Franklin N. Nyabuga

The status of vegetation and the impacts of mammalian herbivores on rangelands are complex, and such studies in Kenya are scanty. We investigated the dynamics of ground cover vegetation in Hell’s Gate National Park in relation to mammalian herbivory. Removal of palatable vegetation is postulated to enhance the development of invasive plant species. We investigated the influence of mammalian herbivores on vegetation diversity and dynamics in this rangeland. Three sampling blocks approximately 3 Km apart measuring 100 m x 50 m were established, each divided into three belt-transects (100 m x 10 m), and separated by a 10 m buffer zone. 2 m by 2 m quadrats at 20 m intervals were established in each transect. We measured composition the richness of plant and mammal species, and herbivory levels four times for six months (September 2018 to February 2019). Plant cover (P< 0.001) and species diversity (P< 0.001) differed significantly among sampling blocks and between seasons (P< 0...

In Kenya, small-scale farmers are increasingly turning to honeybee keeping to supplement their income. The decline of the honeybee population in Kenya has raised concerns following the important economic and ecological role played by the honeybees. By assessing microbial diversity associated with honeybees in Embu County, Kenya, we sought to determine the colony microbial composition of bees using culture-independent sequencing. Honeybee-associated microbial community in the hive materials was dominated by Lactobacillus, Leuconostoc, Fructobacillus, Bacillus, Gilliamella, Frischella, Enterobacter, Bombella and Serratia across the sampling environment. Across the sample types adult worker bees lacked the Lactococcus genus but had the other phylotypes consistently similar to those in the larvae samples. We report a potential disruption of the microbial bacteria community signified by the presence of genera Serratia and Enterobacter, which are opportunistic environmental microorganisms.

Tsetse flies use antennal expressed genes to navigate their environment. While most canonical genes associated with chemoreception are annotated, potential gaps with important antennal genes are uncharacterized in Glossina morsitans morsitans. We generated antennae-specific transcriptomes from adult male G. m. morsitans flies fed/unfed on bloodmeal and/or exposed to an attractant (ε-nonalactone), a repellant (δ-nonalactone) or paraffin diluent. Using bioinformatics approach, we mapped raw reads onto G. m. morsitans gene-set from VectorBase and collected un-mapped reads (constituting the gaps in annotation). We de novo assembled these reads (un-mapped) into transcript and identified corresponding genes of the transcripts in G. m. morsitans gene-set and protein homologs in UniProt protein database to further annotate the gaps. We predicted potential protein-coding gene regions associated with these transcripts in G. m. morsitans genome, annotated/curated these genes and identified the...

Yield loss caused by insect pests remains a substantial problem in agriculture. Chemical control, with potential negative effects on non-target organisms, is still the main tool for pest management. For pest species with limited dispersal capacity, rotation of the crop in time and space has potential as an alternative management measure. This is particularly important in organic farming, where most agrochemicals are prohibited, but also relevant as a complementary pest management strategy in conventional agriculture. Clover is an important crop used for animal feed and as green manure; however, seed-eating weevils can severely limit the seed yield. We hypothesized that the previous year’s clover seed fields constitute the major sources of weevil pests. Consequently, a greater distance to, and a smaller pest load from, this source should reduce the number of weevils colonizing the new seed fields. To map population dynamics and dispersal range ofProtapion fulvipes,an economically imp...

