Nutritional composition of black soldier fly larvae feeding on agro-industrial by-products

Black soldier fly (BSF) larvae, Hermetia illucens L. (Diptera: Stratiomyidae), bio-convert organic side streams into high-quality biomass, the composition of which largely depends on the side stream used. In the present study, BSF larvae were reared on feed substrates composed of dried brewers’ spent grains, each supplemented with either water, waste brewer’s yeast, or a mixture of waste brewer’s yeast and cane molasses to obtain 12 different substrates: barley/water, barley/yeast, barley/yeast/molasses, malted barley/water, malted barley/yeast, malted barley/yeast/molasses, malted corn/water, malted corn/yeast, malted corn/yeast/molasses, sorghum-barley/water, sorghum-barley/yeast, and sorghum-barley/yeast/molasses. The crude protein, fat, ash, and mineral contents of the BSF larvae fed each feed substrate were quantified by chemical analyses. The effect of substrate, supplementation, and their interaction on crude protein, fat, and ash contents of BSF larval body composition was significant. Calcium, phosphorus, and potassium were the most abundant macrominerals in the larvae and their concentrations differed significantly among substrates. These findings provide important information to support the use of BSF larval meal as potential new source of nutrient-rich and sustainable animal feed ingredients to substitute expensive and scarce protein sources such as fishmeal and soya bean meal.     

Cross-correlation analysis of invasive mango mealybug and its associated natural enemies in relation to meteorological factors: implications for biological control

Damage caused by invasive downey snow line mealybug, Rastrococcus iceryoides Green (Hemiptera: Pseudococcidae) has been reported to vary between 30% to complete crop loss where no control measure is applied. The current studies seek to determine factors influencing R. iceryoides population outbreaks, parasitoid – host and predator–prey relationships as well as predict optimal management strategies through weather modelling over a period of 28 months from 2008 to 2010 in Tanzania. The highest incidence of R. iceryoides was recorded during the dry season coinciding with the major mango fruiting season. The relationship between R. iceryoides and the parasitoid was positive but not significant, which implies the influence on outbreaks was negligible probably due to low percent parasitism (<12%). However, the predator abundance was directly and significantly related to that of R. iceryoides. Average temperature, average relative humidity, rainfall, and R. iceryoides abundance were autocorrelated to each other. Cross-correlation coef?cients vary significantly from ?0.286 to 0.589 for the pair-variable between R. iceryoides, temperature, relative humidity, rainfall, parasitism and predators. Our findings showed that temperature was the key climatic variable that significantly influenced R. iceryoides outbreaks while rainfall was significantly negatively associated with the pest. Time series analyses show R. iceryoides population increased 4 months after an increase in average temperature in all the sites, 11 months after rainfall and 11 months after relative humidity in Kibaha and Dar es Salaam, respectively. Our findings revealed that R. iceryoides is an excellent target for classical biological control. Thus, the importation of promising co-evolved parasitoid specific to R. iceryoides from the aboriginal home is crucial in formulating an efficient and sustainable management approaches against the invasive mealybug pest in mango agro-ecosystems.     

Distribution,degree of damage and risk of spread of Trioza erytreae (Hemiptera: Triozidae) in Kenya

The African citrus triozid (ACT), Trioza erytreae Del Guercio, is a destructive pest particularly on citrus, and vectors, “Candidatus” Liberibacter africanus (CLaf), which is the causal agent of the African citrus greening disease. Our study seeks to establish the distribution and host‐plant relationship of ACT across citrus production areas in Kenya. We also modelled the risk of spread using the maximum entropy modelling algorithm with known occurrence data. Our results infer that ACT is widely distributed and causes severe damage to four alternative host plants belonging to the family Rutaceae. The adults, immature stages (eggs and nymphs), galls and the percentage of infested leaves were significantly higher in shaded than unshaded trees. However, adult ACTs preferred Kenyan highlands to Victoria Lake and coastal regions. The average area under the curve of the model predictions was 0.97, indicating an optimal model performance. The environmental variables that most influenced the prediction were the precipitation of wettest quarter, precipitation of wettest month, mean diurnal range, temperature seasonality and mean temperature of the coldest quarter. The current prediction of ACT exceeded its existing range, especially in the Western, Nyanza, Central, Rift valley and Eastern regions of Kenya. The model predicted a contraction of suitable habitats for a potential spread in 2040 with an inland shift to higher altitudes in the cooler regions. The potential for further expansion to climatically suitable areas was more pronounced for the 2080 forecast. These findings provide relevant information to improve monitoring/surveillance and designing IPM strategies to limit its spread and damage.     

