Abstract
Armyworm, Spodoptera exempta (Wlk.) feed on cereals and grassland in eastern and southern Africa. Data on the yield losses and economic effects of an attack on cereals is sparse. They can be an indirect cause of cattle deaths. The need to examine the situation at the farm level has been recognized. A national survey was conducted in 1987, and is currently being analysed. The work entails identifying representative areas and farmers, completing a questionnaire with each farmer, noting the frequency of outbreaks experienced, the farmers’ response, the level of government support, the effectiveness of control measures and the costs incurred. Proposals are outlined for future work within the region to determine the reduction in cereal yields due to this insect and to set up action thresholds for control activities. A major difficulty with the survey approach is the disaggregation of various loss-causing factors. At a sub-sample of survey sites, where outbreaks are present, the damage to the crop and the subsequent yield of the damaged crop or the planting of a replacement crop would be recorded to build up data from which action thresholds might be determined.
Résumé
Les chenilles legionnaires, Spodoptera exempta (Wlk.), se nourrissent des cereales et des terres de l’herbe dans l’Afrique de l’est et du sud et sont la cause indirecte de la mort du betail. Les données sur la perte de la recolte et les effets economiques d’une attaque sur les cereales sont peu abondantes. Des propositions pour le travail dans la region a l’avenir sont esquissees pour determiner la reduction en recolte à cause de cet insecte et pour etablir des seuils d’action pour les activités de controle. Le travail comprendra l’identification des régions et des fermiers representatives et le remplissement par chaque fermier d’une questionnaire, en prenant note du nombre des eruptions, de la reaction des fermiers, du niveau de l’appui du gouvernement, de l’efficacité des mesures de contrôle et des couts réalisés. Dans les mêmes endroits ou les eruptions se présentent, on enregistrera la destruction de la récolte, et enfin la récolte après la destruction, ou la poussée d’une récolte de remplacement, afin d’établir des données pour déterminer les seuils d’action.
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Rose, D.J.W., Iles, M.J. & Ward, A. Cereal Losses Caused by Armyworm in Eastern and Southern Africa: Current Information and Research Proposals. Int J Trop Insect Sci 9, 697–699 (1988). https://doi.org/10.1017/S1742758400005567
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DOI: https://doi.org/10.1017/S1742758400005567