First Report of Outbreaks of the Fall Armyworm Spodoptera frugiperda (J E Smith) (Lepidoptera, Noctuidae), a New Alien Invasive Pest in West and Central Africa

Abstract

The fall armyworm Spodoptera frugiperda is a prime noctuid pest of maize on the American continents where it has remained confined despite occasional interceptions by European quarantine services in recent years. The pest has currently become a new invasive species in West and Central Africa where outbreaks were recorded for the first time in early 2016. The presence of at least two distinct haplotypes within samples collected on maize in Nigeria and São Tomé suggests multiple introductions into the African continent. Implications of this new threat to the maize crop in tropical Africa are briefly discussed.

Fig 1. Adult male of S. frugiperda (Benin, Calavi Akassato, 6.vi.2016, G. Goergen).

Photo by GG.

Fig 2. The phylogenetic relationships of 6 samples, 4 from Nigeria and 2 from São Tomé & Príncipe (arrows), inferred from the 633 bp mitochondrial cytochrome oxidase I (COI) sequence using the Maximum Likelihood method based on the Tamura-Nei model [20].

Bootstrap values (1,000 replications) reproduced in <60% replicates were collapsed and the bootstrap values are shown at the branch points. The GenBank accession numbers of the corresponding reference sequence are indicated. The analysis involved 30 nucleotide sequences and there were a total of 603 positions in the final dataset. Initial tree(s) for the heuristic search were obtained automatically by applying Neighbor-Join and BioNJ algorithms to a matrix of pairwise distances estimated using the Maximum Composite Likelihood (MCL) approach, and then selecting the topology with superior log likelihood value. The tree is drawn to scale, with branch lengths measured in the number of substitutions per site. Codon positions included were 1st+2nd+3rd+Noncoding. All positions containing gaps and missing data were eliminated. The nucleotide sequences were aligned using the MUSCLE [21] and the evolutionary analyses were conducted in MEGA6.06 [20].

Fig 3. Fifth instar larva of S. frugiperda (Benin, Calavi Akassato, 2.vi.2016, G. Goergen).

Photo by GG.

Fig 4. Adult male of S. frugiperda (Benin, Calavi Akassato, 6.vi.2016, G. Goergen).

Photo by GG.