Browsing by Author "Opoke, Robert"
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Item Apparent density, trypanosome infection rates and host preference of tsetse flies in the sleeping sickness endemic focus of northwestern Uganda(BMC Veterinary Research, 2021) Opiro, Robert; Opoke, Robert; Angwech, Harriet; Nakafu, Esther; Oloya, Francis A.; Openy, Geoffrey; Njahira, Moses; Macharia, Mercy; Echodu, Richard; Malinga, Geoffrey M.African trypanosomiasis, caused by protozoa of the genus Trypanosoma and transmitted by the tsetse fly, is a serious parasitic disease of humans and animals. Reliable data on the vector distribution, feeding preference and the trypanosome species they carry is pertinent to planning sustainable control strategies. Methodology: We deployed 109 biconical traps in 10 villages in two districts of northwestern Uganda to obtain information on the apparent density, trypanosome infection status and blood meal sources of tsetse flies. A subset (272) of the collected samples was analyzed for detection of trypanosomes species and sub-species using a nested PCR protocol based on primers amplifying the Internal Transcribed Spacer (ITS) region of ribosomal DNA. 34 blood-engorged adult tsetse midguts were analyzed for blood meal sources by sequencing of the mitochondrial cytochrome c oxidase 1 (COI) and cytochrome b (cytb) genes. Results: We captured a total of 622 Glossina fuscipes fuscipes tsetse flies (269 males and 353 females) in the two districts with apparent density (AD) ranging from 0.6 to 3.7 flies/trap/day (FTD). 10.7% (29/272) of the flies were infected with one or more trypanosome species. Infection rate was not significantly associated with district of origin (Generalized linear model (GLM), χ2 = 0.018, P = 0.895, df = 1, n = 272) and sex of the fly (χ2 = 1.723, P = 0.189, df = 1, n = 272). However, trypanosome infection was highly significantly associated with the fly’s age based on wing fray category (χ2 = 22.374, P < 0.001, df = 1, n = 272), being higher among the very old than the young tsetse. Nested PCR revealed several species of trypanosomes: T. vivax (6.62%), T. congolense (2.57%), T. brucei and T. simiae each at 0.73%. Blood meal analyses revealed five principal vertebrate hosts, namely, cattle (Bos taurus), humans (Homo sapiens), Nile monitor lizard (Varanus niloticus), African mud turtle (Pelusios chapini) and the African Savanna elephant (Loxodonta africana). Conclusion: We found an infection rate of 10.8% in the tsetse sampled, with all infections attributed to trypanosome species that are causative agents for AAT. However, more verification of this finding using large-scale passive and active screening of human and tsetse samples should be done. Cattle and humans appear to be the most important tsetse hosts in the region and should be considered in the design of control interventions.Item Artificial diets determine fatty acid composition in edible Ruspolia differens (Orthoptera: Tettigoniidae)(Journal of Asia-Pacific Entomology, 2018) Rutaro, Karlmax; Malinga, Geoffrey M.; Opoke, Robert; Lehtovaara, Vilma J.; Omujal, Francis; Nyeko, Philip; Roininen, Heikki; Valtonen, AnuThere are increasing interests in rearing edible insects in Africa, but information on how the feeds modify their fatty acids is largely lacking. In this work, the influence of artificial diets on the fatty acid contents and composition in the edible Ruspolia differens (Serville, 1838), in Uganda was assessed. R. differens was reared on the mixtures of six gradually diversified diets of two, three, four, six, eight and nine feeds. The diets were formulated from rice seed head, finger millet seed head, wheat bran, superfeed chicken egg booster, sorghum seed head, germinated finger millet, simsim cake, crushed dog biscuit pellet and shea butter. Fatty acid methyl esters were prepared using direct transesterification method, and analysed using gas chromatography. The contents of saturated, monounsaturated and polyunsaturated fatty acid differed significantly among the diets. The more diverse diets resulted in increased content of the polyunsaturated fatty acids. The n6:n3 ratio differed significantly among the diets and between the sexes, with R. differens fed on the four-feed diet having a higher n6:n3 ratio than those fed on other diets. Also, the fatty acid composition differed significantly among the diets, and diet diversification corresponded with the proportions of polyunsaturated fatty acids, especially linoleic acid. Overall, our results