Fruit fly identification, population dynamics and fruit damage during fruiting seasons of sweet oranges in Rusitu Valley, Zimbabwe

In 2003, the pest species Bactrocera dorsalis (Hendel) was reported for the first time in Kenya, Africa, and subsequently on many other African countries. In this work, 20 locations along the Rusitu Valley (Zimbabwe) were sampled in 2014 during the sweet oranges fruiting seasons, to verify the fruit fly taxonomy, invasion source, population dynamics, and fruit damage. The trapped fruit flies were identified using morphological traits and molecular techniques, as B. dorsalis. The haplotype network analysis revealed that Zimbabwe COI sequences were identical to other African B. dorsalis sequences. Fruit fly trappings per day varied during the year, although it remained always high. The same applies to fruit damage, most likely due to the permanent availability of cultivated and wild fruit varieties during the year. Rusitu Valley was invaded by B. dorsalis, most likely from neighbouring countries. Ten years after the first report in Kenya, the complete or near complete invasion of Africa has been achieved by B. dorsalis. In northern Africa the distribution is clearly limited by the Sahara desert. The large population size, the polyphagous nature of the species, and the continuous availability of suitable host fruit species during the year complicates the eradication of this species.The authors would like to thank the project Norte-01-0145-FEDER-000008-Porto Neurosciences and Neurologic Disease Research Initiative at I3S, supported by Norte Portugal Regional Operational Programme (NORTE2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (FEDER) for financing this work. Fruit fly trapping and data collection was financed by the Chinhoyi University of Technology under the Postgraduate Grant PG4001. Travel and stay at the University of Porto was financed by Erasmus Mundus Dream project, Action 2 - STRAND 1, Lot 18, ACP Countries, Master Mobility Scholarship

Host tree-based scenario modelling for predicting a key edible insect, mopane worm Gonimbrasia belina (Westwood, 1894) distribution in Southern Africa

Gonimbrasia belina, known as the mopane worm, is a large edible caterpillar in tropical and subtropical regions. However, little is known about the bioecology of this species as influenced by its host trees. This study evaluated the importance of different potential host trees in understanding mopane worms’ behaviour and spatial distribution. To assess their relative importance, the study compared models incorporating various mopane worm host trees and predictor variables. Using the species distribution modelling (SDM) package in R, an ensemble of random forest (RF), support vector machine (SVM), and boosted regression tree (BRT) algorithms were used to assess the spatial extent of mopane worm distribution in Southern Africa. Four host tree-based scenarios were developed to assess their contribution to the relative distribution of the mopane worm i.e. (1) by excluding all the potential host trees as explanatory variables and considering only the environmental variables, (2) focusing on the primary host tree, Colophospermum mopane as an explanatory variable together with the other environmental variables, (3) incorporating all the host trees, including C. mopane and (4) examining all other host trees excluding C. mopane. Results demonstrated that incorporating all host trees enhanced the models’ predictive abilities (mean AUC = 0.87) underscoring the significant impact of the alternative host trees on the mopane worm distribution patterns beyond just the C. mopane. This study highlights the significance of host trees in predicting the behaviour and distribution of mopane worm populations, providing valuable insights and decision-making for mopane worm use as an alternative protein source, conservation efforts, and land management practices.https://brill.com/view/journals/jiff/jiff-overview.xmlhj2024Zoology and EntomologySDG-15:Life on lan

Host plant effects on morphometric characteristics of Liriomyza huidobrensis, L. sativae and L. trifolii (Diptera: Agromyzidae)

