9 results on '"Obonyo, J."'
Search Results
2. The Cotesia sesamiae story: insight into host-range evolution in a Hymenoptera parasitoid and implication for its use in biological control programs
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Kaiser, L., Dupas, S., Branca, A., Herniou, E. A., Clarke, C. W., Capdevielle Dulac, C., Obonyo, J., Benoist, R., Gauthier, J., Calatayud, P. A., Silvain, J. F., and Le Ru, B. P.
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- 2017
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3. Impact of the exotic fall armyworm on larval parasitoids associated with the lepidopteran maize stemborers in Kenya
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Sokame, B. M., Obonyo, J., Sammy, E. M., Mohamed, S. A., Subramania, S., Kilalo, D. C., Juma, G., and Calatayud, Paul-André
- Subjects
nonagrioides ,Busseola fusca ,Cotesia typhae ,Chilo partellus ,Biological control ,Non-reproductive host mortality ,Sesamia calamistis ,Cotesia flavipes ,Cotesia sesamiae ,Sesamia - Abstract
Exotic invasive insect herbivores have the potential to interfere with existing herbivore-natural enemy interactions in new environments. Fall armyworm (FAW), Spodoptera frugiperda J.E. Smith (Lepidoptera: Noctuidae), is a new invasive pest in maize fields in Africa. Understanding the acceptability and suitability of FAW to existing maize stemborer-parasitoid interactions is the first step in elucidating the impact that this exotic insect pest can have on the existing natural enemies used in biological control of maize stemborers in Kenya. The most commonly used larval parasitoids for biological control programs against maize stemborer communities in East Africa are Cotesia flavipes Cameron (Hymenoptera: Braconidae) and two populations of the native Cotesia sesamiae (Cs-Inland and Cs-Coast) Cameron (Hymenoptera: Braconidae). All these parasitoid species attacked FAW larvae but none yielded offspring, although they induced high non-reproductive host mortality when compared to natural mortality. Furthermore, the parasitoids that inserted their ovipositor into FAW larvae exhibited no significant preference between FAW larvae and their respective stemborer hosts under dual-choice bioassays. In olfactometer bioassays, the parasitoids were more attracted to plants infested by FAW than uninfested plants and even showed a marked preference for the odours of plants infested by FAW over those of plants infested by their natural host counterparts. This study illustrates that exotic pests, such as FAW, can impact existing stemborer-parasitoid interactions associated with maize, even if they cannot be used as hosts by parasitoids associated with these stemborers. Although additional studies are needed, FAW might therefore have a negative impact on stemborer biological control existing before its invasion.
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- 2020
4. The Effectiveness of Interactive Text Messaging and Structured Psychosocial Support Groups on Developmental Milestones of Children From Adolescent Pregnancies in Kenya: Quasi-Experimental Study.
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Mwenda V, Makena I, Ogweno V, Obonyo J, and Were V
- Abstract
Background: In sub-Saharan Africa, one-quarter of all pregnancies occur in adolescents. Children born to adolescent mothers have poorer physical and socio-cognitive development. One reason may be inadequate knowledge on childcare and psychosocial support during pregnancy and post partum, since adolescent mothers have less antenatal care attendance and overall interaction with the health care system. Mobile health technology has been used to relay health information to special groups; however, psychosocial support commonly requires physical interaction., Objective: We aimed to assess the efficacy of an interactive mobile text messaging platform and support groups in improving adolescent mothers' knowledge and practices as well as infant growth and development., Methods: This was a quasi-experimental study, conducted among adolescent mothers with infants younger than 3 months, in Homa Bay County, Kenya. Five of the 8 subcounties in Homa Bay County were purposively selected as study clusters. Four subcounties were assigned as intervention clusters and 1 as a control cluster. Adolescent mothers from 2 intervention subcounties received interactive text messaging only (limited package), whereas those from the other 2 subcounties received text messaging and weekly support groups, moderated by a community health extension worker and a counselor (full package); the control cluster only received the end-line evaluation (posttest-only control). The follow-up period was 9 months. Key outcomes were maternal knowledge on childcare and infant development milestones assessed using the Developmental Milestones Checklist (DMC III). Knowledge and DMC III scores were compared between the intervention and control groups, as well as between the 2 intervention groups., Results: We recruited 791 mother-infant pairs into the intervention groups (full package: n=375; limited package: n=416) at