Successful Establishment and Subsequent Recycling of Romanomermis Culicivorax (Mermithidae: Nematoda) in a California Rice Field Following Postparasite Application

An early season application of postparasites of the mosquito-parasitic nematode Romanomermis culicivorax demonstrated that the nematodes could mature to adults, mate, and lay eggs in the rice field environment. Preparasites hatching from these eggs provided continuous partial control of larval Anopheles freeborni and Culex tarsalis throughout the rice growing season. Control of An. freeborni was comparable to that obtained in the past by direct applications of preparasites and exceeded that achieved previously for Cx. tarsalis . The mean weekly infection level for both species exceeded 60%. Infection was observed up to 12 m from the original point of application. R. culicivorax successfully overwintered within the rice check and again parasitized mosquitoes the following summer.