Bioecology of fall armyworm Spodoptera frugiperda (J. E. Smith), its management and potential patterns of seasonal spread in Africa

Fall armyworm, Spodoptera frugiperda (J. E. Smith) has rapidly spread in
sub-Saharan Africa (SSA) and has emerged as a major pest of maize and
sorghum in the continent. For effective monitoring and a better
understanding of the bioecology and management of this pest, a
Community-based Fall Armyworm Monitoring, Forecasting, Early Warning and
Management (CBFAMFEW) initiative was implemented in six eastern African
countries (Ethiopia, Kenya, Tanzania, Uganda, Rwanda and Burundi). Over
650 Community Focal Persons (CFPs) who received training through the
project were involved in data collection on adult moths, crop phenology,
cropping systems, FAW management practices and other variables. Data
collection was performed using Fall Armyworm Monitoring and Early Warning
System (FAMEWS), a mobile application developed by the Food and
Agricultural Organization (FAO) of the United Nations. Data collected from
the CBFAMFEW initiative in East Africa and other FAW monitoring efforts in
Africa were merged and analysed to determine the factors that are related
to FAW population dynamics. We used the negative binomial models to test
for effect of main crops type, cropping systems and crop phenology on
abundance of FAW. We also analysed the effect of rainfall and the spatial
and temporal distribution of FAW populations. The study showed variability
across the region in terms of the proportion of main crops, cropping
systems, diversity of crops used in rotation, and control methods that
impact on trap and larval counts. Intercropping and crop rotation had
incident rate 2-times and 3-times higher relative to seasonal cropping,
respectively. The abundance of FAW adult and larval infestation
significantly varied with crop phenology, with infestation being high at
the vegetative and reproductive stages of the crop, and low at maturity
stage. This study provides an understanding on FAW bioecology, which could
be vital in guiding the deployment of FAW-IPM tools in specific locations
and at a specific crop developmental stage. The outcomes demonstrate the
relevance of community-based crop pest monitoring for awareness creation
among smallholder farmers in SSA.