Title : Insect natural enemies of the fall armyworm Spodoptera frugiperda in Côte d Ivoire
Abstract:
Maize production has been compromised in Côte d'Ivoire since the discovery of the fall armyworm, Spodoptera frugiperda, in 2017. As chemical control has shown its limitations, the search for alternative solutions, including insect biological control agents, is being encouraged. An exhaustive inventory of this pest's natural enemies was therefore carried out in three main maize-growing areas in Côte d'Ivoire (forest, transition, savannah). In addition, the predatory capacity of adults and stage 3, 4 and 5 larvae of Rhynocoris albopilosus, a generalist predator present in maize plots, was assessed on stage 2 S. frugiperda caterpillars in the laboratory. In a semi-controlled environment, only adults and stage 5 larvae of the predator were tested. A total of 10,409 natural enemy insects in six orders were collected. Hymenoptera and Coleoptera were the most abundant, with an average of 156.14 ± 18.21 and 124.03 ± 34.70 individuals respectively. Natural enemies were caught to a greater extent in forested areas and in untreated maize plots. Predators were in the majority, with 67.84% of natural enemies captured. The predatory capacity of R. albopilosus increases with the stage of development. In the laboratory, R. albopilosus stages 3, 4, 5 and adult insects consumed 7.37, 8.92, 12.25 and 11.78 prey per day respectively. In a semi-controlled environment, stage 5 of the predator was the most voracious, with an average of 8.83 S. frugiperda larvae consumed in 48h. Among the natural enemies of S. frugiperda, R. albopilosus was remarkably active on the pest and can be considered a good candidate as a biological control agent.
