Jump to ContentJump to Main Navigation
Show Summary Details
More options …

Open Agriculture

Covered by: Elsevier - SCOPUS

Clarivate Analytics - Emerging Sources Citation Index

CiteScore 2018: 0.78

SCImago Journal Rank (SJR) 2018: 0.246
Source Normalized Impact per Paper (SNIP) 2018: 0.916

Open Access
See all formats and pricing
More options …

Interaction of the fluctuation of the population density of sweet potato pests with changes in farming practices, climate and physical environments: A 11-year preliminary observation from South-Kivu Province, Eastern DRCongo

Théodore Munyuli
  • Corresponding author
  • Laboratory of Entomology & Plant Health Management, Departments of Biology & Environment Florida, USA
  • National Center for Research in Natural Sciences, CRSN-Lwiro, D.S. Bukavu, South-Kivu Province, eastern of DRCongo
  • Email
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Yajuamungu Kalimba
  • Department of Environments and Geography, Institute of Higher Education, ISP-Nyiragongo, Goma, North-Kivu Province, eastern DRCongo
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Emmanuel Kizungu Mulangane / Théodore Tshilumba Mukadi
  • National Institute for Agricultural Research and Studies, INERA-Gandajika, Lomami Province, Central DRCongo
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Meschac Tshibingu Ilunga
  • National Institute for Agricultural Research and Studies, INERA-Kipopo, Haut-Katanga Province, Southern DRCongo
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Remy Tshibingu Mukendi
  • National Institute for Agricultural Research and Studies, INERA-Gandajika, Lomami Province, Central DRCongo
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
Published Online: 2017-10-31 | DOI: https://doi.org/10.1515/opag-2017-0054


Sweetpotato is a major food security crop grown in eastern Democratic Republic of Congo. Its production is however limited due to high prevalence of pests and diseases among other abiotic and biotic factors. A study was designed to aid understanding the knowledge of farmers about pests and their perception about climate variability impacts, as well as documenting the phenology of sweetpotato pests (pest population dynamics) in relationship with weather factors. The paper aimed at determined which climatic factors may be used as best predictors of the different status of pest populations (declines, outbreaks). Farmer based data was obtained using a semi structured questionnaire administered to several of farmers. Population dynamics of sweetpotato pests were monitored year-round from 2005 to 2015 in South Kivu province, eastern DRCongo. Field monitoring (visual counts) observations (population dynamic of different soil-dwelling and surface dwelling arthropods visiting sweetpotato fields) combined with a survey of farmers’ knowledge on sweetpotato pests and their practices in the management of these pests in South- Kivu Province were conducted for 11 years. Monitoring (with field observations and counts) was carried out in fields under different farming practices (monocropping and inter-cropping) in sites located at different altitudes. Similarly, data for climatic factors, for the same period, were collected from Lwiro Research center. Regression models were applied to understand the linkages between environmental factors (rainfall and temperature) and pest population dynamics. The results indicated that different varieties (local and improved ones) of sweetpotato are grown three times (3 seasons) per annum under various cropping systems (sole crop, mixed crops) in various agroecological zones at different altitudes. Various arthropod species visit the crop at its different stages of development including classically known pests (Acraea acerata, Cylas spp.) or as vectors of diseases (Bemisi tabaci, Aphis spp.). The results indicated a high fluctuation in the population density of different pests. The change in the population dynamics were characterized by gradual increase in the populations during rainy seasons followed by decline during dry seasons (hot months of the year). Significant (P<0.05) differences were observed in the population dynamics between sole sweetpotato and mixed sweetpotato intercropping. There was a synchronization of multiple pest generations (biannual, multiannual cycles of reproduction) built up with early rains. The results indicate that rainfall and maximum temperature were critical to the survival and population built up of the pest population. High rainfall in the previous months caused increases in the population density in the subsequent months within a year. The population dynamic (seasonal occurrence) over months and years was likely to coincide with favorable feeding and breeding conditions available within sweetpotato biotopes when temperatures were sufficiently high or after heavy rainfall. For some species, maximum temperature and dry seasons were associated with declines in the pest populations whereas for other species, heavy rainfall was associated with subsequent outbreaks (high populations) in the following months of the years. It is likely that perturbations in temperature/ rainfall patterns may cause serious changes in the pest population, therefore favoring the build-up of multiple generations within a year, thus. Rainfall and maximum temperatures were reliable predictors of key pest species. In fact, regressions analyses indicated that there were significant relationships (P<0.01) between the fluctuation of the population density of different pest species and the variability of climatic factors (mean monthly maximum/ minimum temperature, average rainfall). The population density of different insect pest species varied according to cropping system and to altitude. For example, a significant relationship (P<0.001) was observed between adult aphid population density and average maximum temperature whereas Cylas spp. correlated significantly (P<0.05) with rainfall at high and mid altitudes in both sole and mixed crops. The population density of Acraea acerata was not related to variability in rainfall because the species seemed to occur in number in crops (mono cropping and mixed crops) in marshland areas in June-July and December-February. The virus pressure (measured as the number of leaves symptomatically showing virus attack) followed the population density of whiteflies and aphids. Population trends of other arthropod groups (millipedes, beetles) were not affected by crop variety (clones) or by the altitude or the climate variability but more by the farming practice (mixed or monoculture) implemented by the farmer. It is possible that the resistance or tolerance of some varieties (bio-fortified/vitamin-rich/orange flesh varieties) may be reduced in the future under changing climatic conditions of crop growing in the region with Maximum temperature as the key driver of changes in the population density. The ability to predict the severity of pest populations from mean monthly rainfall/temperature data will provide a significant input into the development of IPM programme for sweetpotato pest species. The data indicates that building resilient sweetpotato crops will require the consideration of various approaches. It is likely that climate change may affect both the pests and vectordiseases and therefore the yield of the crop in eastern DRCongo. Such situation may endanger food security of small scale farmers in the future. Further investigations would be better focus on the understanding on the interacting of climatic, anthropogenic, environmental and soil factors on the pressure of sweetpotato pest in different agro-ecological zones of DRCongo.

