Species composition of the Anopheles gambiae complex across eco-vegetational zones in Bayelsa State, Niger Delta region, Nigeria

Background & objectives: Correct vector identification is an important task in the planning and implementationof malaria vector control programmes. This study was designed to provide baseline information on the speciescomposition and distribution of members of the Anopheles gambiae complex in three eco-vegetational zones inBayelsa state, Nigeria.Methods: Adult mosquitoes were collected by pyrethrum spray catch (PSC) in randomly selected houses duringSeptember 2009–August 2010. Anopheles mosquitoes were identified using standard morphological keys.Mosquitoes identified as An. gambiae s.l. were used for species specific PCR-assays.Results: Out of 203 Anopheles gambiae s.l. successfully amplified, 180 (88.7%) were Anopheles gambiae s.s.,14 (6.9%) were An. melas and 9 (4.4%) were An. arabiensis. The variation in the sibling species composition ofAn. gambiae s.l. was not significant (p >0.05). Anopheles gambiae s.s. was predominant in all the collectionswith three sibling species occurring in all the eco-vegetational zones.Interpretation & conclusion: The observation of An. melas in the fresh water swamp forest of Yenagoa is ofimportance in malaria epidemiology. These findings are of importance in the planning and implementation ofmalaria vector control strategy in the three eco-vegetational zones of Bayelsa state

The Bouguer Gravity Anomaly Map of the Calabar Flank, Southeastern, Nigeria

Raw gravity data acquired using a Lacoste and Romberg (model G446) gravimeter and its accessories have been converted to a digital data set and were contoured to produce the first Bouguer gravity anomaly map of Calabar Flank. The data were corrected for drift and elevation (Bouguer and free air). The average crustal density of 2.67g/cm3 was used to compute the Bouguer correction. The effect of the curvature of the earth was taken into consideration. To account for tidal effect, an observational time window for forty-eight hours was determined prior to the actual field survey. Humidity/temperature correction was made to remove effects caused by humidity/temperature variations on raw data. The data was latitude-corrected based on the 1967 Geodetic Reference System (GRS67). This invariably gave the theoretical gravity. A comprehensive computer program for processing raw gravity data was used to compute the Bouguer and free air anomalies and were converted from their geodetic coordinates to x-y coordinates. The data were then transformed to an equally spaced grid (1km). The Bouguer and free air anomaly maps were produced from this grid using a Surfer Plot program. The results from these analyses showed a close relationship between the Bouguer and free air anomaly data; which is compatible with mid-continental results. Calabar Flank is largely not in isostatic equilibrium judging from the dominance of shortwavelength free-air anomaly patterns. The circular, elliptical contours in the Bouguer and free air anomaly maps are lineaments with distinctive trends. These trends indicate structural features that pre-date exposed geology and that have probably controlled the tectonic expressions of the geological province

Species identification of adult African blowflies (Diptera: Calliphoridae) of forensic importance:

Necrophagous blowflies can provide an excellent source of evidence for forensic entomologists and are also relevant to problems in public health, medicine, and animal health. However, access to useful information about these blowflies is constrained by the need to correctly identify the flies, and the poor availability of reliable, accessible identification tools is a serious obstacle to the development of forensic entomology in the majority of African countries. In response to this need, a high-quality key to the adults of all species of forensically relevant blowflies of Africa has been prepared, drawing on high-quality entomological materials and modern focus-stacking photomicroscopy. This new key can be easily applied by investigators inexperienced in the taxonomy of blowflies and is made available through a highly accessible online platform. Problematic diagnostic characters used in previous keys are discussed

Alternative models for the interpretation of aeromagnetic data in areas around the

