[ Influence de la densité des populations de la cochenille Africaine de racines
et tubercules (Stictococcus vayssierei Richard) sur le rendement des variétés améliorées de manioc (Manihot esculenta CRANTZ) dans différentes zones agro-écologiques de Beni (Nord Kivu, RD Congo) ]
Volume 16, Issue 2, June 2016, Pages 247–259
Nestor Eleko Ndengo1, Albert Lema Ki – Munseki2, Rachid Hanna3, N. M. Mahungu4, and Koto-te-Nyiwa Ngbolua5
1 Université de Kinshasa, Faculté des Sciences Agronomiques, Département de Phytotechnie, BP117 Kinshasa XI, RD Congo
2 Université de Kinshasa, Faculté des Sciences Agronomiques, Département de Phytotechnie, BP117 Kinshasa XI, RD Congo
3 International Institute of Tropical agricultural, BP 2008 (Messa) Yaundé, Cameroun
4 International Institute of Tropical agricultural, Kinshasa, RD Congo
5 Département de Biologie, Faculté des Sciences, Université de Kinshasa, BP 190 Kinshasa XI, RD Congo
Original language: French
Copyright © 2016 ISSR Journals. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Cassava crop yield is reduced by numerous constraints among which African root and tuber scale Stictococcus vayssierei Richard, a devastator of cassava and other crops. This scale damage causes a decrease in amount and quality of cassava tuberous roots in case of serious infestations. It is in this context that a study on influence of the population density African root and tuber scale on cassava (Manihot esculenta CRANTZ) was conducted to determine the damage influence on the yields of two improved varieties and one local variety in different agro-ecological areas of Beni Territory. The objective of this study is to identify among these improved and a local varieties those can be grown in an agro ecological area where the population of african root and tuber scale has no harmful influence on tuberous root yields. To achieve this objective, we verified the hypothesis according to which a good knowledge of the population density helps to determine the rational growing site of cassava varieties. The experiment was conducted in four sites under average altitudes (800-1200 m) and high altitudes (1200-1400 m) with variable infestation rates. The populations of African root and tuber scale with various stages of life and the marketable tuberous root production of each of the varieties as well as climatic factors were determined every three months for two years. The randomized complete block with four repetitions was used. The cluster analysis findings on the effects of the population density of the scale on the yields of these three varieties show that improved varieties were more infested than the local variety under mild altitude. Consequently, their yields were low compared to the local variety. Butamu and Mvuazi improved varieties produced low yields under mild altitudes where there were serious infestations of African root and tuber scale. The yields obtained from these two improved varieties under mild altitudes were respectively 13.1 T/ha and 18.8T/ha compared to Mbayilo local variety that produced 22.5 T/ha at 12 months after plantation (12MAP) on second year screening. Serious infestations of scale under mild altitudes were the cause for low yields of these improved varieties. In high altitude agro ecological areas where the population density of African root and tuber scale was low. Butamu improved variety yielded 25.3 T/ha compared to Mbayilo local variety that produced 37 T/ha at 12MAP on second year of screening. Our results show that the tuberous root production of the released improved varieties of cassava decreases in agro ecological areas with serious infestations of the scale. For the choice of the growing site of the improved varieties, Beni Territory high altitudes with low infestation of African root and tuber scale seem to be better indicated since Mvuazi variety produced 63.8 T/ha.
Author Keywords: Manihot esculenta, Stictococcus vayssierei, population density, altitude, yield.
