|Fukuda, Tok - USDA/ARS/CMAVE/RETIRED|
|Day, Johnathan - IFAS/UF|
Submitted to: American Mosquito Control Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 3, 2002
Publication Date: June 1, 2002
Citation: FUKUDA, T., KLINE, D.L., DAY, J.F. AN IRIDESCENT VIRUS AND A MICROSPORIDIUM IN THE BITING MIDGE, CULICOIDES BARBOSAI FROM FLORIDA. AMERICAN MOSQUITO CONTROL ASSOCIATION. 2002. v.18. p.128-130. Interpretive Summary: Adult biting midges affect the quality of life, decrease property values, and adversely affect tourism due to the annoyance caused by their fierce biting habits. Public outcries for relief have increased as residential neighborhoods encroach their wetland habitats. Few control options exist. Limited relief has been achieved with chemical pesticides and the use of repellents, which are much less effective against biting midges than against mosquitoes. The development of insecticide resistance and the subsequent lack of chemicals to control adult populations has increased the emphasis on habitat modification and biological control. This paper reports the discovery of an iridescent virus and a microsporidium infecting biting midge larvae by scientists at the Center for Medical, Agricultural and Veterinary Entomology, Gainesville, Florida. Studies to understand the mechanisms of infection and transmission of these pathogens may lead to their use as biological control agents.
Technical Abstract: An iridescent virus and a Nosema sp., microsporidium were found infecting larvae of the biting midge, Culicoides barbosai collected in Boyton Beach, Palm Beach County, Florida. Larvae were extracted from mud collected weekly during a 22 month period from March 1998 to December 1999. Virus infected larvae were present in 4 collections made in March, April and May 1998 and the average infection level was 4.7 percent (range 2.3-7.1). The virus infected primarily the fat body and produced an iridescent blue color in larvae due to the crystalline arrays of the particles. These virus particles were hexagonal, measured 99nm side to side and had an electron dense inner core. The site of infection of the Nosema sp. Was also the fat body of the larva which became opaque white. These opaque areas were the result of masses of oval binucleate spores measuring 2.7 plus or minus 0.1 x 4.4 plus or minus 0.3 micro meter (n plus 25). The Nosema sp. Was present in larvae of 14 collections during the entire collection period with an average infection level of 6.6 percent (range 0.6-21.4). Although individual larvae infected with the iridescent virus and Nosema sp. Occurred in 4 collections no dual infections were observed. Patently infected larvae of the iridescent virus and Nosema sp. died before pupation.