Brown planthopper, Nilaparvata lugens is giving enormous damage to rice production. In this work, virulence of four Beauveria bassiana isolates against brown planthoppers was investigated by applying fungal granules on the water of pots, and we further examined the growth of hypha on the rice plants from the water surcae to explain the insecticidal mode of action. We used Beauveria bassiana (Bb) ERL 836, 1170, 1575 and 1578 isolates, which produced ~2×108 conidia/g of millet grain in a solid culture. Rice seeding was grown in breeding boxes at 28±2℃ for 5 days. Mycotized millet grains were treated on the water in a box at 1 g/box and the rice seeding was infested with 18~25 brown planthopper adults per box. A chemical pesticide and water treatment served as controls. Among the treatments, Bb ERL 836-treated plants had the lowest damage, rather than the other fungal treatments in laboratory assays. Hyphal growth on the stem of rice plants was observed in Petridish conditions under a fluorescent microscopy. This work suggests a possible control of brown planthoppers using entomopathogenic fungi.

Mealworms, Tenebrio molitor (L.) is used as an important animal feed additive for growth promotion and health management, but potentially exposes to fungal infection. In this work, virulence of two species of entomopathogenic fungi against the insect, and the relationship between abiotic features and virulence were investigated. Secondly our consideration was also given to the effect of chemical fungicides on conidial germination for risk control. Between Beauveria bassiana (Bb) and Metarhizium roberstii (Mr) (previously M. anisopliae), Bb isolates had much higher virulence (~100% mortality in 3~4 days after the treatment), rather than Mr isolates in laboratory assays. Next, fungus-treated mealworms were kept at wheat bran at 20, 25, 30 and 35℃ with 3, 6, 9 times of water spray to the feeds for set-up of different humidity conditions. Inoculation of fungi to mealworms was conducted by fungal spray and feeding methods, which resulted in higher virulence in feeding method. In the feeding method, all temperature treatments except 35℃ showed high virulence against mealworms, but any significant relationship between virulence and humidity was not observed. In the chemical fungicide screening, fluazinam (CAS No. 79622-59-6) and mancozeb (8018-01-7) significantly inhibited the germination of Bb and Mr conidia. This work suggest that contamination of wheat bran with fungal pathogens, particularly B. bassiana may induce mycosis of mealworms, but introduction of effective fungicides possibly reduce fungal infection.