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Biological control of Chilo sacchariphagus (Lepidoptera: Crambidae) in Moçambique : The firsts steps

Conlong D.E., Goebel F.R.. 2002. Proceedings of the Annual Congress of the South African Sugar Technologists' Association, 76 : p. 310-320. Annual Congress of the South African Sugar Technologists' Association (SASTA). 76, 2002-07-30/2002-08-02, Durban (Afrique du Sud).

In 1999, it was confirmed that Chilo sacchariphagus Bojer was attacking sugarcane at Açucareira de Moçambique, Mafambisse, and in 2001 from Companhia de Sena, Marromeu. In 2000, Açucareira de Moçambique requested that the South African Sugar Association Experiment Station investigate a classical biological control programme against this exotic borer using Xanthopimpla stemmator Thunberg. To this end, during March and June 2001, intensive pre-release surveys for this borer and possibly already established parasitoids were completed. No pupal parasitoids were recorded, and only 1.3% parasitism of the larval population was found. However, many egg batches were parasitised by Trichogramma bournieri Pintureau and Babault. Because of the absence of pupal parasitoids in these collections, it was deemed safe to release X. stemmator, as it was likely that no native species would be displaced. Releases were planned to coincide with the C. sacchariphagus pupal peak expected during July/August 2001. One thousand mated female parasitoids were released in five selected sugarcane fields, in batches of 200 at fortnightly intervals over the two-month period. When post-release surveys were completed in October 2001, population reductions of between 31% to 90% in C. sacchariphagus larval and pupal numbers were recorded in all the release fields, when compared to control fields. In the light of these findings, it seems that a classical biocontrol programme against C. sacchariphagus using X. stemmator in Moçambiquan sugarcane is beneficial. The way forward is discussed, as well as an augmentation biocontrol programme using T. bournieri. The possibility of importing and introducing larval parasitoids of C. sacchariphagus is proposed. (Résumé d'auteur)

Mots-clés : ichneumonidae; parasitoïde; lutte biologique; lutte anti-insecte; chilo sacchariphagus; insecte déprédateur des tiges; saccharum; mozambique; xanthopimpla stemmator

Thématique : Ravageurs des plantes

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