Effects of Serratia marcescens (SM1) and its interaction with common biocontrol agents on the termite, Odontotermes formosanus (Shiraki).

Odontotermes formosanus (Shiraki), a black-winged subterranean termite, is a common forest pest. A red pigment-producing bacterial strain isolated from the termite was identified as Serratia marcescens and named SM1. A bioassay of SM1 on O. formosanus show that the LD₅₀ ranged from 1.77 × 10⁴ to 10.82 × 10⁴ cells/termite over 21–39 h. Three biological control agents, Beauveria bassiana (2 × 10¹⁰ cells/mL), Metarhizium anisopliae (1 × 10¹⁰ cells/mL) and Bacillus thuringiensis (1.6 × 10⁸ IU/mL), were used for an O. formosanus bioassay. The results show that the insecticidal effect of B. bassiana was stronger than that of M. anisopliae. In addition, two mixtures were obtained by combining B. bassiana (2 × 10¹⁰ cells/mL) with SM1 (1.5 × 10¹⁰ cells/mL), and M. anisopliae (1 × 10¹⁰ cells/mL) with S. marcescens (SM1) (1.5 × 10¹⁰ cells/mL) in equal volumes. The results show that B. bassiana and SM1 was less effective than SM1 alone. However, the insecticidal effect of M. anisopliae and SM1 was better than that of M. anisopliae or SM1 individually. These studies provide an important contribution for termite biocontrol. [ABSTRACT FROM AUTHOR]