Population Dynamic of Fall Armyworm and Stem Borers and Their Impact on Maize: An Approach towards Innovative Management Strategies

Abstract

Maize (Zea mays) is one of the major cereal crops grown for its food and feed values. It is one of the most important staple foods providing calories for consumers and income for traders, but pest complex as major constraints to its production. The fall armyworm (FAW), Spodoptera frugiperda and Lepidopteran stem borers are the most devastating pests of maize. In view of the recent arrival of the fall armyworm in 2016 in Africa, there is paucity of information on the distribution and abundance together with stem borers in Cameroon. This study was conducted to generate baseline information on the effect of fall armyworm and stem borers, distribution, population dynamics and damage on maize in Buea. The study was carried out at the Faculty of Agriculture Teaching and Research Farm, University of Buea. There were 3 treatments including control. (Control (Traps only), Trap + wood ash and Trap + detasseling) replicated thrice and arranged in a randomized complete block design. Two varieties of maize; UBMS0001 and CMS8704 were used in the study and baited traps were deployed in maize fields, hung on wooden poles at an approximate height of about 1.5 m above ground, to assess moth’s population and variations over time. Captured moth species were counted, and the attractant renewed weekly. Wood ash was applied gently on the leaves and stems of the plants manually soon as infestation was detected. Detasseling was done when the maize had tasseled because the 1st and 2nd instar larvae of the pests go up the tassel to feed on the pollen. The incidence of damaged plants abundance was monitored by visual sampling using the following indicators: exit holes on stems, frass, dead heart, lodged plants, irregular damage (cuts) on leaves in each maize variety. The findings of this study indicate that, more insects were found on the maize variety UBMS0001 compared to CMS8704, the mean number of plants damaged by fall armyworm and stem borers was higher for UBMS 0001 compared to CMS8704 but UBMS0001 had a higher yield compared to CMS8704.The results demonstrated that catches increased steadily from time of plants emergence and afterwards, catches declined significantly when the plants were growing into the reproductive stage. The larvae of three species which affects the growth and development of maize were observed in the stems of both maize varieties at harvest: the whitish purple Busseola fusca larvae, the dark to blackish Eldana saccharina and the pink Sesamia calamistis larvae, Eldana saccharina being the most abundant species. A higher number of FAW, Stem borers and damaged plants during the rainy season compared to the dry season was recorded. According to the results of this study, the performance of trap + detasseling on the yield of maize was significantly better than most of the other treatments. There was a higher number of damaged plants of 78 in the rainy season as compared to 55 in the dry season caused by FAW and 19 in the rainy season as compared to 10 in the dry season by stem borers. From the results of this study, the combined effect of trapping and detasseling (Trap + Detasseling) against fall armyworm and stem borers was significantly better than most of the other treatments.