Natural enemies associated with rice stemborers in the Kou Valley, Burkina Faso

Abstract

Stemborers are a major constraint to the production of rice in the Kou Valley, Burkina Faso. Biological control is a good alternative to the use of agrochemicals that are harmful to human and animal health, and the environment. A survey of natural enemies of stemborers was conducted during the 2014 rice-cropping season across three transplanting periods (P1, P2 and P3). Plant and insect samples were collected by mowing and trapping at weekly intervals until harvest, starting 21 days after transplanting, and examined microscopically. Immature stages of the parasitized stemborers were reared to maturity for a positive identification of the parasitoids. Three genera of stemborers were identified:Chilo(Lepidoptera: Pyralidae),Maliarpha(Lepidoptera: Pyralidae) andSesamia(Lepidoptera: Noctuidae). TheChilogenus was the most important with an average percentage of 41.4% of the pre-imaginal population in P2 followed byMarliarpha(1.1%) andSesamia(0%). A total of 15 hymenopteran parasitoid species that included nine genera and seven families were identified. All the parasitoids were associated withChiloand only two of the species parasitizedMaliarpha. The most frequent parasitoids encountered wereBracon testacerofatus,Goniozus indicus,Dolichogenidea oryzaeandBraconspp. A total of 28 predator species were recorded from 22 genera, 6 orders and 15 families.Leucaugesp.,Agriocnemissp.,Lycosa pseudoannulataandLycosasp. were the most important predators with frequencies reaching 15% of the arthropods caught in some fields. These results will be employed to develop a sustainable system to manage rice stemborers.