Unexpected diversity of Wolbachia associated with Bactrocera dorsalis (Diptera: Tephritidae) in Africa

Bactrocera dorsalis (Hendel) is an important pest of fruit-bearing plants in many countries worldwide. In Africa, this pest has spread rapidly and has become widely established since the first invasion report in 2003. Wolbachia is a vertically transmitted endosymbiont that can significantly influence aspects of the biology and, in particular, the reproduction of its host. In this study, we screened B. dorsalis specimens collected from several locations in Africa between 2005 and 2017 for Wolbachia using a PCR-based assay to target the Wolbachia surface protein wsp. Of the 357 individuals tested, 10 were positive for Wolbachia using the wsp assay. We identified four strains of Wolbachia infecting two B. dorsalis mitochondrial haplotypes. We found no strict association between the infecting strain and host haplotype, with one strain being present in two different host haplotypes. All the detected strains belonged to Super Group B Wolbachia and did not match any strains reported previously in B. dorsalis in Asia. These findings indicate that diverse Wolbachia infections are present in invasive populations of B. dorsalis

The Endophyte Trichoderma asperellum M2RT4 induces the systemic release of methyl Salicylate and (Z)-jasmone in tomato plant affecting host location and herbivory of Tuta absoluta

The use of endophytic fungi has dramatically increased plant performance through the enhancement of plant protection against abiotic and biotic stressors. We previously demonstrated that the endophytic fungus Trichoderma asperellum M2RT4 improves tomato defenses against the tomato leafminer Tuta absoluta through the reduction of oviposition, leafmining, pupation, and adult emergence. However, the underlying mechanism by which the presence of this endophytic fungus within tomato host plant affects T. absoluta host selection and life-history traits is unknown. We tested the behavioral responses of T. absoluta in Y-tube olfactometer bioassays and found that females preferred non-inoculated tomato plants against those inoculated by endophytes. Additionally, T. absoluta females were not attracted to non-inoculated infested nor to inoculated-infested tomato plants. Chemical analysis revealed the emission of methyl salicylate in inoculated tomato plant and an increase in the amounts of monoterpenes emitted from non-inoculated infested plants. Additionally, we found that upon herbivory, T. asperellum M2RT4 modulates tomato plant chemistry through the production of (Z)-jasmone thus activating both salicylic and jasmonic acid defense pathways. Further, T. absoluta females were attracted to monoterpernes including α-pinene, 2-carene, and β-phellandrene but repelled by methyl salicylate. Methyl salicylate could therefore be considered as a good semiochemical-based candidate for sustainable T. absoluta management using a “push-pull” approach. However, in dose-response bioassays, females of T. absoluta did not show any preference to the four component-blend (α-pinene, 2-carene, β-phellandrene, and methyl salicylate). (Z)-jasmone-treated tomato leaflets significantly reduced the leafmining activity of the pest at the concentration of 10 ng/µL and causing the highest larval mortality rate (83%) with the shortest LT50 (1.73 days) 7 days post-treatment. T. asperellum M2RT4 effect on herbivore performance was then (Z)-jasmone-mediated. These findings expand our understanding of how the endophytic fungus T. asperellum M2RT4 could mediate chemical interactions between T. absoluta and its host plant which are potentially important for development of environmentally friendly T. absoluta management programs.https://www.frontiersin.org/journals/plant-sciencedm2022Forestry and Agricultural Biotechnology Institute (FABI)Zoology and Entomolog

Diversity, host plants and potential distribution of edible Saturniid Caterpillars in Kenya

Saturniids are big colorful caterpillars with spines on their bodies, usually found in shrubs and trees in Sub-Saharan Africa. They are rich in proteins, vitamins, and minerals. The study identifies edible saturniids, diversity, their host plants, their current distribution and to predict possible effects of climate change on their distribution. The paper provides detailed information (including photographs) of seven species of edible saturniids namely Gonimbrasia zambesina, Gonimbrasia krucki, Bunaea alcinoe, Gonimbrasia cocaulti, Gonimbrasia belina, Gynanisa nigra and Cirina forda. Despite being highly nutritious, the diversity of edible saturniid caterpillars has not been studied in Kenya.Federal Ministry for Economic Cooperation and DevelopmentBioInnovate Africa ProgrammeAustralian Centre for International Agricultural Research (ACIAR

Identification of edible short- and long-horned grasshoppers and their host plants in East Africa

