Ahmed Hassanali

Ahmed Hassanali
Kenyatta University · Department of Chemistry

BSc Hons, PhD

About

271
Publications
70,747
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11,548
Citations
Additional affiliations
November 2008 - present
Kenyatta University
Position
  • Professor (Full)
Description
  • See under research group
Education
September 1967 - October 1969
University of Nottingham
Field of study
  • Chemistry of Antibiotics

Publications

Publications (271)
Article
Full-text available
The fruit fly, Bactrocera dorsalis, is a polyphagous pest that damages a wide variety of fruits in the tropics, including East Africa. In this paper, we aimed to evaluate the attraction of kairomones shared by three hosts of Bactrocera dorsalis to lay the groundwork towards the development of attractants for the management of pests by targeting fem...
Article
Plant-based constituents have been proposed as eco-friendly alternatives to synthetic insecticides for control of mosquito vectors of malaria. In this study, we first screened the effects of methanolic leaf extracts of curry tree (Murraya koenigii) growing in tropical (Mombasa, Malindi) and semi-arid (Kibwezi, and Makindu) ecological zones of Kenya...
Preprint
Full-text available
Abstract - Previously, 4-methylguaiacol, a major constituent of cattle anal odour, was found to have a high repellence on Rhipicephalus appendiculatus. In the present study, 10 structural analogues of the phenol were tested for repellence against R. appendiculatus in order to assess the effects of (i) absence or presence of the 4-alkyl group of var...
Article
Full-text available
Adults of the Brown Ear Tick (Rhipicephalus appendiculatus) have a predilection for feeding inside and around the ears of cattle and other hosts. A previous study has shown that the tick locates the host ears by ‘push–pull’ deployment of a repellent blend emitted at the anal region and an attractant blend emitted at the ears. Interestingly, the two...
Article
Full-text available
On-host behaviour of Rhipicephalus appendiculatus was studied in the field in Bungoma County in Kenya to evaluate the putative repellent effects of essential oils of Tagetes minuta and Tithonia diversifolia at its predilection feeding site. Oils of both plants caused a disruption of orientation, movement and attachment behaviour of ticks. More tick...
Article
Full-text available
Effects of formulated essential oils of Tagetes minuta and Tithonia diversifolia on Rhipicephalus appendiculatus infesting livestock were evaluated in semi-field experiments. Forty-five zebu cattle naturally infested with ticks were randomly selected from 15 herds, three animals from each. Of three animals within each herd, one was treated with 1g...
Article
Full-text available
Plant volatile signatures are often used as cues by herbivores to locate their preferred hosts. Here, we report on the volatile organic compounds used by the subterranean root-knot nematode (RKN) Meloidogyne incognita for host location. We compared responses of infective second stage juveniles (J2s) to root volatiles of three cultivars and one acce...
Conference Paper
Full-text available
Effects of formulated essential oils of Tagetes minuta and Tithonia diversifolia on Rhipicephalus appendiculatus infesting livestock were evaluated in semi-field experiments. Forty-five zebu cattle naturally infested with ticks were randomly selected from 15 herds, three animals from each. Of three animals within each herd, one was treated with 1g...
Data
Effects of formulated essential oils of Tagetes minuta and Tithonia diversifolia on Rhipicephalus appendiculatus infesting livestock were evaluated in semi-field experiments. Forty-five zebu cattle naturally infested with ticks were randomly selected from 15 herds, three animals from each. Of three animals within each herd, one was treated with 1g...
Article
Full-text available
A global North–South divide in research, and its negative consequences, has been highlighted in various scientific disciplines. Northern domination of science relevant to climate change policy and practice, and limited research led by Southern researchers in Southern countries, may hinder further development and implementation of global climate cha...
Article
Previously, we reported a chain of effects induced by phenylacetonitrile, the gregarious-phase adult cohesion pheromone of the desert locust, Schistocerca gregaria (Forskål) (Orthoptera: Acrididae), on conspecific hoppers. Specifically, the nymphs became hyperactive and displayed high levels of intraspecific predation, as surviving individuals grad...
Conference Paper
Full-text available
Rhipicephalus appendiculatus (Brown Ear Tick), the vector of East Coast Fever (ECF), feeds dominantly inside the cattle ear. Previous studies have shown that the adults are attracted by ear volatiles and repelled by anal volatiles, and this ‘pull-push’ effect guides them to their preferred feeding site. In a preliminary observation, release of the...
