Alligator weed (Alternanthera philoxeroides) is one of the most serious exotic noxious weeds in China, theflea beetle (Agasicles hygrophila) has been introduced as a biocontrol agent for the management ofalligator weed. Recent researches find that the flea beetle also attacks the native congener sessile joyweed (A. sessilis). However, whether and how theflea beetle integrates into food webs within recipient habitats and influences nativeinsects remains unclear. 

In order to reveal the indirect trait-mediated non-target effect of biocontrol agent on nativetortoise beetleand related mechanisms,Invasion Ecology Group led by Prof.HUANG Wei from Wuhan Botanical Garden conductedrelatedanalyses. 

Field surveyrevealed that the tortoise beetle abundance wasindependent with sessile joyweed coverage, but negatively related to flea beetles abundance. In addition, non-target effect offlea beetles decreased native insect abundance on native plant according to the common garden experiment.  

Theinfluencesof flea beetle herbivory on tortoise beetle development and oviposition,andsessile joyweed metabolites were alsoinvestigated. Results illustrated that biocontrol agent flea beetle inhibited the native insect tortoise beetle through exploitation competition on the shared native plant sessile joyweed, and such exploitation competition was likely due to trait-mediated effects by reducing sessile joyweed nutritional value and inducing repellent volatile production. 

These findings remindthat great caution should be exercised in releasing a biocontrol agent, even without significant attack on non-target. 

This article entitled “ Herbivory of a biocontrol agent on a native plant causes an indirect trait-mediated non-target effect on a native insect” was published in Journal of Ecology.     

This work was funded by the National Key Research and Development Program, the National Natural Science Foundation of China, the Natural Science Foundation of Hubei Province and Application Foundation Frontier Project of Wuhan. 

  

Herbivory of flea beetle onsessile joyweed causes an indirect trait-mediated non-target effect on tortoise beetle (Image by HUANG wei)