Field optimization of pheromone traps for monitoring and controlling cocoa mirids, Sahlbergella singularis

Field optimization of pheromone traps for monitoring

and controlling cocoa mirids, Sahlbergella singularis

Bagny Beilhe Leïla

_{, Mahob R.}

_{, Pith Yédé}

_{, Hall D.}

_{, ten Hoopen G. M.}

_{, Babin R.}

1_{CIRAD, UPR Bioagresseurs analyse et maîtrise du risque, Montpellier, France;} 2 _{IRAD, Central Laboratory of Entomology, P.O Box 2067 IRAD-Nkolbisson,}

Yaoundé-Cameroun; 3 _{University de Yaoundé I, Faculté des Sciences, Yaoundé-Cameroun;} 4 _{Natural Resources Institute, University of Greenwich at Medway, Kent, UK;}

E-mail: leila.bagny@cirad.fr

Sahlbergella singularis Hagl., is the main pest of cocoa plantation in Cameroon

Since 1960, the fight against mirid is mainly based on chemical control but nowadays there is development of Integrated Pest

Management due to controversies over the negative effects of pesticides on environment and health

The development of synthetic sex pheromone allowed the development of pheromone trapping used for monitoring of pests and

mass trapping that should lead to reduction of pests population and associated damage

Preliminary studies showed efficiency of pheromones traps for S. singularis catching in cocoa plantation in Cameroon (Mahob et al. 2011)

for population monitornig

Two pheromones blends were efficient in Ghana (Sarfo et al. 2006) and Cameroon (Mahob et al. 2011) : Diester : Monoester in proportion

500 : 1000 et 1000 : 1000

Density of traps per ha is important for catching rate per traps (Sarfo et al. 2006)

In Cameroon experiments were already conducted in innovative plantation (pers. comm.) but not in traditional cocoa plantation

How to improve the efficiency of pheromone trapping?

Identifying traps characteristics allowing maximum S. singularis males catching

Determining traps deployment that ensure decrease in pests populations on the

field and associated damage

Tube PVC Feuille plastique engluée Diffuseur de phéromones Tube PVC Feuille plastique engluée Diffuseur de phéromones 10 0 m 100 m

The experiments take place in traditional cocoa system in Obala

10 plots to compare the attractiveness of traps of different colors and baited with different

pheromone blends: mirids populations are counted biweekly from March to December (Fig.1) 21 plots to compare traps deployment: each trap receives the most attractive pheromone

blend. Mirid associated damage are evaluated in August/September on 100 cocoa trees in different plantations (Fig.2)

Medium traps density Low traps density

10

0 m

100 m

High traps density

25 m 25 m 25 m 25 m _{25 m} 25 m 25 m 25 m 50 m 50 m 15 m 15 m Fig.2 Fig.1

The results of these experiments are still on-going

In the future, we want to evaluate the costs of use of pheromone traps

We also want to compare these costs with the costs of insecticide treatments in order to find the best trade off between

envrionmental and financial costs to set up an effective IPM in Cameroun

Sarfo, J. E., Padi, B., Hall, D. H., Downham, M. C. & Ackonor, J. B. (2006) Effects of cocoa mirid pheromone trap positioning and density on trap catches In Proceedings of the 15th International Cocoa Research Conference . Sarfo, J. E., Hall, D. H., Campbell, C. A. M., Downham, M. C. A. & Cudjoe, A. R. (2010) Improving the management of cocoa mirids, Distantiella theobroma (Dist.) and Sahlbergella singularis Hagl. (Heteroptera: Miridae) through pheromone trapping. In Proceedings of the 16th International Cocoa Research Conference