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.

Production of maize, Zea mays L. (Poaceae), in sub‐Saharan Africa is threatened by a new invasive pest, fall armyworm (FAW), Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae). To mitigate this threat, push–pull companion cropping, a system originally developed for management of lepidopteran stemborers, may be used to control FAW. The original system involved trap crops that functioned as a ‘pull’ component to attract moths away from the main crop. How grass species can be used as trap crops in a push–pull system to control FAW is a question that remains to be answered, because maize is already a highly preferred host plant. Therefore, we tested oviposition preference of FAW female moths in no‐choice and two‐choice experiments and larval performance on six selected grasses (Poaceae) to assess their roles as trap crop ‘pull’ plants in the system. In no‐choice tests, numbers of eggs deposited on Brachiaria brizantha (Hochst. ex A. Rich.) R. Webster cv. ‘Piata’, cv. ‘Mulato II’, and cv. ‘Xaraes’, and Napier grass (Pennisetum purpureum K. Schumach) cv. ‘South Africa’ were not statistically different from those deposited on maize. In two‐choice tests between grasses and maize, there were no significant differences in number of eggs laid when the plants were of the same size. However, in two‐choice tests with maize plants half of the size of the grasses, significantly more eggs were laid on B. brizantha cv. Xaraes and P. purpureum cv. South Africa than on maize, suggesting that crop phenology could make a difference. Numbers of larvae arrested on grass leaf cuts were considerably lower than those on maize leaf cuts after 48 h. In two‐choice tests with maize, molasses grass (Melinis minutiflora P. Beauv.) was the only grass that was significantly preferred to maize for larval settlement after 24 h. After 48 h in the two‐choice test, it was the only grass that retained larvae, although the larval count was significantly lower than on maize. Our data show that none of the grasses tested were strongly preferred to maize, but the results indicate plants attractive to FAW adults and larvae that could be utilized in a multiple trap crop approach to target various stages of the pest. Furthermore, results indicate the importance of planting these companion plants earlier than maize.

Background: The fall armyworm (FAW), Spodoptera frugiperda (Lepidoptera: Noctuidae), has invaded new geographical regions, now spanning Africa, Asia, Oceania and Europe, from its native distribution in the last decade. Little is known about FAW host plants in recently invaded habitats; although more than 300 hosts have been reported in the Americas, its native habitat. In our study, we evaluated the acceptability and suitability of 12 cultivated varieties of plants from Africa, in the family Poaceae, for FAW herbivory and oviposition. Methods: Experiments investigating larval development, no-choice oviposition, and no-choice larval arrestment-feeding were conducted to evaluate the insect´s ability to utilize these plants for survival. Results: We found that Pennisetum ex. Sengerema, Brachiaria brizantha , Brachiaria ex. Mwanza, Panicum maximum ex. Machakos, Melinis minutiflora and S . bicolor cv. Ochuti were unsuitable plants for FAW larvae. In contrast, Zea mays HB WH505, Panicum glaucum Nutrifeed, S . bicolor cv. Serena and P . purpureum were suitable plants and S . bicolor cv. Ochuti was well accepted for egg-laying. However, M . minutiflora was not accepted for egg-laying but retained early instar larvae. S . bicolor cv. Andiwo was not well accepted for egg-laying and S . bicolor cv. Gadam yielded lighter pupae. Conclusions: Our findings provide insights into the performance of FAW larvae on different Poaceae plants and how well they are accepted by FAW female moths for oviposition. We recommend to study further selected plants ( M . minutiflora , S . bicolor cv. Andiwo and S . bicolor cv. Ochuti), as potential trap or repellent plants for different FAW life stages, in choice tests. This knowledge will help to design ecologically based management strategies for FAW in its new habitats in Kenya and beyond.