Efficacy of entomopathogenic hypocrealean fungi against Periplaneta americana.

The American cockroach Periplaneta americana, one of the worlds' most important urban insect pests was tested with entomopathogenic fungi. Most promising Metarhizium anisopliae, Metarhizium robertsii and Beauveria bassiana killed nymphs (≥ 81.7% mortality, 25 days after treatment), and these fungi developed on all dead insects. Other fungi tested were less virulent (Metarhizium frigidum and Purpureocillium lilacinum) or avirulent (Isaria cateniobliqua, Isaria farinosa, Simplicillium lanosoniveum, Sporothrix insectorum and Tolypocladium cylindrosporum). Intrageneric and intraspecific variability of fungal activity was detected. Adults were highly susceptible, and oothecae proved to be more resistant than nymphs and adults to infection with M. anisopliae IP 46. Findings of the study underscore the potential of fungi as biocontrol agents against this pest.

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

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.

Pathogenicity of some hypocrealean fungi to adult Aedes aegypti (Diptera: Culicidae).

The pathogenicity of 19 hypocrealean entomopathogenic fungi from seven different genera in adult Aedes aegypti was tested. All fungi proved to be pathogenic, and Isaria fumosorosea, Lecanicillium muscarium, Lecanicillium psalliotae, Metarhizium anisopliae, Metarhizium lepidiotae, Metarhizium majus, Metarhizium frigidum, Paecilomyces carneus, and Paecilomyces lilacinus caused total mortality within 15 days of exposure of mosquitoes to the fungal culture. All fungi developed on dead individuals. The high susceptibility of adults to most tested strains underlines the interest of entomopathogenic fungi-especially those of the genera Metarhizium, Isaria, Paecilomyces and Lecanicillium--for biological control of A. aegypti.