Article
Full-text available
The chemical composition of plant surfaces plays a role in selection of host plants by herbivorous insects. Once the insect reaches the plant, these cues determine host acceptance. Laboratory studies have shown that the stem borer Busseola fusca (Lepidoptera: Noctuidae), an important pest of sorghum and maize in sub-Saharan Africa, is able to diffe...
Article
The essential oils of three aromatic plant species, Lantana viburnoides sp. viburnoides var. kisi (A. Rich.) Verdc., Clausena anisata (Willd.) Benth. and Uvariodendron gorgonis Verdc., were analysed for their chemical compositions and repellency activity against Anopheles gambiae s.s. The major chemical constituents were piperitenone (25.25%) and a...
Article
Full-text available
Trans-generational transfer of gregarious-phase traits in the desert locust Schistocerca gregaria (Forskål, 1775) is mediated by primer gregarizing pheromonal signals produced by ovipositing females that experience crowding. We monitored time-course proteomic events in eggs from solitary-reared locusts that had been exposed for 1, 3, 5, 7, 10 and 1...
Article
Our earlier studies on the comparative behavioural responses of caged savanna tsetse (Glossina morsitans morsitans and G. pallidipes) on a preferred host (ox) and a non-host (waterbuck) suggested the presence of allomonal constituents on the latter. Follow up comparison of the compositions of odours of waterbuck with those of ox and buffalo led to...
Article
Full-text available
Artemisinin from the plant Artemisia annua (A. annua) L, and used as artemisinin combination therapy (ACT), is the current best therapeutic for treating malaria, a disease that hits children and adults especially in developing countries. Traditionally, A. annua was used by the Chinese as a tea to treat "fever". More recently, investigators have sho...
Article
Full-text available
Background Plants represent one of the most accessible resources available for mosquito control by communities in Tanzania. However, no documented statistics exist for their contribution in the management of mosquitoes and other insects except through verbal and some publications. This study aimed at assessing communities’ knowledge, attitudes and...
Patent
Full-text available
Methods and compositions suitable for influencing insect behavior are provided. In a preferred embodiment, the compositions comprise a blend of between two and eight insect attractant compounds selected from the group consisting of: a) compounds of formula (I); b) compounds of formula (II); c) compounds of formula (III). Wherein: n is zero or an in...
Patent
Full-text available
Methods and compositions suitable for influencing insect behavior are provided. In a preferred embodiment, the compositions comprise a blend of between two and eight insect attractant compounds selected from the group consisting of: a) compounds of formula (I); b) compounds of formula (II); c) compounds of formula (III). Wherein: n is zero or an in...
Article
Two bisbenzylisoquinoline and one hasubanane alkaloids: (-)-pseudocurine (1), (-)-pseudoisocurine (2) and (-)-10-oxoaknadinine (3), were isolated from leaf extract of Stephania abyssinica, a plant used in traditional medicine in South Nyanza region of Kenya. They were characterized using 1D ((1)H, (13)C and DEPT) and 2D (COSY, NOESY, HMQC and HMBC)...
Article
Full-text available
Essential oils of eight plants, selected after an ethnobotanical survey conducted in Bukusu community in Bungoma County, western Kenya (Tagetes minuta, Tithonia diversifolia, Juniperus procera, Solanecio mannii, Senna didymobotrya, Lantana camara, Securidaca longepedunculata, and Hoslundia opposita), were initially screened (at two doses) for their...
Article
Parts of the plant Thalictrum rhyncocarpum are used in herbal medicine in Kenya to treat various infections. The aim of this study was to evaluate in-vitro anti-bacteria activities and phytochemical profiles of solvent extracts of the leaves, stem bark and root of Thalictrum rhyncocarpum against Bacillus subtilis-6633, Staphylococcus aures-SG 511,...
Data
◄► Available from: David M Mburu DownloadPlain Text Page 1 Relationship between virulence and repellency of entomopathogenic isolates of Metarhizium anisopliae and Beauveria bassiana to the termite Macrotermes michaelseni D.M. Mburua,b,*, L. Ocholaa, N.K. Manianiaa, P.G.N. Njagia, L.M. Gitongab, M.W. Ndung’ub, A.K. Wanjoyab,c, A. Hassanalia,d aBeha...
