Biological control of soil-dwelling pests in traditional cacao agroforests of Cameroon using encapsulated CO2 associated with endophytic fungi

The project aims to explore the potential efficacy of entomopathogenic fungi isolated from cacao leaves in combination with CO₂ for termite control. We will determine whether subterranean termites are attracted to CO₂ sources by behavioral observations in the laboratory and in the field. In addition, we will test a variety of CO₂-generating sources for behavioral effects in the laboratory and in the field. We will explore the potential antagonistic activity of several strains of entomopathogenic fungi against subterranean termites, aiming at elucidating their possible mechanism of antagonism in a two-step process using a non-destructive behavioral observation device: in step 1 we will quantify the distribution of subterranean termites to evaluate the attractiveness of CO₂ emitting capsules. In step 2 we will assess the attract and kill strategy (A&K) by combining CO₂ emitting capsules with isolated strains of entomopathogenic fungi to evaluate the potential of this approach to enhance the control efficacy of subterranean termites over a conventional application. Finally, we will compare the differences in virulence and in vivo growth kinetics of these isolates of entomopathogenic fungi using qt-PCR analysis. Based on the findings that the diversity of fungal endophytes differs with land use management and environmental factors, we hypothesize that these endophytes, isolated from cacao leaves may be good biological control candidates against termites when associated with CO₂. We definitely expect that in case the system (A&K) works for termites and cacao, it will work for other crops and termites as well. The project will focus on biodiversity and ecosystem functioning in agroforests along a rainfall gradient with regard to ecosystem services provided by endophytic fungi. The research proposed here will also support an initiative aimed at establishing a certification scheme for “rainforest friendly” cacao production in rainforest buffer zones.

Funded by Volkswagen Foundation

Partners:
Dr Bisseleua Daghela Hervé Berti, International Institute of Tropical Agriculture, Yaounde, Cameroon.
Prof. Dr. Stefan Vidal, Agricultural Entomology, Department of Crop Sciences, University of Göttingen, Germany