Evaluation naturelle de l’impact de Beauveria bassiana : Champignon enthomopathogène 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

Pesticides use in cocoa sector in Cameroon: characterization of supply source, nature of actives ingredients, fashion and reasons for their utilization

The chemical control is the widely control method applied in Cameroon for pests and diseases by all the cocoa producers without technical suitable assistance by the State as before 1980’S. However, it is known that farmers have less knowledge on the good pesticides use for the control of a specific pest. The objective of this study was to provide insight in current pesticide use in the cocoa sector in Cameroon. A stratified sampling scheme was used. A total of 251 cocoa farmers, 20 post-harvest cocoa traders and 37 chemical retailers were randomly selected and interviewed. The study showed that 35 different chemicals were marketed in Cameroon for use in cocoa: 4 herbicides, 11 fungicides and 20 insecticides. Of 251 farmers consulted, 96.8% said that they use pesticides on their farms while 3.2% did not. Fungicides were used most often by farmers 61.8%) followed by insecticides (38.2%). Eight active ingredients although, officially banned, were still being used on cocoa farms. Over 77% of farmers do not respect the official spray recommendations for chemicals. Moreover, 64% do not respect recommended doses. Two main pesticide-supply-pathways exist in Cameroon: a legal and illegal supply chain, which provides 51% of pesticides to cocoa farmers, resulting in an estimated loss of value added tax for the Cameroonian government of about 550 000 to 2.4 million Euros per year. These results suggest that improved pests and diseases control by the State and raising farmer awareness about pesticide use in cocoa could greatly attribute to more sustainable cocoa economy in Cameroon.Keywords : Cocoa, pesticides, insecticides, fungicides, Cameroon

Pheromone traps and climate variations influence populations of Sahlbergella singularis (Hemiptera: Miridae) and associated damage of cocoa in Cameroon

Knowledge of insect pest ecology and biology is important for maximizing crop protection and reducing crop losses. Currently, we lack an efficient control program for the cocoa mirid Sahlbergella singularis Haglund (Hemiptera: Miridae), the principal insect pest of cocoa in West and Central Africa. A 2-yr study was conducted in 11 plantations across Ayos and Konye, two of the largest cocoa growing areas of Cameroon. We evaluated the effects of mirid sex pheromone and climatic variations on mirid population dynamics and their associated cocoa damage. Sex pheromone traps caught 1.5-fold higher mirids in Ayos than in Konye, with more overall counts in 2015 than in 2016. Cocoa pod counts were also significantly higher in 2015 than in 2016 and were negatively correlated with temperature and relative humidity. In both localities, mirid populations and associated cocoa pod damage were suppressed in plantations where sex pheromone traps were used. Damage incidence was positively correlated with mirid counts, confirming that the cocoa pod is the preferential site for mirid feeding and reproduction. As such, damage incidence could be used as proxy for comparative mirid population level due to the mirid’s cryptic habit. Of the recorded weather variables, only relative humidity was correlated (negatively) with damage severity. Our data on the relationships between damage caused by mirids and their population dynamics and sex pheromone trap catches suggest that an effective control strategy using mass trapping could be developed for mirid management in cocoa plantations