Preference of Laelia coenosa for native and introduced populations of invasive Spartina alterniflora

Abstract

Exotic plants may modify their resistance to herbivory in response to new phytophagous insects in their introduced ranges. Studying the variation in such resistance may help us understand the in-depth mechanisms of plant invasions. Spartina alterniflora is one of the most serious invasive plants in China’s coastal salt marshes. Investigating how S. alterniflora responds to the phytophagous insects in the introduced ranges may partially explain the mechanism of its invasion success. We conducted choice tests under controlled conditions to compare the preferences of Laelia coenosa (native to China) for native (US) and introduced (China) S. alterniflora populations. In relation to smell, caterpillars of L. coenosa did not show any preference for native or introduced populations, but the relative choice index for taste of native populations was significantly higher than that of introduced populations. This feeding preference of the caterpillars for populations of the plant from its native range suggests that S. alterniflora has altered its defense against the native phytophagous insects in their introduced range, thereby reducing insect herbivore attacks.