Pathogenicity test on cocoa mirid

The brown cocoa mirid, Sahlbergella singularis (Hemiptera: Miridae), causes cocoa yield loss of about 30 % to 70 % in Cameroon. The pathogenicity of six indigenous isolates of Beauveria bassiana (BIITAC) and Metarhizium anisopliae (MIITAC) to the fourth and fifth nymphal stages of S. singularis was evaluated under laboratory conditions. Two methods of inoculation were tested at various conidial concentrations: (1) immersing the pod in 200 ml of the suspension for 3 min (ingestion method) and (2) immersing each insect in 1 ml of the suspension for 5 s (immersion method). Tween® 80 at 0.1 % (v/v) was used as a control. After 14 days from initial exposure to conidia, corrected mortality ranged from 35 to 100% for immersion and from 16 to 94.3% for ingestion. Mortalities due to fungi isolates were significantly different from that of their control (P < 0.05). The effect of immersion was more significant than that of ingestion, and mortalities increased with increasing spore concentration. Mycelial outgrowth and sporulation after seven days on some of the dead insects, kept on humidified filter paper in dark conditions, demonstrated that death was due to fungal infection (mycosis). Based on pathogenicity results, LC50, LT50 and LT90 fungal outgrowth, B. bassiana isolates BIITAC10.3.3, BIITAC6.2.2, MIITAC6.2.2 and the M. anisopliae isolate MIITAC11.3.4 could be selected for their virulence, and advanced to field trials for the development of microbial control.

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Additional Info

Field Value
Creator Mahot, Hermine
Creator Affiliation International Institute of Tropical Agriculture (IITA)
Creator ID Type ORCID
Creator ID 0000-0003-1005-1111
Subject Vocab (AGROVOC/GACS/CAB) Cocoa, Sporulation, Mortality, Virulence, Fungi, Mirids, Bugs, Conidia, Isolation, Insects
Subject(s) Mycosis
Publisher International Institute of Tropical Agriculture (IITA)
Contributor Person Gertrude Membang, Rachid Hanna, BAD Begoude, L Bagny Beilhe, BCF Bilong
Contributor Role Other
Contributor Project Lead Organisation Center International Institute of Tropical Agriculture (IITA)
Contributor Project Lead Center International Institute of Tropical Agriculture (IITA)
Contributor CRP CGIAR Research Program on Livestock
Contributor Partner Not Applicable
Contributor Donor PROCISA /Centre d'innovation verte pour le secteur agroalimentaire
Contributor Project UN SEULE MONDE sans faim
Contributor Affiliation International Institute of Tropical Agriculture (IITA)
Open-Access status Open Access
Production Date 2015-11-07
Embargo End Date
Content Type Dataset
File Format csv
Identifier Type DOI
Identifier https://doi.org/10.25502/gr0a-p977/d
Identifier Citation "Mahot H.C., G. Membang, R. Hanna , B.A.D. Begoude, L. Bagny Beilhe & B.C.F. Bilong (2019). Laboratory assessment of virulence of Cameroonian isolates of Beauveria bassiana and Metarhizium anisopliae against mirid bugs Sahlbergella singularis Haglund (Hemiptera: Miridae)"" African Entomology 27(1): 86–96 "
Source UN SEULE MONDE sans faim
Language English
Relation Not applicable
Agroecological Zone Humid warm tropics
Coverage Region Sub-Saharan Africa
Coverage country Cameroon
Coverage Admin Unit Not applicable
Coverage X
Coverage Y
Coverage Start Date
Coverage End Date
Contact Mahot, Hermine; International Institute of Tropical Agriculture (IITA)
Contact Email H.Mahot@cgiar.org
Restriction CC-BY 4.0
Email Permission Not applicable
Rights CC-BY 4.0