Article
Full-text available
Chromatographic separation of Acridocarpus chloropterus extract led to the isolation and identification of five triterpenes: β-sitosterol (1), stigmasterol (2), friedelin (3), oleanolic acid (4), ursolic acid (5); and five flavonoids: apigenin (6), luteolin (7), vitexin (8), kaempferol (9) and quercetin (10). Quercetin (10) exhibited moderate in vi...
Article
Long used as a therapeutic tea by the Chinese to treat fever, Artemisia annua is more recently being studied and used for eventual treatment for not only malaria, but also many other diseases. This chapter describes studies using in vitro systems, animal models, and humans to evaluate use of not only combinations of pure compounds from the plant, b...
Article
Full-text available
Bactrocera invadens is an invasive fruit fly species of Asian origin that was first detected in Kenya in 2003 and now has been reported in many parts of the African continent. The responses of B. invadens towards odour blends emitted from three host fruits, namely mango (Mangifera indica), marula (Sclerocarya birrea), and Indian almond (Terminalia...
Article
Full-text available
Acetone, methanol and aqueous extracts of the leaves, stem bark and root bark of Vitex schiliebenii belonging to the family Verbenaceae were evaluated for their larvicidal activity against late 3rd/early 4th Anopheles gambiae Giles s.s. larvae (Diptera: Culicidae). The extracts of the acetone leaves and stem bark were active with LC50 values of 14....
Article
Full-text available
Background Malaria, trypanosomiasis and leishmaniasis have an overwhelming impact in the poorest countries in the world due to their prevalence, virulence and drug resistance ability. Currently, there is inadequate armory of drugs for the treatment of malaria, trypanosomiasis and leishmaniasis. This underscores the continuing need for the discovery...
Article
Full-text available
The bioassay-guided purification of Zanthoxylum paracanthum (Rutaceae) extracts led to the isolation of three new alkaloids, namely 1-hydroxy-10-methoxy-7H-dibenzo[de,g]quinolin-7-one (zanthoxoaporphine A, 2), 1-hydroxy-7H-dibenzo[de,g]quinolin-7-one (zanthoxoaporphine B, 3) and 1,8-dihydroxy-9-methoxy-7H-dibenzo[de,g]quinolin-7-one (zanthoxaporphi...
Article
Full-text available
Objectives: To determine the growth-disrupting effects of polar phyto-extracts of V. schilibenii on Anopheles gambiae larvae in a simulated semi-field condition and to undertake phytochemical screening of constituents present. Materials & Method: 3 rd and early 4 th instars of An. gambiae larvae were exposed to acetone and methanol extracts of stem...
Article
Polar constituents of Kotschya uguenensis Verdc. (Fabaceae) do not exhibit acute toxicity but cause growth disruption of Anopheles gambiae s.s. Gile (Diptera: Culicidae) larvae with eventual death. Time-course larvicidal effects of powders of root and stem barks and their crude methanol extracts in form of emulsions were compared in the laboratory...
Article
Full-text available
The plant Conyza newii has been reported to posses, mosquito repellent and fumigant toxicity properties. In this study headspace vapors emitted by the plant were obtained by adsorption on porapak Q® through headspace trapping under field conditions in West Pokot (35oE, 1oN) and Kericho (35oE, 0o) and analyzed using Gas Chromatography-Mass Spectrome...
Article
Isolates of the fungus Beauveria bassiana have different levels of virulence and repellency against the termite Macrotermes michaelseni. In the present study, we compared the volatile profiles and gene sequences of two isolates of the fungus with different levels of virulence and repellence to the termites. Gas chromatography-mass spectrometric ana...
Article
Full-text available
A survey was undertaken to determine the pest status of herbivorous blister beetles, Hycleus spp., in western Kenya where they attack crops such as Desmodium spp., other leguminous plants and sweetpotato. Desmodium spp. are important intercrops in the ‘push–pull” strategy adopted for Striga and stemborer control in maize and sorghum. Production of...
Article
Full-text available
To date, nomadic communities in Africa have been the primary focus of ethnoveterinary research. The Bukusu of western Kenya have an interesting history, with nomadic lifestyle in the past before settling down to either arable or mixed arable/pastoral farming systems. Their collective and accumulative ethnoveterinary knowledge is likely to be just a...
