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Articles 1411 - 1440 of 1443

Full-Text Articles in Life Sciences

Towards The Selection Of Cattle For Tick Resistance In Africa, J. J. De Castro, P. B. Capstick, S. Nokoe, H. Kiara, F. Rinkanya, R. Slade, O. Okello, L. Bennun Oct 1991

Towards The Selection Of Cattle For Tick Resistance In Africa, J. J. De Castro, P. B. Capstick, S. Nokoe, H. Kiara, F. Rinkanya, R. Slade, O. Okello, L. Bennun

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Half-body tick collections and visual assessment of tick burdens were performed monthly over six months on 100 bulls at the Kenya National Boran Stud, Mutara Ranch, Kenya. Boophilus decoloratus predominated among several tick species infesting the animals. Burdens of B. decoloratus and total tick burdens were highly correlated. Rankings of relative tick resistance among bulls were consistent from month to month. Rankings based on visual assessment were very close to those based on actual tick burdens. Animals with thin skins appeared to carry fewer ticks, but tick burden bore no relationship to coat colour. The results suggest that simple visual …

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Bionomics Of Tetrastichus Sesamiae [Hymenoptera: Eulophidae], A Pupal Endo-Parasitoid Of Maruca Testulalis [Lepidoptera: Pyralidae], J. B. Okeyo-Owuor, G. W. Oloo, P. O. Agwaro Sep 1991

Bionomics Of Tetrastichus Sesamiae [Hymenoptera: Eulophidae], A Pupal Endo-Parasitoid Of Maruca Testulalis [Lepidoptera: Pyralidae], J. B. Okeyo-Owuor, G. W. Oloo, P. O. Agwaro

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The biology and behaviour of Tetrastichus sesamiae Risbec, a pupal endoparasitoid of Maruca testulalis Geyer, were studied under laboratory conditions. Most adults emerged from the host pupae between 08.00 h and 09.00 h and mating and oviposition started almost immediately. Both ♂♂ and ♀♀ mated repeatedly, and each ♀ could lay eggs for up to 6 days and in up to 5 host pupae. Progeny production ranged from 0-263 offspring per ♀ and adult longevity was from 4.3-13.9 days. The quality of food available to the adults was a major factor influencing progeny production, and longevity. The species was capable …

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Turnover In The Populations Within Mature Nests Of The Termite Macrotermes Michaelseni In Kenya, J. P.E.C. Darlington Sep 1991

Turnover In The Populations Within Mature Nests Of The Termite Macrotermes Michaelseni In Kenya, J. P.E.C. Darlington

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Production in mature termite nests consists of a seasonal brood of reproductives and a continuous turnover of steriles. The sterile population of the nest remained fairly constant, with no regular seasonal fluctuations. Growth rates of steriles were estimated by interrupting the input and following the "missing cohort". Estimated mean values of standing crop biomass and annual production in a mature nest were used to calculate a production-to-biomass ratio. In conjunction with data on the density of nests in the field, the biomass and production per hectare were estimated. © 1991 Birkhäuser Verlag.

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Electrophoretic Study Of Enzymes From A Glossina Fuscipes Fuscipes Newstead Population From Western Kenya, G. F. Rajendram Jan 1991

Electrophoretic Study Of Enzymes From A Glossina Fuscipes Fuscipes Newstead Population From Western Kenya, G. F. Rajendram

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Enzymes were investigated, by electrophoresis, in a population of Glossina fuscipes fuscipes Newstead collected from Rusinga Island in Lake Victoria, Western Kenya. The following enzymes were tested: glucose phosphate isomerase. glucose-6-phosphate dehydrogenase (G6PDH). hexokinase, isocitrate dehydrogenase (IDH), malate-dehydrogenase (MDH), phosphoglucomutase, and xanthine dehydrogenase (XDH). Single monomorphic bands were stained by the following enzymes apparently under the control of single loci: G6PDIL MDH, and XDH. The enzyme IDH showed two bands with very close mobilities and no variation among individuals in the population. Hence IDH was considered as representing a single locus. Glucose phosphate isomerase manifested three alleles and apparently six …

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Enhancement Of Diapause Development In A Stem Borer, Busseola Fusca (Lep.: Noctuidae) By Dry Conditions, Takashi Okuda Jan 1991

Enhancement Of Diapause Development In A Stem Borer, Busseola Fusca (Lep.: Noctuidae) By Dry Conditions, Takashi Okuda

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Water was an important factor for diapause termination only during the late stage of the diapause in Busseola fusca. Exposure to dry conditions for 2 months accelerated diapause development more. Diapause development proceeded at warm temperatures only. © 1991, JAPANESE SOCIETY OF APPLIED ENTOMOLOGY AND ZOOLOGY. All rights reserved.

