Study On The Pathogenicity Of Beauveria Bassiana To Gynaikothrips Ficorum

Gynaikothrips ficorum(sanoptera:Phlaeothripida)is one of the main pests in Ficus species,which damaging hosts by foraging and oviposition of nymphs and adults.This thesis screened highly pathogenic Beauveria bassiana strain against G.ficorum,and studied its biological characteristics.Analysed the compatibility and synergism between the virulence strain and low toxicity insecticides.By mean of mensurated the antioxidant enzymes,studied the stress of G.ficorum the infection by B.bassiana at different temperatures.The results as follows:1.The virulence of 12 strains B.bassiana against G.ficorum were screened out the strain with high pathogenicity by means of immersion method.The result indicated that the strains of Bsx-04 exhibited the most effective virulence against G.ficorum after inoculation with(1 ±0.5)× 107 spore·mL-1 for 9 days.Respectively for adults and nymphs,the corrected mortality were(100.00±0.00)%and(94.06± 1.20)%,the median lethal time(LT50)were(4.03±0.05)d and(4.71±0.08)d.The LCso of Bsx-04 strain to adults and nymphs were 4.786×106 spore·mL-1 and 1.849x108 spore·mL-1 on the 4th day.A time-dose-mortality model was employed to estimate parameters of time and dose,showing that Bsx-04 strain had a strong lethal effect on adult and nymphs of G.ficorum after 5 day.2.Study the mycelial growth,conidial production and spore germination rate of the Bsx-04 strain in 5 kinds of commonly used medium and different temperature conditions.The result showed that the mycelial growth of Bsx-04 strain on SDAY,PPDA and SMAY were significantly higher than those on SDA and PDA.But the conidial production were no significant among the 5 kinds of medium after 10 d.The growth and sporulation on PPDA were relatively better.In addition,the optimum temperature for the mycelial growth and sporulation of the Bsx-04 strain were from 20? to 25?,but it did not growth and sporulation at 35?.The spores could germinate in the 18?-30?,but the optimum temperature was 25?.3.Study the compatibility of Bsx-04 strain to 6 kinds of low toxicity insecticides and the virulence of toxicity insecticides ? Bsx-04-toxicity insecticides to G.ficorum.The result showed that the inhibition rate of Bsx-04 spore germination mixed Sulfoxaflo WG was the lowest,their compatibility was the best.In toxicity insecticides,Spinetoram SC and Dinotefuran SG had the best effect on the adult of G.ficorum and Dinotefuran SG had the best effect on the nymph.Sublethal concentration of Metaflumizone SC and low sublethal concentration of Sulfoxaflor WG mixed with B.bassiana individually had synergism on the adult.However,6 kinds of Bsx-04-toxicity insecticides had no synergism on the nymphs.4.Analysed the stress of antioxidant enzymes(SOD,POD and CAT)that G.ficorum were being infected by B.Bassiana at different temperatures.The result showed that the response of POD was the strongest in the temperature stress,and then SOD.while the activity of CAT was less affected by temperature under the condition of keeping the vitality of the insect.At relatively low or high temperature,3 kinds of antioxidant enzymes of G.ficorum had no significant difference with CK after being inoculated.the activities of SOD,CAT and POD were increased at initial infection stage,but dropped at the later period at the optimum temperature.The stress response of antioxidant enzymes was being ahead when the temperature made for the infection of G.Ficorum.During the infection stage,SOD was important for defending against the invasion of B.bassiana in the first,and then POD and CAT.