Research On The Adaptability Of Local Insects And Weeds To Invasive Plant Flaveria Bidentis

With the prolongation of F. bidentis’s invasion, the interaction between local insects, plants and F.bidentis become more closely. Using field investigations and laboratory experiments, the diversity ofinsects and associated weeds, the ants’ function and status in the invaded area and the competition effectamong Helianthus tuberosus L, Althaea rosea,Artemisia annua L, Kochia scoparia L and ChenopodiumL in the F. bidentis’s growing area were ecophysiologically studied.6orders and13families relevant insects and Tetranychus cinnabarinus(Boisduval)were found inthe F. bidentis growing area in Baoding, which included leaf miner, defoliator, sucking insect,flower-visiting insect and insect natural enemy.It was observed that only one kind of ant moved the seeds of F. bidentis, which was identified asTetramorium caespitum(L.). About200seeds were removed every day by Tetramorium caespitum(L.).Few of them abandoned the seeds outside their anthill, most of the seeds were removed into there nests.Seed germination experiments indicated that, the seed removed into nests almost not germination, itinitially showed that the ants’ movement could impede the dispersal of F. bidentis. The removalefficiencies of Tetramorium caespitum(L.) related to temperature, only a few ants activities when thetemperature above20℃in May in Hebei, and the ants’ moving decreased with rising temperature, thecarrying mainly occurred from the night to the early morning.There were42kinds of associated weeds growing in the F. bidentis’s invaded area. So F. bidentisdid not form a single community. The weeds belonged to17families and Compositae、Gramineaeaccounted for most of them. Among them, Monocots had2families: Gramineae had9genus,Cyperaceae had1genus. Dicotyledons had15families and25genus.The field density of F. bidentiswas lower than that of the gramineae, chenopodiaceae and artemisia weeds. There were not significanceheight differences between the seeding of F. bidentis and associated weeds. In late growth stage, theaverage height for F. bidentis was lower than that of Chenopodiaceae and Artemisia. The average heightof Bidens pilosa L., Conyza Canadensis(L.)Cronq., Amaranthus retroflexus L. et al were almost same toF. bidentis’s.De Wit experiments indicated that, Helianthus tuberosus L, Artemisia annua L., Kochia scopariaL.and Chenopodium L. could compete with F. bidentis, all of them were used as replacement plants forF. bidentis potentially.When F. bidentis planted with Helianthus tuberosus L, Artemisia annua L., Kochia scoparia L.andChenopodium L. in mixture, F. bidentis’s height and biomass were inhibited significantly, and the suppression effect enhanced with the density increasing. When F. bidentis planted with that4test plantsin mixture, interspecific competition was greater than the intraspecific competition, the4test plantscould antagonize F. bidentis. When F. bidentis planted with Artemisia annua L.and Kochia scoparia L.in mixture under the ratio of4:2and2:4, they required the same resources, one of them could removeanother one by competing with it. Helianthus tuberosus L and Artemisia annua L. had better able tocompete with F. bidentis under any ratio, the competitive power of Kochia scoparia L. under the ratio of4:2and3:3, and Chenopodium L. under the ratio of4:2were better than that of F. bidentis.