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Trap-Catches, Nutritional Condition And The Timing Of Activity Of The Tsetse Fly Glossina Longipennis (Diptera: Glossinidae), Sarah E. Randolph, D. J. Rogers, R. D. Dransfield, R. Brightwell Jan 1991

Trap-Catches, Nutritional Condition And The Timing Of Activity Of The Tsetse Fly Glossina Longipennis (Diptera: Glossinidae), Sarah E. Randolph, D. J. Rogers, R. D. Dransfield, R. Brightwell

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Samples of Glossina longipennis Corti, taken over four days in traps (baited with acetone, cow urine and octenol) at half-hourly intervals during their restricted activity periods at dusk and dawn, were analysed for their nutritional condition. For both sexes, trap catches were highest at the end of dusk, between 19.00 and 19.30 h, associated with a significant increase in numbers with the low haematin content characteristic of flies estimated to have fed more than 60 hours previously. Also, the mean fat content of these flies was significantly lower than that of those trapped earlier. There was considerable day-to-day variation in …

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Infection Rates In Glossina Morsitans Morsitans Fed On Waterbuck And Boran Cattle Infected With Trypanosoma Congolense, Steve Mihok, Reardon O. Olubayo, David F. Wesonga Jan 1991

Infection Rates In Glossina Morsitans Morsitans Fed On Waterbuck And Boran Cattle Infected With Trypanosoma Congolense, Steve Mihok, Reardon O. Olubayo, David F. Wesonga

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Teneral Glossina morsitans morsitans were fed on waterbuck (Kobus defassa) and Boran cattle (Bos indicus) infected experimentally with Trypanosoma congolense clone IL2895. Infection rates in tsetse varied from 9 to 31% when fed on cattle, and from 2 to 59% when fed on waterbuck. In waterbuck, infections were often detected through the development of parasites in tsetse at times when parasitaemia could not be detected through microscopic examination of blood. Male and female, and 1- and 2-day-old flies were equally susceptible to infection on both hosts. Infection in tsetse was associated with a 14% absolute reduction in survival during the …

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Predation On Livestock Ticks By Chickens, S. M. Hassan, O. O. Dipeolu, A. O. Amoo, T. R. Odhiambo Jan 1991

Predation On Livestock Ticks By Chickens, S. M. Hassan, O. O. Dipeolu, A. O. Amoo, T. R. Odhiambo

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Chickens were shown to be natural predators of ticks. Rhipicephalus appendiculatus were recovered in large numbers from the crops and gizzards of chickens which had scavenged for 30 min-1 h among tick-infested cattle. Other ticks recovered were Amblyomma variegatum and Boophilus decoloratus. The numbers of ticks recovered ranged from 3 to 331, with an average of 81 per chicken. Cattle facilitated the predation of ticks by certain behavioural actions. Chickens also picked up both engorged and unengorged ticks seeded on vegetation, but unengorged ticks were preferred. The possibility of tick predation by chickens forming a viable biological control component in …

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Juvenile Hormone Binding To A 500-K Diapause-Associated Protein Of The Stem-Borer, Busseola Fusca, Ellie O. Osir, Gopalan C. Unnithan, Glenn D. Prestwich Jan 1991

Juvenile Hormone Binding To A 500-K Diapause-Associated Protein Of The Stem-Borer, Busseola Fusca, Ellie O. Osir, Gopalan C. Unnithan, Glenn D. Prestwich

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1. 1. The larval haemolymph of the stem-borer, Busseola fusca Fuller (Lepidoptera: Noctuidae) contains a high molecular weight protein (Mr ∼ 500,000) that is induced only during diapause. This diapause-induced protein, termed Busseola diapause protein (BDP), has been previously isolated and characterized. 2. 2. In this study, BDP has been shown to be a specific juvenile hormone (JH) binder by labelling with epoxybisfarnesyl diazoacetate (EBDA), the photoactivatable analog of JH I (10R, 11S). 3. 3. In a direct binding assay, BDP was also shown to bind [3H]-JH I (10R, 11S) with high affinity (Kd ∼ 120 nM). 4. 4. These …

