Acta Entomologica Sinica (2000) 43, 264-270

Shu-Qing Wan, Han-Hong Xu, Shan-Huan Zhao, Zhi-Zhen Shang and Zhun Liu (2000)
Phototoxicity of synthetic polyacetylenes against mosquito larvae (Culex quinquefasciatus)
Acta Entomologica Sinica 43 (3), 264-270
Abstract: Eleven new synthetic polyacetylenes were screened for their biological activity to the 4th instar larvae of the mosquito Culex quinquefasciatus. The toxicities of some compounds to the tested insects were found to be enhanced greatly by irradiation with near-UV. Compound 5 (1-phenyl-4-(3,4-methylenedioxy) -phenyl-diacetylene) is an effective photosensitizer, of which LC₅₀ + UV-A (in the presence of UV-A) and LC₅₀ - UV-A (in the absence of UV-A) to the larvae were 0.35 µg/mL and 8.89 µg/L respectively. The ratio of photoactivity [(LC₅₀ - UV-A) / (LC₅₀ + UV-A) ] was 25.65.. The results in simulated field experiment showed the phototoxicity of compound 5 also was enhanced greatly to the tested larvae by sunlight. The mortality of presence and absence of sunlight were 81.63 and 11.40 percent respectively. The result of preliminary experiment by adding different kinds of antioxidants showed the compound 5 belongs to the type of yielding superoxygen radical in organism and it differs from alpha-terthienyl (alpha-T) in the mechanism of photodynamic action. The analysis of structure-bioactivity shows that diacetylene of biphenyl-containing derivatives has higher activity in photoxicity than diacetylene of bialkyl substitute. Different substitutes on phenyl also affect its effect, the order in activity is methylene dioxy>methoxy>o-nitro > m-nitro > methyl ester.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
(original language: Chinese)

Research topic(s) for pests/diseases/weeds:
control - general

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Culex quinquefasciatus