Entomofaune parasitaire des foreurs des Graminées a Madagascar

Résumé

Après un bref rappel des différentes espèces de foreurs des tiges de graminées dont il importe de réduire le niveau des populations, l'inventaire des parasites tant indigènes qu'étrangers de chacune d'entre elles a été établi d'après les travaux effectués aussi bien à Madagascar qu'à Maurice et en Afrique.

Chaque parasite indigène et la plupart des parasites étrangers font l'objet d'un commentaire concernant leur répartition géographique, leur abondance, leurs hôtes, leur intérêt éventuel et les introductions pratiques.

Summary

An account of the problems in the biological control of graminaceous stemborers in Madagascar and Comoros, begins with a list of the principal Lepidopterous stalk-borers of tropical cereals and sugar-cane in these countries, together with their Malagasy and foreign parasites and is followed by a discussion of the importance of these parasites.

In Madagascar, surveys carried out by the Department of Entomology of the I.R.A.T. have thrown light on the status, distribution, abundance and hosts of a number of parasites but little work has been done on their life-history and biology. Any Malagasy parasite may be recommended for trial in other countries.

Introductions of exotic Hymenopterous parasites, such asApanteles flavipes, for control of sugar cane spotted borer,Chilo sacchariphagus, andPediobius furvus for pink borer,Sesamia calamistis, have been successful.

Moliarpha separatella is the commonest borer of rice in most parts of Madagascar.Chilo partellus is the major pest of maize in Comoros, and it also occurs in Madagascar.Chilo orichalcociliellus appears to be spreading on sorghum and maize. With a view to controlling these borers, an attempt to establish many promising species of parasites from Asia and Africa is being made. In 1972,Dentichasmias busseolae andItoplectis narangae have already been introduced.Apanteles flavipes is established in the North and it can be considered for introduction in Comoros and other parts of Madagascar.Hyperchalcidia soudanensis should be introduced in the near future.

As more information on different parasites becomes available, some species may be recommended for trial in France and Spain for biological control ofChilo suppressalis.