Perhaps you should try some spelling variations:
host plants » host plant
plants lice » plant lice, plant life, plants fires
shang hai » shang kai, dang hai, chang ha
yan yang » yang yang, yao yang, dan yang
yang oil » yang zili, yang di, yang xi
oil host » oil cost
wong yue » wang yue, hong yu
wan yan » wang yan, nan yan, wai yan

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: wan yan yang oil host plants lice ((shang hai) or (wong yue)) ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: wan yan yang oil host plants lice ((shang hai) OR (wong yue)) ;.
• Adding a wildcard symbol may retrieve word variants: wan yan yang oil host plants lice ((shang hai) or (wong yue)) ;*.