LAGENIDIUM GIGANTEUM IN CULEX TARSALIS LARVAE - PRODUCTION OF INFECTIVE PROPAGULES

Zoospore and oospore production of the entomopathogenic fungus, Lageni dium giganteum, was quantified from Culex tarsalis larvae in rice irri gation water. For the first through fourth instars, respectively, the average zoospore production (+/-SE) was 521 +/- 106, 2458 +/- 365, 10, 546 +/- 582, and 14,360 +/- 1076, and the average oospore production w as 17 +/- 1.8, 33 +/- 3.5, 44 +/- 2.6, and 34 +/- 3.1. Zoosporogenesis varied with the water sample. The ionic composition of the water samp les was significantly correlated with zoospore production. The correla tions, however, changed as different subsets of the data were analyzed , suggesting that other factors also affected zoosporogenesis. The ext ent to which a cadaver was colonized by other microorganisms had a cle ar effect on the resulting Lagenidium reproduction. The interval of pe ak zoosporogenesis occurred between 24 and 36 hr postmortem for the fi rst instar and 12 to 24 hr postmortem for the other instars. Measurabl e production was observed up to 96 hr postmortem from fourth instar la rvae. (C) 1995 Academic Press, Inc.