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Effects of pesticides on Romanomermis wuchangensis a mermithid nematode parasite of mosquito larvae
Luo Qigui;et al
The tolerance of
R. wuchangensis in different stages to pesticide was different, It was postparasitie juveniles>adults>eggs>preparasites>2nd-instar
Culex pipiens quinquefascitus. The preparasitic juveniles of
R. wuchangensis and 2nd-instar Culex were exposed to 4ppm methamidophos, 0.25 ppm dichlorvos, 0.125ppmmeothrin, 0.125ppm decis and 0.25 ppm sumieshading, after 24 hr the survival rate of the nematode were 75.6, 27.7, 95.5, 38.8, and 55.5% resepectively. All the Culex larvae were dead. The eggs of the nematode were exposed to 16 ppm methamidophos, 2ppm dichlorvos, 0.25 ppm meothrin, 0.5 ppm sumieshading and 0.125 ppm decis. Their hatching rate were 52.4, 51.06, 47.0, 53.86, and 40.58%, the hatching rate of untreated eggs was 80.88%. In the conditions of 1.0ppm methamidophos, 0.125ppm meothrin, 0.0156ppm decis, 0.0078ppm sumieshading and 0.0156ppm dichlorvos, the infection rate of infective stage
R.wuchangensis to 2nd instar
Cx. p.quinque fascitus were 71.4, 75.0, 77.5, 81.0 and 80.0%, while that of control (H
2O) was 88.0%. The treatment of postparasitic juveniles with 20 ppm methamidophos. 1 ppm meothrin, 2 ppm decis, 4 ppm sumieshading and 8 ppm dichlorvos, after 48 hr, had no obvious effect. The nematodes were able to molt, mate, and lay viable eggs.
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