Multifunctional Grasslands in a Changing World Volume Ⅱ 瞯 8 35 瞯 ]
Study on the current dituation of caragana seed pests and their methods of invasion in Inner Mongolia
Jin H ua , X ing Qi SU , Lenggaow a G rassland Investigation and Design Institute in Inner Mongolia , huhhot , 010051 , E‐mail : cky j inhua＠ yahoo .Com .cn
Key words : Caragana seed , Seed pest ; methods of invasion , invading degree ,Control pests ‐ Cultivated caragana fabr . are generally called caragana . Their great adaptability and rapid self reproduction make them effective in control６li６ng soil erosion . Moreover , they are useful１a６s industrial raw materials , feed , wood , fuel , oil and fertilizer . Presently ＇there are species of caragan、a fabr . in China , and of them are located in Inner Mongolia where the main cultivated species are caragana korshinskii kom caragana intermedia and caragana microphylla Lam . Since the area of cultivation of caragan１a０h０a０‐s been increasing recently , the price of caragana seed has also risen . However , problems such as low germination and low grain weight , which are mostly caused by seed pests , impede the developm３ e１n２t of the caragana seed industry . Study on caragana seed sho９ws５１th％at the average loss of weight in every thousands seeds is . g , and the average decre４a０s％e in germination rate reaches . because of seed pests in Inner Mongolia . The percentage of damaged seeds is about in Hanjinqi , Inner Mongolia . Therefore caragana seed pests are the main factors hindering the development of the caragana seed industry . ２００３ An investigation in July showed that caragana seed pests of bruchophagus neocaraganae , kytorhinus immixtus and etiella zinchenella spread widely in Inner Mongolia . Accordin＋g ＋to the cl４a０s％sification criterion for the degree of pest invasion ,＋th＋e invad６i０n％g degree in every sample point was higher than ＋, ＋wi＋th sample points having invasion values higher than and sample points with invading degrees higher than . Evidently , the damage caused by seed pests was immense .
On the other hand , percentage ３o９f d５a５m％aged seeds varied in the different areas . The seed pests badly invaded caragana seeds３１in ９O５r％dos , where the damage was . ; it was slightly lower in２X０ il３in２g％uole２w３ h７e０re％ the perc１e４nta８g２e％ of damaged seeds was . . Correspondingly , the percentage of damaged seeds were . , . , and . in Chifeng , Hohhot and Tongliao , respectively . 摧 The three seed pests methods of invasion are as following : kytorhinus immixtus adults oviposit on the peels , and after hatching , the larvae bore into fruit under the eggshell , then bore in seed by holing the hilum ; etiella zinchenella adults oviposit under the calyx , and after hatching , the larvae bore into dorsal suture under eggshell ; bruchophagus neocaraganae adults oviposit in seed .
The study also evaluated chemical and biological control methods for caragana８s０e％ed pests . The field experiments revealed that preventative chemical control methods achieved and efficiency r２ea０c０h４ing over . However , using natural enemies are the more important measures to control pests . Since March in , we conducted a study on parasite of bruchophagus neocaraganae and kytorhinus immixtus by investigating seeds that had been collected the previous year . The result showed that natural enemies of these pests were apanteles sp . ,bracon nigrovufum ( Cushman) and eulophidae . References ２００２ NI３U ３X５i‐w３６u , .Cultivating caragana to control the sandstorm . Soil and Water Conservation Science and Technology in Shanxi , . １９９６ Grassland o f ZHCAhNinGa ６Enh２o５‐u３,０GE Gentana , . Study on numerical taxonomy of genus caragana fabr . in Inner Mongolia . , . １９９７ China Forestry Press , ３８８‐４８５ ZHANG Zhizhong , .Forest Entomology .Beijing : .
Grasslands/Rangelands Production Systems——— Integrated Management of Harmful Organisms of Grasslands/Rangelands