Keywords: Sweetpotato; Pest population dynamics; Climate change and variability; Forecasting; Farming practices; Crop resilience; Yield reduction; Altitude; Agroecological zones; Kivu; eastern DRCongo


  • Alicai T., Seasonal changes in whitefly numbers and their influence on incidence of sweetpotato chlorotic stunt virus and sweetpotato virus disease in sweetpotato in Uganda. International Journal of Pest Management, 1999, 45, 51-55Google Scholar

  • Ames T., Smit N.E.J.M., Braun A.R., O’Sullivan J.N., Skoglund L. G., Sweetpotato: Major Pests, Diseases, and Nutritional Disorders. Lima, Peru: International Potato Center, 1996Google Scholar

  • Anyanga M.O., Muyinza H., Talwana H., Hall D.R., Farman D.I., Ssemakula G.N., Mwanga R.O.M., Stevenson P.C., Resistance to the weevils Cylas puncticollis and Cylas brunneus conferred by sweetpotato root surface compounds. Journal of Agricultural and Food Chemistry, 2013, 61(34), 8141-8147CrossrefWeb of ScienceGoogle Scholar

  • Azerefegne F., Solbreck C., Ives A.R., Environmental forcing and high amplitude fluctuations in the population dynamics of the tropical butterfly Acraea acerata (Lepidoptera: Nymphalidae). Journal of Animal Ecology, 2001, 70, 1032-1045CrossrefGoogle Scholar

  • Bale J.S., Masters G.J., Hodkinson L.D., Awmack C., Bezemer T.M., Brown V.K., Butterfield J. et al., Herbivory in global climate change research: direct effects of rising temperature on insect herbivores. Glob. Change. Biol., 2002, 8, 1-16CrossrefGoogle Scholar

  • Bassey E.E., Field evaluation of yield and resistances of local and improved sweetpotato (Ipomoea batatas (L) Lam) accession to Cylas puncticollis and Meloidogyne incognita in Southeastern Nigeria. Asian Journal of Agricultural Sciences, 2012, 4, 390-394Google Scholar

