Response of maize stemborers and associated parasitoids to the spread of grasses in the rainforest zone of Kisangani, DR Congo: effect on stemborers biological control

1. The challenge with respect to nourishing the human population should be met in the context of global environmental change. Land-use change has the potential to affect insect pest – natural enemy interactions.
2. In the Democratic Republic of Congo, the rainforest zone is subjected to intense anthropogenic disturbances that lead to the spread of habitats with a higher proportion of grasses in the landscape. Such a land-use change raises the question of its effects on the biological control of insect pests.
3. The proximity of varying vegetation types around agroecosystems is expected to influence species fitting differently and hence the population dynamics of insect pests and their biological control.
4. Thus, the response of maize stemborers and their parasitoids to the spread of habitats with a higher proportion of grasses was assessed along an anthropogenic disturbance gradient in the rainforest zone of Kisangani, Democratic Republic of Congo.
5. The present study identified a decreased density of stemborers and infestation rates on maize as a result of an increased larval/pupal parasitism in wild habitats as the amount of grasses increased in the landscape. This effect was attributed to an increased parasitoid diversity subsequent to the settlement of an abundant and diverse stemborer community in wild habitats.

Auteurs: Onésime M. Kankonda, Benjamin  D. Akaibe, Ntambo M. Sylvain  and Bruno-Pierre Le Ru