Analysis of the chemical ecological mechanism by which red imported fire ant Solenopsis invicta avoids entomopathogenic fungi
To identify the differences in avoidance behavior of red imported fire ant Solenopsis invicta towards three entomopathogenic fungi and to clarify the role of semiochemicals in the habitat selection of this ant,the selection behavior of workers in bi-directional selection devices was measured.The fun-gi tested were Beauveria bassiana,Metarhizium anisopliae,and Cordyceps javanica,using conidia-con-taining soil from different nest areas(mound,scattered,and cryptopyle types).The avoidance and motor response behavior of individual worker to conidia-containing soil were assessed using a Petri-dish selec-tivity experiment.Dynamic headspace adsorption and gas chromatography-mass spectrometry were used to analyze the differences in the response of red fire ants to volatile compounds from conidia-con-taining soils.The results showed significant avoidance behavior by workers towards soils containing B.bassiana and M.anisopliae,while no obvious avoidance was observed with C.javanica.There were significant differences in the volatiles emitted from soil with the conidia of the three entomopathogenic fungi.Volatile components of B.bassiana and M.anisopliae were relatively similar,both containing a higher proportion of esters of ketones(44.86％and 35.10％,respectively)and hydrocarbons(35.76％and 51.33％,respectively).Aldehydes were specific to B.bassiana,while pyrazines were specific to M.anisopliae.In contrast,soil with conidia of C.javanica emitted fewer volatiles,with only three volatile compounds detected.These findings indicate that the volatile compounds in conidia-containing soil af-fect the selective behavior of S.invicta workers.The lack of avoidance response of S.invicta towards C.javanica may due to the low volatile composition and content of the soil.This characteristic of C.javan-ica suggests its potential application in developing new fungal agents for controlling this insect pest.
万方数据
维普