  • Bonhof M.J., van Huis A., Kiros F.G., Dibogo N., Farmers’ perceptions of importance, control methods and natural enemies of maize stemborers at the Kenya coast. Insect Science and its Applications, 2001, 21, 33-43Google Scholar

  • Braun A.R., Van De Fliert E., Evaluation of the impact of sweetpotato weevil (Cylas formicarius) and of the effectiveness of Cylas sex pheromone traps at the farm level in Indonesia. International Journal of Pest Management, 1999, 45, 101-110CrossrefGoogle Scholar

  • Brunke A.J., Bahlai C.A., Sears M.K., Hallett R.H., Generalist predators (Coleoptera: Carabidae, Staphylinidae) associated with millipede populations in sweetpotato and carrot fields and implications for millipede management. Environmental Entomology, 2009, 38, 1106-1116CrossrefGoogle Scholar

  • Brunke A.J., O’Keefe L., Bahlai C.A., Sears M.K., Hallett R.H., Guilty by association: an evaluation of millipedes as pests of carrot and sweetpotato. Journal of Applied Entomology, 2012, 136, 772-780Google Scholar

  • Byamukama E., Gibson R.W., Aritua V., Adipala E., Within-crop spread of sweetpotato virus disease and the population dynamics of its whitefly and aphid vectors. Crop Protection, 2004, 23, 109-116Google Scholar

  • Chalfant R.B., Jansson R.K., Dakshina R.S., Schalk J.M., Ecology and management of sweetpotato insects. Annual Review of Entomology, 1990, 35, 157-180Google Scholar

  • Coley P.D., Markham A., Possible effects of climate change on plant / herbivore interactions in moist tropical forests. Climate Change, 1998, 39, 455-472Google Scholar

  • Dowiya N.B., Rweyemamu C.L., Maerere A.P., Banana (Musa spp. Colla) cropping systems, production constraints and cultivar preferences in eastern Democratic Republic of Congo. Journal of Animal and Plant Sciences, 2009, 4(2), 341 - 356Google Scholar

  • Downham M.C.A., Smit N.E.J.M., Laboke P.O., Hall D.R., Odongo B., Reduction of pre-harvest infestations of African sweetpotato weevils Cylas brunneus and C. puncticollis (Coleoptera: Apionidae) using a pheromone mating-disruption technique. Crop Protection, 2001, 20,163-166Google Scholar

  • Ebregt E., Struik P.C., Abidin P.E., Odongo B., Farmers’ information on sweetpotato production and millipede infestation in north-eastern Uganda. I. Associations between spatial and temporal crop diversity and the level of pest infestation. NJAS - Wageningen Journal of Life Sciences, 2004a, 52, 47-68CrossrefGoogle Scholar

  • Ebregt E., Struik P.C., Abidin P.E., Odongo B., Farmers’ information on sweetpotato production and millipede infestation in northeastern Uganda. II. Pest incidence and indigenous control strategies. NJAS - Wageningen Journal of Life Sciences, 2004b, 52, 69-84Google Scholar

  • Evans H., Straw N., Watt A., Climate change: implications for insect pests. Forestry Comm. Bull., 2002, 125, 99-118Google Scholar

  • El-Dessouki S.A., EI-Awady S.M., El-Khawass K.A.M.H., Mesbah A.H., El-Dessouki W.A.A., Population fluctuation of some insect pests infesting sugar beet and the associated predatory insects at Kafr El-Sheikh Governorate. Annals of Agricultural Science, 2014, 59(1), 119-123Google Scholar

  • Gibson R.W., Aritua V., Byamukama E., Mpembe I., Kayongo J., Control strategies for sweetpotato virus disease in Africa. Virus Research, 2004, 100, 115-122Google Scholar

  • Hance T., van Baaren J., Vernon P., Boivin G., Impact of extreme temperatures on parasitoids in a climate change perspective. Annual Review of Entomology, 2007, 52, 107-126CrossrefWeb of ScienceGoogle Scholar