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Feeding Responses Of Chilo Partellus (Swinhoe) (Lepidoptera: Pyralidae) Larvae To Sorghum Plant Phenolics And Their Analogs, Baldwyn Torto, Ahmed Hassanali, Kailash N. Saxena, Sagary Nokoe Jan 1991

Feeding Responses Of Chilo Partellus (Swinhoe) (Lepidoptera: Pyralidae) Larvae To Sorghum Plant Phenolics And Their Analogs, Baldwyn Torto, Ahmed Hassanali, Kailash N. Saxena, Sagary Nokoe

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Phagostimulatory responses of third-instar larvae of Chilo Partellus to phenolic components identified in an ethyl acetate extract of the leaf whorls of 3-week-old plants of Sorghum bicolor cultivar IS 18363 were studied in no-choice bioassays. The major components in the extract were identified as 4-hydroxybenzaldehyde and 4-hydroxybenzoic acid, with 4-hydroxy-3-methoxycinnamic acid, 3,4-dihydroxycinnamic acid, and 4-hydroxycinnamic acid present in minor amounts. All but 4-hydroxycinnamic acid were stimulatory at the doses tested. 4-Hydroxybenzaldehyde was more stimulatory than other potential biogenetic analogs. Hydroxybenzoic acids generally elicited greater feeding response than cinnamic acids, and the pattern of oxygen substitution in the benzene ring was …

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Commitment To Metamorphosis In Tsetse (Glossina Morsitans Centralis): Temporal, Nutritional And Hormonal Aspects Of The Decision, David L. Denlinger, Jan Žďárek Jan 1991

Commitment To Metamorphosis In Tsetse (Glossina Morsitans Centralis): Temporal, Nutritional And Hormonal Aspects Of The Decision, David L. Denlinger, Jan Žďárek

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Larvae of Glossina morsitans centralis were manually extruded from the uterus of the female at different times during the third (final) larval instar to evalute their competence to initiate metamorphosis. Parturition is a gated response in tsetse, and in this species the peak of activity occurred 8.7 h after the onset of the daily 12 h photophase. Larvae aborted a few hours prematurely were completely competent to crawl and pupariated within 1-2 h, but a portion of the puparia blackened before tanning. Younger larvae (22.9 mg vs full grown weight of 33.6 mg) were also competent to crawl, but after …

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Monitoring Secondary Outbreaks Of The African Armyworm In Kenya Using Pheromone Traps For Timing Of Bacillus Thuringiensis Application, M. Broza, M. Brownbridge, B. Sneh Jan 1991

Monitoring Secondary Outbreaks Of The African Armyworm In Kenya Using Pheromone Traps For Timing Of Bacillus Thuringiensis Application, M. Broza, M. Brownbridge, B. Sneh

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The arrival of male moths of the African armyworm, Spodoptera exempta Walker, was monitored in Kenya using pheromone traps. Peak trap counts were obtained during March 1989, and were concentrated in three out of nine traps distributed in small farms in an area of 625 km2 in Lambwe valley, South Nyanza. Large numbers of egg masses were located on dry stalks of last year's cereals in wild cynodon grass situated around the crop fields. Smaller numbers were found on the underside of the first emerged leaves of maize seedlings. Few egg masses were found on millet crops. Application of a …

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Pathogenicity Of Tsetse-Transmitted Trypanosoma Congolense For Waterbuck (Kobus Defassa) And Boran Cattle (Bos Indicus), R. O. Olubayo, S. Mihok, D. F. Wesonga, E. R.M. Mbwabi Jan 1991

Pathogenicity Of Tsetse-Transmitted Trypanosoma Congolense For Waterbuck (Kobus Defassa) And Boran Cattle (Bos Indicus), R. O. Olubayo, S. Mihok, D. F. Wesonga, E. R.M. Mbwabi

