Stem borers are the most important maize pests in the humid forest zone of Cameroon. Field trials were conducted in the long and short rainy seasons of 2002 and 2003 to assess the level of damage and yield reductions caused by stem borers in monocropped maize and in maize intercropped with non-host plants such as cassava, cowpea and soybean. The intercrops were planted in two spatial arrangements, i.e. alternating hills or alternating rows. All intercrops and the maize monocrop were grown with and without insecticide treatment for assessment of maize yield loss due to borer attacks. The land-use efficiency of each mixed cropping system was evaluated by comparing it with the monocrop. The temporal fluctuation of larval infestations followed the same pattern in all cropping systems, but at the early stage of plant growth, larval densities were 21.3\uffe2\uff80\uff9348.1% higher in the monocrops than in intercrops, and they tended to be higher in alternating rows than alternating hills arrangements. At harvest, however, pest densities did not significantly vary between treatments. Maize monocrops had 3.0\uffe2\uff80\uff938.8 times more stems tunnelled and 1.3\uffe2\uff80\uff933.1 times more cob damage than intercrops. Each percentage increase in stem tunnelling lowered maize grain yield by 1.10 and 1.84 g per plant, respectively, during the long and short rainy season in 2002, and by 5.39 and 1.41 g per plant, respectively, in 2003. Maize yield losses due to stem borer were 1.8\uffe2\uff80\uff933.0 times higher in monocrops than in intercrops. Intercrops had generally a higher land-use efficiency than monocrops, as indicated by land-equivalent-ratios and area-time-equivalent-ratios of >1.0. Land-use efficiency was similar in both spatial arrangements. At current price levels, the net production of mixed cropping systems was economically superior to controlling stem borers with insecticide in monocropped maize. The maize\uffe2\uff80\uff93cassava intercrop yielded the highest land equivalent ratios and the highest replacement value of the intercrop. At medium intensity cropping this system is thus recommended for land-constrained poor farmers who do not use external inputs such as fertilizer and insecticides.
", "keywords": ["0106 biological sciences", "2. Zero hunger", "Manihot", "Glycine max", "Rain", "Agriculture", "Fabaceae", "Humidity", "Moths", "15. Life on land", "Zea mays", "01 natural sciences", "Host-Parasite Interactions", "Trees", "Larva", "Animals", "Biomass", "Cameroon", "Seasons"], "contacts": [{"organization": "Christian Nolte, A. Chabi-Olaye, Christian Borgemeister, Fritz Schulthess,", "roles": ["creator"]}]}, "links": [{"href": "https://doi.org/10.1079/ber2005373"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Bulletin%20of%20Entomological%20Research", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1079/ber2005373", "name": "item", "description": "10.1079/ber2005373", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1079/ber2005373"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2005-10-01T00:00:00Z"}}, {"id": "10.1079/ber2004347", "type": "Feature", "geometry": null, "properties": {"updated": "2026-07-25T16:18:10Z", "type": "Journal Article", "created": "2005-05-04", "title": "Abundance, Dispersion And Parasitism Of The Stem Borer Busseola Fusca (Lepidoptera: Noctuidae) In Maize In The Humid Forest Zone Of Southern Cameroon", "description": "AbstractThis study was conducted in the humid forest zone of Cameroon, in 2002 and 2003. The main objective was to investigate the effects of intercropping on infestation levels and parasitism of the noctuid maize stem borer Busseola fusca Fuller. Two trials were planted per year, one during the long and one during the short rainy season. Maize monocrops were compared with maize/legume or maize/cassava intercrops in two spatial arrangements: maize on alternate hills or in alternate rows. Spatial analyses showed that the stemborer egg batches were regularly dispersed in the maize monocrop and aggregated in the intercrops, as indicated by b, the index of dispersion of Taylor's power law. Depending on the crop association and planting pattern, intercrops reduced the percentage of plants with stem borer eggs by 47.4\uffe2\uff80\uff9358.4% and egg densities by 41.2\uffe2\uff80\uff9354.5% compared to monocropped maize. Consequently, larval densities were 44.4\uffe2\uff80\uff9361.5% lower in intercrops compared to monocrops. Intercropping maize with non-host plants did not affect larval parasitism. Up to two-fold higher levels of egg parasitism by scelionid Telenomus spp. were recorded in inter- compared to monocrops during the short rainy seasons of 2002 and 2003. No differences were found among the mixed cropping treatments and parasitism was lower during the long compared to the short rainy seasons. It was proposed that differences in levels of parasitism were due to density dependence effects rather than the effect of the presence of non-host plants in the system.
