Submitted to: Society for Invertebrate Pathology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: May 29, 2001
Publication Date: August 1, 2001
Citation: DELALIBERA, I., HAJEK, A.E., HUMBER, R.A., CHERRY, A. LONG-TERM IMPLEMENTATION OF A CLASSICAL BIOLOGICAL PROGRAM USING A MITE PATHOGENIC SPECIES OF NEOZYGITES IN AFRICA: FROM EXPLORATION TO DETECTION ESTABLISHMENT. SOCIETY FOR INVERTEBRATE PATHOLOGY ANNUAL MEETING. 2001.
Cassava is a major food crop in many tropical regions. Cassava green mite (CGM), MONONYCHELLUS TANAJOA, became an important pest of cassava in Africa after its introduction from South America. Among South American natural enemies potentially useful for biocontrol, the fungus NEOZYGITES sp. causes mortality in CGM populations. Entomophthoralean fungi have rarely been used for classical biological control, and the NEOZYGITES project is a goo case study to show the difficulties with this group. The first exploration for Brazilian antagonists of CGM was done in 1988. We conducted studies on selection of isolates, epizootiology, non-target effects, in vivo and in vitro growth. While the steps to introduce a biological agent are similar for most pathogens, NEOZYGITES presents unique challenges not found with other pathogens. Standardizing bioassays using capilliconidia produced from mummified CGM was a major problem for strain selection. NEOZYGITES is a very fastidious pathogen, and the difficulty of isolating and growing it i vitro limited other key studies, e.g., molecular characterization for pathogen detection. However, we described a culture medium giving good growth and developed a protocol to store CGM isolates (techniques routinely used to store other fungi cryogenically were useless for CGM isolates). The CGM pathogen has been identified by some as N. FLORIDANA but we have enough physiological and molecular data to prove that this pathogen is a new species of NEOZYGITES. This new species does occur in Africa, but African strains have limited impact on CGM. Brazilian NEOZYGITES isolates were released in Benin in 1998/1999 when probes to distinguish exotic from native strains were not yet unavailable but the fate of releases of Brazilian isolates in Africa is now being monitored by molecular means.