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Five waterbuck (Kobus defassa) and four Boran cattle (Bos indicus) were infected with Trypanosoma congolense IL2895 using Glossina morsitans morsitans. At the same time, two waterbuck and two cattle were inoculated intravenously with bloodstream forms. With both methods of challenge, cattle had short prepatent periods followed by a continuous high parasitaemia. All cattle became severely anaemic and had to be treated with trypanocidal drugs to prevent death. In contrast, tsetse and intravenous challenge of waterbuck resulted in a long prepatent period, followed by brief, intermittent levels of low parasitaemia, and eventual selfcure. Waterbuck did not become anaemic, even during short …

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Pheromonal Trapping Of Chilo Partellus (Swinhoe) (Lepidoptera: Pyralidae) Moths In Relation To Male Population Density And Competition With Females, Gopalan Chandran Unnithan, Kailash Narain Saxena Jan 1991

Pheromonal Trapping Of Chilo Partellus (Swinhoe) (Lepidoptera: Pyralidae) Moths In Relation To Male Population Density And Competition With Females, Gopalan Chandran Unnithan, Kailash Narain Saxena

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The numbers of laboratory-reared males of Chilo partellus (SWINHOE) which were released, both in a screenhouse and in the field, and recaptured in virgin female-baited traps were positively correlated. Pheromone trap catches were reduced by 75–100% when 18 or 36 virgin females were placed in two concentric circles of radii 10 m and 20 m occupying an area of 1,257 sq m. around the trap. Mated females surrounding the trap did not cause a significant decrease in the trap catch. Tethered virigin females surrounding a virgin female-baited trap competed successfully among themselves and with the trap for receptive males, the …

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Host Plant Selection By Helicoverpa Armigera (Lepidoptera: Noctuidae): The Role Of Some Herbivore Attributes, S. Firempong, M. P. Zalucki Jan 1991

Host Plant Selection By Helicoverpa Armigera (Lepidoptera: Noctuidae): The Role Of Some Herbivore Attributes, S. Firempong, M. P. Zalucki

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The effect of various ‘herbivore’ attributes on oviposition in Helicoverpa armigera were considered in a series of laboratory experiments. Larval diet did not influence the rank order of adult host preference, but early adult experience around a host increased oviposition on that host in subsequent trials. The presence of eggs laid 12 h before did not influence subsequent oviposition on a plant, although newly laid eggs may have. The presence of larvae, larval damage to plants and larval frass reduced oviposition on a plant. These results are discussed in relation to polyphagy in H. armigera. © 1991, CSIRO. All rights …

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Mechanisms Of Resistance In Wild Rice Oryza Brachyantha To Rice Leaffolder Cnaphalocrocis Medinalis (Guenée) (Lepidoptera: Pyralidae), R. Ramachandran, Z. R. Khan Jan 1991

Mechanisms Of Resistance In Wild Rice Oryza Brachyantha To Rice Leaffolder Cnaphalocrocis Medinalis (Guenée) (Lepidoptera: Pyralidae), R. Ramachandran, Z. R. Khan

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A wild rice, Oryza brachyantha, was rated as highly resistant to rice leaffolder, Cnaphalocrocis medinalis (Guenée), while its F1 hybrid from a cross with a high-yielding, leaffolder-susceptible rice, IR31917-45-3-2, was rated resistant in a standard screening test. In comparison with IR31917-45-3-2, O. brachyantha and the F1 hybrid were unsuitable for oviposition, survival, and growth of C. medinalis. However, growth and survival of larvae in artificial diets containing lyophilized leaf powder of IR31917-45-3-2 and O. brachyantha were comparable. Studies on the feeding and settling preference of the larval stages suggested that the mechanism of resistance of O. brachyantha is that of …

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Volatile Components Of Banana Pseudostem Of A Cultivar Susceptible To The Banana Weevil, Isaiah O. Ndiege, William J. Budenberg, Wilber Lwande, Ahmed Hassanali Jan 1991

Volatile Components Of Banana Pseudostem Of A Cultivar Susceptible To The Banana Weevil, Isaiah O. Ndiege, William J. Budenberg, Wilber Lwande, Ahmed Hassanali

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Volatiles from banana ('githumo''cultivar) pseudostem were trapped using porapak S. The trapped volatiles were desorbed from porapak columns by elution with dichloromethane and analysed using GC and GC-MS. The volatile compounds identified included α-pinene, β-pinene, β-myrcene, limonene, α-cubebene, α-copaene, α-cedrene, β-caryophyllene and α-humulene. © 1992.

