Parasites of the Asian tiger mosquito and other container-inhabiting mosquitoes (Diptera:Culicidae) in northcentral Florida.

Seven microorganisms including 4 protozoans, 2 fungi, and a bacterium infected Aedes albopictus (Skuse) larvae collected from 12 counties in northecentral Florida. Ae albopictus and 14 other species of mosquitoes were collected from tires, flower-holding vases in cemeteries, other types of artificial containers, and treeholes. Ascogregarina taiwanensis (Lien & Levine) was the most common parasite of Ae. albopictus throughout the year. The microsporidium Vavraia culicis (Weiser) infected Aedes aegypti (L.), Ae. albopictus, Aedes triseriatus (Say), and Orthopodomyia sinifera (Coquillett). A vibrio bacterium and 2 fungi (Leptolegnia sp. and Smittium culisetae Lichtwardt), infected Ae. albopictus larvae but were observed infrequently. A. taiwanensis, S. culisetae, and the vibrio bacterium previously have been reported from Ae. albopictus. This is the 1st report of the other 4 microorganisms parasitizing Ae. albopictus larvae.

Comparison of bi-directional Fay, omni-directional, CDC, and duplex cone traps for sampling adult Aedes albopictus and Aedes aegypti in north Florida.

We compared the number of Aedes albopictus and Aedes aegypti females collected in CDC, duplex cone, bi-directional Fay, and new omni-directional traps in a series of trials in northern Florida during 1992 and 1993. Bi-directional Fay and omni-directional traps collected significantly more Ae. albopictus females than did the other traps tested. The bi-directional Fay trap collected significantly more Ae. aegypti females than did any other trap. The results of these studies indicate that these traps may be useful tools for sampling Ae. albopictus and Ae. aegypti adults.

Distribution of Anopheles quadrimaculatus and An. crucians larvae within rice field habitats in southwestern Louisiana.

This study, conducted in 3 parishes of Louisiana, documented the distribution pattern of Anopheles quadrimaculatus and An. crucians during the first crop season. Ratios of numbers of 3rd and 4th instar larvae of An. quadrimaculatus to the number of An. crucians 3rd and 4th instar larvae (Q/C), varied both spatially and temporally. The mean Q/C ratio during 1984 was 1.37; during 1985 it was 1.40. The ratios changed from week to week during each year, and increases or decreases in a particular week of 1984 were paralleled by increases or decreases during that same week of 1985. The changes in relative abundance of the 2 species were strongly related to the timing of irrigation practices and to a succession of habitat conditions. Anopheles quadrimaculatus larvae were dominant or exclusively present for several days after fresh water was added to the field. Anopheles crucians larvae then became dominant or exclusively present as the habitat progressed towards a eutrophic condition. Irrigation influenced the conditions of the habitat by freshening and deepening the water, causing a reversion towards a more oligotrophic condition.

Release of Romanomermis culicivorax for the control of Anopheles albimanus in El Salvador I. Mass production of the nematode.

The mosquito parasite, Romanomermis culicivorax, was mass produced for the treatment of 144,000 m2 of Anopheles albimanus breeding area in El Salvador. The production of the necessary inoculum required the exposure of 1.6 X 10(6) first-instar Culex p. quinque-fasciatus larvae to 137 X 10(6) preparasites (1:14 ratio) each week for 6 weeks. The method employed produced an average 13.7 g (ca. 2,200/g) of postparasitic nematodes per rearing tray (20,000 mosquitoes), a total of 6,392 g (14.1 lb) for the 6-week period, and 425 cultures.

Release of Romanomermis culicivorax for the control of Anopheles albimanus in El Salvador II. Application of the nematode.

The mosquito breeding area of Lake Apastepeque, El Salvador, was treated 11 times over a 7-week period with Romanomermis culicivorax to control Anopheles albimanus and An. p. pseudopunctipennis. Parasitism averaged 58% but varied greatly from treatment to treatment and from site to site. However, three applications made during evening hours to avoid wind and wave action on the lake produced an average 86% parasitism. No significant differences in susceptibility to R. culicivorax were found between instars or between species. Also, no correlation was found between nematode dosage rates and levels of parasitism. Though the parasitism averaged about 60% of the desired level, Anopheles populations dropped from more than 10 per dip at the beginning of the release program to 0.6 per dip at the end of the release period (a 94% reduction). This is the first successful attempt to control mosquitoes on a large scale by using a parasite or pathogen.