Characterisation of larval habitats,species composition and factors associated with the seasonal abundance of mosquito fauna in Gezira,Sudan

Background:Larval source management(LSM),which requires an understanding of the ecology and composition of the local mosquito fauna,is an important parameter in successful vector control programmes.The present study was conducted to understand the distribution of larval habitats,species composition and factors associated with the seasonal abundance of mosquito larvae in Gezira irrigation Scheme in Gezira state,central Sudan.Methods:Cross-sectional larval surveys were carried out in the communities of Barakat(urban)and El-Kareiba(semi-urban),in Wad Madani,Gezira.A standard dipper was used for sampling larvae in all possible breeding sites and enamel bowls were employed for larvae sorting.Habitats were characterised using physical features and all larvae specimens were identified morphologically.Results:A total of 331 larval habitats were surveyed,out of which 166 were found to be positive breeding sites for Anopheles(56.78%),Culicinae(29.67%)and Aedes(13.55%)species.A total of 5525 larvae collected were categorised as Culex(2617,47.37%),Anopheles(2600,47.06%)and Aedes(308,5.57%).There was a high number of positive habitats during the rainy season,while the lowest proportion was reported during the hot dry season,in both study sites(Barakat[χ^(2)=10.641,P=0.0090],El-Kareiba[χ^(2)=23.765,P=0.0001]).The main breeding site for Anopheles larvae was leaking water pipes(51.5%),followed by irrigation channels(34.2%),hoof prints(6.4%),tyre tracks(5.5%)and water tanks(2.4%).A logistic regression analysis showed that the abundance of Anopheles larvae was reduced by the presence of predators(backswimmers,tadpoles)and grass cover.Adult productivity(number of adult females emerged/m2)was not homogeneousfor all habitats;the highest productivity was found in irrigation channels(0.78 females/m2)for Anopheles,and in septic tanks(2.86 females/m2)for Culicinae and(0.86 females/m2)for Aedes.Anopheles arabiensis was found to be the dominant Anopheles species.This study documented the presence of An.funestus in central Sudan for the first time.Conclusions:Maintaining leaking water pipes and adopting intermittent irrigation are recommended for LSM,as these surveyed habitats represent the main source of maintaining the local mosquito population during the hot dry season.

Vertical and seasonal distribution of flying beetles in a suburban temperate deciduous forest collected by water pan trap

Vertical and seasonal distributions of flying beetles were investigated in asuburban temperate deciduous forest in Kanazawa, Japan using water pan traps to determine the abundance and composition among vertical strata, change in the abundance and composition through seasons and determinant factors in generating the distributions. Traps were placed at three levels (0.5 m, 10 m, and 20 m above ground) on a tower. Samplings were carried out seasonally from May to November in 1999 and 2000. Variations in the abundance of flying beetles were observed from different layers. The results showed that the abundance and composition of flying beetles varied among strata and seasons. In both 1999 and 2000,Elateridae was consistently most abundant in the bottom layer, while Attelabidae and Cantharidae were most abundant in the upper layer. In 1999, Eucnemidae and overall scavengers were most abundance in the bottom layer, but results were not consistent with those in 2000. In general, the abundance of herbivores reaches a peak in the early season(May/June) and decreases in the following months. Peaks of abundance in predators vary vertically. In the bottom layer a peak was observed in the early season (May/June), while in the upper layer this was observed in July. Scavengers had two peaks, in May/June and September. These patterns indicated that vertical distributions in the abundance of differentfeeding guilds varied through seasons.

Demography, reproductive biology and diet of the bushveld gerbil Tatera leucogaster (Rodentia: Gerbillinae) in the Lake Rukwa valley, south-western Tanzania

Seasonal abundance, reproductive biology and feeding ecology of the bushveld gerbil Tatera leucogaster (Peters,1852) were investigated in small-scale maize field–fallow land mosaics in south-western Tanzania. The gerbilswere collected over a 2-year period using Sherman live and Victor hold-fast snap traps in permanent 4.5-ha grids. Atotal of 664 individuals were captured over 13 650 trap nights, giving an overall trap success rate of 4.9%. Trapsuccess varied between seasons with and without crops in the field but not between habitat types. At this site, thebreeding activity of this species is seasonal. All individuals whose stomachs were analyzed ate a wide range ofitems, indicating omnivory in this species at this site;however, seeds were the most preferred diet category, with amean contribution of 50.4%, followed by arthropods, with a mean contribution of 25.7%. Other plant materialsbecame important during the very dry periods.