Characterization and risk assessment of the invasive papaya mealybug,Paracoccus marginatus,in Kenya under changing climate

The present study was conducted to characterize the newly invasive papaya mealybug Paracoccus marginatus Williams and Granara de Willink in Kenya using molecular techniques and to establish the potential risk of spread of the pest. Although abundant literature of P. marginatus outbreaks exists in other parts of the world, studies from Africa are rare. Our results revealed significant similarity between Kenyan samples with GenBank accession number KP692333.1 of P. marginatus. Phylogenetic analyses generated a tree that was paraphyletic with two clusters showing low genetic distance values for the P. marginatus sequences, which diverged from that of Planococcus citri. Our models displayed an optimal performance with mean area under the curve value of 0.82 and 0.98 for Genetic Algorithm for Rule-Set Production (GARP) and maximum entropy modelling (MaxEnt), respectively. Isothermality was the most influential variable in determining the potential distribution of P. marginatus with a 69% contribution to the models. Other variables included temperature mean diurnal range temperature seasonality, temperature annual range and annual precipitation in decreasing order of contribution. Current prediction by both models exceeded the existing range of P. marginatus, exacerbating the potential threat of the pest. GARP was more conservative in predicting suitable areas for P. marginatus, while MaxEnt showed further expansion by the year 2050. Our findings provide important information to guide biosecurity agencies in decision-making to prevent the spread and enhance control efforts of P. marginatus.     

Host suitability and feeding preference of the African citrus triozid Trioza erytreae Del Guercio (Hemiptera: Triozidae), natural vector of “Candidatus Liberibacter africanus”

African citrus greening (ACGD) and huanglongbing (HLB) diseases are the most damaging diseases of citrus worldwide. Currently, the disease has no cure and has been attributed to the collapse of the citrus industry in several countries. In Africa, the causative agent “Candidatus” Liberibacter africanus is vectored by African citrus triozid (ACT) Trioza erytreae Del Guercio (Hemiptera: Triozidae). African citrus triozid is native to Africa but has been recently reported in Asia and Europe. Apart from citrus, Murraya koenigii (L.) and Clausena anisata (Willd) Hook. F. ex Benth. are also considered as preferred host plants. At present, there is scant information on host plant suitability and preference of T. erytreae. Also, there are contradictory reports on its reproduction and survival on rutaceous and non‐rutaceous host plants. In the present study, we tested the suitability and preference of rutaceous and non‐rutaceous trees and shrubs as potential ACT host plants in choice and no‐choice bioassays. The development from egg to the adult stage was longest on Calodendrum capense (Wright & Arn.) Engl. Host plants of superior quality accordingly to several ACT's biological parameters measured also revealed significantly higher morphometric characteristics. Our findings on the host status of the five rutaceous plants imply that these plants can greatly influence the population dynamics of ACT as well as the epidemiology of ACGD, and these can be a useful guide in the area‐wide management of the pest in Kenya.     

Comparative analysis of development and survival of two Natal fruit fly Ceratitis rosa Karsch (Diptera,Tephritidae) populations from Kenya and South Africa

