Preliminary Studies On The Pathogenesis Of Metarhizium To Locusta Migratoria Manilensis

In this article, two isolates of Metarhizium anisopliae were selected to study the pathogenesis in Locusta migratoria manilensis(Meyen). The histopathology, defense response of hemocytes, change of the total hemocytes, esterase activity and extracellular protease of the infected nymphs of Locusta migratoria munilensis(Meyen) were studied. The primary results are as follows:The results of histologial section observations implied that the 5-th instar nymphs integument was the major invasion route of Metarhizium anisopliae. After 72 hr of inoculation, the hyphae could be observed in the coelurn and began to reproduced in the hemocoele. And then, the epiploon, muscle tissue, malpighian tubules and digestive tract carry on a series of pathological changes.The cells in the midgut tissues were rarefaction and inner membrane were disintegrated. Most of the nymphs died at the fifth day , and the digestive tract was filled up with hyphae outside and inside.In the 5-th instar nymphs Locusta migratoria manilensis , changes in the hemocytes population were effected following the injection with the spores of the two isolate LA and LD. After 15 minutes of the injection, the total hemocytes count (T1IC) was slightly reduced than the untreated nymphs, 30 minutes later it reach the maximal level ,50% higher than the normal, then the HTC declined steadily till the nymphs died. Changes of the THC were not greatly different between the isolate LA and LD. Defence response of hemocytes in Locusta migratoria man Hens is were observered that the hemocytes could phagocytize and encapsulate the conidia of Metarhizium anisopliae , but failed to suppress the spore germination in the nomules,only taking a temporary defense response.The analytic result of esterase of infected nymphs and the healthy nymphs were analyzed with PAGE analysis show that the enzyme band number of the infected nymphs decreased and the band got more blurred, especiallyin the later infection stage. In the meantime, the activity of acetycholinesterase was lower than that of healthy one. The activity of acetychoiinesterase which was infected the isolate LA declined faster than that of the isolate LD.The production of extracellular protease of two isolates of Metarhizium anisopliac was analyzed both in gelation and in Locusta migratoria manilens is cadaver power medium. The activity of protease in cadaver power medium was higher than that in gelat ion. What is more, the' extracellular protease of two isolates of Metarhizium anisopline was also measured. The suitablest temporaluer of the isolate LA and LD was 33℃ and 27℃. There was a obvious linear relationship between protease production, either in gelation or in cadaver power medium ,and the virulence to the Locusta migratoria manilensis.