Article
Environmental Fate of Pesticides: Progress in Pesticide Biochemistry and Toxicology. Edited by HutsonD. H. (Shell Research Limited, Sittingbourne) and RobertsT. R. (Hazleton UK, Harrogate). 286 pp. ISBN 0-471-91711-7. Vol. 7. John Wiley & Sons, Chichester, New York, Brisbane, Toronto, Singapore1990. - Volume 11 Issue 6 - Ahmed Hassanali
Article
Full-text available
This study aimed to quantify and evaluate the level of Azadirachtin in neem seed kernel from ten ecotypes in Sudan over two seasons and establish relationship to the agro-ecological attributes. Extraction was done in two replicates using 12 g. After extraction, separation and concentration to 10 ml the samples quantified using HPLC. Neem trees grow...
Article
Herbicides: Progress in Pesticide Biochemistry and Toxicology, Vol. 6. Edited by HutsonD. H. and RobertsT. R. (Shell Research Limited, Sittingbourne). 372 pp. ISBN 0-471-91619-6. John Wiley & Sons, Chichester, New York, Brisbane, Toronto, Singapore, 1987. - Volume 9 Issue 3 - Ahmed Hassanali
Article
Insect attraction to host plants may be partly mediated by visual stimuli. In the present study, the responses of adult Hycleus apicicornis (Guér.) (Coleoptera: Meloidae) to plant models of different colours, different combinations of two colours, or three hues of blue of different shapes are compared. Single-colour models comprised the colours sky...
Article
Full-text available
Previously, we reported an interesting relationship between virulence and repellency of different isolates of the fungus Metarhizium anisopliae towards the termite Macrotermes michaelseni: the higher the virulence of a given isolate, the greater its repellency. In the present study, we compared the volatile profiles of two isolates, one that was mo...
Article
Full-text available
The responses of adult solitarious desert locust to odors from a host plant were evaluated in a two-choice wind tunnel. Solitarious desert locusts collected from the field (Red Sea Coast) were more attracted to volatiles from potted Heliotropium ovalifolium in scotophase than in photophase. The attraction towards the host plant odors rather than to...
Patent
Full-text available
The invention provides methods and compositions suitable for influencing insect behavior. In one aspect, the invention provides insect-repellent compounds. Such compounds, and compositions comprising such compounds, are useful in masking insect-attractant compounds associated with animal body odours. Accordingly, such compounds and compositions are...
Patent
Full-text available
Methods and compositions suitable for influencing insect behavior are provided. In a preferred embodiment, the compositions comprise a blend of between two and eight insect attractant compounds selected from the group consisting of: a) compounds of formula (I); b) compounds of formula (II); c) compounds of formula (III). Wherein: n is zero or an in...
Article
Field observations have demonstrated that gravid Anopheles gambiae Giles s.s. (Diptera: Culicidae) are selective in their choice of oviposition sites. For example, immature stages of An. gambiae s.s. are rarely found in water that contains Culex quinquefasciatus Say immatures. The possibility that this may, in part at least, reflect a response by o...
Article
The biological activity of camphor, a major component of essential oil of the basil shrub, Ocimum kilimandscharicum, against the beetles, Sitophilus granarius, S. zeamais, Tribolium castaneum and Prostephanus truncatus, was investigated in the laboratory using contact toxicity, grain treatment and repellency assays. Camphor applied either topically...
Article
The repellent activity of the essential oil of the catmint plant, Nepeta cataria (Lamiaceae), and the main iridoid compounds (4aS,7S,7aR) and (4aS,7S,7aS)-nepetalactone, was assessed against (i) major Afro-tropical pathogen vector mosquitoes, i.e. the malaria mosquito, Anopheles gambiae s.s. and the Southern house mosquito, Culex quinquefasciatus,...
Article
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Article
Full-text available
Background: Individual human subjects are differentially attractive to mosquitoes and other biting insects. Previous investigations have demonstrated that this can be attributed partly to enhanced production of natural repellent chemicals by those individuals that attract few mosquitoes in the laboratory. The most important compounds in this respe...
Article
Full-text available
The process of strain selection is an important step in the development of insect pathogens for biological control. Bioassays were conducted in the laboratory to evaluate the efficacy of different methods of inoculation using Rhipicephalus pulchellus Gerstäcker (Acari: Ixodidae) as a model. Initially, an oil-based formulation of Metarhizium anisopl...
Article
Full-text available
In traditional African communities, repellent volatiles from certain plants generated by direct burning or by thermal expulsion have played an important role in protecting households against vectors of malaria and other diseases. Previous research on volatile constituents of plants has shown that some are good sources of potent mosquito repellents....
