CANCELLED: Invasive fall armyworm herbivory upregulates maize defense genes relative to resident stemborers Busseola fusca and Chilo partellus

Plant-insect interactions presents a dynamic and complex paradigm whereby one insect feeding deters subsequent performance of other insects. Initial feeding by fall armyworm (FAW), Spodoptera frugiperda (Lepidoptera: Noctuidae) adversely affected subsequent performance of resident stemborers; Busseola fusca (Lepidoptera: Noctuidae) and Chilo partellus (Lepidoptera: Crambidae). However, the underlying mechanism mediating this phenomenon remain unknown. We delved into interspecific differential expression of defense genes upon herbivory by the three herbivore pests to unravel plant-mediated competition between S. frugiperda and stemborers in maize crop. We further evaluated larval feeding preferences and weight gain of the three herbivore pests upon initial damage by interspecies. Spodoptera frugiperda feeding induced higher levels of maize proteinase inhibitor (mpi), pathogenesis-related protein-5 (pr-5) and lipoxygenase-3 (lox-3) defense genes than stemborers. Neonates of B. fusca and C. partellus consumed less leaf tissue on plants initially exposed to S. frugiperda compared to B. fusca- and C. partellus-fed and undamaged plants. Additionally, larval weight of stemborers significantly reduced upon feeding on S. frugiperda-damaged plants relative to feeding on stemborer-damaged and undamaged plants. There was strong negative correlation between induction of mpi defense gene upon S. frugiperda herbivory and subsequent stemborers’ larval feeding. Overall, this study revealed increased expression of defense genes upon feeding by S. frugiperda as one of strategies o used to deter subsequent feeding and growth of other herbivore pests. These findings highlight the importance of differential interspecific induction of defense genes in mediating host-plant competition in lepidopteran community and provide novel information for the management of these herbivore pests.