demonstrate that higher levels of essential fatty acids can be achieved by rearing R. differens on highly diversified diets. These findings are important in informing the design of future mass-rearing program for this edible insectItem The Edible Katydid Ruspolia Differens Is A Selective Feeder On The Inflorescences And Leaves Of Grass Species(Entomologia Experimentalis et Applicata, 2018) Valtonen, Anu; Malinga, Geoffrey M.; Junes, Petra; Opoke, Robert; Lehtovaara, Vilma J.; Nyeko, Philip; Roininen, HeikkiRuspolia differens (Serville) (Orthoptera: Tettigoniidae, Conocephalinae) (its common names including ‘African edible bush-cricket’, ‘edible grasshopper’, and ‘nsenene’) is an important source of food for humans in East Africa, but its ecology and biology are poorly understood. We explored the host plants of R. differens with a series of no-choice and multiple-choice laboratory experiments using 18 local common grass and sedge species in Uganda. In no-choice experiments, the degree of acceptance differed significantly among the studied plant species, but in only three species were leaves rejected and in one species were inflorescences rejected. The pattern of acceptance among plant species was different in the local vs. swarming populations. Leaves were generally more accepted by the local population, whereas inflorescences were generally more accepted by the swarming population. Both leaves and inflorescences were more readily accepted by males than by females. According to the multiple-choice experiments, R. differens preferred inflorescences over leaves. Our results demonstrate that R. differens is a facultatively oligophagous grass-specialist, which has a clear preference for certain grass or sedge species (especially inflorescences), but it accepts many host plants if the preferred ones are not available. To preserve viable natural populations of R. differens in East Africa in the long term, our results draw special attention to the availability of grasslands where accepted and preferred host plants are available year-round.Item An ethnobotanical study of plants used for the treatment of malaria in Budondo sub-county, Eastern Uganda(Ethnobotany Research and Applications, 2020) Malinga, Geoffrey M.; Baana, Kalori; Rutaro, Karlmax; Atube, Francis; Opoke, Robert; Opika-Opoka, Hector; Oryema, ChristineMalaria is a leading cause of morbidity and mortality in most developing countries, and in Uganda over 95% of the country is endemic with malaria. Given the increasing widespread resistance to current drugs, the use of herbal medicines is seen as a sustainable solution to malaria treatment. This study documented medicinal plants that are traditionally used for the treatment of malaria in Budondo sub-county, Eastern Uganda. Methods: The ethnobotanical survey was conducted between December 2017 to January 2018. A total of 273 household members were interviewed on knowledge and use of anti-malarial plants, using semistructured questionnaires administered in five parishes of Budondo sub-county. Voucher specimen of each plant species were preserved at the Makerere University herbarium, Uganda. Results: Overall, 97.5% of the respondents had knowledge regarding the plants used to treat malaria. A chi-square analysis shows a significant association between respondents’ knowledge regarding antimalarial plants and gender (p-value =0.008) and occupation (p-value =0.025) but not with age (p-value =0.379), educational status (p-value =0.066), average monthly income (p-value =0.419), and religious affiliation (p-value =0.064) of respondents. A total of 37 plant species, belonging to 25 plant families were used to treat malaria. The most cited plant was Vernonia amygdalina Delile (64.8%), followed by Aloe vera (L.) Burm.f. (41.9%), Callistemon citrinus (Curt.) Stapf (29.3%), Mormodica feotida Schumach (22.0%), Cyphostemma adenocaule (A. Rich) wild & Drumm. (16.1%) and Eucalyptus globulus Labill. (15.4%). Among the plant parts, stem bark (99.6%) and leaves (90.8%) were the most frequently used. The habits of the plants encountered were shrub, tree, herb, rhizomes and climber. The commonest modes of preparation included boiling in water, squeezing fresh leaves, crushing and pounding, and chewing. Oral route/drinking was the most common mode of administration, followed by steam inhaling of vapours from the aqueous extracts and skin bathing. Conclusion: The present study shows that the people living in Budondo sub-county traditionally use diverse flora to treat malaria. Further