Four interpretational models are recognized in areas around the magnetic equator. They are point pole, line of poles, point dipole and line of dipoles. Point pole models are recognized by adjacent circular contours of magnetic high and low, while line of poles models are identified by elliptical contours of magnetic high and low adjacent to each other. When magnetic contours are simply circular or nearly circular, the source is approximated as point dipole and contours of line of dipole model are always elliptical in shape. A decision between dipolar and monopolar model is made using the shape of magnetic signature. When a magnetic signature has completely dominant low, the correct model will be a dipole. While a magnetic high flanked by low is approximated as point pole/line of pole (monopole). Magnetic signature that does not assume any of these shapes is a pointer to remanent magnetization. The four interpretational models have close relationship with half-width of magnetic anomalies and are therefore valuable for depth determination. The four interpretational models have been employed to analyse aeromagnetic data from crystalline basement and sedimentary areas of Nigeria. Global Journal of Pure and Applied Sciences Volume , No 1 January (2001) pp. 111-116 KEY WORDS: Equator, Model, Dipole, Remanent, Anomaly

Prevalence of Trypanosome Infections in Ruminants in the Southern Guinea Savanna, Nigeria.

A survey was conducted to determine the prevalence of trypanosomes in cattle and sheep in Kaura Local Government Area (LGA) of Kaduna State, southern guinea savanna, Nigeria. Animals were sampled in 12 villages from the districts of Bondong, Fada, Kadarko, Kukum, Manchok and Zankan. Sampling visits were undertaken on seasonal basis in the late wet season (October), early dry season (December), late dry season (February) and early wet season (June). Three- ml blood samples were collected from the jugular vein of 395 cattle and 37 sheep. The results revealed that 21.53 ± 1.97% (range 9.4-43.8% per village) of the total animals were infected with various species of trypanosomes, with the prevalence in bovine and ovine being 20.51 ± 2.03% and 32.43 ± 7.69% respectively. Trypanosoma vivax had the highest infection rates (64.52%), followed by T. brucei (18.30%) and T. congolense (17.20%). Infections varied significantly among the districts, ranging from 9.7% at Zankan to 36.9% at Manchok (t=13.08; df=3; p<0.05; p-value=0.001). Infections were significantly higher in the early dry season compared to the other sub-seasons (t=5.12; df=5; p<0.05; p-value=0.004). Thirty three percent of the 12 villages screened had low prevalence figures (0-20%) while the remaining had high figures up to 40%. From the figures obtained, it appears that infections with trypanosomes are highly prevalent in cattle and sheep in Kaura LGA and may be a serious constraint to profitable livestock production in the area. The need to develop an effective control/eradication programme against the disease to boost the poverty eradication programme of the Federal Government is recommende

Isolation of Residuals Determined from Polynomial Fitting to Gravity Data of Calabar Flank, Southeastern Nigeria

ABSTRACT The first degree polynomial order is fitted to the Bouguer gravity anomaly data to produce the first residual gravity anomaly map of Calabar Flank. The residual gravity data was computed by subtracting the regional trend from the Bouguer gravity field. The regional trend in the flank is the first degree surface fit and represents anomaly of long wavelength while the residual component have their origin from short wavelength sources (shallow sources). This quantitative approach is advantageous over the wavelength filtering methods. The result of this low order fitting shows that the residual gravity field is characterized by positive and negative gravity anomalies. This is consistent with the geologic setting and tectonics of the Calabar Flank

Species Diversity, Abundance and Seasonal Occurrence of Some Biting Flies in Southern Kaduna, Nigeria.

A survey of biting dipterans was conducted in Kaura LGA of Kaduna State between November 2000 and October 2001. Fifteen species of biting flies were caught in two families, Tabanidae and Muscidae distributed in the following 4 genera: Tabanus 10, Haematopota 2, Chrysops 1 and Stomoxys 2. The genus Stomoxys represented by Stomoxys calcitrans Linnaeus and S. nigra Macquart had the highest abundance (62.5%), followed by the Tabanus (34.6%), Haematopota (1.8%) and Chrysops (1.1%). Generally, more flies were collected during the wet (1431; 85.1%) than the dry season (250; 14.9%) with some species occurring all year round. The widespread presence of haematophagous dipterans in the study area suggest that they could be playing a greater role in disease transmissions than previously thought. Optimum temperatures that stimulate rapid reproduction appear to fall between mean temperatures of 22.8-24.1°C. The species showed a general increase in relative abundance during the wet season and a decline in the dry season. No new country record was found