11 research outputs found
Evaluation naturelle de lâimpact de Beauveria bassiana : Champignon enthomopathogĂšne dans la dynamique de population de Hypothenemus hampei, scolyte de baies des cerises de Coffea canefora
A study of finding out natural enemies of the coffee cherry borer beetle Coffea canephora, Hypothenemus hampei (Ferrari) (Coleoptera, Scolytidae) was carried out at two ecologically different sites of Cameroon: Nkoemvone in the South region of the country and Nkolbisson around Yaoundé in the central region. For six months, 500 berries were randomly collected monthly at each site. The presence of entomopathogenic fungus was observed on berries infested by the borer beetle. Rates of borer insect mortality due to Bauveria bassiana at Nkoemvone are: 70.6% in August, 64.6% in September, 32% in October, 43.2% in November, 39.2% in December and very low in January (8.6%). On the other hand, these rates at Nkolbisson are: 42.6% in October, 10% in November, 3.4% in December, 2.6% in January, 1.4% in February and 0% in March. From these observations, it was possible to carry out a research on the pathogenicity tests through its natural presence and on artificial-infection trials of the borer beetle with this fungus in order to protect better the coffee grains with a biological product
QualitĂ© du cacao camerounais : Facteurs influençant la prĂ©sence et lâactivitĂ© des moisissures productrices de lâochratoxine A (OTA)
La qualitĂ© du cacao peut ĂȘtre influencĂ©e par la microflore fongique, en particulier toxinogĂšne. Des cabosses de cacao, rĂ©coltĂ©es dans la rĂ©gion de Kumba au Cameroun, ont subi deux types de traitements post-rĂ©colte (fermentation en caisse et en tas de cabosses saines ou blessĂ©es). La numĂ©ration des moisissures contaminantes donne une teneur maximalede 5,5 ± 1,4 x 107 CFU.g-1. Quel que soit lâĂ©tat des cabosses traitĂ©es et le type de traitement, la microflore fongique totale reste qualitativement identique. Elle est essentiellement constituĂ©e dâAspergillus niger aggregate, A. carbonarius, A. flavus, A. tamari, A. fumigatus, Penicillium sclerotiorum, P. crustosum, P. paneum, Fusarium spp. LâĂ©tude de la toxinogĂ©nĂšse montre que, parmi les souches isolĂ©es, seuls Aspergillus carbonarius et A. niger sont capables de produire lâOTA avec desteneurs maximales Ă©gales Ă 2.772 ng/g et 3,6 ng/g respectivement. Le cacao issu des cabosses abĂźmĂ©es est le plus contaminĂ© par les moisissures toxinogĂšnes et donc par lâOTA. LâĂ©tude des conditions de toxinogĂ©nĂšse de A. carbonarius montre une forte sensibilitĂ© Ă lâactivitĂ© de lâeau du milieu.. Cocoa quality can be influenced by the fungal microflora, in particular the toxinogenic one. Cocoa pods, harvested in Kumba region of Cameroon, were submitted to two types of post - harvest treatments (fermentation in boxes and in heap of healthy either wounded cocoa pods). The numeration of contaminating moulds gives a maximal content of5.5 ± 1.4 x 107 UCF.g-1. Whatever the state of treated pods is and the type of treatment, the total fungal microflora remained qualitatively identical. It is essentially constituted of Aspergillus niger aggregate, A. carbonarius, A. flavus, A. tamari, A. fumigatus, Penicillium sclerotiorum, P. crustosum, P. paneum, Fusarium spp,. The study of the toxinogenesisshows that, among isolated strains, only Aspergillus carbonariuses and A. niger are able to produce Ochratoxin A with respective maximal contents of 2.772 ng/g and 3,6 ng/g. The cocoa from damaged pods is more contaminated by toxinogenic moulds and therefore by Ochratoxin A. The study of toxinogenic conditions of A. carbonarius shows a strong sensitivity to the water activity of the media.
EVALUATION NATURELLE DE L\u2019IMPACT DE BEAUVERIA BASSIANA : CHAMPIGNON ENTHOMOPATHOG\uc9NE DANS LA DYNAMIQUE DE POPULATION DE HYPOTHENEMUS HAMPEI , SCOLYTE DE BAIES DES CERISES DE COFFEA CANEFORA COFFEA CANEFORA
A study of finding out natural enemies of the coffee cherry borer
beetle Coffea canephora , Hypothenemus hampei (Ferrari) (Coleoptera,
Scolytidae) was carried out at two ecologically different sites of
Cameroon: Nkoemvone in the South region of the country and Nkolbisson
around Yaound\ue9 in the central region. For six months, 500 berries
were randomly collected monthly at each site. The presence of
entomopathogenic fungus was observed on berries infested by the borer
beetle. Rates of borer insect mortality due to Bauveria bassiana at
Nkoemvone are: 70.6% in August, 64.6% in September, 32% in October,
43.2% in November, 39.2% in December and very low in January (8.6%). On
the other hand, these rates at Nkolbisson are: 42.6% in October, 10% in
November, 3.4% in December, 2.6% in January, 1.4% in February and 0% in
March. From these observations, it was possible to carry out a research
on the pathogenicity tests through its natural presence and on
artificial-infection trials of the borer beetle with this fungus in
order to protect better the coffee grains with a biological product.Une \ue9tude de recherche des ennemis naturels contre le scolyte des
cerises de caf\ue9ier Coffea canephora , Hypothenemus hampei
(Ferrari) (Coleoptera, Scolytidae), a \ue9t\ue9 men\ue9e dans
deux sites au Cameroun : Nkoemvone une r\ue9gion du Sud du pays et
Nkolbisson pr\ue8s de Yaound\ue9, une r\ue9gion du centre.
Pendant six mois, 500 baies \ue9taient mensuellement
pr\ue9lev\ue9es de mani\ue8re al\ue9atoire dans chaque site. La
pr\ue9sence du champignon entomopathog\ue8nes a \ue9t\ue9
observ\ue9e sur les baies attaqu\ue9es par les scolytes. Les taux
de mortalit\ue9 du scolyte due \ue0 Bauveria bassiana \ue0
Nkoemvone sont de 70,6 en ao\ufbt, 64,6% en septembre, 32% en
octobre, 43,2% en Novembre, 39,2% en d\ue9cembre et tr\ue8s faible
en janvier (8,6%). Par contre ce taux \ue0 Nkolbisson est de 42,6% en
octobre, 10% en Novembre, 3,4% en d\ue9cembre, 2,6%en janvier, 1,4%
en f\ue9vrier et 0% en Mars. A partir de ces observations, il a
\ue9t\ue9 possible de proposer par sa pr\ue9sence naturel une
cherche sur le test de pathogenicit\ue9 et des essais
d\u2019infection artificielle du scolyte avec ce champignon \ue0 fin
mieux prot\ue9ger les grains de caf\ue9ier avec un produit
biologique