Adaptability of two weevils (Neochetina bruchi and Neochetina eichhorniae) with potential to control water hyacinth in the Rift Valley of Ethiopia |
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| Institution: | 1. Farming Systems Ecology, Plant Sciences, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands;2. Centre for Crop Systems Analysis, Plant Sciences, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands;3. School of Graduate Studies, Plant Sciences, Ambo University, P.O. Box 37, Ambo, Ethiopia;1. Faculty of Agriculture, Iwate University, Morioka, Iwate 020-8550, Japan;2. Faculty of Humanities & Social Sciences, Iwate University, Morioka, Iwate 020-8550, Japan;3. Technical Division, Iwate University, Morioka, Iwate 020-8551, Japan;4. Faculty of Engineering, Iwate University, Morioka, Iwate 020-8551, Japan;1. Department of Entomology, Louisiana State University, Baton Rouge, USA;2. Instituto Nacional de Investigación Agropecuaria, INIA LA Estanzuela, Uruguay;3. Fundación para el Estudio de Especies Invasivas, Buenos Aires, Argentina;4. Invasive Plant Research Laboratory, United States Department of Agriculture, ARS, Fort Lauderdale, USA;1. Department of Biology, Ecology & Biodiversity Research Unit, Vrije Universiteit Brussel, Brussels, Belgium;2. Centre for Biological Control, Department of Zoology & Entomology, Rhodes University, Makhanda, South Africa;3. Multidisciplinary Institute for Teacher Education, Science & Technology (MILO), Vrije Universiteit Brussel, Brussels, Belgium;4. Centre for Biological Control, Department of Botany, Rhodes University, Makhanda, South Africa;1. Centre for Biological Control, Department of Zoology and Entomology, Rhodes University, Makhanda, Eastern Cape 6140, South Africa;2. Centre for Biological Control, Department of Botany, Rhodes University, Makhanda, Eastern Cape 6140, South Africa;3. University of Florida, Ft. Lauderdale Research and Education Center, 3205 College Avenue, Davie, FL 33314, USA;1. Leibniz Center for Tropical Marine Research (ZMT), Fahrenheitstraße 6, 28359 Bremen, Germany;2. Ethiopian Institute of Agricultural Research-National Fisheries and Aquatic Life Research Center, P.O. Box: 64, Sebeta, Ethiopia |
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| Abstract: | Neochetina weevils have potential as biocontrol agents for water hyacinth, an aquatic weed which seriously affects irrigation water supply in sugarcane, vegetables and other horticultural crop production in the Rift Valley of Ethiopia. A study was conducted on (i) the adaptability and duration of developmental stages of Neochetina weevils and (ii) the damage they cause to water hyacinth in the Rift Valley of Ethiopia. The Rift Valley weather conditions appeared to be suitable for the two weevil species studied, enabling them to produce four generations per year. The egg hatching period of Neochetina bruchi ranged from 4 to 10 days, while Neochetina eichhorniae took 8–12 days. Larvae of N. bruchi took a comparatively shorter period (32–38 days) than N. eichhorniae (52–60 days) to complete their development. N. bruchi laid a maximum of 10.4 eggs female?1 day?1, whereas N. eichhorniae laid 8.2 eggs female?1 day?1. The intrinsic rate of increase of N. bruchi was found to be 0.06 with a generation time of 74.8 days and a population doubling period of 14.3 days. The intrinsic rate of increase of N. eichhorniae was 0.046 accompanied by a generation time of 94.8 days and a doubling period of 18.7 days. Feeding by adult weevils and tunnelling by larvae significantly impacted the vigour and reproduction of water hyacinth plants. N. bruchi and N. eichhorniae affected plants had about 72% (76%) and 66% (58%) reduction in fresh (and dry) weight, respectively. Thus, based on their damage potential and difference in rate of population growth, it is concluded that N. bruchi could be considered as a promising candidate for biological control of water hyacinth under Ethiopian conditions. |
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| Keywords: | Population dynamics Insect–plant interactions Herbivory Biology Intrinsic rate Aquatic weeds |
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