baseline and 220 controls at end line. Attrition from the intervention groups was 15.8% (125/791). Compared with the control group, adolescent mothers receiving the full package had a higher knowledge score on infant care and development (9.02 vs 8.01; P<.001) and higher exclusive breastfeeding rates (238/375, 63.5% vs 112/220, 50.9%; P=.004), and their infants had higher average DMC III scores (53.09 vs 48.59; P=.01). The limited package group also had higher knowledge score than the control group (8.73 vs 8.01; P<.001); this group performed better than the full package group on exclusive breastfeeding (297/416, 71.4% vs 112/220, 50.9%; P<.001) and DMC III scores (58.29 vs 48.59; P<.001) when compared with the control group. We found a marginal difference in knowledge scores between full and limited package groups (9.02 vs 8.73; P=.048) but no difference in DMC III scores between the 2 groups (53.09 vs 58.29; P>.99)., Conclusions: An interactive text messaging platform improved adolescent mothers' knowledge on nurturing infant care and the development of their children, even without physical support groups. Such platforms offer a convenient avenue for providing reproductive health information to adolescents., Trial Registration: Pan African Clinical Trials Registry PACTR201806003369302; https://tinyurl.com/kkxvzjse., (©Valerian Mwenda, Ireen Makena, Vincent Ogweno, James Obonyo, Vincent Were. Originally published in JMIR Pediatrics and Parenting (https://pediatrics.jmir.org), 01.05.2023.)
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- 2023
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5. Genome-Wide Patterns of Bracovirus Chromosomal Integration into Multiple Host Tissues during Parasitism.
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Muller H, Chebbi MA, Bouzar C, Périquet G, Fortuna T, Calatayud PA, Le Ru B, Obonyo J, Kaiser L, Drezen JM, Huguet E, and Gilbert C
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- Animals, Gene Transfer, Horizontal, DNA, Viral, Genome, Viral, Host-Parasite Interactions genetics, Polydnaviridae genetics, Wasps virology
- Abstract
Bracoviruses are domesticated viruses found in parasitic wasp genomes. They are composed of genes of nudiviral origin that are involved in particle production and proviral segments containing virulence genes that are necessary for parasitism success. During particle production, proviral segments are amplified and individually packaged as DNA circles in nucleocapsids. These particles are injected by parasitic wasps into host larvae together with their eggs. Bracovirus circles of two wasp species were reported to undergo chromosomal integration in parasitized host hemocytes, through a conserved sequence named the host integration motif (HIM). Here, we used bulk Illumina sequencing to survey integrations of Cotesia typhae bracovirus circles in the DNA of its host, the maize corn borer (Sesamia nonagrioides), 7 days after parasitism. First, assembly and annotation of a high-quality genome for C. typhae enabled us to characterize 27 proviral segments clustered in proviral loci. Using these data, we characterized large numbers of chromosomal integrations (from 12 to 85 events per host haploid genome) for all 16 bracovirus circles containing a HIM. Integrations were found in four S. nonagrioides tissues and in the body of a caterpillar in which parasitism had failed. The 12 remaining circles do not integrate but are maintained at high levels in host tissues. Surprisingly, we found that HIM-mediated chromosomal integration in the wasp germ line has occurred accidentally at least six times during evolution. Overall, our study furthers our understanding of wasp-host genome interactions and supports HIM-mediated chromosomal integration as a possible mechanism of horizontal transfer from wasps to their hosts. IMPORTANCE Bracoviruses are endogenous domesticated viruses of parasitoid wasps that are injected together with wasp eggs into wasp host larvae during parasitism. Several studies have shown that some DNA circles packaged into bracovirus particles become integrated into host somatic genomes during parasitism, but the phenomenon has never been studied using nontargeted approaches. Here, we use bulk Illumina sequencing to systematically characterize and quantify bracovirus circle integrations that occur in four tissues of the Mediterranean corn borer (Sesamia nonagrioides) during parasitism by the Cotesia typhae wasp. Our analysis reveals that all circles containing a HIM integrate at substantial levels (from 12 to 85 integrations per host cell, in total) in all tissues, while other circles do not integrate. In addition to shedding new light on wasp-bracovirus-host interactions, our study supports HIM-mediated chromosomal integration of bracovirus as a possible source of wasp-to-host horizontal transfer, with long-term evolutionary consequences.
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- 2021
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6. Carry-Over Niches for Lepidopteran Maize Stemborers and Associated Parasitoids during Non-Cropping Season.