Comparative analysis of development and survivorship of two geographically divergent populations of the Natal fruit fly Ceratitis rosa Karsch designated as Ceratitis rosa R1 and Ceratitis rosa R2 from Kenya and South Africa were studied at seven constant temperatures (10, 15, 20, 25, 30, 33, 35 °C). Temperature range for development and survival of both populations was 15–35 °C. The developmental duration was found to significantly decrease with increasing temperature for Ceratitis rosa R1 and Ceratitis rosa R2 from both countries. Survivorship of all the immature stages of Ceratitis rosa R1 and Ceratitis rosa R2 from Kenya was highest over the range of 20–30 °C (87–95%) and lowest at 15 and 35 °C (61–76%). Survivorship of larvae of Ceratitis rosa R1 and Ceratitis rosa R2 from South Africa was lowest at 35 °C (22%) and 33 °C (0.33%), respectively. Results from temperature summation models showed that Ceratitis rosa R2 (egg, larva and pupa) from both countries were better adapted to low temperatures than R1, based on lower developmental threshold. Minimum larval temperature threshold for Kenyan populations were 11.27 °C and 6.34 °C (R1 and R2, respectively) compared to 8.99 °C and 7.74 °C (R1 and R2, respectively) for the South African populations. Total degree-day (DD) accumulation for the Kenyan populations were estimated at 302.75 (Ceratitis rosa R1) and 413.53 (Ceratitis rosa R2) compared to 287.35 (Ceratitis rosa R1) and 344.3 (Ceratitis rosa R2) for the South African populations. These results demonstrate that Ceratitis rosa R1 and Ceratitis rosa R2 from both countries were physiologically distinct in their response to different temperature regimes and support the existence of two genetically distinct populations of Ceratitis rosa. It also suggests the need for taxonomic revision of Ceratitis rosa, however, additional information on morphological characterization of Ceratitis rosa R1 and Ceratitis rosa R2 is needed.     

Hospital-Based Surveillance for Viral Hemorrhagic Fevers and Hepatitides in Ghana

Background

Viral hemorrhagic fevers (VHF) are acute diseases associated with bleeding, organ failure, and shock. VHF may hardly be distinguished clinically from other diseases in the African hospital, including viral hepatitis. This study was conducted to determine if VHF and viral hepatitis contribute to hospital morbidity in the Central and Northern parts of Ghana.

Methodology/Principal Findings

From 2009 to 2011, blood samples of 258 patients with VHF symptoms were collected at 18 hospitals in Ashanti, Brong-Ahafo, Northern, Upper West, and Upper East regions. Patients were tested by PCR for Lassa, Rift Valley, Crimean-Congo, Ebola/Marburg, and yellow fever viruses; hepatitis A (HAV), B (HBV), C (HCV), and E (HEV) viruses; and by ELISA for serological hepatitis markers. None of the patients tested positive for VHF. However, 21 (8.1%) showed anti-HBc IgM plus HBV DNA and/or HBsAg; 37 (14%) showed HBsAg and HBV DNA without anti-HBc IgM; 26 (10%) showed anti-HAV IgM and/or HAV RNA; and 20 (7.8%) were HCV RNA-positive. None was positive for HEV RNA or anti-HEV IgM plus IgG. Viral genotypes were determined as HAV-IB, HBV-A and E, and HCV-1, 2, and 4.

Conclusions/Significance

VHFs do not cause significant hospital morbidity in the study area. However, the incidence of acute hepatitis A and B, and hepatitis B and C with active virus replication is high. These infections may mimic VHF and need to be considered if VHF is suspected. The data may help decision makers to allocate resources and focus surveillance systems on the diseases of relevance in Ghana.     

Ecological diversity of edible insects and their potential contribution to household food security in Haut‐Katanga Province,Democratic Republic of Congo

Democratic Republic of the Congo (DR Congo) has a wide diversity of edible insects making it one of the most important biodiversity hot spots in Africa. The aim of this study was to give the first insight into the food plant range, seasonal availability of edible insects, community preference and willingness to consume them. The study revealed a list of eleven edible insect species belonging to four families. Twenty‐six plant species were recorded as food plants of nine edible caterpillar species. Seasonal availability of these insects coincided with the rainy season and was strongly linked to relatively high level of consumption. The caterpillars Elaphrodes lactea Gaede, Lobobunaea saturnus Fabricius and Cinabra hyperbius (Westwood) as well as the termites Macrotermes falciger Gerstäcker were the most dominant species of edible insects preferred and consumed among the different communities. Our study demonstrates that entomophagy is a common practice among the ethnic populations with married, tertiary and university‐level individuals recording significantly higher consumption of edible caterpillars. Populations between the ages of 18 and 45 years as well as the Bemba tribe were also more actively involved in entomophagy. Further research would be necessary to exploit edible insect biodiversity and ethno‐entomophagy and initiate actions for food plant conservation in DR Congo.     