investigations are required to evaluate the potential toxicological effects and to isolate the active components of the reported plants whose antimalarial activities have not been investigated which could be developed into effective, safe and affordable anti-malarial medicines in the future.Item The fatty acid composition of edible grasshopper Ruspolia differens (Serville) (Orthoptera: Tettigoniidae) feeding on diversifying diets of host plants(Entomological Research, 2018) Rutaro, Karlmax; Malinga, Geoffrey M.; Lehtovaara, Vilma J.; Opoke, Robert; Valtonen, Anu; Kwetegyeka, Justus; Nyeko, Philip; Roininen, HeikkiRuspolia differens (Serville) (Orthoptera: Tettigoniidae) is a highly valued edible grasshopper species in Africa. However, the effects of plant diets on lipid content and fatty acid composition of R. differens are not well understood. We tested the effects of four diets on the total lipid content and fatty acid composition of R. differens. Sixth instar nymphs of R. differens were reared on one, and mixtures of two, three, and six natural plant inflorescences. Individuals collected from the field constituted a control treatment.We extracted lipids and analyzed the fatty acidmethyl esters using gas chromatography–mass spectrometry. We analyzed if the total lipid content, body weight, and fatty acid composition differed among diets and between the sexes using two-way ANOVAs and a PERMANOVA model, respectively. The total lipid content and weight of R. differens did not differ among the diets. The nine common fatty acids were palmitic (mean across treatments, 26%), oleic (22%), palmitoleic (18%), linoleic (13%), stearic (7%), myristic (6%), myristoleic (4%), α-linolenic (2%) and arachidic acid (1%). The composition of fatty acids and the proportion of essential fatty acids significantly differed among the diets. The proportion of essential fatty acids was highest in the control treatment (21%) but low in less diversified (one to three feed) diets (12–13%). This study demonstrates that the fatty acid composition in R. differens can be influenced through diet. Thus, with dietary manipulations, using local plants in Africa, it is possible to produce R. differens with preferred high quality essential fatty acids for human consumption.Item Fatty acid content and composition in edible Ruspolia differens feeding on mixtures of natural food plants(BMC Research Notes, 2018) Rutaro, Karlmax; Malinga, Geoffrey M.; Lehtovaara, Vilma J.; Opoke, Robert; Nyeko, Philip; Roininen, Heikki; Valtonen, AnuTo develop successful mass-rearing programs of edible insects, knowledge of the feeds and their influence on nutritional content is critical. We assessed the influence of natural food plants (grass inflorescences) and their mixtures on fatty acid profiles of edible Ruspolia differens. We reared neonate nymphs to adult on six dietary treatments consisting of one, and mixtures of two, three, five, six and eight plants. Results: The contents of saturated, monounsaturated and polyunsaturated fatty acids, omega-6/omega-3 ratio, and adult body weight did not differ among dietary treatments. However, the composition of fatty acids differed significantly among insects fed on six dietary treatments, but only for the rare fatty acids. Our results demonstrate that even if natural diets (grass inflorescences) do not strongly modify fatty acid contents or compositions of R. differens, when reared from neonate nymphs to adults, their n − 6/n − 3 fatty acid ratio is generally low and thus good for a healthy human diet.Item Host plants of the non‐swarming edible bush cricket Ruspolia differens(Ecology and Evolution, 2019) Opoke, Robert; Nyeko, Philip; Malinga, Geoffrey M.; Rutaro, Karlmax; Roininen, Heikki; Valtonen, AnuThe edible Ruspolia differens (Orthoptera: Tettigoniidae) is a widely-consumed insect in East Africa but surprisingly little is known of its host plant use in the field. We studied host plants used by non-swarming R. differens for 15 months, in central Uganda. In particular, we assessed the use of host plant species with respect to host cover in the field and host parts used by R. differens, also recording their sex, developmental stages, and colour morph. Ruspolia differens were found on 19 grass and two sedge species and they were observed predominantly (99% of 20,915 observations) on seven grasses (namely, Panicum maximum, Brachiaria ruziziensis, Chloris gayana, Hyparrhenia rufa, Cynodon dactylon, Sporobolus pyramidalis, and Pennisetum purpureum). Ruspolia differens was