This study adopted morphological and molecular analysis to identify edible grasshoppers and their associated food host plants in Kenya and Uganda. Host plants were identified through molecular analysis of the gut contents of the grasshoppers. Grasshoppers are among the most popular edible insects in East Africa. As an alternative protein, they contribute to improved nutrition and food security, livelihoods, and employment. The study provides a detailed breakdown of morphometric data and species identification factors along with sequencing, identification and phylogenetic analysis of plant and insect DNA.Federal Ministry for Economic Cooperation and Development (BMZ)Netherlands Organization for Scientific ResearchWOTRO Science for Global Development (NWO-WOTRO)Bioresources Innovations Network for Eastern Africa Development (BioInnovate Africa)Rockefeller FoundationAustralian Centre for International Agricultural Research (ACIAR

Efficacy of Metarhizium anisopliae and (E)–2–hexenal combination using autodissemination technology for the management of the adult greenhouse whitefly, Trialeurodes vaporariorum Westwood (Hemiptera: Aleyrodidae

DATA AVAILABILITY STATEMENT : The original contributions presented in the study are included in the article. Further inquiries can be directed to the corresponding author.The efficiency of an autodissemination technique in controlling adult whiteflies, Trialeurodes vaporariorum Westwood (Hemiptera: Aleyrodidae) on tomato, Solunum lycopersicum was investigated with previously identified potent fungal isolates of Metarhizium anisopliae ICIPE 18, ICIPE 62 and ICIPE 69 under screenhouse or semi-field conditions. The autodissemination device was inoculated with dry conidia of the M. anisopliae isolates, while control insects were exposed to a fungus–free device. Sampling for conidia uptake, conidial viability and persistence, and insect mortality was done at 1, 2, 3, 5 and 8 days post–exposure, and collected insects were monitored for mortality over ten days. Overall, mortality was higher in insects exposed to ICIPE 18 (62.8%) and ICIPE 69 (61.8%) than in those exposed to ICIPE 62 (42.6%), with median lethal times, (LT50) ranging between 6.73–8.54 days. The control group recorded the lowest mortality rates (18.9%). A general linear reduction in conidial viability with exposure time was observed, although this was more pronounced with M. anisopliae ICIPE 62. Insects exposed to M. anisopliae ICIPE 69 also recorded the highest conidia uptake, hence selected for further evaluation with a T. vaporariorum attractant volatile organic compound, (E)–2–hexenal. The volatile inhibited fungal germination in laboratory compatibility tests, therefore, spatial separation of M. anisopliae ICIPE 69 and (E)–2–hexenal in the autodissemination device was conducted. The inhibitory effects of the volatile were significantly reduced by spatial separation at a distance of 5 cm between the fungus and the volatile, which was found to be more suitable and chosen for the subsequent experiments. Results showed that (E)–2–hexenal did not influence conidia uptake by the insects, while fungal viability and the subsequent mortality variations were more related to duration of exposure. The fungus–volatile compatibility demonstrated with spatial separation provides a basis for the optimisation of the volatile formulation to achieve better T. vaporariorum suppression with an excellent autodissemination efficiency when used in the management of whiteflies under screenhouse conditions.BioInnovate Africa Phase I project “Promoting smallholder access to fungal biopesticides through Public Private Partnerships in East Africa” (BA/CI/ 2017-02/PROSAFE), and UK’s Foreign, Commonwealth and Development Office (FCDO) (FCDO Biopesticide Project, B2291A - FCDO - BIOPESTICIDE) through the International Centre of Insect Physiology and Ecology (icipe). The icipe core funding provided by UK’s Foreign, Commonwealth and Development Office (FCDO); Swedish International Development Cooperation Agency (Sida); the Swiss Agency for Development and Cooperation (SDC); the Federal Democratic Republic of Ethiopia; and the Government of the Republic of Kenya.https://www.frontiersin.org/journals/insect-sciencehj2023Forestry and Agricultural Biotechnology Institute (FABI)Zoology and Entomolog

Virulence and horizontal transmission of Metarhizium anisopliae by the adults of the greenhouse whitefly Trialeurodes vaporariorum (Hemiptera: Aleyrodidae) and the efficacy of oil formulations against its nymphs