  • Harrington R., Fleming R.A., Woiwod P., Climate change impacts on insect management and conservation in temperate regions: can they be predicted? Agric. For. Entomol., 2001, 3, 233-240CrossrefGoogle Scholar

  • Hódar J.A., Zamora R., Herbivory and climatic warming: a Mediterranean outbreaking caterpillar attacks a relict boreal pine species. Biodiversiy and Conservation, 2004, 13, 493-500Google Scholar

  • Jackson D.M., Bohac J.R., Evaluation of pheromone traps for monitoring sweetpotato weevils. Journal of Agricultural and Urban Entomology, 2006, 23, 141-158Google Scholar

  • Jackson D.M., Lawrence J., Dalip K.M., Chung P., Clarke-Harris D., Bohac J.R., Tolin S., Edwards C., Seal D.R., The sweetpotato leaf beetle, Typophorus nigritus viridicyaneus Crotch (Coleoptera: Chrysomelidae), an emerging pest in Jamaica: distribution and host plant resistance. Tropical Agriculture, 2003, 80, 235-208Google Scholar

  • Konvicka M., Maradova M., Venes J., Fric Z., Kepka P., Uphill shifts in distribution of butterflies in the Czech Republic: effects of changing climate detected on a regional scale. Glob. Ecol. Biogeogr., 2003, 12, 403-410Google Scholar

  • Kodjo T.A., Komi A., Komi Mawufe A.K., Komlan W., Maize stemborers distribution, their natural enemies and farmers’ perception on climate change and stemborers in southern Togo. Journal of Applied Biosciences, 2013, 64, 4773-4786Google Scholar

  • Korada R.R., Naskar S.K., Palaniswami M.S., Ray R.C., Management of sweetpotato weevil [Cylas formi-carius (Fab.)]: an overview. Journal of Root Crops, 2010, 36, 14-26Google Scholar

  • Lebesa L.N., Khan Z.R., Krueger K., Bruce J.A., Hassanali A., Pickett J.A., Farmers ’ knowledge and perceptions of blister beetles, Hycleus spp. (Coleoptera: Meloidae), as pest herbivores of Desmodium legumes in western Kenya. Int. J. Pest Manag., 2012, 58, 165-174Web of ScienceGoogle Scholar

  • Morgan D., Temperature changes and insect pests: a simulation study. Asp. Appl. Biol., 1996, 45, 277-283Google Scholar

  • Mukanga M., Derera J., Tongoona P., Laing M.D., Farmers ’ perceptions and management of maize ear rots and their implications for breeding for resistance. Afr. J. Agric. Res., 2011, 6, 4544-4554Google Scholar

  • Munyuli T.M.B., Yield loss evaluation of sweetpotato due to leaf caterpillar, Acraea acerata, (Lepidoptera: Nymphalidae), in Kivu, D.R.Congo. African Potato Association Conference Proceedings, 2000, 5, 233236Google Scholar

  • Munyuli T.M.B., Farmers’ perceptions of pollinators’ importance incoffee production in Uganda. Agricultural Sciences, 2011, 2(3), 318-333Google Scholar

  • Munyuli T.M.B., Trends in response to drivers by different bee ecological traits and functional groups in agricultural landscapes in Uganda. Trends in Entomology, 2013, 58(9), 1-23Google Scholar

  • Munyuli T.M.B., Mbaka Kavuvu J-M., Mulinganya G., Mulinganya Bwinja G., The Potential Financial Costs of Climate Change on Health of Urban and Rural Citizens: A Case Study of Vibrio cholerae Infections at Bukavu Town, South Kivu Province, Eastern of Democratic Republic of Congo. Iranian J Publ Health, 2013, 42(7), 707-725Google Scholar

  • Munyuli T.M.B., Assessment of the current status of pesticide use, trade and regulation and outline of action plans for safer application of pesticides in DRCongo. A draft consultancy report submitted to The Cadmus Group/GEMS under ther PERSUAP-USAID/RDCongo mission-wide agricultural activities in North-Kivu and South-Kivu Provinces, 2016, p. 222Google Scholar

