Metarhizium anisopliae blastospores are highly virulent to adult Aedes aegypti, an important arbovirus vector

Abstract

Background The use of entomopathogenic fungi (EPF) for the control of adult mosquitoes is a promising alternative to synthetic insecticides. Previous studies have only evaluated conidiospores against adult mosquitoes. However, blastospores, which are highly virulent against mosquito larvae and pupae, could also be effective against adults. Methods Metarhizium anisopliae (ESALQ 818 and LEF 2000) blastospores and conidia were first tested against adult Aedes aegypti by spraying insects with spore suspensions. Blastospores were then tested using an indirect contact bioassay, exposing mosquitoes to fungus-impregnated cloths. Virulence when using blastospores suspended in 20% sunflower oil was also investigated. Results Female mosquitoes sprayed with blastospores or conidia at a concentration of 108 propagules ml−1 were highly susceptible to both types of spores, resulting in 100% mortality within 7 days. However, significant differences in virulence of the isolates and propagules became apparent at 107 spores ml−1, with ESALQ 818 blastospores being more virulent than LEF 2000 blastospores. ESALQ 818 blastospores were highly virulent when mosquitoes were exposed to black cotton cloths impregnated with blastospores shortly after preparing the suspensions, but virulence declined rapidly 12 h post-application. The addition of vegetable oil to blastospores helped maintain virulence for up to 48 h. Conclusion The results showed that blastospores were more virulent to adult female Ae. aegypti than conidia when sprayed onto the insects or applied to black cloths. Vegetable oil helped maintain blastospore virulence. The results show that blastospores have potential for use in integrated vector management, although new formulations and drying techniques need to be investigated. Graphical abstract

Entomopathogenic Fungi from South Sumatra (Indonesia) Pathogenicity to Egg, Larvae, and Adult of Aedes aegypti

“…Eco-friendly alternate control uses botanical insecticides from plant extracts, attractants, and entomopathogens (pathogens that cause insect disease) (Nur Athen et al 2020;Raveen et al 2017). There are two Entomopathogens, bacteria, such as Bacillus thuringiensis (Pruszynski et al 2017) and fungi, such as Metarhizium anisopliae (Butt et al 2013;de Paula et al 2021;Leles et al 2012) and Beauveria bassiana (Lee et al 2019). Entomopathogenic fungi are one of the most widely used groups of entomopathogen agents for controlling Ae.…”

“…aegypti (Alkhaibari et al 2017) and the blastospores kill faster (only 12-24 hours) compared to the conidia (Alkhaibari et al 2016). M. anisopliae (Butt et al 2013;de Paula et al 2021;Leles et al 2012) and B. bassiana also effectively kill larvae of Ae. aegypti (Lee et al 2019).…”

Beauveria bassiana interacts with gut and hemocytes to manipulate Aedes aegypti immunity

“…Conidia and blastospores (similar to hyphal bodies) of EPF have been tested to control Ae. aegypti [ 10 , 14 , 15 , 18 ]. However, both are distinct in several ways [ 19 ].…”

Editorial: Entomopathogenic Fungi for the Control of Arthropod Pests

“…The virulence of EPF depends on the infectivity of their conidia or blastospores, propagules with distinct morphological and physiological characteristics (Mascarin et al, 2019) that in turn present advantages and disadvantages to their use (de Paula et al, 2021). In this Research Topic, Paixão et al describe two other Metarhizium robertsii propagules (microsclerotia and mycelial pellets) that are morphologically similar but differ in biomass production and tolerance to UV-B radiation and heat.…”