most frequently observed on the most common grass of each study site but P. maximum, and S. pyramidalis were used more frequently than expected from their cover in the field. Furthermore, R. differens were observed predominantly on inflorescences (97% of feeding observations) and much less frequently on the leaves (3.0%), stems (0.1%), and inflorescence stalks (0.1%) of grasses and sedges. Host use was not independent of sex, developmental stage, or colour morph. Panicum maximum was the preferred host of the youngest nymphs of R. differens. Overall, our findings indicate that a continuous supply of diverse grass resources with inflorescences is necessary for the management and conservation of wild populations of R. differens.Item Mixed Artificial Diets Enhance The Developmental And Reproductive Performance Of The Edible Grasshopper, Ruspolia Differens (Orthoptera: Tettigoniidae)(Applied Entomology and Zoology, 2018) Malinga, Geoffrey M.; Valtonen, Anu; Lehtovaara, Vilma J.; Rutaro, Karlmax; Opoke, Robert; Nyeko, Philip; Roininen, HeikkiDiet mixing is a common feeding habit among polyphagous insect herbivores and is believed to be advantageous for performance-related factors like growth, survival and oviposition. However, relatively little is known about the influence of artificial diet or their mixtures on the performance of edible insects. We examined the effects of artificial diet mixtures on the developmental and reproductive performance (survival, developmental time, fresh adult weight and female fecundity) of an edible grasshopper, Ruspolia differens (Orthoptera: Tettigoniidae). We raised individuals from eggs and reared newly hatched nymphs to adult stage on six different dietary treatments consisting of a single diet, and mixtures of two, three, five, six and eight artificial diets. More diversified diets resulted in shorter development time and greater adult fresh weight and female fecundity compared to the single diet or less diversified diets. Even with slight diet diversification, survival to adult stage was greatly improved. Overall, these results highlight the potential of diet mixtures in achieving maximum adult weights and female fecundity and shortening development time, information which could be used when designing mass-rearing programs for this edible grasshopper.Item Prevalence of diarrhoea and associated risk factors among children under five years old in Pader District, northern Uganda(BMC Infectious Diseases, 2020) Omona, Stephen; Malinga, Geoffrey M.; Opoke, Robert; Openy, Geoffrey; Opiro, RobertDiarrhoea remains a major cause of morbidity and mortality in children under 5 years in sub-Saharan Africa. Of the three East African countries, Uganda has the worst mortality rate in children < 5 years, with 22% of these deaths attributed to diarrhoea. For proper planning and implementation of control, an understanding of the prevalence and determinants of the disease is crucial. This study assessed the prevalence of diarrhoea and related risk factors among children < 5 years in Pajule Subcounty, Pader District in northern Uganda. Methods: A cross-sectional survey was conducted in April 2018, covering 244 randomly selected households having children < 5 years old in the study area. A semi-structured questionnaire was used to interview the households about diarrhoeal history in their children in the last 2 weeks preceding the survey, and on the risk factors predisposing children to diarrhoeal infections. Bivariate and multivariate logistic regression analyses with a 95% confidence interval and p < 0.05 was used to identify the risk factors associated with childhood diarrhoeal disease. Results: We found a prevalence of diarrhoea of 29.1% [95% CI (23.7–35.0)] among children < 5 years in Pajule Subcounty during the 2 weeks preceding the survey. Use of unprotected water sources, age of child caretaker, child weaning time and family size had significant associations with diarrhoeal morbidity. Conclusion: The prevalence of childhood diarrhoea among children < 5 years of age in rural settings of Pajule Subcounty was higher than the Ugandan national average. Use of unprotected water sources, age of child caretaker, child weaning time and family size were identified as predictors of diarrhoeal occurrence. These findings underscore the need for improving access to clean water and providing community health education as the best methods for fighting childhood diarrhoea in the study area.Item Seasonal Pattern In Population Dynamics And Host Plant Use Of