Submitted to: Journal of Invertebrate Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 15, 1996
Publication Date: N/A
Interpretive Summary: Cassava, a major subsistence crop throughout the tropical world, suffers economic damage from a relatively few insect pests; mealybugs are among the most serious such pests. A globally distributed insect-pathogenic fungus, NEOZYGITES FUMOSA, exerts significant natural biocontrol over cassava mealybugs in West Africa but has not been known previously to affect the dominant species of cassava mealybug in South America. During joint ARS/EMBRAPA studies in North-eastern Brazil in 1994, this fungus was found for the first time affecting mealybug. This study opens a real possibility that the fungus might be developed for widespread control of mealybug populations on cassava and -- if this fungus also proves to be infective to other Brazilian mealybug species -- possibly on other major crops. The recovery of Brazilian collections of the fungus (and related species affecting cassava green mites) provides significant new material to oincorporate into ongoing studies to clarify the very confused taxonomy of this genus of fungal pathogens affecting aphids, mealybugs and other scales insects, and mites worldwide.
Neozygites fumosa (Speare) Remaudiere & Keller (Zygomycetes: Entomophthor- ales) was found in 1994 for the first time as a pathogen of cassava mealy- bug, Phenacoccus herreni Cox & Williams (Hemiptera: Pseudococcidae), in Brazil. Infection levels of 9.3 - 64.6% of scales were found in fields in Cruz das Almas, Bahia. The fungus produces globose hyphal bodies (9.5 - 14.2 um diam.) in vivo and ellipsoid to broadly fusoid, tetranucleate primary conidia (16.5 +/- 0.5 8.1 +/- 0.9 um). Few secondary capillicondia and no zygospores (resting spores) were observed. The interphasic nuclei (1.2-1.8 um diameter) showed an unexpected quantity of condensed (and readily stainable) chromatin. N. fumosa is being studied further as a potentially significant biocontrol agent of cassava mealybug in Northeastern Brazil.