Browsing by Author "Forchibe, E.E."
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Item Differential effects of weather, plant phenology and predators on the seasonal variation of aphids on cabbage(Journal of Applied Entomology, 2023) Forchibe, E.E.; Fening, K.O.; Narh-Madey, B.; Afreh-Nuamah, K.; Cobblah, M.A.; Wamonje, F.O.; Carr, J.P.The aphids Lipaphis erysimi pseudobrassicae (Davis) and Myzus persicae (Sulzer) pose serious threats to the production of cruciferous crops in the tropics. Understanding their population dynamics is important for developing integrated pest management programmes to minimize their damage to crops. This study investigated the effects of climatic factors, natural enemies and plant age on the population dynamics of these pests. The population density of aphids and their natural enemies in 20 cabbage plants, and weather conditions were monitored for five cropping seasons from 2019 to 2021 in two agroecological zones of Ghana (Coastal Savannah and Deciduous Forest zones). The highest population density of L. e pseudobrassicae was recorded in January (dry season) in both agroecological zones, while the highest population density for M. persicae occurred in September (minor rainy season) and August (dry spell) in the Coastal Savannah and Deciduous Forest zones, respectively. The highest aphid densities were noted to occur during periods with low relative humidity and low rain fall. The population density of L. e. pseudobrassicae was significantly negatively related to plant age, air temperature and relative humidity, and positively related to syrphids (Paragus borbonicus) and spiders in the Coastal Savannah zone, while in the Deciduous Forest zone, it was significantly positively related to coccinellids. On the other hand, M. persicae population density was significantly positively related to syrphids and coccinellids in the Deciduous Forest zone. Rainfall negatively affected syrphids in the Coastal Savannah zone, while air temperature positively affected syrphids and negatively affected spiders in the Deciduous Forest zone. Coccinellids had a significant positive relationship with relative humidity in the Deciduous Forest zone. This study provides important insights into the key factors that regulate aphid population densities on cabbage and will support development of timely interventions to manage these pests.Item Effect Of Different Pesticide Management Options On The Population Dynamics Of Aphids And Their Natural Enemies On Cabbage(University of Ghana, 2016-07) Forchibe, E.E.Cabbage is a popular vegetable grown in Ghana and serves as an important source of livelihood for small-scale farmers, especially in urban areas. However, its cultivation encounters several constraints such as attack by insect pests. A key insect pest is aphid that cause significant to the crops as they serve as vectors of plant diseases. Farmers thus resort to indiscriminate use of insecticides to reduce the damage caused by insect pests. However, insecticides are associated with adverse environmental and health implications. The current study sought to investigate the effect of commonly used management options on the population dynamics of aphids and their natural enemies. Cabbage seedlings were planted during the major and minor seasons of 2015 in 3 x 3 m plots. Treatments comprised, two (2) synthetic insecticides (chlorpyrifos and lambda-cyhalothrin) three (3) botanicals (hot pepper fruit extract, neem seed extract, solution of local soap (‘alata samina’) and water. Ten cabbage leaves per treated plot were randomly sampled weekly into 70% alcohol to obtain counts of aphids and their natural enemies. Weekly field observations were carried out to determine the number of other natural enemies and insect pests per treatment plot. Incidence and severity of a ‘suspected’ disease transmitted by aphids were monitored and scored twice for each season per sample. The least number of Lipaphis erysimi and Myzus persicae were recorded for the neem-treated plots, while lambda-cyhalothrin-treated plots recorded the highest number of aphids. The control and bio-pesticide-treated plots recorded the highest numbers of the natural enemies (hoverflies, ladybirds and spiders). Other insect pests observed in the field were Plutella xylostella, Hellula undalis and Bemisia tabaci. High population of P. xylostella was recorded in the chemical-treated plots compared to the biopesticide-treated plots, with neemtreated plot recording the least number. Helula undalis was highest in the control plots while B. tabaci was lowest in the neem-treated plot compared to the others. Disease incidence and severity of ‘suspected’ viral disease was highest in the control and pepper-treated plots, followed by alata samina and lambda-cyhalothrin-treated plots. The highest marketable yield was recorded for the neem-treated plots for both seasons. The yield and marketability of cabbages obtained from plots sprayed with alata samina and pepper were also higher than that obtained from control, lambdacyhalothrin and chlorpyrifos-treated plots, with the insecticide treated plots recording the least number of marketable heads. It was concluded that, neem effectively controlled the aphids, with mild effect on their natural enemies and also improved the yield and marketability of cabbage, followed by alata samina and pepper. The current findings suggest neem seed extract, local soap alata samina and pepper, as effective and safe options for managing aphids on cabbage and other insect pests. Effect of temperature, percentage relative humidity and rainfall on the population of aphids was also investigated. Results showed that, temperature and rainfall had a significant negative correlation for the major and minor seasons on the aphid populations except relative humidity that had a positive correlation on the population.Item Effects of different pesticide management options on the population dynamics of aphids, Lipaphis erysimi pseudobrassicae (Davis) and