Evaluation of Susceptibility of Some Sorghum (Sorghum bicolor L. Moench) to Stem Borers in Far North Region of Cameroon: A Case of Off Season Local Varieties
Jacques Djodda *
Department of Biological Sciences, University of Maroua, Cameroon and University of Yaounde I, Laboratory of Zoology, P.O.Box 46, Cameroon.
Elias Nukenine Nchiwan
Department of Biological Sciences, University of Ngaoundere, P.O.Box 454, Ngaoundere, Cameroon.
Pierre Ngassam
University of Yaounde I, Laboratory of General Biology, Cameroon.
Bouba Djilé
Department of Plants Genetic and Biotechnology, Agriculture Research for Development Institute (IRAD), P.O.Box 33, Maroua, Cameroon.
*Author to whom correspondence should be addressed.
Abstract
Introduction: Among cereals, Sorghum is the most consumed as food in the Far North of Cameroon. Muskuwari, which is an off season sorghum, plays a key role in the regulation of its availability. On the other hand, stem borers (Sesamia cretica Lederer) constitute a major constraint, compromise its yield and reduce cereal supply. Despite this fact, ecological control measures to reduce losses are still little known.
Objective: The present research aimed at evaluating the susceptibility of ten local varieties of Muskuwari against Lepidoptera stem borers in natural conditions.
Place and Duration of Study: The study was conducted during the 2012 and 2013 agricultural campaign at Ngassa, a locality of Maroua.
Methodology: Experimentation was carried out in a Completely Randomized Block design with tree replications. Ten local varieties were then under natural infestations. Degrees of infestation were estimated by visual observation and destructive methods. Each year, Seed losses in term of percentage of total harvest loosed, were estimated from 30 ears per variety randomly selected from infested and uninfected plants.
Results: The results showed a large variation in agronomic performance depending on the parameters considered. Mandouéri, Bourgouri, Tchangalari and Soukatari with infestation rates ranging from 4% to 11% and seed losses ranging from 0.96% to 23.42% are more tolerant or less susceptible than other varieties while Safra’s varieties are always the most susceptible to stem borers with over to 40% seed loss.
Conclusion: The study showed there are resistant or tolerant varieties of Muskuwari able to cope with the attacks of stem borers not exploited to mitigate damages. Degree of infestation, seed loss, number of caterpillars and gallery length per plant are suitable parameters for varietal screening of stem borer resistance. Since varietal resistance is an ecological and easily adoptable option, investigations that could lead to Muskuwari varietal improvement could boost cereal supplly in the Far North Region of Cameroon.
Keywords: Muskuwari, infestation parameters, Sesamia cretica Lederer, Diamaré-Maroua.