Article
Full-text available
Organic extracts of the leaves of Azadirachta indica A. Juss. yielded ten antitrypanosomal terpenoids. Three of these (1-3), are novel and are derivatives of nimbolide and nimbin. They were extracted from chloroform fraction of methanol extract. These compounds were found to exhibit strong antitrypanosomal activities against Trypanosoma brucei rhod...
Article
Experiments were carried out to evaluate the efficacy of Metarhizium anisopliae (Metsch.) Sorok. (Ascomycota: Hypocreales)-treated semiochemical-baited traps for control of Amblyomma variegatum Fabriscius (Acari: Ixodidae) under field conditions. Unfed A. variegatum adults (118) were seeded in each 100-m plot and allowed to acclimatise for 3 days....
Article
In East African small-holder farming of maize, the cattle forage legume, Desmodium uncinatum is used as an intercrop due to its allelopathic inhibition of parasitism by Striga hermonthica, an obligate parasitic weed that can devastate the maize crop. Bioassay-guided fractionation of the root extract of D. uncinatum revealed isoschaftoside to be the...
Article
Full-text available
The global rate of heavy metal pollution is rapidly increasing in various habitats. Anopheles malaria vector species (Diptera: Culicidae) appear to tolerate many aquatic habitats with metal pollutants, despite their normal proclivity for 'clean' water (i.e. low levels of organic matter). Investigations were conducted to establish whether there are...
Article
Previous studies had demonstrated stage differentiation in the cohesion (aggregation) pheromone systems of the desert locust, Schistocerca gregaria. In laboratory arena, the nymphal and adult stages responded aggregatively to their own pheromone, but dispersed evenly within the arena in the presence of the other. In the present study, we explored t...
Article
The clerodane diterpenoids trans-kolavenolic acid, 18-oxocleroda-3,13(E)-dien-15-oic acid, ent-(18-hydroxycarbonyl)-cleroda-3,13(E)-dien-15-oate, 2-oxo-ent-cleroda-3,13(Z)-dien-15-oic acid and trans-2-oxo-ent-cleroda-13(Z)-en-15-oic acid, and the chlorobenzenoid O-(3-hydroxy-4-hydroxycarbonyl-5-pentylphenyl)-3-chloro-4-methoxy-6-pentyl-2-oxybenzoic...
Article
Full-text available
A study to determine the association of fertilizer with soil water deficit in tea [Camellia sinensis (L.) O. Kuntze] was conducted in a rain-out shelter using potted plants, in which five rates of fertilizer (0, 75, 150, 225 and 300 kg Nitrogen ha) and six levels of soil water content (38, 34, 30, 26, 22 and 18% v/v) were applied in a complete rand...
Article
Use of farmers as extension agents to disseminate new technologies to others is increasingly being adapted in smallholder farming systems. This paper examined technical efficiency (TE) of farmer teachers in the uptake and dissemination of a ‘push–pull’ technology (PPT) for control of Striga weed and stemborers in Western Kenya. A total sample of 11...
Article
Smallholder farming systems in eastern Africa are characterized by cereal/edible legume intercrops in fields severely constrained by parasitic weed, Striga hermonthica, cereal stemborers and declining soil fertility. The push–pull technology concurrently addresses these constraints. It involves intercropping maize with stemborer repellent fodder le...
Conference Paper
Gravid Anopheles gambiae Giles makes a choice of an appropriate oviposition site. The presence of Culex quinquifasciatus in an oviposition site influences gravid An. gambiae decision to oviposit at a specific site or not. The effect of volatiles emanating from varying numbers of egg rafts and/or larvae of C. quinquifasciatus in relation to oviposit...
Article
Full-text available
Anopheles mosquitoes have been shown to adapt to heavy metals in their natural habitats. In this study we explored the possibility of using Anopheles gambiae sensu stricto as bio-reporters for environmental heavy metal pollution through expressions of their metal-responsive metallothionein and alpha-tubulin genes. The study was undertaken with thir...
Article
Full-text available
The antiplasmodial, anti-trypanosomal and anti-leishmanial activity of 25 plant extracts obtained from seven Tanzanian medicinal plants: Annickia (Enantia) kummeriae (Annonaceae), Artemisia annua (Asteraceae), Pseudospondias microcarpa (Anacardiaceae), Drypetes natalensis (Euphorbiaceae), Acridocarpus chloropterus (Malpighiaceae), Maytenus senegale...