Incidence of Aspergillus flavus in roasted and raw groundnuts from supermarkets and other vendors in Pietermaritzburg, South Africa and its management using biological control agents

2017 ◽  
Vol 50 (15-16) ◽  
pp. 815-827
Author(s):  
Kwasi Sackey Yobo ◽  
Phiwokuhle Mazibuko ◽  
Reshika Kallideen ◽  
Mark Delmege Laing
Keyword(s):  
South Africa ◽  
Biological Control ◽  
Aspergillus Flavus ◽  
Biological Control Agents

Identification of Aspergillus flavus Isolates as Potential Biocontrol Agents of Aflatoxin Contamination in Crops

2013 ◽  
Vol 76 (6) ◽  
pp. 1051-1055 ◽  
Author(s):  
L. J. ROSADA ◽  
J. R. SANT'ANNA ◽  
C. C. S. FRANCO ◽  
G. N. M. ESQUISSATO ◽  
P. A. S. R. SANTOS ◽  
...  
Keyword(s):  
Biological Control ◽  
Aspergillus Flavus ◽  
Filamentous Fungus ◽  
Microscopic Examination ◽  
Genetic Recombination ◽  
Aflatoxin Contamination ◽  
Biocontrol Agents ◽  
Biological Control Agents ◽  
Nit Mutants ◽  
The Stability

Aspergillus flavus, a haploid organism found worldwide in a variety of crops, including maize, cottonseed, almond, pistachio, and peanut, causes substantial and recurrent worldwide economic liabilities. This filamentous fungus produces aflatoxins (AFLs) B1 and B2, which are among the most carcinogenic compounds from nature, acutely hepatotoxic and immunosuppressive. Recent efforts to reduce AFL contamination in crops have focused on the use of nonaflatoxigenic A. flavus strains as biological control agents. Such agents are applied to soil to competitively exclude native AFL strains from crops and thereby reduce AFL contamination. Because the possibility of genetic recombination in A. flavus could influence the stability of biocontrol strains with the production of novel AFL phenotypes, this article assesses the diversity of vegetative compatibility reactions in isolates of A. flavus to identify heterokaryon self-incompatible (HSI) strains among nonaflatoxigenic isolates, which would be used as biological controls of AFL contamination in crops. Nitrate nonutilizing (nit) mutants were recovered from 25 A. flavus isolates, and based on vegetative complementation between nit mutants and on the microscopic examination of the number of hyphal fusions, five nonaflatoxigenic (6, 7, 9 to 11) and two nontoxigenic (8 and 12) isolates of A. flavus were phenotypically characterized as HSI. Because the number of hyphal fusions is reduced in HSI strains, impairing both heterokaryon formation and the genetic exchanges with aflatoxigenic strains, the HSI isolates characterized here, especially isolates 8 and 12, are potential agents for reducing AFL contamination in crops.

scholarly journals First Screening of Entomopathogenic Nematodes and Fungus as Biocontrol Agents against an Emerging Pest of Sugarcane, Cacosceles newmannii (Coleoptera: Cerambycidae)

Insects ◽  
2019 ◽  
Vol 10 (4) ◽  
pp. 117 ◽  
Author(s):  
Marion Javal ◽  
John S. Terblanche ◽  
Desmond E. Conlong ◽  
Antoinette P. Malan
Keyword(s):  
South Africa ◽  
Biological Control ◽  
Chemical Control ◽  
Entomopathogenic Nematodes ◽  
Biocontrol Agents ◽  
Sugar Production ◽  
Biological Control Agents ◽  
Sugarcane Stalk ◽  
Reduce Sugar ◽  
Steinernema Yirgalemense

Cacosceles newmannii (Coleoptera: Cerambycidae) is an emerging pest of sugarcane in South Africa. The larvae of this cerambycid beetle live within the sugarcane stalk and drill galleries that considerably reduce sugar production. To provide an alternative to chemical control, entomopathogenic nematodes and fungus were investigated as potential biological control agents to be used in an integrated pest management system. The nematodes Steinernema yirgalemense, S. jeffreyense, Heterorhabditis indica, and different concentrations of the fungus Metarhizium pinghaense were screened for efficacy (i.e., mortality rate) against larvae of C. newmannii. The different biocontrol agents used, revealed a low level of pathogenicity to C. newmannii larvae, when compared to control treatments.

