Effects of Culture Age on the Shipment Survival of the Mosquito Parasite Romanomermis culicivorax.

were significantly lower than in second or third instars and about the same as for the fourth instars. Infection levels of firstand fourth-instar larvae exposed in mixed larval stages were significantly different (P < 0.05) than first and fourth instars exposed alone under similar conditions, whereas differences were not significant for secondand third-instar larvae. These data clearly indicated that under laboratory conditions the susceptibility of a given instar is affected by the stage of development of the mosquito popula t ion in which it is exposed. This may also be the case in nature and could be a major factor in the reduced levels of infection encountered in first-instar larvae in previously ment ioned studies (1,3). Romanomermis culcivorax: Petersen 229