Evaluation of African Maize Cultivars for Resistance to Fall Armyworm Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) Larvae.

Xavier Chiriboga Morales,Toby J. A. Bruce,Charles A. O. Midega,Islam S. Sobhy,Zeyaur Khan,Amanuel Tamiru

doi:10.3390/plants10020392

Abstract

The fall armyworm (FAW) has recently invaded and become an important pest of maize in Africa causing yield losses reaching up to a third of maize annual production. The present study evaluated different aspects of resistance of six maize cultivars, cropped by farmers in Kenya, to FAW larvae feeding under laboratory and field conditions. We assessed the arrestment and feeding of FAW neonate larvae in no-choice and choice experiments, development of larvae-pupae, food assimilation under laboratory conditions and plant damage in a field experiment. We did not find complete resistance to FAW feeding in the evaluated maize cultivars, but we detected differences in acceptance and preference when FAW larvae were given a choice between certain cultivars. Moreover, the smallest pupal weight and the lowest growth index were found on ’SC Duma 43′ leaves, which suggests an effect of antibiosis of this maize hybrid against FAW larvae. In contrast, the highest growth index was recorded on ‘Rachar’ and the greatest pupal weight was found on ‘Nyamula’ and ‘Rachar’. The density of trichomes on the leaves of these maize cultivars seems not to be directly related to the preference of neonates for feeding. Plant damage scores were not statistically different between cultivars in the field neither under natural nor artificial infestation. However, plant damage scores in ‘Nyamula’ and ‘Jowi’ tended to be lower in the two last samplings of the season compared to the two initial samplings under artificial infestation. Our study provides insight into FAW larval preferences and performance on some African maize cultivars, showing that there are differences between cultivars in these variables; but high levels of resistance to larvae feeding were not found.

Highlights

Introductionfall armyworm (FAW) invasion has become the biggest threat to maize production in sub-Saharan Africa due to its rapid spread to almost all countries in the region and associated crop damage [2]
We found significant differences (F5,54 = 11.24, p < 0.001) in arrestment behavior of fall armyworm (FAW) neonate larvae on leaf cuts of different maize cultivars after 24 h in no-choice experiments
We found significant differences for orientation and settling of FAW neonate larvae on leaf cuts of some choice-combinations of maize cultivars after 24 h

Summary

Introduction

FAW invasion has become the biggest threat to maize production in sub-Saharan Africa due to its rapid spread to almost all countries in the region and associated crop damage [2]. The pest has further spread, during the last two years to India [3], Yemen, Sri Lanka, Bangladesh, Myanmar, Thailand, China [4,5,6], Indonesia, Laos, Malaysia, Vietnam, Egypt, the Republic of Korea, and Japan [7] and the most recent invasions has been detected in Australia, Mauritania, and East Timor [8]. The impact of FAW on maize yield in Africa has been severe [9]. Baudron et al have estimated that, with an incidence of FAW ranging between 32 and 48%, the impact of FAW on maize yield is around 11.5% [9]

Methods

Results

Discussion

Conclusion