( ( ( Their ( main advantage ) ) ( over ( ( other insecticides ) ( currently used ) ) ) ) ( ( is ( ( their ( low toxicity ) ) ( to ( ( vertebrates and ) ( ( specific activity ) ( confined ( to ( ( insects and ) ( other arthropods ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (PRP$ Their) (JJ main) (NN advantage)) (PP (IN over) (NP (NP (JJ other) (NNS insecticides)) (VP (ADVP (RB currently)) (VBN used))))) (VP (VBZ is) (NP (NP (PRP$ their) (JJ low) (NN toxicity)) (PP (TO to) (NP (NP (NNS vertebrates)) (CC and) (NP (NP (JJ specific) (NN activity)) (VP (VBN confined) (PP (TO to) (NP (NP (NNS insects)) (CC and) (NP (JJ other) (NNS arthropods)))))))))) (. .)))
Their main advantage over other insecticides currently used is their low toxicity to vertebrates and specific activity confined to insects and other arthropods.
(ROOT (S (NP (NP (DT The) (JJ main) (NN advantage)) (PP (IN of) (NP (NN urea)))) (VP (VBZ is) (NP (PRP$ its) (ADJP (RB very) (JJ low)) (NN toxicity))) (. .)))