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Sokame BM, Rebaudo F, Musyoka B, Obonyo J, Mailafiya DM, Le Ru BP, Kilalo DC, Juma G, and Calatayud PA
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Sources of infestation are the key elements to be considered in the development of habitat management techniques for the control of maize stemborers. Several wild plants, grasses mostly, have been identified that serve as hosts for stemborers and their parasitoids during the off-season when maize is not present in the field. However, their abundance is much lower in wild plants compared to cultivated fields. Thus, the role of wild plants as a reservoir for cereal stemborers and their parasitoids is still controversial, particularly in agro-ecosystems with reduced wild habitat. We studied the occurrence of different maize stemborers and associated parasitoids in maize stem residues and wild grasses during non-cropping seasons as potential carry-over populations to subsequent early season maize plants. Surveys were conducted in the central region of Kenya during long and short dry seasons in maize residues and wild grasses as well as during the two rainy seasons in maize plants at earlier and late whorl stages during the years of 2017 and 2018. Wild habitat had a higher species diversity than maize residues habitat, but maize residues had a higher abundance of maize stemborer species, such as Busseola fusca , Sesamia calamistis , and Chilo partellus , and of associated parasitoid species (i.e., Cotesia flavipes and Cotesia sesamiae ) than wild plants. Our surveys, complemented by field parasitoid releases of C. flavipes and C. sesamiae , indicated that maize residues constitute a better refugia reservoir not only of the maize stemborers but also of C. flavipes and C. sesamiae during non-cropping seasons as compared to wild plants and, thus, might constitute in this region the main source of both stemborers and C. flavipes / C. sesamiae carry-over in maize plants during the subsequent cropping season. Thus, systematic destruction of maize residues would not help the biological control of lepidopteran stemborers. This is particularly true in areas with reduced wild habitat.
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- 2019
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7. Systematics and biology of Cotesia typhae sp. n. (Hymenoptera, Braconidae, Microgastrinae), a potential biological control agent against the noctuid Mediterranean corn borer, Sesamia nonagrioides .
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Kaiser L, Fernandez-Triana J, Capdevielle-Dulac C, Chantre C, Bodet M, Kaoula F, Benoist R, Calatayud PA, Dupas S, Herniou EA, Jeannette R, Obonyo J, Silvain JF, and Ru BL
- Abstract
Many parasitoid species are subjected to strong selective pressures from their host, and their adaptive response may result in the formation of genetically differentiated populations, called host races. When environmental factors and reproduction traits prevent gene flow, host races become distinct species. Such a process has recently been documented within the Cotesia flavipes species complex, all of which are larval parasitoids of moth species whose larvae are stem borers of Poales. A previous study on the African species C. sesamiae , incorporating molecular, ecological and biological data on various samples, showed that a particular population could be considered as a distinct species, because it was specialized at both host ( Sesamia nonagrioides ) and plant ( Typha domingensis ) levels, and reproductively isolated from other C. sesamiae . Due to its potential for the biological control of S. nonagrioides , a serious corn pest in Mediterranean countries and even in Iran, we describe here Cotesia typhae Fernandez-Triana sp. n. The new species is characterized on the basis of morphological, molecular, ecological and geographical data, which proved to be useful for future collection and rapid identification of the species within the species complex. Fecundity traits and parasitism success on African and European S. nonagrioides populations, estimated by laboratory studies, are also included.
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- 2017
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8. Cost-effectiveness of routine rapid human immunodeficiency virus antibody testing before DNA-PCR testing for early diagnosis of infants in resource-limited settings.
