We investigated the nematicidal and insecticidal activities of the aqueous extract from Bidens pilosa var. radiata on pine-wood nematode (Bursaphelenchus xylophilus) and Japanese pine sawyer (Monochamus alternatus) larvae and adults, the causal agent and vector of pine wilt, respectively. The aqueous extract killed the pine-wood nematode, adults, and larvae of the vector in vitro at all concentrations tested, and the effect decreased significantly with increasing extract dilution. Repellent activity was observed on the nematode and the vector adults as well, although the activity decreased with time in case of the vector. Furthermore, the aqueous extract of B. pilosa effectively promoted approximately 3.0-9.0 mm of hyphal growth in Beauveria spp., when compared with the control treatment. A minor insecticidal effect was also observed on two species of click beetle (Cryptalaus larvatus pini and Paracalais berus), which are natural predators of the Japanese pine-sawyer larvae. Pesticidal and repellent activities of the aqueous extract observed on several organisms related to pine wilt suggest that a multifactorial approach may effectively control this devastating disease.Study Implications: Preventing infestation by adults or larvae of the Japanese pine sawyer-or killing the insect-would prevent infection by the pathogenic pinewood nematode; indeed, preventing the multiplication and migration of the nematode would prevent the tree from dying, even if infected with it. Therefore, here we explored the possibility that the nematode might be controlled by the aqueous extract or the active ingredient present in such an extract obtained from Bidens pilosa var. radiata, which, in addition to insecticidal activity against the organisms associated with pine-wilt disease, effectively promoted the growth of the natural microbial predators of the insect vector. Furthermore, being a natural product, and thus presumably harmless to pine trees, the biological control of the pine-wood nematode and the insect vector by means of this extract clearly favors environmental preservation while allowing a substantial reduction in the use of agricultural chemicals for disease control, and will surely prove useful to the scientific community and decisionmakers (forest managers and planners) involved in prospective research focused on the implementation of control strategies for pine-wilt disease.