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Now showing items 1961-1980 of 8126
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Relative impact of spider predation and cover crop on population dynamics of Erythroneura variabilis in a raisin grape vineyard
(2003-06)Experimental and correlative evidence has steadily mounted over the past 30 years implicating spiders in the suppression of insect herbivore pests in crop fields. A large body of evidence has also shown that increasing agroecosystem vegetation diversity often influences the abundance of herbivores and their natural enemies. In previous experiments, the abundance of several species of spiders on grapevines in a raisin grape vineyard was twofold enhanced in vineyard plots vegetationally diversified ... -
Reciprocal effects in true potato seed breeding
(2003-06)Reciprocal crosses may have significantly distinct performances regarding tuber characteristics in potato, suggesting the importance of cytoplasmic effects in this crop. The selection of parents for true potato seed breeding therefore needs to consider this potential effect when determining the direction of a cross. The aim of this research was to determine whether a broad-based true potato seed breeding population, developed at the Centro Internacional de la Papa, could be affected by cytoplasmic ... -
Importance of Alternative Host Plants for the Annual Cycle of the Legume Pod Borer, Maruca vitrata Fabricius (Lepidoptera: Pyralidae) in Southern and Central Benin
(2003-06)The use pattern of alternative host plants by Maruca vitrata was investigated in southern and central Benin. Among the wild host plants, Pterocarpus santalinoides, Pueraria phaseoloides and Centrosema pubescens were found to be key relay hosts during the long dry season, Lonchocarpus sericeus and L. cyanescens were the most important hosts during the main rainy season, while Tephrosia platycarpa was an essential relay host during the short wet season in between. Cowpea was the major cultivated ... -
Effect of detopping on disease incidence and symptom severity of African cassava mosaic virus disease (ACMD) on some newly developed cassava cultivars form landraces introgression
(2003)Twenty-five cassava genotypes were exposed to natural infection by African cassava mosaic disease (ACMD) in plots at the International Institute of Tropical Agriculture (IITA), Ibadan (forest-savanna transition zone), Nigeria. The effect of removing the shoot tips (detopping) of cassava plants on disease incidence and symptom severity was assessed fortnightly for 14 weeks, starting 8 weeks after planting (WAP). There were highly significant differences (P < 0.01) in disease incidence (DI) and ... -
Release, establishment, spread, and impact of the weevil Neohydronomus affinis (Coleoptera: Curculionidae) on water lettuce (Pistia stratiotes) in Benin, West Africa
(2003-09)The weevil Neohydronomus affinis Hustache (Coleoptera : Curculionidae) of Neotropical origin was imported into Benin in 1993 and released in 1995 for the biological control of water lettuce Pistia stratiotes L. (Araceae). After the release of N. affinis in water bodies linked to the Mono River system, southwestern Benin, larval mines characteristic of immature stages were observed in all seasons in the first year and the weevil was considered established. Two years later, it had spread 90 km from ...
