UV‐B radiation reduces in vitro germination of Metarhizium anisopliae s.l. but does not affect virulence in fungus‐treated Aedes aegypti adults and development on dead mosquitoes

Abstract

Aims Control of diurnal Aedes aegypti with mycoinsecticides should consider the exposure of fungus‐treated adults to sunlight, and especially to UV‐B radiation that might affect activity of conidia applied on the mosquito′s surface. Methods and Results Germination of Metarhizium anisopliae s.l. IP 46 conidia on SDAY medium was not affected at the lowest level of radiation with UV‐B, 0·69 kJ m−2, but was retarded and reduced at higher 2·075 and 4·15 kJ m−2, and completely inhibited at ≥8·3 kJ m−2. In contrast, germination of conidia applied onto fibreglass nettings and exposed from 0 to 16·6 kJ m−2 did not differ significantly among levels of irradiance exposure and the controls. There was also no significant impact of UV‐B up to 16·6 kJ m−2 on the adulticidal activity of IP 46 and on the subsequent conidiogenesis on cadavers. The Quaite‐weighted UV‐B irradiance in the laboratory (1152 mW m−2) was higher than the natural sunlight irradiance observed in the city of Goiânia in Central Brazil on midday (706 mW m−2 in August to 911 mW m−2 in October 2015). Conclusions UV‐B does not impair the activity of IP 46 conidia applied previously to radiation on A. aegypti adults. Significance and Impact of the Study Findings contribute to a better understanding of the effectiveness of M. anisopliae against day‐active A. aegypti and its potential for biological mosquito control.