Detection of <Emphasis Type="Italic">Diaphorina citri</Emphasis> Kuwayama (Hemiptera: Liviidae) in Kenya and potential implication for the spread of Huanglongbing disease in East Africa

The Asian citrus psyllid Diaphorina citri Kuwayama (Hemiptera: Liviidae) is a damaging pest of citrus globally and has recently been detected in Tanzania. Although direct damage by the pest is seldom of economic importance, the insect is more notorious for its ability to vector the fastidious phloem-limited bacterium Candidatus Liberibacter asiaticus (CLas), the putative causal bacterium of Huanglongbing or Asian citrus greening disease. For many years, Trioza erytreae (Del Guercio) (Hemiptera: Triozidae) was known to be the main vector of the African citrus greening disease caused by Candidatus Liberibacter africanus (CLaf), but the recent arrival of D. citri on the continent adds to the dynamics of infection and spread of both diseases on mainland Africa. Following the recent report of the presence of D. citri in Tanzania, an additional delimiting survey was carried out in the region, focusing on Kenya, mainland Tanzania and Zanzibar to detect the presence and ascertain the extent of spread of D. citri. We employed molecular tools based on the use of DNA barcoding to confirm the identity of D. citri. In addition to D. citri, the occurrence of T. erytreae in the same sampling locations is also reported. Adults and nymphs of either D. citri or T. erytreae were collected from citrus at many of the surveyed sites ranging from 19 to 668 m above sea level (masl) in Tanzania, 20–1666 masl in Kenya, and 42–48 masl in Zanzibar. Diaphorina citri was sympatric with T. erytreae at the mid to higher elevations of 1375–1666 masl and no T. erytreae or its open-gall symptoms were detected below 523 masl. Sequences obtained were queried via BLAST and all linked to D. citri of different accession numbers already available on GenBank. This is the first report of the presence of D. citri in Kenya and Zanzibar. The potential implication of the detection and spread of the two pathogens, CLaf and CLas to the citrus industry in East Africa and movement of suitable host plants is discussed.     

Composition,structure, and functional shifts of prokaryotic communities in response to co-composting of various nitrogenous green feedstocks

Sigma factor B (SigB) is the central regulator of the general stress response in Bacillus subtilis and regulates a group of genes in response to various stressors, known as the SigB regulon members. Genes that are directly regulated by SigB contain a promotor binding motif (PBM) with a previously identified consensus sequence. In this study, refined SigB PBMs were derived and different spacer compositions and lengths (N12-N17) were taken into account. These were used to identify putative SigB-regulated genes in the B. subtilis genome, revealing 255 genes: 99 had been described in the literature and 156 genes were newly identified, increasing the number of SigB putative regulon members (with and without a SigB PBM) to >?500 in B. subtilis. The 255 genes were assigned to five categories (I-V) based on their similarity to the original SigB consensus sequences. The functionalities of selected representatives per category were assessed using promoter-reporter fusions in wt and ΔsigB mutants upon exposure to heat, ethanol, and salt stress. The activity of the PrsbV (I) positive control was induced upon exposure to all three stressors. PytoQ (II) showed SigB-dependent activity only upon exposure to ethanol, whereas PpucI (II) with a N17 spacer and PylaL (III) with a N16 spacer showed mild induction regardless of heat/ethanol/salt stress. PywzA (III) and PyaaI (IV) displayed ethanol-specific SigB-dependent activities despite a lower-level conserved ??10 binding motif. PgtaB (V) was SigB-induced under ethanol and salt stress while lacking a conserved ??10 binding region. The activities of PygaO and PykaA (III) did not show evident changes under the conditions tested despite having a SigB PBM that highly resembled the consensus. The identified extended SigB regulon candidates in B. subtilis are mainly involved in coping with stress but are also engaged in other cellular processes. Orthologs of SigB regulon candidates with SigB PBMs were identified in other Bacillales genomes, but not all showed a SigB PBM. Additionally, genes involved in the integration of stress signals to activate SigB were predicted in these genomes, indicating that SigB signaling and regulon genes are species-specific. The entire SigB regulatory network is sophisticated and not yet fully understood even for the well-characterized organism B. subtilis 168. Knowledge and information gained in this study can be used in further SigB studies to uncover a complete picture of the role of SigB in B. subtilis and other species.