Susceptibility of Romanomermis culicivorax (Nematoda: Mermithidae) postparasites to agrichemicals used in Louisiana rice production.

Susceptibility of Romanomermis culicivorax postparasites to riceland agrichemicals was evaluated during 1983. Nematode mortalities for all agrichemicals at 2 days posttreatment ranged from 0 to 11.4% with fentin hydroxide + urea responsible for the highest mortality. Fertilizers were significantly more toxic to nematodes at 2 and 25 days posttreatment than were insecticides. Carbofuran and methyl parathion produced less than 1% mortalities at 2 days and less than 5% mortalities at 25 days posttreatment. Approximately 80-84% of the surviving females exposed to insecticides as postparasites became gravid. Infectivity of the subsequent F1 generation preparasites resulted in greater than 92% parasitism in Culex quinquefasciatus larvae, except those produced by nematodes exposed to carbofuran (76.4%), 2,4-D (70.9%) and fentin hydroxide (67.4%).