Body size of herbivorous insects may be directly related to host plant characteristics (e.g. nutrition, chemical composition) and positively linked to performance of the herbivore and its parasitoids. Differences in adult body size of Liriomyza huidobrensis, L. sativae and L. trifolii reared on Pisum sativum, Phaseolus vulgaris, Vicia faba and Solanum ycopersicum were assessed to determine the effect of host plants on adult size. Furthermore, morphometric wing and hind tibia measurements were used to determine suitability as proxy measures for adult size. Based on canonical and linear discriminant analyses, two distinct Liriomyza morphospecies groups were recognized across all plant species. The first cluster represented L. huidobrensis and the second L. sativae and L. trifolii. The overall degree of correct classification of the three species across all plants tested (correct observation) with cross validation was estimated at 85%. Liriomyza huidobrensis, the largest species, showed no differences in the variables measured when reared on the four plant species. However, different plant species seem to influence wing and hind tibia measurements in L. trifolii to a greater extent than in L. huidobrensis and L. sativae. The first two canonical variates could not separate the populations of L. huidobrensis and L. sativae reared on different plant species, but showed separation of L. trifolii populations into two clusters: firstly, insects reared on V. faba and secondly, insects reared on P. vulgaris and S. lycopersicum. Hind tibia length strongly correlated with wing length. Both can be used to determine adult size of the three Liriomyza species. This study provides some new evidence for the existence of differential preferences by Liriomyza species for the four host plant species. This, therefore, warrants larger scale field studies to test for positive preference- performance of Liriomyza species on these plant species and to determine possible consequences at the third tritrophic level

Nutrient and anti-nutrient composition of Henicus whellani (Orthoptera: Stenopelmatidae), an edible ground cricket, in south-eastern Zimbabwe

The purpose of this study was to investigate nutritional and phytochemical composition of Henicus whellani Chopard, a seasonally occurring ground-dwelling cricket consumed in south-eastern Zimbabwe. Insects were sampled from four quadrants (approximately 100m2) in one representative site (approximately 3000m2) in Bikita District, and were hand-picked or dug out from burrows in a manner similar to traditional insect-harvesting practices. Proximate composition using whole-dried insects and bioactive components using dried pulverized material were analysed using standard procedures. The proportional nutrient composition was 53.6% crude protein, 4.3% fat, 13.4% ash, 10.6% crude fibre, 4.0% carbohydrate and 268.3 kcal/100 g energy. Phenolics, tannins, alkaloids, cyanogenic glycosides, oxalates, saponins and flavonoids were present in the extracts of insects. The quantities of saponins (53.3 mg/g) and alkaloids (52.3mg/g) were higher than those of other phytochemicals, with the quantity of tannins (0.168 mg/g) being the lowest. Radical-scavenging capacity determined using di(phenyl)-(2,4, 6-trinitrophenyl)iminoazanium (or 2,2-diphenylpicrylhydrazyl) and methanol extracts was 42%, which is lower than those of the standards. This study shows that H. whellani provides potential nutritional benefits in terms of protein, fibre and flavonoid contents. The relatively high ash content compared with that from other edible insects indicates a rich source of minerals such as calcium, iron, magnesium, phosphorus and potassium. However, the presence of saponins, oxalates and tannins could be a limitation and requires further studies. There is a need to evaluate the bioaccessibility of the nutrients and the safety of bioactive compounds in relation to human consumption

Nutritional profile of the wild harvested armoured cricket (<i>Acanthoplus discoidalis</i>) (Orthoptera: <i>Tettigoniidae</i>) in northern region of Zimbabwe

Armoured crickets are an important food source in some parts of Zimbabwe. These insects are abundant in some regions but however, they are under utilised and not much is known about their nutritional value. The aim of this study was to determine the nutritional profile of the armoured cricket (Acanthoplus discoidalis). Armoured crickets were collected from a structured sampling framework in Mbire district Mashonaland Central province of Zimbabwe. Removal of the head and thorax, degutting and boiling were done. A proximate analysis was carried out followed by mineral, amino acid and fatty acid profiling of the prepared insects. Analyses were done on a dry basis. A. discoidalis contained 69.2% protein, 16.8% fat, 8.6% ash, 1.2% carbohydrate, 4.2% chitin and 454.3 Kcal/100 g energy. A 100 g dry weight quantity of insect contains 11.48 mg iron which is enough to meet the required daily intake of 10.0-20 mg/day for an adult. The zinc (4.37 mg/100 g dry weight) and phosphorus (491.4 mg/100 g dry weight) content in A. discoidalis almost meets the reference nutrient intake for adults. Essential amino acids, leucine (60.7 mg/g protein) had the highest concentration followed by phenylalanine+tyrosine (59.3 mg/g protein), valine (48.4 mg/g protein), lysine (46.7 mg/g protein), threonine (37.4 mg/g protein), isoleucine (26.4 mg/g protein), methionine+cysteine (20.9 mg/g protein) and histidine (16.5 mg/g protein) the least concentration. In total, 9 saturated fatty acids were determined of which stearic acid and palmitic acid had the highest concentrations of 2,034.5 mg/100 g and 2,005.3 mg/100 g respectively. Four mono unsaturated fatty acids were determined of which oleic acid and palmitoleic acid had the highest concentrations of 361.4 mg/100 g and 305.2 mg/100 g respectively. Four poly-unsaturated fatty acids were determined of which eicosapentaenoic and α-linolenic acid had the highest concentrations of 1,598.0 mg/100 g and 185.6 mg/100 g respectively. A. discoidalis is good source of protein, the minerals iron, zinc and phosphorus, some essential amino acids and poly-unsaturated fatty acids. </jats:p

