Host Range Expansion by the Invasive HerbivoreCorythucha marmorata (Uhler, 1878) is not Causedby Better Quality of New Hosts

Abstract

Phytophagous insects may become serious pests of crops when introduced into a new place. Betternutritional quality and lower toxicity of new host plants and escape from natural enemies can enhancesurvival. The chrysanthemum lace bug, Corythucha marmorata (Hemiptera: Tingidae), is native to NorthAmerica, where it exploits mainly goldenrod and its relatives (Asteraceae). It was accidentally introducedinto Japan by about 2000. Since then, many reports of injury to sweet potato (Convolvulaceae) andeggplant (Solanaceae) by this species have been published. Here, we tested larval performance ongoldenrod, sweet potato, eggplant, and three other known or potential host plants to investigate whythe lace bug began to exploit the new host plants. Survival to adult stage was nil on eggplant, extremelylow on blue daze (Convolvulaceae) and crown daisy (Asteraceae), moderate on sweet potato, and ca.80% on goldenrod and sunflower. Developmental time was shorter and adults grew larger on goldenrodand sunflower than on the other plants. These results show that plant nutritional or toxicological qualitiesare not major factors that facilitate host range expansion of C. marmorata in Japan. Possible factors arediscussed.