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Leishmaniasis In A Domestic Goat In Kenya, A. Olufemi Williams, J. Mutinga, M. Rodgers Jan 1991

Leishmaniasis In A Domestic Goat In Kenya, A. Olufemi Williams, J. Mutinga, M. Rodgers

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The pathological and electron-microscopic features of the first case of autochthonous leishmaniasis affecting a domestic goat in Kenya are described. They are similar to what have been described in man and other animals. Using a short amino-acid sequence common to all the species of leishmania as primers for kDNA synthesis, the intervening sequence of 120 bases was amplified in the goat's tissues by polymerase chain reaction (PCR). The leishmania kinetoplast DNA sequence was detected in all the different infected tissues of the goat examined. The sensitivity and specificity of this assay are discussed. The result of the assay used was …

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Histopathology Of Attachment Sites Of Amblyomma Variegatum And Rhipicephalus Appendiculatus On Zebu Cattle Of Varying Resistance To Ticks, A. A. Latif, D. K. Punyua, P. B. Capstick, S. Nokoe, A. R. Walker, J. D. Fletcher Jan 1991

Histopathology Of Attachment Sites Of Amblyomma Variegatum And Rhipicephalus Appendiculatus On Zebu Cattle Of Varying Resistance To Ticks, A. A. Latif, D. K. Punyua, P. B. Capstick, S. Nokoe, A. R. Walker, J. D. Fletcher

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Mature, unimproved East African Zebu cattle (Bos indicus) naturally exposed to ticks from birth were ranked for resistance to ticks by repeated whole-body counts of infesting ticks. Four cattle of high resistance, four of low resistance and two of intermediate resistance were artificially infested with nymphs of Amblyomma variegatum and Rhipicephalus appendiculatus. Two Friesian cattle (Bos taurus) with less exposure to ticks were similarly infested. Biopsies of tick attachment sites were examined histologically. All attachment sites showed acute inflammatory lesions, and sites of both tick species on high resistance cattle showed delayed hypersensitive reactions with intra-epidermal pustulation and significant increases …

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Lipophorin From The Tsetse Fly, Glossina Morsitans Morsitans, James O. Ochanda, Ellie O. Osir, Edward K. Nguu, Norah K. Olembo Jan 1991

Lipophorin From The Tsetse Fly, Glossina Morsitans Morsitans, James O. Ochanda, Ellie O. Osir, Edward K. Nguu, Norah K. Olembo

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1. 1. Lipophorin was isolated from the haemolymph of adult tsetse fly, Glossina morsitans morsitans, by ultracentrifugation in a potassium bromide density gradient. 2. 2. The tsetse fly lipophorin (Mr {reversed tilde equals} 600,000) has a density of {reversed tilde equals} 1.11 g/ml and consists of two apoproteins, apolipophorin-I (apoLp-I, Mr {reversed tilde equals} 250,000) and apolipophorin-II (apoLp-II, Mr {reversed tilde equals} 80,000), both of which are glycosylated as shown by staining with periodate-Schiff reagent. The protein complex is composed of 49% protein and 51% lipids. 3. 3. The finding of lipophorin in tsetse fly haemolymph suggests that, although these …

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Structural Studies On The Major Milk Gland Protein Of The Tsetse Fly, Glossina Morsitans Morsitans, Ellie O. Osir, Michael Kotengo, Mohammed F.B. Chaudhury, Leonard H. Otieno Jan 1991

Structural Studies On The Major Milk Gland Protein Of The Tsetse Fly, Glossina Morsitans Morsitans, Ellie O. Osir, Michael Kotengo, Mohammed F.B. Chaudhury, Leonard H. Otieno

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1. 1. The major protein in the milk gland secretions of the tsetse fly, Glossina morsitans morsitans, was isolated by a combination of gel permeation chromatography and crystallization. 2. 2. It has a native Mr ∼47,000 and is composed of two identical polypeptide chains (Mr ∼21,000) as determined by chemical cross-linking studies. The protein has no covalently-bound carbohydrates or lipids. Amino acid analysis of the protein revealed relatively high amounts of the aromatic amino acids, tyrosine (9.1 mol.%) and phenylalanine (8.5 mol.%). Immunoblotting experiments using antiserum against the protein revealed no cross-reactivity with any other milk proteins. 3. 3. Quantitation …