  • Nderitu J., Silai M., Nyamasyo G., Kasina M., Insect species associated with sweetpotatoes (Ipomoea batatas (L.) Lam.) in eastern Kenya. Int. J. Sustain. Crop Prod., 2009, 4, 14-18Google Scholar

  • Obopile M.D., Munthali C., Matilo B., Farmers’ knowledge, perceptions and management of vegetable pests and diseases in Botswana. Crop Prod., 2008, 27, 1220-1224Google Scholar

  • Okonya J., Mwanga R.O.M., Syndikus K., Kroschel J., Insect pests of sweetpotato in Uganda: farmers’ perceptions of their importance and control practices. SpringerPlus, 2014, 3, 303Google Scholar

  • Okonya J.S., Kroschel J., Incidence, abundance and damage by the sweetpotato butterfly Acraea acerata Hew. and the African sweetpotato weevils (Cylas spp.) across an altitude gradient in Kabale district, Uganda. International Journal of Agri. Science, 2013, 3, 814-824Google Scholar

  • Okonya J.S., Kroschel J., Pest status of Acraea acerata Hew and Cylas spp. in sweetpotato (Ipomoea batatas (L.) Lam.) and incidence of natural enemies in the Lake Albert crescent agro-ecological zone of Uganda. Int. J. Insect Sci., 2013b, 5, 41 -46Google Scholar

  • Parr M.C., Ntonifor N.N., Jackai L., The effect of planting/harvesting periods and seasons on the dynamics and damage by sweetpotato weevils in the S.W. region of Cameroon. Journal of Biology, Agriculture and Healthcare, 2014, 4, 25-33Google Scholar

  • Porter J.H., Parry M.L., Carter T.R., The potential effects of climate change on agricultural insect pests. Agric. For. Meteorol., 1991, 57, 221-240Google Scholar

  • Sseruwu G., Shanahan P., Melis R., Ssemakula G., Farmers awareness and perceptions of Alternaria leaf petiole and stem blight and their preferred sweetpotato traits in Uganda. J. Plant Breed. Genet., 2015, 03(02), 25-37Google Scholar

  • Schaefers G.A., Terry E.R., Insect transmission of sweetpotato disease agents in Nigeria. Phytopathology, 1976, 66, 642-645 Google Scholar

  • Sharma H.C., Sullivan D.J., Bhatnagar V.S., Population dynamics of the Oriental armyworm, Mythimna separata (Walker) (Lepidoptera: Noctuidae) in South-Central India. Crop Protection, 2002, 21, 721-732Google Scholar

  • Talekar N.S., Cheng K.W., Nature of damage and sources of resistance to sweetpotato vine borer (Lepi doptera: Pyralidae) in sweetpotato. Journal of Economic Entomology, 1987, 80, 788-791CrossrefGoogle Scholar

  • Tounou A.K., Agboka K., Agbodzavu K.M., Wegbe K., Maize stemborers distribution, their natural enemies and farmers’ perception on climate change and stemborers in southern Togo. J. Appl. Biosci., 2013, 64, 4773-4786Google Scholar

  • Wosula E.N., Clark C.A., Davis J.A., Effect of host plant, aphid species, and virus infection status on transmission of Sweetpotato feathery mottle virus. Plant Disease, 2012, 96, 1331-1336Google Scholar

  • Zhou X., Harrington R., Woiwod I.P., Perry J.N., Bale J.S., Clark S.J., Effects of temperature on aphid phenology. Glob. Chang. Biol., 1995, 1, 303-313Google Scholar

About the article

Received: 2016-01-02

Accepted: 2017-03-19

Published Online: 2017-10-31

Published in Print: 2017-10-26

Citation Information: Open Agriculture, Volume 2, Issue 1, Pages 495–530, ISSN (Online) 2391-9531, DOI: https://doi.org/10.1515/opag-2017-0054.

Export Citation

© 2017. This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License. BY-NC-ND 4.0

Comments (0)

Please log in or register to comment.
Log in