Non‐Swarming Ruspolia Differens Serville (Orthoptera: Tettigoniidae)(Journal of Applied Entomology, 2019) Opoke, Robert; Malinga, Geoffrey M.; Rutaro, Karlmax; Nyeko, Philip; Roininen, Heikki; Valtonen, AnuThe edible Ruspolia differens (Serville) (Orthoptera: Tettigoniidae) is an important source of food in East Africa, but the seasonality of its population dynamics and host plant use are not fully understood. We studied seasonal patterns in the population density and relative frequency of developmental stages, sexes, colour morphs and host plants of the non-swarming R. differens at two study sites in central Uganda over 15 months. Linear mixed models were used to study how precipitation and Enhanced Vegetation Index (EVI) predict population density and relative frequency of developmental stages, sexes, colour morphs and host plants. The results showed that all developmental stages of non-swarming R. differens were found in the field throughout the year. The population densities of R. differens were high in wet seasons and low in dry seasons and were best predicted by the EVI of the previous month. The sex ratio of the non-swarming R. differens populations was female biased. The proportion of males and green colour morphs increased during and after the rainy season. The use of host plants fluctuated seasonally so that during the greener seasons individuals used the more preferred host Panicum maximum more frequently. Overall, our work indicates that R. differens has a seasonal dynamic so that vegetation greenness can be used to forecast non-swarming R. differens population densities. Our results also suggest that source populations for swarming individuals might have a local origin. This is important for the management of habitats for reproduction and conservation of viable populations of R. differens in East Africa.Item Spatial Distribution of Tsetse Flies and Trypanosome Infection Status in a Vector Genetic Transition Zone in Northern Uganda(Journal of Parasitology Research, 2022) Opiro, Robert; Okello Allele, Moses,; Opoke, Robert; Oloya, Francis A.; Nakafu, Esther; Iwiru, Teresa; Echodu, Richard; Malinga, Geoffrey M.; Bargul, Joel L.; Opiyo, Elizabeth A.Tsetse flies are vectors of the genus Trypanosoma that cause African trypanosomiasis, a serious parasitic disease of people and animals. Reliable data on the vector distribution and the trypanosome species they carry is pertinent for planning sustainable control strategies. This study was carried out to estimate the spatial distribution, apparent density, and trypanosome infection rates of tsetse flies in two districts that fall within a vector genetic transition zone in northern Uganda. Materials and Methods. Capturing of tsetse flies was done using biconical traps deployed in eight villages in Oyam and Otuke, two districts that fall within the vector genetic transition zone in northern Uganda. Trapped tsetse flies were sexed and morphologically identified to species level and subsequently analyzed for detection of trypanosome DNA. Trypanosome DNA was detected using a nested PCR protocol based on primers amplifying the internal transcribed spacer (ITS) region of ribosomal DNA. Results. A total of 717 flies (406 females; 311 males) were caught, all belonging to the Glossina fuscipes fuscipes species. The overall average flies/trap/day (FTD) was 2:20 ± 0:3527 (mean ± SE). Out of the 477 (201 male; 276 females) flies analyzed, 7.13% (34/477) were positive for one or more trypanosome species. Three species of bovine trypanosomes were detected, namely, Trypanosoma vivax, 61.76% (21/34), T. congolense, 26.47% (9/34), and T. brucei brucei, 5.88% (2/34), and two cases of mixed infection of T. congolense and T. brucei brucei, 5.88% (2/34). The infection rate was not significantly associated with the sex of the fly (generalized linear model (GLM), χ2 = 0:051, p = 0:821, df = 1, n = 477) and district of origin (χ2 = 0:611, p = 0:434, df = 1, n = 477). However, trypanosome infection was highly significantly associated with the fly’s age based on wing fray category (χ2 = 7:56, p = 0:006, df = 1, n = 477), being higher among the very old than the young. Conclusion. The relatively high tsetse density and trypanosome infection rate indicate that the transition zone is a highrisk area for perpetuating animal trypanosomiasis. Therefore, appropriate mitigation measures should be instituted targeting tsetse and other biting flies that may play a role as disease vectors, given the predominance of T. vivax in the tsetse samples.