Ovicidal Activity of Entomopathogenic Hyphomycetes on <I>Aedes aegypti</I> (Diptera: Culicidae) Under Laboratory Conditions

Abstract

The ovicidal activity of 21 hyphomycete fungi species against Aedes aegypti (L.) (Diptera: Culicidae) was tested. Fungi with ovicidal activity developed on high numbers of eggs (> or =70%) during 25 d of exposure. A clear ovicidal activity with low values of hatch (1.3-40%) was observed after 25 d of incubation with Isaria farinosa (Holm: Fries) Fries, Paecilomyces carneus (Duché & Heim) Brown & Smith, Paecilomyces marquandii (Massee) Hughes, Isaria fumosorosea (Wize), Metarhizium anisopliae (Metschnikoff) Sorokin, Penicillium sp., Paecilomyces lilacinus (Thom) Samson, Beauveria bassiana (Balsamo) Vuillemin, and Evlachovaea kintrischica Borisov & Tarasov. More than 63% of eggs hatched after 25-d exposures to 11 other fungi species deemed as ineffective. These are the first results to show the effects of entomopathogenic fungi against eggs of Ae. aegypti, and they suggest their potential as control agents of this vector.

Biopesticidal Formulation Of Beauveria Bassiana Effective Against Larvae Of Helicoverpa Armigera.

“…Beauveria bassiana was grown on Czapek Dox media modified with maize flour as per findings of Ramle et al [15] and on Sabouraud-dextrose media with yeast extract [16] for growth optimization of the entomopathogenic fungus. Once the fungus was identified [17], pure cultures were obtained followed by flask cultures to develop the fungal mat.…”

Impact of moisture on survival of Aedes aegypti eggs and ovicidal activity of Metarhizium anisopliae under laboratory conditions

“…Moreover, eggs out of water resist prolonged desiccation during distinct dry seasons, and the surviving larvae contribute to a reestablishment of vector populations at the beginning of the rainy season, thus increasing the risk of dengue epidemics (Sota & Mogi 1992, Silva & Silva 1999. Inside eggs, diapausing larvae are exposed to predation and infection by pathogens, particularly fungi that may invade eggs actively through the egg shell or affect larvae with toxic metabolites produced on the egg surface (Russell et al 2001, Luz et al 2007). Moisture is a limiting factor for both egg survival and fungal activity but there is still little information about the impact of relative humidity (RH) on the survival of larvae inside eggs or a possible effect of entomopathogenic fungi.…”

“…This fungal species is pathogenic to larvae and adults of A. aegypti (Scholte et al 2004, Silva et al 2004, and recent studies indicated that it is also effective against eggs of this vector (Luz et al 2007). The fungal isolate tested here, IP 46, originated from a soil sample collected in 2001 in the Cerrado of Central Brazil and was stored at the IPTSP, UFG, Goiânia, Brazil.…”

“…Mosquitoes were reared under laboratory conditions as described by Silva et al (1998). Eggs were prepared using the method related by Luz et al (2007), and then topically treated with 50 µl water-suspended conidia or hyphal bodies, at 5x10 6 propagules/cm 2 or with water only for the controls and incubated for up to six months at 25°C and 43%, 75%, 86% or > 98% RH regulated in the test chambers with saturated solutions of K 2 CO 3 , NaCl, KCl and K 2 SO 4 , respectively (Winston & Bates 1960). Each month, fungal development on eggs and egg viability were tested.…”

“…Each month, fungal development on eggs and egg viability were tested. Eggs were submerged in water and quantitative eclosion evaluated for the next 10 days (Luz et al 2007). Four independent replicates, each test using different fungal cultures, were carried out.…”