Legume intercropping for sustainable management of fall armyworm (Spodoptera frugiperda) in maize in the north-eastern Himalayas, India

Abstract

 Maize (Zea mays L.) is an essential crop in
northeast India, widely cultivated for food, fodder, and
industrial purposes. However, maize cultivation in this
region faces significant challenges, including poor soil
fertility, pest infestations, and a lack of access to modern
inputs. The 2018 invasion of the fall armyworm (FAW)
(Spodoptera frugiperda) has further threatened maize
production, leading to substantial yield losses. In northeast
India, where smallholder farmers rely on rainfed, low
input farming systems, there is an urgent need for
sustainable pest management strategies. Intercropping,
particularly maize-legume systems, offers a potential
solution by enhancing soil fertility through nitrogen fixation
and providing ecological pest control benefits. This study
was conducted in Manipur, a key maize-growing state in
northeast India, to evaluate the effectiveness of maize
legume intercropping in managing FAW infestations and
improving maize productivity. Field experiments were
conducted over two years (2020 in experimental field
and 2021 in farmers field), using a randomized block
design (RBD) with treatments including sole maize and
maize intercropped with legumes such as soybean,
groundnut, green gram, and cowpea in different row
ratios. The study assessed grain yield, stover yield, maize
equivalent yield, and pest infestation levels. The results
showed that maize-legume intercropping significantly reduced FAW infestation compared to sole maize. The
maize-groundnut intercropping system recorded the
highest grain yield (5869 kg/ha in 2020 and 3430 kg/ha
in 2021) and the lowest pest infestation. Additionally,
intercropped exhibited higher economic returns, making
this practice both agronomically and economically viable
for smallholder farmers in the region