Myzus persicae (Sulzer) (Hemiptera: Aphididae), their natural enemies and the yield of cabbage(Science and Development, 2017) Forchibe, E.E.; Fening, K.O.; Afreh-Nuamah, K.Cabbage is a popular vegetable grown in Ghana and it serves as an important source of livelihood for smallscale farmers. Aphids are major pests of cabbage in the field and as such, farmers have resorted to the indiscriminate use of insecticides which have had adverse environmental and health implications. The current study sought to investigate the effect of commonly used management options on the population of aphids, Lipaphis erysimi pseudobrassicae (Davis) and Myzus persicae (Sulzer) (Hemiptera: Aphididae), their natural enemies and the yield of cabbage. Cabbage seedlings were planted during the major and minor seasons of 2015 in 3 x 3 m plots and the treatments used included Chlorpyrifos, Lambda-cyhalothrin, hot pepper, Capsicum futescens fruit extract, neem, Azadirachta indica seed extract, solution of local soap (alata samina) with water as a control. Ten cabbage leaves per treated plot were randomly sampled weekly into 70% alcohol to obtain actual counts of aphids and their natural enemies. The least number of aphids was recorded in the neem treated plots, while Lambda-cyhalothrin treated plots recorded the highest number of aphids. The control and biopesticide treated plots recorded the highest numbers of the natural enemies (hoverflies, ladybirds and spiders). The highest yield and marketability was recorded in the neem treated plots for both seasons. The yield and marketability of cabbages obtained from plots sprayed with alata samina and pepper was also higher than that obtained from the control, Lambdacyhalothrin and Chlorpyrifos treated plots, with the insecticide treated plots recording the least number of marketable heads. It offered the most promising solution. The current findings suggest that the crude neem seed extract, and to some extent local soap, alata samina, and pepper, are effective and safe options for managing aphids on cabbage.Item First Report and Distribution of the Indian Mustard Aphid, Lipaphis erysimi pseudobrassicae (Hemiptera: Aphididae) on Cabbage (Brassica oleracea var capitata) in Ghana(Horticultural Entomology, 2020-04-09) Fening, K.O.; Forchibe, E.E.; Wamonje, F.O.; Adama, I.; Afreh-Nuamah, K.; Carr, J.P.The presence of large colonies of aphids is associated with a devastating novel necrotic disease of cabbage (Brassica oleracea var. capitata) in Ghana that is thought to be of viral etiology. In this study, we used molecular taxonomic tools to identify the aphid species present on these diseased cabbage plants. This was confirmed using two key features for morphological identification, involving the length of cornicles and shape of cauda for the wingless forms of the aphids. Two species of aphids were identified and their distribution in Ghana indicated. One was the generalist aphid Myzus persicae (Sulzer) (Hemiptera: Aphididae) but the most abundant was the brassica specialist aphid, Lipaphis erysimi pseudobrassicae (Davis) (Hemiptera: Aphididae), which is one of the most destructive pests of brassica crops in some countries in Africa and other parts of the world. L. erysimi has been reported in Benin, Mali, South Africa, India, China, and United States, but this is the first formal report of L. erysimi pseudobrassicae in Ghana. The correct identification of L. erysimi is crucial, suggesting that it has recently become one of the most common species of aphid found on cabbage plants in Ghana.Item Marching across and beyond West Africa: First record of the stem-galling fly Cecidochares connexa (Diptera: Tephritidae) in Central Africa and the implications for biological control of Chromolaena odorata (Asteraceae)(PLOS, 2021) Aigbedion-Atalor, P.O.; Idemudia, I.; Adom, M.; Forchibe, E.E.; Tossou, H.; Wilson, D.D.; Day, M.D.The Neotropical invasive plant Chromolaena odorata R.M. King and H. Robinson (Astera ceae) is a serious weed in West and Central Africa and two biological control agents that have been introduced into West Africa to help reduce its impacts on agriculture and biodiver sity, have established. The stem-galling fly, Cecidochares connexa (Macquart) (Diptera: Tephritidae), has spread widely across West Africa since its release in only Coˆte d’Ivoire, occurring in six countries. This study aimed to investigate whether the gall fly had spread fur ther across West Africa and into Central Africa. Here, we surveyed C. odorata for C. con nexa galls in Cameroon between October 2018 and October 2020, along roadsides, on farms, residential areas, and abandoned plots, encompassing various vegetation types. Additional surveys were conducted across four countries (Ghana, Togo, Benin Republic and Nigeria) in West Africa that we considered the probable pathway for the spread of the gall fly into Central Africa. Cecidochares connexa was present at five of the six locations sur veyed in Cameroon, albeit in varying abundance. In Africa, these findings represent the first ever report of C. connexa outside of West Africa. In West Africa, we recorded significant expansion in the geographic range of C. connexa, as reflected in the absent-present record of C. connexa in two locations in Nigeria and one in Ghana, as well as its occurrence in all locations surveyed in Benin Republic and Togo. Clearly, Ghana, Togo, Benin Republic and Nigeria served as the dispersal pathway of C. connexa from the release sites in Coˆte d’Ivoire into Cameroon, covering over 2,300 km. Following the spread and establishment of C. con nexa into Cameroon, we anticipate that it will continue to spread further into other parts of Central Africa which are climatically suitable. Cecidochares connexa is currently the only biological control agent for C. odorata in Central Africa. Given that it has significantly reduced populations of C. odorata in other countries where it has established, it is expected to have a similar impact in Central Africa.