Effets d'introductions renouvelées deLixophaga diatraeae [Diptera, Tachinidae] sur des populations naturelles du parasite et de son hote,Diatraea saccharalis

Résumé

Cette note étudie les conséquences d'une introduction régulièrement renouvelée deLixophaga diatraeae, Tachinaire parasite deDiatraea saccharalis sur les populations de cette Pyrale dans les parcelles de Canne à sucre en Guadeloupe.

Des apports mensuels de 500 ou 1000 parasites adultes permettent d'accroître la population de l'auxiliaire lorsque celle-ci est naturellement basse (saison humide). Les populations larvaires de l'hôte déclinent simultanément. Les introductions n'accroissent pas de façon durable la population du parasite.

Summary

The effect of periodical introduction in Sugarcane fields of the Cuban fly,Lixophaga diatraeae, a Tachinid parasite ofDiatraea saccharalis has been tested in Guadeloupe, French West Indies, from 1960 to 1962. At the beginning of each month 500 or 1000 mature flies of both sexes bred in the laboratory were released in 3 to 4 has plots. At the end of the month, a hundred bored canes are examined and the number ofD. saccharalis egg masses and living larvae as well asL. diatraeae pupae are recorded.

The number of Tachinid pupae recovered has been enhanced by a 500 flies release only when the parasite natural population is low, i. e. during the rainy season of the year. The host population is consequently reduced at the same period. However it seems possible that a 1000 flies release has somewhat affectedD. saccharalis development even in the dry season.

These repeated liberations show apparently no cumulative effects: the quantitative gains observed at times in the parasite populations are completely lost in the following generation.