Effects of Metarhizium anisopliae conidia mixed with soil against the eggs of Aedes aegypti

Abstract

The effectiveness of Metarhizium anisopliae IP 46 conidia mixed with soil was tested against Aedes aegypti eggs. Mycelium and new conidia developed first on eggs between 4.8 and 15 days respectively after incubation of fungus-treated soils at 3.3 × 10(3) up to 3.3 × 10(5) conidia/g soil at 25°C and relative humidities close to saturation. After 15-day incubation, 53.3% of the eggs exposed to soil with 3.3 × 10(5) conidia/g showed external development of mycelium and conidia. Fungus-inoculated soils (but not untreated controls) showed some mycelial growth and sporulation apart from the eggs. Some eggs on treated soils hatched; those larvae died and eventually showed fungal development on their bodies. The cumulative relative eclosion of larvae after submersion of treated eggs in water decreased from 52.2% at 3.3 × 10(3) conidia/g to 25.3% at 3.3 × 10(5) conidia/g. These findings clearly showed that A. aegypti eggs can be infected by M. anisopliae when deposited on fungus-contaminated soil. The effectiveness of M. anisopliae against gravid females, larvae, and also eggs of A. aegypti underscored the possible usefulness of this fungus as a mycoinsecticide, whether naturally occurring or artificially applied, in the breeding sites of this mosquito.

New insights on the effectiveness of Metarhizium anisopliae formulation and application against Aedes aegypti eggs

“…In recent tests, the eclosion of A. aegypti larvae was also stimulated when eggs were exposed to soil mixed with water‐suspended IP 46 conidia (Leles et al . ). In multichoice tests offering water, moist filter paper or mud, gravid A. aegypti females strongly preferred to oviposit on mud (L.S.…”

“…, ; Leles et al . ). The broad insecticidal effect of M. anisopliae against both aquatic and terrestrial mosquito stages enhances the interest in this fungus for integrated control of culicid vectors as a means to diminish their transmission of diseases affecting humans and livestock.…”

“…Leles et al . () recently demonstrated that M. anisopliae conidia mixed with soil were able to infect A. aegypti eggs deposited onto the infested soil and do so at fungal titres substantially lower than those typical for spray applications of the same fungus. More information about targeted fungal application methods will contribute to the development of an effective vector control with mycoinsecticides.…”

Development of Nematophagous Fungi on Dead Adults of Aedes aegypti (Diptera: Culicidae) and Molt Inhibition Experimental

“…Another important point that deserves to be discussed is the concentration of conidia used in the in vitro control of A. aegypti. Most papers mention that concentrations may vary 10 6 -10 8 conidia/mL (Leles et al, 2011;Santos et al, 2009;Scholte et al, 2007). However, these studies focus on the use of entomopathogenic fungi.…”

Effect of formulated Metarhizium anisopliae on eggs and eclosing nymphs of Triatoma infestans

“…Entomopathogenic fungi as antagonists of insect eggs with medical importance only recently gained more interest, especially against mosquito eggs (Luz et al 2007Santos et al 2009;Leles et al 2012;Sousa et al 2013). When it comes to triatomine targets, the only published study confirmed ovicidal activity by B. bassiana in R. prolixus (Romaña and Fargues 1992).…”