摘要
本文报导了 B.S 5个不同高毒菌株在外界不同水质中的持效、再生循环性及生态学规律。2362在污水中的持效最长,投菌后第10天杀蚊幼活性(蚊幼致死率)由36.5％上升为70％,NKⅢ1—1在清水中持效也较长。经长期连续取样观察证明,近期毒效的下降主要是菌的下沉,脱离了蚊幼取食区所致。搅动后毒效的持续时间,不同菌株差异很大,1593下降迅速,而2362持续3个月以上。于投菌后15个月复查毒效完全消失,且 B.S 菌数已极少。这一结果反应出 B.S 沉降—繁殖(底层)—衰亡的过程及规律。
This article repcrts on the persistent etfccts,re- cycling characteristics and the ecological laws of five different highIy poisoning bacterium strains in diffe- rent outside waters.Persistent effects of differen strains in different waters vary greatly wthi 2362 the most durable in polluted water.On the tenth day after putting the bacteria into water,the deatht rate of mosquito larvae rises up from 36.5% to 70%. The persistent effect of NK Ⅲ 1 in clear water is comparatively more durable.Long-term,ccntincus follow-up study shows that the poisoning effect te- mporarily disappears after 10—20 days,with the nu- mber of bacteria deercaecd.Fut after stirring,the poisoning effect is regained quickly with a rise of the bacterium number.This indicates that the dfer ease of the poisoning effect results from the precipi- tation of the baeteria.Duration of the poisoning effect after stirring varies greatly amorg different bacterium strains.The effect of the bacterium strain 1093 decreaes quickly while that of the strain 2362 can remain more than three months.The poisoning effect of the bacteria vanishes entirely one year and three months after they are put into water,and very and very few B.S.remain in the water.The resu- lts of the studies reveal the whole process and hab- its of B.S.in outside waters:precipitation→repro- duction→declination.