Seasonal abundance and parasitism of Mesoclanis seed flies (Diptera: Tephritidae) in South Africa, and implications for the biological control of Chrysanthemoides monilifera (Asteraceae) in Australia

1998 ◽  
Vol 88 (4) ◽  
pp. 407-414 ◽  
Author(s):  
P.B. Edwards
Keyword(s):  
South Africa ◽  
Biological Control ◽  
Nature Reserve ◽  
Seasonal Abundance ◽  
Western Cape ◽  
Flowering Period ◽  
Eastern Cape ◽  
Biological Control Agents ◽  
Kwazulu Natal

AbstractThe seasonal abundance and rates of parasitism of three species of Mesoclanis seed flies was studied in South Africa. The three species occur on Chrysanthemoides monilifera, and were recorded during most months of the year, whenever C. monilifera was flowering. At three sites in KwaZulu-Natal, numbers of eggs per capitulum of Mesoclanis polana Munro were highest on C. monilifera rotundata between June and November (winter/spring), towards the end of the main flowering flush. Parasitism of M. polana was between 50% and 90% for most of the year. Two other species of Mesoclanis (M. magnipalpis Bezzi and M. dubia Walker) occurred together on C. m. rotundata in the Eastern Cape (St Francis Bay), where parasitism during the year was between 55% and 95%. Peak numbers of eggs per capitulum (M. magnipalpis and M. dubia combined) occurred in May/June (winter), in the latter part of the main flowering flush. Mesoclanis magnipalpis was the only species recorded on C. m. pisifera in De Hoop Nature Reserve (Western Cape), where there was only one peak of oviposition (May/June), coinciding with the short and discrete flowering period of this subspecies. Parasitism was between 50% and 65%. At least nine species of parasitoid were reared from immature Mesoclanis stages. Eurytoma sp. (Eurytomidae) was a dominant parasitoid at all sites. Results are discussed in relation to the possible effectiveness of species of Mesoclanis seed flies as biological control agents of C. monilifera in Australia.

scholarly journals Insect Herbivores Associated with Nymphaea mexicana (Nymphaeaceae) in Southern United States: Potential Biological Control Agents for South Africa

2020 ◽  
Vol 103 (1) ◽  
pp. 54
Author(s):  
Megan K. Reid ◽  
Julie A. Coetzee ◽  
Martin P. Hill ◽  
Rodrigo Diaz ◽  
Lyn A. Gettys ◽  
...  
Keyword(s):  
United States ◽  
South Africa ◽  
Biological Control ◽  
Southern United States ◽  
Insect Herbivores ◽  
Biological Control Agents

Reduction in Aflatoxin Content of Maize by Atoxigenic Strains of Aspergillus flavus

1991 ◽  
Vol 54 (8) ◽  
pp. 623-626 ◽  
Author(s):  
ROBERT L. BROWN ◽  
PETER J. COTTY ◽  
THOMAS E. CLEVELAND
Keyword(s):  
Biological Control ◽  
Aspergillus Flavus ◽  
Aflatoxin Contamination ◽  
Biological Control Agents ◽  
Field Plot ◽  
Toxigenic Strain ◽  
Aflatoxin Content ◽  
Potential Use

In field plot experiments, an atoxigenic strain of Aspergillus flavus interfered with preharvest aflatoxin contamination of corn when applied either simultaneously with or one day prior to a toxigenic strain. The atoxigenic strain reduced preharvest aflatoxin contamination 80 to 95%. The atoxigenic strain was also effective in reducing postharvest aflatoxin contamination caused by both an introduced toxigenic strain and by strains resident on the kernels. The results suggest that atoxigenic strains of A. flavus may have potential use as biological control agents directed at reducing both preharvest and postharvest aflatoxin contamination of corn.

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