The Role of Extracellular Enzymes in the Virulence of the Entomopathogenic Fungus, Verticillium lecanii, to Oat-bird Cherry Aphid, Ropalosiphum padi (Homoptera: Aphididae)

蠟蚧幹枝孢菌之分解代謝酵素對麥蚜Ropalosiphum padi（同翅目：蚜科）毒力之影響

蕭文鳳(W. F. Hsiao) ； Khachatourians, G. G.

《中華昆蟲》 17卷4期 (1997/12) Pp. iii+227-236

https://doi.org/10.6660/TESFE.1997023

摘要

The role of extracellular enzymes in the virulence of the entomopathogenic fungus, Verticillium lecanii, to the oat-bird cherry aphid, Ropalosiphum padi, was investigated in the laboratory. Wild type V. lecanii an d its UV-induced mutants have varying degrees of reaction when they were cultured on YPDA, gelatin, casein, yeast minimum medium (YMM), and glycerol media . Mutant 1219 showed a negative reaction while 1499 presented a slightly positive reaction to gelatin. Therefore, this is indicated that mutants 1219 and 1499 are protease-deficient mutants. Mutants 1499 and 1519 presented a negative reaction to casein medium. Strong reactions were found with wild type and mutants 1184, 1259, and 1346 grown on gelatin, caesin, YMM, and glycerol. Weak reactions were found with 1499 and 1519 grown on YMM and glycerol media. With the API ZYM test, all of the mutants exhibited different reactions to the substrates. In API ZYM, the absence of leucine aminopeptidase was shown on mutants 1499 (pro^-) and 1519 (pro^-), and that of acid phosphastase on strain 1519. Wild type, pro^+ mutants, and mutant 1219(pro^-) showed enzymatic activities to all the substrates. In the API rapid CH kit test, wild-type and mutants showed positive reactions to glycerol, 1-O-methyl(α-D-mannoside), 1-O-methyl(α-glucoside), amygdalin, soluble starch, glycogen, gentiobiose, L-fucose, and 5-keto-gluconate. Protease (-) mutants showed negative reactions to melezitose. V. lecanii showed a varying degree of development when cultured in aphid cuticle; however, it could not digest grasshopper cuticle. In the bioassay of wild type and mutants of V. lecanii to R. padi, wild type had the shortest LT_(50) for killing apterae (1.80 d) and alatae (2.02 d), while mutant 1499 had the longest LT_(50) (3.77 d for apterae; 4.93 d for alatae). As to fecundity, the wild type had significantly lower numbers of progeny for infected apterae (= 4.99 progeny/adult) and alatae (= 4.99 progeny/adult). The mutant 1499-infected aptera had significantly higher progeny (8.92 progeny), and mutant 1499- infected alata had 8.84 progeny.

關鍵字

Verticillium lecanii ； API systems ； Ropalosiphum padi ； mutant

並列摘要

在室內進行分解代謝酵素對蟲生真菌Verticillium lecanii對麥蚜Ropalosiphum padi的毒力生物檢定。當野生型及其紫外線誘變的變種以YPD、明膠、酪蛋白、酵母低量培養基上有不同程度的反應。以明膠培養基培養時變種1219呈負反應而變種1499有微弱的正反應，由此指出二者是解蛋白酵素不足（pro-）的變種。變種1499及1519在酪蛋白培養基培養時呈負反應。而野生型及變種1184、1259及1346在明膠及酪蛋白及YMM和甘油培養時有強烈的反應，而變種1499及1519在YMM及甘油培養基上反應微弱。由以上實驗結果變種1219、1499及1519定為解蛋白質酵素不足之變種。在接著的API ZYM測試中，所有的測試變種的反應皆不同，變種1499及1519對leucine aminopeptidase呈反應，而1519對acidphosphastase呈負反應。野生型、具解蛋白質酵素（pro^+）的變種及1219（pro^-）對所有的基質皆呈正反應。在API rapid CH測試中，所有的變種包括野生型對甘油、1-O-methyl(α-D-manoside)、1-O-methyl(α-glucoside)、amygdalin、可溶性澱粉、肝醣、gentiobios、L-fucose及5-keto-gluconate皆呈正反應，而（pro-）變種對Melezitose呈負反應。當V. lecanii無法代謝蝗蟲體皮，而對蚜蟲蛻皮則有不同程度之反應，在對麥蚜的毒性測試時，野生型處理組的LT_(50)最短，無翅型為1.8天，有翅型2.02天，而變種1499則LT_(50)最長，無翅型3.77天、有翅型4.93天。就生殖力而言，野生型處理之有翅及無翅母蟲產4.99隻。變種1499處理之無翅母蟲產8.92隻，有翅母蟲產8.84隻。

並列關鍵字

蠟蚧幹枝孢菌 ； API ZYM系統 ； 麥蚜 ； 變種