Browsing by Author "Matojo, Nicodemus Didas"

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    Biological studies on the ‘senene’ longhorn grasshopper, ruspolia differens serville (orthoptera: tettigoniidae), in northwest Tanzania
    (University of Dar es Salaam, 2012) Matojo, Nicodemus Didas
    The biology of Ruspolia differens, the longhorn grasshopper widely known as senene by its Kiswahili name, was largely unclear although this insect serves broadly as a delicacy relish snack. In this study, the biology of senene from Northwest Tanzania was inferred based on the swarming, morphological and molecular characters, with which its taxonomic status was delineated. Sampling of the species was done in 4 months of swarms and the closest other 4 months of non-swarming phase. Analysis of swarming involved the origin and plasticity of swarms based on the occurrences of the adults, nymphs and eggs, upon which the life cycle of this insect was, for the first time, explicated. Morphological analysis was done based on colour polymorphism and external anatomy whereas the molecular study involved phylogenetic relationship of this species based on the nuclear ribosomal 18S sequences. It was found that the phenology of swarming of senene is highly predictable and taxonomically useful due to its uniqueness. The species also has an exceptional colour polymorphism that is characterized by 6 morphs whose relative frequencies vary interactively with sex ratio and seasonal environmental conditions. Tegminal black speckles are useful genetic biomarkers for the browns and there are unique anatomic features that can serve largely in diagnosis of this species and these include the paired male metathoracic flaps, finger-like prosternal protuberances, hind femoral spines, sub-equal tibial markings and an obvious male biased antennal dimorphism. The closest species to this insect is Ruspolia nitidula and the closest genera to the genus Ruspolia include Conocephalus and Platycleis. The biogeographical profiles have inferred that the genus Ruspolia and relatives originated in the African Tropics.
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    Toxic effects of ammonium sulphate on the gills and gut of the edible cockle Anadara antiquate (Bivalvia;Arcidae)
    (Unversity of Dar es Salaam, 2007) Matojo, Nicodemus Didas
    Toxicity of ammonium sulphate has not been established for most marine organisms in Tanzania. The present study has established the toxicity of ammonium sulphate on the edible cockle Anadara antiquate (Bivalvia,Arcides). The LC50 of this toxicity is 271 mg/L at 95% significance as estimated in vitro in a 96h static bioassay with mean values of pH 8, temperature 25C, salinity 33% and DO>60% of the saturation limit. In three replicates, eight samples of A.antiquada were exposed to 50, 80,130,200,300,400, and 600 mg/L of ammonium sulphate concentrations for 96h. Estimation of LC50 was coupled by stress and histopathological characterization of the gill and intestine. Although toxicity was not significantly acute within the exposure time of 96h, it induced massive deformities that persisted over a two week period in the bivalves. This post-exposures persistence of ammonium sulphate toxicity promoted mortality to 100% at a concentration of 200 mg/l and higher. Toxicity was accompanied by excessive shell gaping, foot protusion, mucus secretion, necrosis, hyperplasia, cilia shortening, lamellar shrinkage, epithelium disruption and abscess formations and eventual ruptures. Moreover, the bivalves showed impaired mobility and sensitivity, leading to death. Nevertheless, cockles that survived a 96h exposure when assessed up to 336h showed complete remission from the toxic effects and this was an indication of absence of chronic toxicity.