Experimental estimation of challenge of a natural population of Glossina palpalis palpalis R-D (Diptera:Glossinidae) on cattle in the southern Guinea Savanna, Nigeria

The challenge posed by Glossina palpalis palpalis Robineau-Desvoidy 1830 to cattle was studied in a riverine forest of Manchok, Kaduna State, Nigeria. The challenge was estimated indirectly from entomological parameters using the number of flies biting the host and the proportion of flies that are potentially infective. Trypanosome infection rates of 26% and 24.3% were recorded in flies sampled from several sites in the dry and wet seasons. From the 134 flies that landed to bite, it was estimated that each animal received an estimated 11 and 15 mean bites per day in the dry and wet season respectively out of which approximately 3 and 4 harbour infections. This means that each animal host received an estimated total infective bite of about 15 (range 0.5-4.1/hr) and 19 (range 0.9-6.6/hr) during the dry and wet seasons, equivalent to 2.96 and 3.8 infective bites per day. Of the estimated infective bites, 12.6 and 2.2 were due to T. vivax Ziemann 1905 and T. congolense Boaden 1904 received during the dry season while 17.3 and 1.5 were received during the wet season. Activity of flies started at 09.00hr during the wet season and one hour later during the dry season. For both seasons, diurnal activity was less pronounced in the early morning (06.00-11.00hr) than mid (11.00-15.00hr) and late afternoon (15.00-18.00hr), and so was the number of potentially infective bites. The number of potentially infective flies feeding per day (06.00-18.00hr) was higher and more consistent during the wet season than in the dry season but the difference was not significant (P>0.50).The results suggest a high tsetse challenge in the area which is exacerbated by several factors including the synchronized activity of the flies and grazing herds, frequency of visit to riverine habitats of the vector and duration of contact between vector and host. Key words: Tsetse fly challenge, Trypanosoma vivax, T. congolense, cattle, Nigeri

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