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

Abstract

Significance and Impact of the Study: The entomopathogenic fungus Metarhizium anisopliae has been extensively studied as a potential agent for biological mosquito control. This study demonstrates the potential of M. anisopliae s.l. strain IP 46, which can infect adults, larvae and eggs of Aedes aegypti, against the eggs of this important vector species by indirect applications of oil-based conidial formulations. AbstractIncreasing needs for innovative control tools against the dengue vector Aedes aegypti have prompted investigations into the development of specific mycoinsecticides. The entomopathogenic fungus Metarhizium anisopliae attacks both larval and adult stages, but its ovicidal activity against A. aegypti is still little explored. This study reports important findings about the effectiveness of conidia formulated in water and oil-in-water emulsions and of direct and indirect application techniques against A. aegypti eggs. The ovicidal activity of M. anisopliae increased with higher conidial concentrations regardless of the application technique, and larvae elimination concentrations were lowest with oil-in-water-formulated conidia (LEC 50 ≤ 4Á8 9 10 3 conidia cm À2 and LEC 90 ≤ 1Á9 9 10 5 conidia cm À2 , respectively). Conidia eventually stimulated larval eclosion. Consequently, the indirect application of oil-based fungal formulations onto substrates where oviposition will later occur appears to be a more efficient means to infect those eggs than the direct fungal application to previously deposited eggs.

Control methods against invasive Aedes mosquitoes in Europe: a review

“…The ovicidal activity of M. anisopliae was also demonstrated on Ae. aegypti eggs, particularly with oil‐and‐water‐formulated conidia . The application of oil‐based fungal formulations onto oviposition substrates appeared to be more effective at infecting eggs than direct fungal application, and required less fungal material.…”

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

“…; Sousa et al. ). When it comes to triatomine targets, the only published study confirmed ovicidal activity by B. bassiana in R. prolixus (Romaña and Fargues ).…”

“…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).…”

Survival and development of immature Aedes aegypti in artificial desiccating breeding sites under laboratory conditions

“…Conidia of the entomopathogenic fungus Metarhizium anisopliae applied to A. aegypti eggs, and the development of this fungus on the eggs also stimulated eclosion of larvae in the following 2 weeks in a moist chamber, but no larvae survived such fungal exposures (Sousa et al. ).…”