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Screening For Highly Effective Isolates Of Bacillus Thuringiensis Against Spodoptera Exempta And Spodoptera Littoralis, M. Hamal, M. Brownbridge, M. Broza, B. Sneh Jan 1991

Screening For Highly Effective Isolates Of Bacillus Thuringiensis Against Spodoptera Exempta And Spodoptera Littoralis, M. Hamal, M. Brownbridge, M. Broza, B. Sneh

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Several new isolates of Bacillus thuringiensis Berliner have shown significantly higher levels of insecticidal activity than the previous best isolates (Bt24- entomocidus and IH-A- aizawai) against both Spodoptera littoralis Boisd. and Spodoptera exempta Walker. The best ones, in the following descending order of potency, were: against S. littoralis — K26–21, MF4B–2, MR1–37, K28–30, K26–8; against S. exempta — Bt-3, K30–3, HD-133, MR1–37, Bt-17, K26–8, K26–21, MF4B-2, HD-593. Larvae of S. exempta were considerably more susceptible (4.12–1.25 fold) to some of the isolates (Bt-3, K30–3, HD-133, MR1–37, Bt-17, K26–8, HD-593) than S. littoralis. © 1991, Springer Science + Business Media B.V.. …

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Attraction Of The Stem Borer Chilo Partellus (Swinhoe) Larvae (Lepidoptera: Pyralidae) By Certain Coloured Surfaces For Trapping, Kailash Narain Saxena, Jeremiah Dickens Onyango Jan 1987

Attraction Of The Stem Borer Chilo Partellus (Swinhoe) Larvae (Lepidoptera: Pyralidae) By Certain Coloured Surfaces For Trapping, Kailash Narain Saxena, Jeremiah Dickens Onyango

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Different colour papers have been shown to attract the first and third instar larvae of Chilo partellus in different degrees. Green bice (No. 329) and light green (No. 323) elicited maximum larval attraction; followed by foliage green (No. 328) and cadmium yellow (No. 307). The green bice paper has been found to be much more effective than foliage green or cadmium yellow paper as a cylindrical sticky trap for the larvae. Even when competing with the host plant, sorghum, these colour paper traps proved more effective than the plants for attracting and trapping the larvae. © 1987, JAPANESE SOCIETY OF …

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Policy Structures And Crop Productivity In Third World Countries, Zerubabel M. Nyiira Jan 1987

Policy Structures And Crop Productivity In Third World Countries, Zerubabel M. Nyiira

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Deciding what should be done in the crop-production sector is a policy issue and a public and management responsibility. Entrusted with that responsibility, governments formulate policies which should ensure maximum crop productivity. The impact of policies and policy structures on crop productivity, and the role of policy makers, administrators and scientists in research and development systems are the subjects of this paper. Observations are made on the role played by government policies in the generation, diffusion and application of crop-production technology and a brief discussion is presented of issues of public and international policies and crop productivity. © 1987.

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Cutaneous Responses Of Cattle To Extracts From Rhipicephalus Appendiculatus Larvae, M. G. Binta, M. P. Cunningham Jan 1984

Cutaneous Responses Of Cattle To Extracts From Rhipicephalus Appendiculatus Larvae, M. G. Binta, M. P. Cunningham

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A component of an extract from Rhipicephalus appendiculatus larval ticks induced an immediate hypersensitivity reaction in sensitized cattle when intra-dermally inoculated. Generally, the magnitude of the cutaneous reaction depended upon the duration of exposure of the cattle to tick infestation. The skin reaction was absent in steers not previously fed on by ticks. Field trials, using the extract in the Narok District of Kenya (Masailand), showed that the skin swelling thus induced was biggest in adult cattle and those over 9 months, moderate in the 6-month age-group and barely palpable in the less-than-1-month age-group. © 1984.

