Impact of imidazolium salts to reduce the infection of Bombyx mori caterpillars by Beauveria bassiana

Abstract

The silkworm, Bombyx mori L. (Lepidoptera: Bombycidae), is susceptible to several entomopathogens, including the fungus Beauveria bassiana (Bals.-Criv.) Vuill. (Hypocreales), which causes white muscardine. Aiming at effective alternatives for disease control, the effect of one pyridinium salt (PS) and seven imidazolium salts (IS) on biological parameters of this fungus – conidia germination, colony-forming units (CFU), vegetative growth, and conidia production – were evaluated in vitro. Then, the in vivo action of the IS on silkworm larvae and pupae was verified. Preventive and curative actions of selected IS for disease suppression in B. mori caterpillars were evaluated either via oral or integumentary administration. When administered daily via feeding sheets, the IS 1,3-di-n-decyl-2-methylimidazolium chloride at 100 μg ml−1 was effective in reducing the mortality of caterpillars by the fungal infection. In addition, it did not show any negative effects on developing B. mori larvae. Therefore, 1,3-di-n-decyl-2-methylimidazolium chloride can be an effective tool in the management of white muscardine in silkworm rearing houses.