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The novel coronavirus disease 2019 (COVID-19) has become a global pandemic with more than 4 million confirmed cases and over 280,000 confirmed deaths worldwide. Evidence exists on the influence of temperature and humidity on the transmission of related infectious respiratory diseases, such as influenza and severe acute respiratory syndrome (SARS). This study therefore explored the effects of daily temperature and humidity on COVID-19 transmission and mortality in Lagos state, the epicenter of COVID-19 in Nigeria. Correlation analysis was performed using incidence data on COVID-19 and meteorological data for the corresponding periods from 9th March to 12th May, 2020. Our results showed that atmospheric temperature has a significant weak negative correlation with COVID-19 transmission in Lagos. Also, a significant weak negative correlation was found to exist between temperature and cumulative mortality. The strength of the relationship between temperature and the disease incidence increased when 1 week and 2 weeks’ predetection delays were put into consideration. However, no significant association was found between atmospheric humidity and COVID-19 transmission or mortality in Lagos. This study contributes more knowledge on COVID-19 and will benefit efforts and decision-making geared towards its control.

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Rotenone is used to clear ponds of unwanted organisms and trash fish which may predate on fish when the ponds are stocked. Toxicity tests using water extract of the leaves of Tephrosia vogelii Hook, which contains rotenone, were conducted on rotifers (Brachionus species), Cyclops, mosquito larvae (Culex species) and fish (Aphyosemion gardneri nigerianum) in static bioassays. The 48-h LC 50 s were derived from probit curves using the probit-analysis method, while chisquare was used to test for significant differences between observed mean mortalities and predicted mean mortality values. These showed no significant differences (P > 0.05). The variance ratio of the replicates in each treatment also showed no significant difference (P > 0.05). The 48-h LC 50 s were found to be 2.89, 1.04, 4.48 and 0.24 mg L )1 for rotifers, Cyclops, mosquito larvae and fish, respectively. The probit mortalities were positively correlated with the log-concentration, except for the rotifers bioassay, which was negative. The fish, A. gardneri nigerianum, was the most sensitive; the mosquito larvae were the least sensitive.

A comparative racial study of Sarotherodon melanotheron (Ruppell) from brackish and fresh water habitats both in south-western Nigeria using morphometric and meristic characters to determine variations showed that they were phenotypically separable populations of the same species. The results revealed significant differences (P < 0.05) in body depth, caudal peduncle depth, number of gill rakers and scales on the lateral line which were suggested to have occurred as a result of difference in the temperature, salinity and substratum in the two water bodies. The results also implied that fresh water broodstock could be preferable to the brackish population for breeding programmes.