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Trail-Following In Termites: Evidence For A Multicomponent System, M. Kaib, O. Bruinsma, R. H. Leuthold Sep 1982

Trail-Following In Termites: Evidence For A Multicomponent System, M. Kaib, O. Bruinsma, R. H. Leuthold

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Several African termite species from different subfamilies and different habitats are sensitive to trail-active extracts or to naturally laid trails from other species. Using single-extract bioassays, it is shown that the response threshold for trail-following is nearly identical for all tested species (except for Hodotermes mossambicus). However, when termite workers have a choice between trails from their own species and from other species, conspecific trail-following is exclusively observed. This phenomenon can be counteracted by dilution (1:10) of the conspecific trail-pheromone extract. Tests of the trail activity of various synthetic alcohols show that among these, the highest sensitivity of termite workers …

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Influence Of The Termite Macrotermes Michaelseni (Sjöst) On Soil Fertility And Vegetation In A Semi-Arid Savannah Ecosystem, M. A. Arshad Jan 1982

Influence Of The Termite Macrotermes Michaelseni (Sjöst) On Soil Fertility And Vegetation In A Semi-Arid Savannah Ecosystem, M. A. Arshad

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The growth and species structure of vegetation in relation to the proximity of termite (M. michaelseni) mounds was studied in a semi-arid savannah ecosystem during 1978-1980. The dry matter yield in the termite-modified area at 1-10 m distance from mounds was significantly greater (P < 0.01) than that in the area beyond 22 m which is relatively unaffected by the termites. Themeda triandra and Digitaria scalarum, dominant grass species of the area, were totally absent in the 1-10 m zone around the mound. The major species in the immediate vicinity of the mound were Pennisetum stramineum and Cynodon dactylon, the latter was a dominant species (over 90%) within the 0-10 m zone and entirely absent beyond 15 m from the mound. The number of grass species increased from 2-3 species around the mound to 6-7 species in the area apparently beyond the influence of the mound. High concentration of nutrients and favourable water availability, together with good drainage, appeared to be the major causes of increased biomass and different species composition of vegetation around the mound. © 1982.

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Precocene-Induced Sterility In F1 Generation Of Glossina Morsitans Morsitans, M. Samaranayaka-Ramasamy, M. F.B. Chaudhury Jan 1982

Precocene-Induced Sterility In F1 Generation Of Glossina Morsitans Morsitans, M. Samaranayaka-Ramasamy, M. F.B. Chaudhury

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Precocene treatment does not disrupt the events of reproduction in Glossina morsitans morsitans or induce any apparent changes in treated tsetse. However, some females of the F1 generation are either sterile or show retardations in follicle development. Sterility is not reversed spontaneously or with juvenile hormone analogues. The critical period for precocene action is related to each ovulation. The corpora allata of precocene-treated tsetse are normal, but those of F1 sterile females are degenerate. The occurrence of retardation has enabled the characterisation of stages in follicle development in G. m. morsitans. © 1982.

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The Influence Of Salinity On Larval Development And Population Dynamics Of Anopheles Merus Dönitz (Diptera: Culicidae), F. W. Mosha, C. M. Mutero Jan 1982

The Influence Of Salinity On Larval Development And Population Dynamics Of Anopheles Merus Dönitz (Diptera: Culicidae), F. W. Mosha, C. M. Mutero

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Variations in density of adults of Anopheles merus Dön. in Jimbo Village on the Kenya Coast were found to be correlated both with rainfall and with salinity at their breeding sites. Densities started to increase at the beginning of the rains when several breeding sites were formed. This was followed by a decline in numbers resulting mainly from the decrease in salinity in the semi-permanent breeding sites. A second rise occurred after the end of the rains, corresponding with an increase in salinity in the semi-permanent breeding sites due to evaporation. Peak density coincided with salinities of 30–50% sea water …

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Precocene Treatment Of The Female Tsetse Fly Glossina Morsitans Morsitans Sterilises Her Female Offspring, M. Samaranayaka-Ramasamy, M. F.B. Chaudhury Sep 1981

Precocene Treatment Of The Female Tsetse Fly Glossina Morsitans Morsitans Sterilises Her Female Offspring, M. Samaranayaka-Ramasamy, M. F.B. Chaudhury

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When adult female Glossina morsitans morsitans were treated with either precocene I or precocene II, females of the F1 generation, emerging from pupae of the 2nd, 3rd and 4th reproductive cycles failed to develop oocytes. © 1981 Birkhüuser Verlag.

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