Effect of sowing dates of sorghum (Sorghum bicolor) on Eurystylus oldi (Hemiptera, Miridae) and Contarinia sorghicola (Diptera, Cecidomyiidae) | Effet de la date de semis du sorgho (Sorghum bicolor) sur Eurystylus oldi (Hemiptera, Miridae) et Contarinia sorghicola (Diptera, Cecidomyiidae)
1998
Bal, A.B. | Anadif, T.I. (Centre regional Agrhymet, Niamey (Niger). Projet DFPV)
A survey of insects of the sorghum panicle (Sorghum bicolor (L.) Moench), was done in 1996 at AGRHYMET Regional Centre in Niamey on the sorghum variety Mota Maradi. This variety was sown on four dates (10/07, 25/07, 09/08 and 23/08) in a completely randomised blocs design with four replications. Eurystylus oldi Poppas was most important on the first two sowing dates and its populations represented respectively 49 and 34/ of the insects collected. Contarinia sorghicola Coquillet was more abundant in the third sowing dates although it was present on all the sowing dates. Populations of this species represented respectively 7/, 30/, 65/ and 44/ of the insects collected from panicles of the four sowing dates respectively. Grain yield on the four sowing dates was 1191 kg per ha, 271 kg per ha, 132 kg per ha and 242 kg per ha respectively. Grain yield losses were mainly due to damage by C. sorghicola. Sowing sorghum later than the first decade of July should not be recommended in this region.
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