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Molecular characterization of Nosema spp. in Diatraea saccharalis and its impact on the ability of dispersion and parasitism of Cotesia flavipes in the field

Grant number: 11/21018-0
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): January 01, 2012
Effective date (End): December 31, 2012
Field of knowledge:Agronomical Sciences - Agronomy
Principal Investigator:Italo Delalibera Júnior
Grantee:Letícia Grigolon Reis
Home Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

Control of the sugarcane borer, Diatraea saccharalis (Lepidoptera: Crambidae), is conducted in more than three million hectares do to endoparasitoid Cotesia flavipes (Hymenoptera: Braconidae) releases. The major problem in the system of mass production of C. flavipes is the reduction in the rearing of D. saccharalis by the pathogen Nosema sp. (Microsporida: Nosematidae). Recently, we showed that Nosema sp. is pathogenic and changes important biological parameters of C. flavipes. The infected parasitoid also has a reduced ability to locate the host in studies conducted in olfactometers compared to healthy subjects. These results reveal that the health of the rearing can have a major economic impact on the production system and the efficiency of biological control. This project aims to study the Nosema impact in the efficiency of parasitism and dispersal of C. flavipes into sugarcane fields. Internodes of sugarcane infested with third instar caterpillar of D. saccharalis will be set at 15, 30 and 45 meters away from a central point of a concentric area where will be released C. flavipes adults. Studies will be made with healthy C. flavipes and with C. flavipes infected by Nosema sp., with 24 and 48 hours of life, released in areas far from each other. The sugarcane internode cuttings will be grouped in pairs, one of them containing a healthy caterpillar and other with a nosemose caterpillar, to study the preference of the parasitoids. After 24 hours, the caterpillars will be recovered and maintained on a diet under controlled conditions for observation of parasitism. Will be also undertaken ribosomal DNA sequencing genes of sampled isolates from 12 mills and laboratories in Sao Paulo, Minas Gerais and Goias states to help in identification of the pathogen and to characterize the diversity associated with Nosema spp. in D. saccharalis and C. flavipes in the country.