The pathogenicity of dry conidia and fungal suspensions of 16 entomopathogenic fungal isolates (10 Metarhizium anisopliae and six Beauveria bassiana) was evaluated against adults and second instar nymphs of the greenhouse whitefly, Trialeurodes vaporariorum respectively. All the tested isolates were pathogenic to T. vaporariorum and caused mortality of 45–93% against the adults and 24–89% against the nymphs. However, M. anisopliae strains showed higher virulence to both developmental stages as compared to B. bassiana strains. The three most virulent isolates that caused high mortalities in adults were M. anisopliae ICIPE 18, ICIPE 62 and ICIPE 69, with cumulative mortalities of 82, 91 and 93%, and median lethal times (LT50) of 5.20, 5.05 and 4.78 days, respectively. These isolates were further assessed for spore acquisition and retention by the adult insects at 0, 24, 48 and 72 h after exposure to dry conidia spores. There was no significant difference among isolates on their acquisition by the insects, although the effect of time on the number of spores retained by each insect was significant. For M. anisopliae ICIPE 62 and ICIPE 69, spore number was significantly higher immediately after exposure at 0 h than at 24, 48 and 72 h, whereas for M. anisopliae ICIPE 18, the spore number remained constant for all the days. The infected “donor” insects were able to horizontally transmit the acquired spores to uninfected “recipient” insects causing high mortality rates in both donor and recipient groups. Metarhizium anisopliae ICIPE 7, ICIPE 18 and ICIPE 62 were the most virulent isolates against the nymphs in aqueous formulation during the first screening with >80% mortality. However, in 2% (v/v) oil formulations at 1 108 conidia/ml, canola formulated ICIPE 62, ICIPE 18 and olive formulated ICIPE 18 were the most effective, resulting in 87.8, 88.1 and 99.4% nymphal mortalities respectively and with lower LT50. Oil formulations significantly enhanced the efficacy and virulence of the isolates against the nymphs compared to aqueous formulations.The German Academic Exchange Service (DAAD) through African Regional Postgraduate Programme in Insect Science (ARPPIS) of icipe. The icipe core funding provided by UK’s Foreign, Commonwealth and Development Office (FCDO); Swedish International Development Cooperation Agency (Sida); the Swiss Agency for Development and Cooperation (SDC); the Federal Democratic Republic of Ethiopia; and the Government of the Republic of Kenya.http://www.cell.com/heliyonam2022Forestry and Agricultural Biotechnology Institute (FABI)Zoology and Entomolog

Temperature‑dependent modelling and spatial prediction reveal suitable geographical areas for deployment of two Metarhizium anisopliae isolates for Tuta absoluta management

Tuta absoluta is one of the most devastating pests of Solanaceae crops in Africa. We previously demonstrated the efficacy of Metarhizium anisopliae isolates ICIPE 18, ICIPE 20 and ICIPE 665 against adult T. absoluta. However, adequate strain selection and accurate spatial prediction are fundamental to optimize their efficacy and formulations before field deployment. This study therefore assessed the thermotolerance, conidial yield and virulence (between 15 and 35 °C) of these potent isolates. Over 90% of conidia germinated at 20, 25 and 30 °C while no germination occurred at 15 °C. Growth of the three isolates occurred at all temperatures, but was slower at 15, 33 and 35 °C as compared to 20, 25 and 30 °C. Optimum temperatures for mycelial growth and spore production were 30 and 25 °C, respectively. Furthermore, ICIPE 18 produced higher amount of spores than ICIPE 20 and ICIPE 665. The highest mortality occurred at 30 °C for all the three isolates, while the LT50 values of ICIPE 18 and ICIPE 20 were significantly lower at 25 and 30 °C compared to those of ICIPE 665. Subsequently, several nonlinear equations were fitted to the mortality data to model the virulence of ICIPE 18 and ICIPE 20 against adult T. absoluta using the Entomopathogenic Fungi Application (EPFA) software. Spatial prediction revealed suitable locations for ICIPE 18 and ICIPE 20 deployment against T. absoluta in Kenya, Tanzania and Uganda. Our findings suggest that ICIPE 18 and ICIPE 20 could be considered as effective candidate biopesticides for an improved T. absoluta management based on temperature and location-specific approach.The African Union (AU), UK’s Foreign, Commonwealth & Development Office (FCDO) through the International Centre of Insect Physiology and Ecology (icipe). The icipe core funding provided by UK’s Foreign, Commonwealth & Development Office (FCDO); the Swedish International Development Cooperation Agency (Sida); the Swiss Agency for Development and Cooperation (SDC); the Federal Democratic Republic of Ethiopia and the Government of the Republic of Kenya.https://www.nature.com/srepam2022Forestry and Agricultural Biotechnology Institute (FABI)Zoology and Entomolog