Techno-functional Properties of Armoured Cricket (Acanthoplus discoidalis) Flour

Acanthoplus discoidalis is an insect that has potential use in new product development because of its nutritional quality. This study focused on function properties of A. discoidalis flour. Protein solubility, bulk density, water and oil holding capacity and foaming and emulsifying properties were determined. Protein solubility values of A. discoidalis protein extract at different temperatures were minimum at pH 5. After sieving of the ground flour, the highest retention yields for both the oven dried and sun dried insect flour were observed at mesh size 150µm thus, 47 % and 45 % respectively. Bulk density ranged from 52.33 to 82.67g/mL. Water holding capacity values ranged from 236 to 183.73g/g. A comparison between the water holding capacity with relation to mesh size revealed that the finer the flour, the lower the water binding capacity. No significant difference (p &lt; 0.05) was observed between water holding capacity of the protein isolate and oven dried A. discoidalis flour ground to 500µm. Oil holding capacity of A. discoidalis flour ranged from 110.57 to 179.67g/g. Significant differences (p &lt; 0.05) for oil holding capacity were observed between air dried and sun dried flour samples. Foaming capacity values of A. discoidalis flour ranged from 4 to 33.83%. Foaming capacity decreased with an increase in mesh size for both the oven dried and sun dried flour samples. No significant difference (p &lt; 0.05) was observed between foaming stability of the protein isolate and that of sun dried flour ground to 300 and 500µm. Emulsion capacity and emulsion stability values ranged from 43.33 to 84.07% and 24.73 to 41.83% respectively. The obtained results could be valuable to industries that would want to take up A. discoidalis in their formulation of improved foods and feeds. Insect flours are rich in protein, good extenders, good thickeners and good gelling agents.</jats:p

<b>Effects of post-harvesting practices on heavy metal levels of mopane caterpillar (</b><b><i>Gonimbrasia belina</i></b><b>) products and associated risk assessment</b>

Mopane caterpillars (Gonimbrasia belina) are one of the most consumed edible insects in Southern Africa, and they contribute nutritional benefits to human health. However, their contribution to the food and nutritional security can be hindered by food safety concerns due to heavy metal contamination associated with harvesting, processing and poor post-harvest practices. This study investigated the effectiveness of post-harvest practices (degutting, charcoal roasting and sun drying, boiling, frying and open pan roasting) in reducing the heavy metal contaminants (cadmium (Cd), mercury (Hg), lead (Pb), nickel (Ni), aluminium (Al), zinc (Zn), copper (Cu) and iron (Fe)) in mopane caterpillar sourced from Gwanda district in Zimbabwe. The post-harvest practice categories used in this study included: unprocessed (ungutted and naturally degutted samples), processed (manually degutted, and charcoal roasted and sun-dried), and cooked (boiled and salted; boiled, salted and roasted, and boiled, salted and fried) samples. An atomic absorption spectrometry (AAS) was used for quantification of metals and the values detected were used to assess health risks to consumers using a quantitative risk assessment calculation method. The unprocessed and manually degutted samples showed higher levels Cd and traces of Pb, while charcoal roasting and sun drying resulted in elevated levels of Al, Zn, Cu and Fe. Hg and Ni were not detected in any of the unprocessed, processed or cooked samples. Cooking processes resulted in reduction of the concentrations of detected metals to levels within the permissible values. The health risk assessment disclosed noncarcinogenic risks based on the high hazard index (HI) values (HI > 1) in unprocessed, processed, boiled and salted, and boiled, salted and roasted samples, indicating that caution should be taken. The overall findings from the study shows that by cooking mopane caterpillars through boiling and frying, health risks associated with heavy metal contamination can be reduced.</p