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International Journal of Microbiology
Volume 2013, Article ID 276168, 9 pages
http://dx.doi.org/10.1155/2013/276168
Research Article

Abiotic and Biotic Factors Affecting Resting Spore Formation in the Mite Pathogen Neozygites floridana

1Department of Entomology and Acarology, ESALQ/University of São Paulo, 13418-900 Piracicaba, SP, Brazil
2Plant Health and Plant Protection Division, Norwegian Institute for Agricultural and Environmental Research (Bioforsk), 1432 Ås, Norway
3Department of Agronomy, Federal Rural University of Pernambuco, 52171-900 Recife, PE, Brazil

Received 21 March 2013; Revised 20 May 2013; Accepted 22 May 2013

Academic Editor: Carla Pruzzo

Copyright © 2013 Vanessa da Silveira Duarte et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Neozygites floridana is an obligate mite pathogenic fungus in the Entomophthoromycota. It has been suggested that resting spores of this fungus are produced as a strategy to survive adverse conditions. In the present study, possible mechanisms involved in the regulation of resting spore formation were investigated in the hosts Tetranychus urticae and Tetranychus evansi. Abiotic and biotic factors mimicking conditions that we, based on earlier field studies, thought might induce resting spores in temperate and tropical regions were tested with isolates from Norway and Brazil. A total of 42 combinations of conditions were tested, but only one induced the formation of a high number of resting spores in only one isolate. The Brazilian isolate ESALQ1420 produced a large number of resting spores (51.5%) in T. urticae at a temperature of 11°C, photoperiod of 10L:14D, and light intensity of 42–46 (μmol m−2 s−1) on nonsenescent plants (nondiapausing females). Resting spores of the Brazilian N. floridana isolate ESALQ1421 were found at very low levels (up to 1.0%). Small percentages of T. urticae with resting spores (0–5.0%) were found for the Norwegian isolate NCRI271/04 under the conditions tested. The percentages of resting spores found for the Norwegian isolate in our laboratory studies are similar to the prevalence reported in earlier field studies.