| Ahy1(Acremonium hansfordii) was isolated from the larva of Myzus persicae Sulzerwhich naturally infected in Yuzhong county of Huangjia village in Gansu province byGansu Agricultural University. Previous studied that Acremonium hansfordii played a greatrole on infection to Pieris rapae and Aphid. Host was infected by Ahy1, consumes itsprotein inside the body, destroy the protein synthesis of the tissues and organs, the body ofdetoxifying enzymes and protective enzyme lost balance. Libo Jiang had studied on thedefense reaction of Acremonium hansfordii in infection to Tetranychus urticae Koch andeffect of infection of common acaricides to its. In order to further reveal infection mode ofAhy1, understand the surface topography of Tetranychus urticae Koch affected infectionbehavior by Ahy1, invasion of variegated mites skin structure changes, the invasion processof the hyphae and top spore mold in the process of invasion of protease and chitinasefunction and change rule of extracellular enzymes, improve the top spore mould of twovariegated mite infection and infection rate. This paper focuses on the epidermal structureof Tetranychus urticae Koch affected infection behavior by Acremonium hansfordii and therelated factors for virulence, so that could be lay a theoretical basis for developing efficientand rapid creatures acaricide of Acremonium hansfordii. The results were as follows:1. It was studied on the infection process of Acremonium hansfordii conidia on cuticle ofTetranychus urticae Koch was observed using scanning electron microscopy. During theinfection process of the conidiophore as an infect unit for infection. After landing on thesurface of host, the conidiophores make physiological and biochemical reaction andstimulate their germination, through extending to produce directional property germ tube,the thallus invaded the cuticle of host could begin to grow, so destroies the immune systemof spider mite causing death.2. Studies on the activity of protease and chitinase two strains of Acremoniumhansfordii,which were cultivated for several days continuously on the culture mediumprepared with cuticle material of Tetranychus urticae Koch shows that when the two strainsmaking the inflection, the activity of protease and chitinase are in a same order. Firstly, protease at the early stage play a major role. Having degradaing the protein in the cuticle,the chitin of the cuticle is exposure, thus inducing the chitinase produced in great quantities,then decomposing the chitin in the epidermal layer by chitinase to help hyphae invading thecuticle successfully, and finally propagate into the body cavity ulteriorly. The activity andrate of increase of protease and chitinase of the strain which were cultivated on culturemedium prepared with cuticle material of Tetranychus urticae Koch that were cultivated for7d were high than that the strain cultivated continuously on SDAY. And contrast theactivity of protease of the two strains, it was found the ability for decomposing the proteinand chitin of the strain which contained cuticle material of Tetranychus urticae Koch weremore stronger than the strain cultivated continuously on SDAY.3. It focuses on the changes of activity of protease and chitinase of Acremoniumhansfordii under the action of Spirodiclofen, Buprofezin and Tebufenpyrad all of which aredifferent concentrations. The results show that different concentrations of Spirodiclofenhave no influence on the activity of protease and chitinase; while the vitality of proteaseshows slightly inhibition effect when be treated with high concentration of Buprofezinmixed Acremonium hansfordii in the first four days.However, the inhibition has nosignificant change as time pass by. And there is an irritation on the activity of protease ofthe Acremonium hansfordii under the action of low concentrated treatment. Tebufenpyradhas influence on the activity of protease and chitinase. In addition, the activity will moreobviouse either with higher concentration or the longer time.4. The activity assays and screening inhibitor for PO from Tetranychus urticae Kochwere studied．The results indicated that benzoic acid and P-hydroxy benzoic couldobviously inhibit PO activity with catechol as substrate. Under the condition of in vitro，thehalf maximal inhibitory concentration of benzoic acid and P-hydroxy benzoic were181.97g/mL and204.17g/mL. By drawing Linerweaver-Burk, it indicated the above twoinhibitor werenon-competitive inhibition and competitive inhibition. When mixing benzoicacid, p-hydroxy benzoic acid with Ahy1, it exhibited a better synergistic effect, the activityof PO had been inhibited at the same time enhanced the infection rate. Above two inhibitorrespectively mixed with Ahy1could increase the infection rate, also the half lethal time were respectively shortened for3～5days. Obviously improve the the effect of thepesticide. |
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