A SEARCH OF MICROBES PATHOGENIC FOR DIFFICULT-TO-CONTROL INSECT PESTS

(1)基因序列分析表明，5株苏云金芽孢杆菌的Cry蛋白属于3个H血清型(Fukuoka、sotto和Galleriae)，它们的Cry蛋白属于单一种类，属于Cry9 Delta-内毒素。(2)在1713株苏云金芽孢杆菌日本分离株中，609株(35.5%)对小菜蛾有较高的杀虫活性。在这些有毒分离物中，有605株属于H型1-10型。共筛选出5株毒力较强的菌株，分属4个H血清型(住友，2株；福冈，1株；加拿大1株；(3)分离实验未能从采集于南极次大陆L-霍尔姆湾沿海地区的土壤和花卉样品中分离到苏云金芽孢杆菌。(4)从巴西蚕场的蚕病幼虫中分离到的微孢子虫的特征表明：(1)具有大中型孢子的分离株属于微孢子虫属，但与家蚕微孢子虫不同。(2)孢子较小的菌株属于侧耳属。

(1) Gene sequence analysis revealed that the Cry proteins of the five Lepidoptera-specific Bacillus thuringiensis strains, that belong to the three H serovars (fukuokaensis, sotto, and galleriae) and produce spherical parasporal inclusions, are of the single category, a novel class belonging to the Cry9 delta-endotoxin.(2) Of 1713 Japanese isolates of Bacillus thuringiensis, 609 (35.5%) exhibited high larvicidal activity against the diamondback moth, Plutella xylostella. Of these toxic isolates, 605 belonged to the H serotypes 1-10. When five selected highly toxic isolates, belonging to four H serovars (sumiyoshiensis, 2 isolates ; fukuokaensis, 1 ; canadensis 1 ; morrisoni, 1), were examined for their delta-endotoxins, the four isolates, excluding the morrisoni isolate, were assigned to the Cry9D-producing strains.(3) Isolation experiments failed to recover Bacillus thuringiensis from soils and floral samples collected in the coastal area of the L_tzow-Holm Bay of the Antarctica sub-continent.(4) Characterization of the microsporidians, isolated from diseased larvae of the silkworm (Bombyx mori) in Brazilian sericultural farms, revealed that (i) the isolates with large- to middle-sized spores belong to the genus Nosema, but differ from the species Nosema bombycis, and (ii) the isolates with small-sized spores belong to the genus Pleistophora.