Endophytic colonisation of Solanum lycopersicum and Phaseolus vulgaris by fungal endophytes promotes seedlings growth and hampers the reproductive traits, development, and survival of the greenhouse whitefly, Trialeurodes vaporariorum

In the scope of mitigating the negative impacts of pesticide use and managing greenhouse whiteflies, Trialeurodes vaporariorum sustainably, 16 endophytic fungal isolates from five different genera (Beauveria, Trichoderma, Hypocrea, Bionectria, and Fusarium) were screened for their ability to colonise two preferred host plant species, namely, tomato (Solanum lycopersicum L.) and French bean (Phaseolus vulgaris L.), through seed inoculation. Seven and nine isolates were endophytic to P. vulgaris and S. lycopersicum, respectively, where significant differences in the endophytic colonisation rates were observed among the fungal isolates in P. vulgaris and its plant parts, with a significant interaction between the isolates and plant parts in S. lycopersicum. Hypocrea lixii F3ST1, Trichoderma asperellum M2RT4, Trichoderma atroviride F5S21, and T. harzianum KF2R41 successfully colonised all the plant parts of both hosts and therefore were selected and further evaluated for their endophytic persistence, effect on plant growth, and pathogenicity to T. vaporariorum adults and F1 progeny. The four endophytes remained in both host plants for the 5-week assessment with varied colonisation rates related to the strong interaction with the time, isolates, and plant parts in both hosts. The effect of the same endophytes on the different host growth parameters varied in P. vulgaris and S. lycopersicum, with T. asperellum M2RT4 not boosting the growth in both host plants while T. atroviride F5S21 resulted in enhanced shoot biomass in S. lycopersicum. T. atroviride F5S21 and T. harzianum KF2R41 inoculated S. lycopersicum plants and H. lixii F3ST1, T. asperellum M2RT4, and T. harzianum KF2R41 inoculated P. vulgaris plants had significantly lower oviposition, while nymph development in both hosts was significantly prolonged in all the endophytically– colonised plants. The endophytes H. lixii F3ST1 and T. asperellum M2RT4 significantly reduced the longevity/survival of the exposed T. vaporariorum adults and the progeny in both S. lycopersicum and P. vulgaris. The findings demonstrate the attributes of the various endophytes in host plant growth promotion as well as their effects on the lifehistory parameters of T. vaporariorum and could consequently be developed as potential endophytic fungal-based biopesticides for the sustainable management of the pest in S. lycopersicum and P. vulgaris cropping systems.This research was funded by the BioInnovate Africa Phase I project “Promoting smallholder access to fungal biopesticides through Public-Private Partnerships in East Africa” (BA/CI/2017- 02/PROSAFE), and the Foreign, Commonwealth, and Development Office of United Kingdom (FCDO) (FCDO Biopesticide Project, B2291A- FCDO -BIOPESTICIDE) through the International Centre of Insect Physiology and Ecology (icipe). We thank the German Academic Exchange Service (DAAD) In-Region Post-graduate Scholarship for the financial assistance provided to VP through African Regional Postgraduate Programme in Insect Science (ARPPIS). We gratefully acknowledge the icipe core funding provided by the Foreign, Commonwealth, and Development Office of United Kingdom (FCDO); Swedish International Development Cooperation Agency (Sida); the Swiss Agency for Development and Cooperation (SDC); the Federal Democratic Republic of Ethiopia; and the Government of the Republic of Kenya.http://www.frontiersin.org/Plant_Scienceam2022Forestry and Agricultural Biotechnology Institute (FABI)Zoology and Entomolog

Organic waste substrates induce important shifts in gut microbiota of black soldier fly (Hermetia illucens L.) : coexistence of conserved, variable, and potential pathogenic microbes

The sustainable utilization of black soldier fly (BSF) for recycling organic waste into nutrient-rich biomass such as high-quality protein additive, is gaining momentum. Its gut microbiota is thought to play an important role. The study provides the first comprehensive analysis of bacterial and fungal communities of BSF gut across untreated substrates and highlights conserved members, potential pathogens, and their interactions. Findings show most bacteria found in the BSF gut are transient, and are affected by the local environment. The study contributes to establishment of safety measures for future processing of BSF larval meals and the creation of legislation to regulate their use in animal feeds.Australian Centre for International Agricultural Research (ACIAR)Norwegian Agency for Development CooperationNetherlands Organization for Scientific ResearchWOTRO Science for Global Development (NWO-WOTRO)The Rockefeller Foundatio