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Menzies NA, Homsy J, Chang Pitter JY, Pitter C, Mermin J, Downing R, Finkbeiner T, Obonyo J, Kekitiinwa A, Tappero J, and Blandford JM
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- Clinical Laboratory Techniques methods, DNA, Viral genetics, Developing Countries, Early Diagnosis, Female, HIV Infections epidemiology, HIV-1 genetics, HIV-1 immunology, Health Workforce, Humans, Immunoassay methods, Infant, Male, Polymerase Chain Reaction methods, Sensitivity and Specificity, Uganda epidemiology, Clinical Laboratory Techniques economics, HIV Antibodies blood, HIV Infections diagnosis, HIV Infections economics, HIV-1 isolation & purification, Immunoassay economics, Polymerase Chain Reaction economics
- Abstract
Background: Infants born to HIV-infected women should receive HIV testing to allow early diagnosis and treatment. Recommendations for resource-limited settings stress laboratory-based virologic assays. While effective, these tests are logistically complex and expensive. This study explored the cost-effectiveness of incorporating initial screening with rapid HIV tests (RHT) into the conventional testing algorithm to screen-out HIV-uninfected infants, thereby reducing the need for costly virologic testing., Methods: Data on HIV prevalence, RHT sensitivity and specificity, and costs were collected from 820 HIV-exposed children (1.5-18 months) attending 2 postnatal screening programs in Uganda during July 2005 to December 2006. Cost-effectiveness models compared the conventional testing algorithm DNA polymerase chain reaction (DNA-PCR with Roche Amplicor v1.5) with a modified algorithm (initial RHT to screen-out HIV-uninfected infants before DNA-PCR)., Results: The model estimated that the conventional algorithm would identify 94.3% (91.8%-94.7%) of HIV-infected infants, compared with 87.8% (79.4%-90.5%) for a modified algorithm using RHT (HIV 1/2 Determine) and excluding the need for DNA-PCR for HIV antibody-negative infants. Costs per infant were $23.47 ($23.32-$23.76) for the conventional algorithm and between $22.75 ($21.89-$23.31) and $7.58 ($6.41-$10.75) for the modified algorithm, depending on infant age and symptoms. Compared with the conventional algorithm, costs per HIV-infected infant identified using the modified algorithm were higher in 1.5-to 3-month-old infants, but significantly lower in 3-month-old and older infants. Models replicating the whole infant testing program showed the modified algorithm would have marginally lower sensitivity, but would reduce total program costs by 27% to 40%, producing an incremental cost-effectiveness ratio of $1489 ($686-$6781) for the conventional versus modified algorithms., Conclusions: Screening infants with RHT before DNA-PCR is cost-effective in infants 3 months old or older. Incorporating RHT into early infant testing programs could improve cost-effectiveness and reduce program costs.
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- 2009
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9. Routine intrapartum HIV counseling and testing for prevention of mother-to-child transmission of HIV in a rural Ugandan hospital.
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Homsy J, Kalamya JN, Obonyo J, Ojwang J, Mugumya R, Opio C, and Mermin J
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- Anti-HIV Agents administration & dosage, Anti-HIV Agents pharmacology, Feasibility Studies, Female, HIV Seropositivity, Humans, Infant, Newborn, Male, Mass Screening, Nevirapine administration & dosage, Nevirapine pharmacology, Patient Acceptance of Health Care, Pregnancy, Rural Population, Uganda, Counseling, HIV Infections diagnosis, Infectious Disease Transmission, Vertical prevention & control, Pregnancy Complications, Infectious diagnosis, Pregnancy Complications, Infectious drug therapy
- Abstract
Objective: In Africa, prevention of mother-to-child HIV transmission (PMTCT) programs are hindered by limited uptake by women and their male partners. Routine HIV counseling and testing (HCT) during labor has been proposed as a way to increase PMTCT uptake, but little data exist on the impact of such intervention in a programmatic context in Africa., Design and Methods: In May 2004, PMTCT services were established in the antenatal clinic (ANC) of a 200-bed hospital in rural Uganda; in December 2004, ANC PMTCT services became opt-out, and routine opt-out intrapartum HCT was established in the maternity ward. We compared acceptability, feasibility, and uptake of maternity and ANC PMTCT services between December 2004 and September 2005., Results: HCT acceptance was 97% (3591/3741) among women and 97% (104/107) among accompanying men in the ANC and 86% (522/605) among women and 98% (176/180) among their male partners in the maternity. Thirty-four women were found to be HIV seropositive through intrapartum testing, representing an 12% (34/278) increase in HIV infection detection. Of these, 14 received their result and nevirapine before delivery. The percentage of women discharged from the maternity ward with documented HIV status increased from 39% (480/1235) to 88% (1395/1594) over the period. Only 2.8% undocumented women had their male partners tested in the ANC in contrast to 25% in the maternity ward. Of all male partners who presented to either unit, only 48% (51/107) came together and were counseled with their wife in the ANC, as compared with 72% (130/180) in the maternity ward. Couples counseled together represented 2.8% of all persons tested in the ANC, as compared with 37% of all persons tested in the maternity ward., Conclusion: Intrapartum HCT may be an acceptable and feasible way to increase individual and couple participation in PMTCT interventions.
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- 2006
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