THUS， BECAUSE

Many entomologists say that campaigns to eradicate the fire ant in the United States have failed because the chemicals that were used were effective only in wiping out the ant’s natural enemies, thus making it easier for the ant to spread.

THUS ， BECAUSE能 一 起 用 吗 ？

多 谢

我觉得简单从语法结构上看可以， 但是在GAMT语法中，这样可能会造成语义重复，一般是错误选项，请大侠指正

campaigns to eradicate the the fire ant in the LACE>United StatesLACE> have failed because the chemicals that were used were effective only in wiping out the ant’s natural enemies, thus making it easier for the ant to spread.

抛开主句（say that...）不谈，把以上结构提出来，主谓宾很清楚了，because是上面这个句子的原因状语句子，thus V.ing结构是这个原因从句的状语部分，表示这个原因造成的后果。I don't think there is any redundancy. Thanks.