Adaptation to a new host plant, Centrosema pubescens (Fabales: Leguminosae), by the phytophagous ladybird beetle, Epilachna vigintioctopunctata (Coleoptera: Coccinellidae), in tropical Asia

Abstract

The host suitability of Centrosema pubescens (Leguminosae) was evaluated within two sympatric populations feeding on Solanum plants (Solanaceae) and C. pubescens in Epilachna vigintioctopunctata in Malaysia (Kuala Lumpur) and Indonesia (Bogor and Padang). In the Bogor and Padang populations, Centrosema strains had a significantly higher emergence rate than sympatric Solanum strains. In Kuala Lumpur, there was no significant difference in emergence rates between the two strains. When Centrosema strains from Kuala Lumpur and Padang were reared and maintained solely on Solanum plants, the emergence rate on C. pubescens gradually decreased with successive rearing generation and resulted in 0% in the 7th or 20th generations. These findings suggest that the current host suitability of C. pubescens depends on the previous experience of each population with the use of this plant as a host. However, we were not able to demonstrate from laboratory selection that Solanum strains increase the host adaptation to C. pubescens because every Solanum strain became extinct in the third generation when reared solely on C. pubescens.