Tropicultura (Jan 2005)
Entomofaune des panicules de sorgho et effet des dates de semis et des variétés sur les populations de Stenidiplosis sorghicola (Dipt. Cecidomyiidae) et Eurystylus oldi (Hemipt. :Miridae) et les pertes de rendement
Abstract
Sorghum Panicle Insects and Effect of Sowing Dates and Varieties on Populations of Stenodiplosis sorghicola (Dipt. Cecidomyiidae) and Eurystylus odi (Hemipt.: Miridae) and Yield Losses. A trial was run in Niamey (Niger) in 2001, to examine the relative abundance of Stenodiplosis sorghicola Coq. and Eurystylus oldi Poppius and their impact on the grain yield of two varieties of sorghum with different panicle compactness. The experimental design was a split-plot, with four replications. The two varieties of sorghum (Mota Maradi, with loose panicles and SEPON-82, with compact panicles) occupied the main plots while two sowing dates (SD1: 26/06/2001 and SD2: 13/07/2001) were in sub-plots. E. oldi and S. sorghicola were present on all the panicles of the two varieties and at the two sowing dates. However the populations of E. oldi remained low on those of the SD1 of Mota Maradi. S. sorghicola was abundant on the panicles of SEPON-82 of the SD2. Two regression equations for the abortions observed with the SD2 (scale of 1-10) and the average weight of the grains of the panicles were determined. These equations were: (on Mota Maradi and () on SEPON-82. From the first to the second sowing dates losses of panicle grains weight equal to 48.3% and 39.4% on Mota Maradi and SEPON-82 respectively were determined. On SEPON-82 the size of which allowed bagging of panicles, the reduction in panicle grain weights due to the insects were 20.2% and 36.8% on SD1 and SD2 respectively.
