeast extract 1.25 g, Glucose 3 g, distilled water 1000 ml) and plug from cultures grown on of the PYG solid medium, incubating for 7 days at 25ºC and 0.18 g (180 rpm) in an orbital shaker, then transferred to 400 ml of each respective culture medium for an additional 7 days of culture under the same laboratory conditions. After the 14-day culture period, biomass from each culture medium was filtered and fresh weight recorded. Cost of production based on biomass obtained in different culture media was estimated and compared. For zoospore formation and release, 10 g of biomass produced in liquid cultures were added to 200 ml sterile distilled water in 500 ml Erlenmeyer flasks on and shaken on an orbital shaker at 0.18 g (180 rpm). Production of zoospores was determined daily for 4 days. Their viability and virulence were confirme...