", "keywords": ["Crops", " Agricultural", "Population Density", "2. Zero hunger", "0106 biological sciences", "Tropical Climate", "Wasps", "Agriculture", "Moths", "15. Life on land", "Zea mays", "01 natural sciences", "Larva", "Linear Models", "Animals", "Cameroon", "Seasons", "Ovum"], "contacts": [{"organization": "A. Chabi-Olaye, Christian Nolte, Christian Borgemeister, Fritz Schulthess,", "roles": ["creator"]}]}, "links": [{"href": "https://doi.org/10.1079/ber2004347"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Bulletin%20of%20Entomological%20Research", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1079/ber2004347", "name": "item", "description": "10.1079/ber2004347", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1079/ber2004347"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2005-04-01T00:00:00Z"}}, {"id": "10.1093/treephys/tpab023", "type": "Feature", "geometry": null, "properties": {"updated": "2026-07-25T16:18:28Z", "type": "Journal Article", "created": "2021-02-05", "title": "Seasonal and elevational variability in the induction of specialized compounds from mountain birch (Betula pubescens var. pumila) by winter moth larvae (Operophtera brumata).", "description": "AbstractThe mountain birch [Betula pubescens var. pumila (L.)] forest in the Subarctic is periodically exposed to insect outbreaks, which are expected to intensify due to climate change. To mitigate abiotic and biotic stresses, plants have evolved chemical defenses, including volatile organic compounds (VOCs) and non-volatile specialized compounds (NVSCs). Constitutive and induced production of these compounds, however, are poorly studied in Subarctic populations of mountain birch. Here, we assessed the joint effects of insect herbivory, elevation and season on foliar VOC emissions and NVSC contents of mountain birch. The VOCs were sampled in situ by an enclosure technique and analyzed by gas chromatography\uffe2\uff80\uff93mass spectrometry. NVSCs were analyzed by liquid chromatography\uffe2\uff80\uff93mass spectrometry using an untargeted approach. At low elevation, experimental herbivory by winter moth larvae (Operophtera brumata) increased emissions of monoterpenes and homoterpenes over the 3-week feeding period, and sesquiterpenes and green leaf volatiles at the end of the feeding period. At high elevation, however, herbivory augmented only homoterpene emissions. The more pronounced herbivory effects at low elevation were likely due to higher herbivory intensity. Of the individual compounds, linalool, ocimene, 4,8-dimethylnona-1,3,7-triene, 2-methyl butanenitrile and benzyl nitrile were among the most responsive compounds in herbivory treatments. Herbivory also altered foliar NVSC profiles at both low and high elevations, with the most responsive compounds likely belonging to fatty acyl glycosides and terpene glycosides. Additionally, VOC emissions from non-infested branches were higher at high than low elevation, particularly during the early season, which was mainly driven by phenological differences. The VOC emissions varied substantially over the season, largely reflecting the seasonal variations in temperature and light levels. Our results suggest that if insect herbivory pressure continues to rise in the mountain birch forest with ongoing climate change, it will significantly increase VOC emissions with important consequences for local trophic interactions and climate.
", "keywords": ["0301 basic medicine", "Volatile Organic Compounds", "0303 health sciences", "secondary metabolites", "VDP::Zoologiske og botaniske fag: 480", "plant\u2013insect interactions", "Moths", "15. Life on land", "geometrid moth", "Plant Leaves", "03 medical and health sciences", "biotic stress", "13. Climate action", "volatile organic compounds", "Larva", "8. Economic growth", "11. Sustainability", "VDP::Zoology and botany: 480", "Animals", "Herbivory", "Seasons", "global change", "Betula", "Research Paper"]}, "links": [{"href": "http://academic.oup.com/treephys/article-pdf/41/6/1019/38497290/tpab023.pdf"}, {"href": "https://doi.org/10.1093/treephys/tpab023"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Tree%20Physiology", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1093/treephys/tpab023", "name": "item", "description": "10.1093/treephys/tpab023", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1093/treephys/tpab023"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2021-02-18T00:00:00Z"}}], "links": [{"rel": "self", "type": "application/geo+json", "title": "This document as GeoJSON", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=Moths&f=json", "hreflang": "en-US"}, {"rel": "alternate", "type": "text/html", "title": "This document as HTML", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=Moths&f=html", "hreflang": "en-US"}, {"rel": "collection", "type": "application/json", "title": "Collection URL", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main", "hreflang": "en-US"}, {"type": "application/geo+json", "rel": "first", "title": "items (first)", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=Moths&", "hreflang": "en-US"}, {"rel": "last", "type": "application/geo+json", "title": "items (last)", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=Moths&offset=3", "hreflang": "en-US"}], "numberMatched": 3, "numberReturned": 3, "distributedFeatures": [], "timeStamp": "2026-07-25T23:38:15.731267Z"}