Volume 16, Issue 2, June 2016, Pages 247–259
Nestor Eleko Ndengo1, Albert Lema Ki – Munseki2, Rachid Hanna3, N. M. Mahungu4, and Koto-te-Nyiwa Ngbolua5
1 Université de Kinshasa, Faculté des Sciences Agronomiques, Département de Phytotechnie, BP117 Kinshasa XI, RD Congo
2 Université de Kinshasa, Faculté des Sciences Agronomiques, Département de Phytotechnie, BP117 Kinshasa XI, RD Congo
3 International Institute of Tropical agricultural, BP 2008 (Messa) Yaundé, Cameroun
4 International Institute of Tropical agricultural, Kinshasa, RD Congo
5 Département de Biologie, Faculté des Sciences, Université de Kinshasa, BP 190 Kinshasa XI, RD Congo
Original language: French
Copyright © 2016 ISSR Journals. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
Cassava crop yield is reduced by numerous constraints among which African root and tuber scale Stictococcus vayssierei Richard, a devastator of cassava and other crops. This scale damage causes a decrease in amount and quality of cassava tuberous roots in case of serious infestations. It is in this context that a study on influence of the population density African root and tuber scale on cassava (Manihot esculenta CRANTZ) was conducted to determine the damage influence on the yields of two improved varieties and one local variety in different agro-ecological areas of Beni Territory. The objective of this study is to identify among these improved and a local varieties those can be grown in an agro ecological area where the population of african root and tuber scale has no harmful influence on tuberous root yields. To achieve this objective, we verified the hypothesis according to which a good knowledge of the population density helps to determine the rational growing site of cassava varieties. The experiment was conducted in four sites under average altitudes (800-1200 m) and high altitudes (1200-1400 m) with variable infestation rates. The populations of African root and tuber scale with various stages of life and the marketable tuberous root production of each of the varieties as well as climatic factors were determined every three months for two years. The randomized complete block with four repetitions was used. The cluster analysis findings on the effects of the population density of the scale on the yields of these three varieties show that improved varieties were more infested than the local variety under mild altitude. Consequently, their yields were low compared to the local variety. Butamu and Mvuazi improved varieties produced low yields under mild altitudes where there were serious infestations of African root and tuber scale. The yields obtained from these two improved varieties under mild altitudes were respectively 13.1 T/ha and 18.8T/ha compared to Mbayilo local variety that produced 22.5 T/ha at 12 months after plantation (12MAP) on second year screening. Serious infestations of scale under mild altitudes were the cause for low yields of these improved varieties. In high altitude agro ecological areas where the population density of African root and tuber scale was low. Butamu improved variety yielded 25.3 T/ha compared to Mbayilo local variety that produced 37 T/ha at 12MAP on second year of screening. Our results show that the tuberous root production of the released improved varieties of cassava decreases in agro ecological areas with serious infestations of the scale. For the choice of the growing site of the improved varieties, Beni Territory high altitudes with low infestation of African root and tuber scale seem to be better indicated since Mvuazi variety produced 63.8 T/ha.
Author Keywords: Manihot esculenta, Stictococcus vayssierei, population density, altitude, yield.
Abstract: (french)
Le rendement de la culture du manioc est compromis par de nombreuses contraintes parmi lesquelles la cochenille africaine des racines et tubercules Stictococcus vayssierei Richard, un ravageur du manioc et d’autres plantes cultivées. Les dégâts de cette cochenille occasionnent la diminution de la quantité et de la qualité de racines tubéreuses du manioc. C’est dans ce contexte qu’une étude sur la densité des populations de la cochenille africaine de racines et tubercules sur le manioc (Manihot esculenta CRANTZ) a été menée pour connaitre son influence sur les rendements de trois variétés dont deux améliorées en diffusion et une variété locale de manioc, dans différentes zones agro-écologiques du Territoire de Beni. L’objectif de cette étude est d’identifier parmi ces variétés celles qui peuvent être exploitées dans une zone agro-écologique où la population de la cochenille n’a pas des effets néfastes sur les rendements. Pour atteindre cet objectif nous avons formulé l’hypothèse selon laquelle une bonne connaissance de la dynamique de la population permet de déterminer le site d’exploitation rationnelle de variétés de manioc. Les essais ont été installés dans quatre sites sous moyenne altitude (800-1200 m) et haute altitude (1200-1400 m) ayant de taux d’infestation variable. Les populations des cochenilles aux différents stades de vie sur chacune des variétés, les productions en racines tubéreuses commercialisables et les facteurs climatiques ont été déterminés tous les trois mois pendant deux ans en blocs randomisés avec quatre répétitions. La classification ascendante hiérarchisée des effets de la densité des populations de la cochenille sur les rendements montrent que les variétés améliorées ont été plus infestées que la variété locale témoin en moyenne altitude. Par conséquent leurs rendements ont été inférieurs par rapport à la variété locale. Les variétés améliorées Butamu et Mvuazi ont accusé des faibles rendements sous moyenne altitude à cause d’une forte densité de populations des cochenilles radicoles.
Author Keywords: Manihot esculenta, Stictococcus vayssierei, altitude, rendement, densité de population.
How to Cite this Article
Nestor Eleko Ndengo, Albert Lema Ki – Munseki, Rachid Hanna, N. M. Mahungu, and Koto-te-Nyiwa Ngbolua, “Influence of the population density of the African root and tuber scale insect (Stictococcus vayssierei Richard) on the yields of Cassava (Manihot esculenta CRANTZ) improved in different Agro-ecological zones of Beni (North Kivu, DR Congo),” International Journal of Innovation and Applied Studies, vol. 16, no. 2, pp. 247–259, June 2016.
