Risk of spread of the Asian citrus psyllid Diaphorina citri Kuwayama (Hemiptera: Liviidae) in Ghana.

The impact of invasive species on biodiversity, food security and economy is increasingly noticeable in various regions of the globe as a consequence of climate change. Yet, there is limited research on how climate change affects the distribution of the invasive Asian citrus psyllid Diaphorina citri Kuwayama (Hemiptera:Liviidae) in Ghana. Using maxnet package to fit the Maxent model in R software, we answered the following questions; (i) what are the main drivers for D. citri distribution, (ii) what are the D. citri-specific habitat requirements and (iii) how well do the risk maps fit with what we know to be correctly based on the available evidence?. We found that temperature seasonality (Bio04), mean temperature of warmest quarter (Bio10), precipitation of driest quarter (Bio17), moderate resolution imaging spectroradiometer land cover and precipitation seasonality (Bio15), were the most important drivers of D. citri distribution. The results follow the known distribution records of the pest with potential expansion of habitat suitability in the future. Because many invasive species, including D. citri, can adapt to the changing climates, our findings can serve as a guide for surveillance, tracking and prevention of D. citri spread in Ghana.

First report of Leucinodes africensis and Leucinodes laisalis on Solanum aethiopicum and Solanum melongena in farmer's fields in southern Ghana.

The eggplant fruit and shoot borer (EFSB) is a devastating pest of eggplants (Solanum aethiopicum L. and Solanum melongena L.) in Ghana, causing significant economic losses. Although initially thought to be the Leucinodes orbonalis Guenee species found in Asia, recent European and Mediterranean Plant Protection Organization reports suggest its absence in Africa. However, eight Leucinodes species have been recently described in Africa, including two new species, Leucinodes africensis sp. n. and Leucinodes laisalis Walker, which were intercepted in eggplant fruits exported from Ghana to the United Kingdom. Despite the reported absence of L. orbonalis in Africa, it remains on the pest list of Ghana as a species known to attack eggplants. To accurately determine the identity of the EFSB complex occurring on eggplant in Southern Ghana, molecular and morphological taxonomic tools were employed, and adult male populations were monitored in on-farm conditions. Our results revealed the presence of two EFSB species, L. africensis and L. laisalis, in the shoot and fruits of eggplants, with L. africensis being the dominant species and widely distributed in Southern Ghana. Notably, L. africensis males were attracted to the pheromone lure of L. orbonalis despite the two species being biologically distinct. This study provides crucial information on correctly identifying the EFSB species attacking eggplants in Southern Ghana and has significant implications for developing management interventions against these pests and their effects on international eggplant trade.

Assessing the Potential of Inoculative Field Releases of Telenomus remus to Control Spodoptera frugiperda in Ghana.

In response to the threat caused by the fall armyworm to African maize farmers, we conducted a series of field release studies with the egg parasitoid Telenomus remus in Ghana. Three releases of ≈15,000 individuals each were conducted in maize plots of 0.5 ha each in the major and minor rainy seasons of 2020, and compared to no-release control plots as well as to farmer-managed plots with chemical pest control. No egg mass parasitism was observed directly before the first field release. Egg mass parasitism reached 33% in the T. remus release plot in the major rainy season, while 72-100% of egg masses were parasitized in the minor rainy season, during which pest densities were much lower. However, no significant difference in egg mass parasitism was found among the T. remus release plots, the no-release control plots and the farmer-managed plots. Similarly, no significant decrease in larval numbers or plant damage was found in the T. remus release fields compared to the no-release plots, while lower leaf and tassel damage was observed in farmer-managed plots. Larval parasitism due to other parasitoids reached 18-42% in the major rainy season but was significantly lower in the minor rainy season, with no significant differences among treatments. We did not observe significant differences in cob damage or yield among the three treatments. However, the lack of any significant differences between the release and no-release plots, which may be attributed to parasitoid dispersal during the five weeks of observation, would require further studies to confirm. Interestingly, a single application of Emamectin benzoate did not significantly affect the parasitism rates of T. remus and, thus, merits further investigation in the context of developing IPM strategies against FAW.

Cabbage Production in West Africa and IPM with a Focus on Plant-Based Extracts and a Complementary Worldwide Vision.

In urban and peri-urban areas in West Africa, the cabbage Brassica oleracea L. (Brassicaceae) is protected using repeated high doses of synthetic insecticides. After a brief description of available IPM components, this paper presents a literature review focused on the botanical extracts that have been experimented with at the laboratory or in the field in West Africa against major cabbage pests. The literature reviewed mentions 19 plant species from 12 families used for cabbage protection in the subregion. The species most used are Azadirachta indica, Capsicum frutescens, Ocimum gratissimum and Ricinus communis. An overview of the world literature showed that a total of 13 plant species belonging to 8 families used to control cabbage pests are reported from the rest of Africa, and 140 plant species belonging to 43 families from the rest of the world. The most commonly used and tested plant species against insect pests in the three geographical areas considered is A. indica.

Parasitoid Complex of Fall Armyworm, Spodoptera frugiperda, in Ghana and Benin.

Keywords: biological control; Chelonus bifoveolatus; Coccygidum luteum; Telenomus remus; Trichogramma; West Africa.

Evidence of Leaf Consumption Rate Decrease in Fall Armyworm, Spodoptera frugiperda, Larvae Parasitized by Coccygidium luteum.

Biological control is one of the best options for the sustainable management of the invasive maize pest Spodoptera frugiperda in Africa. However, there is limited knowledge of the efficacy of native natural enemies of S. frugiperda and their potential use in integrated pest management. The endoparasitoid wasp Coccygidium luteum is one of the natural enemies of S. frugiperda in Africa. This study assessed, under laboratory conditions, the effect of C. luteum on the leaf consumption rate of its host. Fifty first instar S. frugiperda larvae were exposed to C. luteum for oviposition and the maize leaf consumption rate of parasitized larvae was assessed and compared to 50 unparasitized larvae from the same cohort. Coccygidium luteum completed a generation, from egg to adult emergence, in 16.7 days. The leaf consumption rate of parasitized S. frugiperda larvae declined gradually compared to unparasitized larvae and the overall consumption reduction by parasitized S. frugiperda larvae was 89%. Our findings show that C. luteum could reduce damage caused by S. frugiperda to maize farms but, prior to its use in biological control programmes, further studies are needed to assess potential parasitism rates in field conditions and develop a cost-effective mass production system.