Two tansy-feeding aphids – Macrosiphoniella tanacetaria (MA) and Metopeurum fuscoviride (ME) – were studied at a small spatial scale in and around Jena (< 80 km2) using polymorphic microsatellite markers. Both species were found in ~ 60% of sites formerly known to harbour the aphids, although generally when they did occur, they occurred singly (MA ~ 50%; ME ~60%) and rarely together on the same plant at the same time (~10%) and then usually only in the early part of the growing season. This difference may be due to quasi-apparent competition effects elicited to ants farming ME aphids, and preferentially actively eliminating or disturbing MA aphids. In terms of population genetics, both aphids showed extreme genetic heterogeneity within a metapopulation structure, ME more than MA, i.e. higher FST values, ~ 0.4 vs. 0.15, respectively, and limited levels of interpopulation gene flow. Subpopulations often deviated from Hardy-Weinberg equilibrium and showed linkage disequilibria, as expected in animals with extended parthenogenetic reproduction, and had positive FIS values for most large samples, suggesting inbreeding, and possibly philopatry, certainly in ME. Hierarchical analysis (allele range and number per locus, analysis of molecular variance and FST) strongly suggested that the plant rather than site governs the level of genetic variation. Bayesian clustering analysis revealed that both species had heterogeneous historical genetic patterning, with K (number of subgroups) ranging from 3-7. Evidence is also provided from isolation by distance (IBD) and private allele analyses, that in MA, the presence of winged autumn males, absent in ME where males are wingless, influences comparative population genetic structuring, such that ME subpopulations are comparatively more inbred and genetically differentiated than MA subpopulations. Lastly, additional spatial arrangement (ALLELES-IN-SPACE) analysis showed that in both species, certain subpopulations were genetically isolated from the remainder, probably due to geographical barriers, including intervening buildings and woods. As such, the biology of these tansy aphids living in semi-natural habitats is very different from many pest aphid species examined within agro-ecosystems and infesting ephemeral crops, since the former seem much more reluctant to fly and hence show contrastingly much higher levels of interpopulation divergence, even at small spatial scales as here investigated. Indeed, the number of genotypic clusters found for tansy aphids found using Bayesian approaches is similar to that for the major pest the peach-potato aphid, Myzus persicae, globally

Nine polymorphic microsatellite loci were isolated from the specialist aphid parasitoid, Lysiphlebus hirticornis. In addition, two published loci from closely related Lysiphlebus species were also used. Allelic diversity and heterozygosity were quantified in samples collected from eight tansy plants growing in an area of approximately 150 m2 in Jena, Germany.

Das Verstehen von multitrophischen Interaktionen zwischen Parasitoiden und Blattläusen ist von theoretischem und praktischem Interesse. In dieser Arbeit wurden folgende Aspekte untersucht: 1) Metapopulationsdynamik und Genetik eines spezialisierten Parasitoiden und dessen Blattlaus-Wirtes, 2) Paarungsverhalten von Parasitoiden am Schlupfort und deren Beeinflussung durch Interaktionen mit Ameisen, und 3) Resistenzentwicklung von Blattläuse und deren Auswirkung auf die Fitness von Parasitoiden. Lysiphlebus hirticornis ist ein solitärer Parasitoid der die Blattlaus Metopeurum fuscoviride parasitiert, die ihrerseits auf Rheinfarn, Tanacetum vulgare, spezialisiert ist. T. vulgare kommt typischerweise in einer sehr lückenhaften Verteilung vor. Populationen von L. hirticornis folgen einer klassischen Metapopulationsdynamik, geprägt durch Prozesse des Aussterbens und der Wiederbesiedlung. Dieses tritrophische System wird verwendet um i) die genetische Differenzierung von L. hirticornis auf ...

In order to reduce parasite‐induced mortality, hosts may be involved in mutualistic interactions in which the partner contributes to resistance against the parasite. The pea aphid, Acyrthosiphon pisum Harris (Hemiptera: Aphididae), harbours secondary bacterial endosymbionts, some of which have been reported to confer resistance against aphid parasitoids. Although this resistance often results in death of the developing parasitoid larvae, some parasitoid individuals succeed in developing into adults. Whether these individuals suffer from fitness reduction compared to parasitoids developing in pea aphid clones without symbionts has not been tested so far. Using 30 pea aphid clones that differed in their endosymbiont complement, we studied the effects of these endosymbionts on aphid resistance against the parasitoid Aphidius ervi Haliday (Hymenoptera: Braconidae: Aphidiinae), host–parasitoid physiological interactions, and fitness of emerging adult parasitoids. The number of symbiont s...

In the interaction between two ecologically-associated species, the population structure of one species may affect the population structure of the other. Here, we examine the population structures of the aphidMetopeurum fuscoviride, a specialist on tansyTanacetum vulgare, and its specialist primary hymenopterous parasitoidLysiphlebus hirticornis, both of which are characterized by multivoltine life histories and a classic metapopulation structure. Samples of the aphid host and the parasitoid were collected from eight sites in and around Jena, Germany, where both insect species co-occur, and then were genotyped using suites of polymorphic microsatellite markers. The host aphid was greatly differentiated in terms of its spatial population genetic patterning, while the parasitoid was, in comparison, only moderately differentiated. There was a positive Mantel test correlation between pairwise shared allele distance (DAS) of the host and parasitoid, i.e. if host subpopulation samples wer...