Abstract
Investigations were conducted in six farm fields (1.5 to 3 ha each) in Burkina Faso with objectives to (1) study adult Smicronyx spp. (Coleoptera: Curculionidae) population dynamics during Striga hermonthica (Scrophulariaceae) seed-pod production, (2) assess the impact of different population levels of Smicronyx spp. on St. hermonthica capsule production and, (3) estimate Smicronyx female reproductive success in seed-pod galls. A Univac portable sampler was used to sample adult Smicronyx spp. and St. hermonthica densities were assessed using a 1 m2 metal quadrat. Fifty St. hermonthica shoots per field were sampled each week. Before the emergence of St. hermonthica, Smicronyx adults were found on nearby Striga aspera (Willd) Benth. fields. Striga hermonthica shoots produced on average ca. 24 seed capsules each, while each female Smicronyx galled froml2 to 32 seed pods. Seed-pod galling alone was not sufficiently high to be considered as a successful reduction factor for St. hermonthica seed production in natural conditions. Smicronyx spp. adult population levels decreased during the St. hermonthica capsule production period. Increased population levels of Smicronyx spp. resulted in higher percentages of St. hermonthica seed-pod galls, suggesting that augmentative techniques, if used as part of an integrated control programme could be a worthwhile strategy.
Résumé
Des recherches ont été menées dans six champs (chacun mesurant de 1.5 à 3 ha) de paysans avec pour objectifs (1) d’étudier la dynamique des adultes durant la période de production des graines de St. hermonthica, (2) d’étudier l’impact de niveaux différents de populations de Smicronyx spp. sur la production de capsule de St. hermonthica et (3) d’estimer le succès de reproduction des femelles dans les galles. Les populations d’adultes Smicronyx spp. ont été échantillonnées à l’aide d’un aspirateur portable Univac. Cinquante tiges de St. hermonthica ont été échantillonnées chaque semaine et la densité des adultes Smicronyx a été évaluée à l’aide d’un quadrat métallique de 1m2. Avant l’émergence de St. hermonthica, les adultes Smicronyx ont été trouvés sur des plantes de Striga aspera (Willd) Benth. situés dans des champs en proximité. Les tiges de St. hermonthica ont produit en moyenne 24 capsules chacunes, et chaque femelle Smicronyx a gallé de 12 à 32 capsules. La seule action gallicole des capsules n’était pas suffisante pour être considérée comme étant un facteur ayant du succès pour réduire la production de graines de St. hermonthica. Les niveaux de populations d’adultes de Smicronyx spp. ont diminué pendant la période de production de capsules de St. hermonthica. Des populations plus élevées de Smicronyx ont causé des dommages plus élevées de capsules de St. hermonthica, ce qui suggère qu’une approche augmentative pourrait être une stratégie intéressante dans le cadre d’un programme de lutte intégrée
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Otoidobiga, L.C., Vincent, C. & Stewart, R.K. Relationship between Smicronyx spp. Population and Galling of Striga hermonthica (Del.) Benth. Int J Trop Insect Sci 18, 197–203 (1998). https://doi.org/10.1017/S1742758400023407
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DOI: https://doi.org/10.1017/S1742758400023407