The fall armyworm, Spodoptera frugiperda, a moth originating from tropical and subtropical America, has recently become a serious pest of cereals in sub-Saharan Africa. Biological control offers an economically and environmentally safer alternative to synthetic insecticides that are being used for the management of this pest. Consequently, various biological control options are being considered, including the introduction of Telenomus remus, the main egg parasitoid of S. frugiperda in the Americas, where it is already used in augmentative biological control programmes. During surveys in South, West, and East Africa, parasitized egg masses of S. frugiperda were collected, and the emerged parasitoids were identified through morphological observations and molecular analyses as T. remus. The presence of T. remus in Africa in at least five countries provides a great opportunity to develop augmentative biological control methods and register the parasitoid against S. frugiperda. Surveys should be carried out throughout Africa to assess the present distribution of T. remus on the continent, and the parasitoid could be re-distributed in the regions where it is absent, following national and international regulations. Classical biological control should focus on the importation of larval parasitoids from the Americas.

The fall armyworm, Spodoptera frugiperda, a moth originating from the American continent, has recently invaded most African countries, where it is seriously threatening food security as a pest of cereals. The current management methods rely heavily on the use of synthetic insecticides but there is a need for more sustainable control methods, including biological control. Surveys were conducted in two West African countries, Ghana and Benin, to determine the native parasitoid complex and assess parasitism rates of S. frugiperda. Samples of S. frugiperda eggs and larvae were collected in maize fields located in 56 and 90 localities of Ghana and Benin, respectively, from July 2018 to July 2019. Ten species were found parasitizing the pest, including two egg parasitoids, one egg–larval, five larval and two larval–pupal parasitoids. The two most abundant parasitoids in both countries were two Braconidae: the egg-larval parasitoid Chelonus bifoveolatus and the larval parasitoid Coccygidum luteum. Parasitism rates were determined in three Ghanaian regions and averages varied from 0% to 75% between sites and from 5% to 38% between regions. These data provide an important baseline for the development of various biological control options. The two egg parasitoids, Telenomus remus and Trichogramma sp. can be used in augmentative biological control and investigations should be conducted to assess how cultural practices can enhance the action of the main parasitoids, C. luteum and Ch. bifoveolatus, in the field. Understanding the parasitoid complex of S. frugiperda in Africa is also necessary before any development of classical biological controls involving the introduction of parasitoids from the Americas.

In October 2001, a wilting disorder of new aetiology was reported affecting banana ( Musa sp.) within the Mukono district of Uganda. The disorder was characterized by a rapid yellowing and wilting of the younger leaves, a discoloration of the internal vascular vessels, occasionally a dieback initiating from the male floral parts with internal rotting of banana fruits. These symptoms were notably distinct from fusarium wilt ( Fusarium oxysporum ) and 'Matooke wilt' (a wilt-like disorder of unknown aetiology), but strongly resembled Moko disease caused by Ralstonia solanacearum , although this particular pathogen had not previously been recorded on banana in Africa.A bacterium was isolated on nutrient agar that was identified by fatty acid (Microbial ID Inc. [MIDI]) and metabolic (Biolog, Inc, Hayward, CA, USA) analyses as Xanthomonas axonopodis (ID probability score < 0·4) and Xanthomonas campestris (ID probability score ∼ 0·9), respectively. The presence of the Xanthomonas specific fatty acids 11:0 ISO, 11:0 ISO 3OH and 13:0 ISO 3OH was recorded. Pathogenicity tests on disease-free tissue culture-derived banana plantlets by stem inoculation with a bacterial suspension induced wilt symptoms consistent with field observations after 3 weeks. Reisolation and identification, as outlined above, confirmed Koch's postulates. Reference to the literature suggested the bacterium was Xanthomonas campestris pv. musacearum (Yirgou & Bradbury, 1968). However, this bacterium is relatively poorly described and not contained within either the MIDI or Biolog databases. To support the identification, rep-PCR (Louws et al ., 1994) using ERIC and BOX primers was performed on the Ugandan banana isolate, cultures of X. campestris pv. musacearum from Ensete and Musa in Ethiopia (IMI 349461, IMI 349986, IMI350025) and other cultures of Xanthomonas spp. from Africa. These analyses revealed an identical DNA fingerprint for all isolates from Musa and Ensete , but distinct fingerprints for the isolates from other hosts. This is the first report of X. campestris pv. musacearum outside of Ethiopia, where it is recorded as a pathogen of ensete and, to a lesser extent, banana. Accordingly, this pathogen has been given the common name of ensete bacterial wilt, although the aptness of this now looks questionable. The risk posed by this new disease record to the contiguous banana plantation of Uganda is undetermined, but significant spread is already being observed. The causative organism for this new disease record has been deposited within the CABI Genetic Resource Collection as IMI 386970. References

Genetic diversity among isolates of the bacterial plant pathogen Burkholderia solanacearum (synonym Pseudomonas solanacearum) race 3 biovar II of Kenya was determined by PCR with repetitive sequences (ERIC and BOX repetitive primer sets) and pulsed-field gel electrophoresis of genomic DNA digested by rare-cutting restriction endonucleases (RC-PFGE). The study comprised 46 isolates collected during 1992 from the major potato-growing regions of Kenya (45 were identified as race 3 biovar II, and 1 belonged to race 3 biovar N2) and 39 reference isolates from 19 other countries. RC-PFGE identified 10 distinct profile types among the Kenyan race 3 biovar II isolates (29 of the isolates exhibited identical profiles) and a further 27 distinct profile types among the reference isolates. ERIC and BOX primer sets were unable to differentiate race 3 biovar II isolates within the Kenyan population but differentiated a further two distinct profile types among the reference isolates. The race 3 biovar N2 isolate had a highly distinct RC-PFGE and repetitive sequence PCR profile. Statistical analysis of the data identified biogeographic trends consistent with conclusions drawn from previous studies on the origin and worldwide dissemination of race 3 biovar II isolates; however, genomic fingerprinting by RC-PFGE revealed a level of genetic diversity previously unrealized.

Invasive alien species have environmental, economic and social impacts, disproportionally threatening livelihood and food security of smallholder farmers in low- and medium-income countries. Fall armyworm (FAW) (Spodoptera frugiperda), an invasive insect pest from the Americas, causes considerable losses on maize to smallholder farmers in Africa since 2016. The increased use of pesticides to control FAW in Africa raises concerns for health and environmental risks resulting in a growing interest in research on biological control options for smallholder farmers. In order to evaluate the occurrence of local natural enemies attacking FAW, we collected on a weekly basis FAW eggs and larvae during a maize crop cycle in the rainy season of 2018–2019 at four locations in the Lusaka and Central provinces in Zambia. A total of 4373 larvae and 162 egg masses were collected. For each location and date of collection, crop stage, the number of plants checked and amount of damage were recorded to analyse which factors best explain the occurrence of the natural enemy species on maize. Overall parasitism rates from local natural enemies at each location varied between 8.45% and 33.11%. We identified 12 different egg-larval, larval and larval-pupal parasitoid species. Location, maize growth stage, pest density and larval stage significantly affected parasitoid species occurrence. Our findings indicate that there is potential for increasing local populations of natural enemies of FAW through conservation biological control programmes and develop safe and practical control methods for smallholder farmers.