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The main insect pest of stored paddy is Sitophilus oryzae (rice weevil). Huge amounts of rice are produced by peasant farmers each year, but the bulk of it is wasted due to insufficient storage facilities and insect pest attacks brought on by careless handling. In this study, the insecticidal effects of biochar on S. oryzae were assessed in femurs from Sus scrofa (pig), Gallus gallus (chicken), and Bos taurus (cattle). Adult mortality, adult emergence, weight loss, seed damage, and weevil perforation index are among the indicators evaluated. To apply the biochar, different dosages were used: 0.2, 0.4, 0.6, 0.8, and 1.0 g/20 g of paddy rice. In this work, the population of adult S. oryzae on paddy rice was dramatically reduced by all animal bones biochar tested for insecticidal activity (p < 0.05). The animal bone biochar became more effective with increasing dosage. After 24 h of treatment, pig biochar induced a 36.67 % mortality rate of adult S. oryzae, followed by cow biochar's 20 % mortality rate of rice weevils. The fatal dose of cattle, pig, and chicken biochar at which 50 % (LD50) of the population of adult S. oryzae responded after 24 h of treatment were 0.83g, 0.43g, and 0.90g, respectively. It should be encouraged to utilize biochar made from animal bones to combat the S. oryzae in stored paddy. They could be utilized as a green control measure to lessen the risk brought on by the usage of synthetic chemical insecticides in the environment.
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This study investigated the possibility of COVID-19 medical face masks to affect bacterial and macrofaunal communities in open soil environment. An estimated 1.24 trillion of face masks have been used and discarded as a result of the COVID-19 pandemic, with a significant part of this ending up in the soil environment, where they degrade gradually over time. Because bacteria and macrofauna are sensitive indicators of changes in soil ecosystem, we investigated possible impacts of face masks on population, distribution, and diversity of these soil species. Effect on soil bacterial community was studied by both culture-based and advanced molecular (metagenomics) approach, while impact on macrofauna was investigated by examining monoliths around heap of masks for soil insects. In both cases, control soil experiments without face masks were also set up and monitored over a period of 48 weeks. The study found that the presence of face masks led to a more diverse bacterial community, although no influence on overall bacterial population was evidenced. More importantly, bacteria belonging to the genera Cellulomonas and Acinetobacter were found prominently around face masks and are believed to be involved in biodegradation of the masks. The bacterial community around the masks was dominated by Proteobacteria (29.7-38.7%), but the diversity of species increased gradually with time. Tiny black ants (Monomorium invidium) were attracted to the face masks to take advantage of water retained by the masks during the period of little rainfall. The heaps of face masks also provided shelter and breeding "haven" for soil insects, notably the red cotton bug (Dysdercus suturellus) and house cricket (Acheta domesticus), thereby impacting positively on the population of insect species in the environment. This study provides insights into the actual impacts of face masks on soil organisms under normal outdoor environmental conditions.
Asunto(s)
COVID-19 , Cellulomonas , Gryllidae , Heterópteros , Animales , Humanos , Pandemias , Ecosistema , Máscaras , Insectos , BacteriasRESUMEN
Cowpea, Vigna unguiculata is a popular agricultural produce known as poor man's meat among Africans because it is very cheap and affordable. In spite of its importance, its infestation by cowpea seed bruchid, Callosobruchus maculatus has been a major constrain hindering its storage. Considering the high level of infestation of cowpea by C. maculatus and the high level of pollution caused by agricultural products, this research investigated the entomotoxicant effectiveness of rice husk, wheat husk and groundnut pod ash and powder in the control of cowpea beetle in storage. This study was carried out under laboratory condition of ambient temperature 28 ± 2 °C and 70 ± 5% relative humidity. The wastes (rice husk, groundnut pod and wheat husk) were pulverized separately and another portion was burnt to ashes at 525 °C. The powders and the ashes were analyzed for their proximate composition, phytochemical content (powders) and silica content (ashes). The powders and the ashes were tested at 0.1, 0.2, 0.3, 0.4 and 0.5 g/20 g of cowpea. Rice husk ash resulted in the highest mortality of 100% of adult beetles at dosage of 0.5g/20g cowpea after 96 h post-application. Wheat husk ash at 0.4 and 0.5 g per 20 g cowpea seed had the highest protectant ability on cowpea as it reduced fecundity to 4.67% and prevented adult emergence, seed damage and weight loss. The ash of the wastes caused more mortality of the adult beetles than their powders. The results obtained showed that the wastes caused high mortality of C. maculatus. It was also found that the wastes had some phytochemicals which might be responsible for the recorded high mortality. The findings showed that the tested agro-wastes have a promising insecticidal potential against C. maculatus, and can be used as possible alternatives to synthetic chemical insecticides for the control of stored product insects.
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Callosobruchus maculatus is the most damaging insect pest of stored cowpea (Vigna unguiculata) seeds in Nigeria. Thus, this present research work was put in place to assess the insecticidal activities of the extracts obtained from the leaf and stem bark of Kigelia africana (Lam.) Benth against the cowpea seed beetle, C. maculatus. The parameters that were assessed were adult mortality, oviposition and adult emergence of C. maculatus. The experiments were conducted under laboratory conditions of 28±2 °C temperature and 75 ± 5% relative humidity. The extracts were applied at dosages of 0.3, 0.6, 0.9 and 1.2 mL per 20 g of cowpea seeds. The two extracts of K. africana were found to be toxic to the survival of the C. maculatus. However, the extract obtained from the leaf was more potent to the beetle than the extract obtained from the stem bark of the same plant. The two extracts also reduced ovipositipon and completely suppressed adult emergence at the highest dose of 1.2 mL per 50 g of cowpea seeds. The results obtained in the present research work showed that the two extracts of K. africana were effective in suppressing the population of the infamous stored pest of cowpea seed beetle, C. maculatus and could therefore be recommended to replace the harmful synthetic chemical insecticides in protecting cowpea seeds in storage.
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Toxicities of leaf powders and extracts of Acanthus montanus, Acanthospermum hispidum, Alchornea laxiflora and Argyreia nervosa against maize weevil (Sitophilus zeamais) were evaluated. Powders were tested at dose 3.0g/20g while extracts were tested at concentration 3%/20g of maize grains. Mortality, oviposition, and adult emergence rates as well as weight loss, seeds damage and weevil perforation index (WPI) were evaluated. Phytochemical constituents of the experimental plants were also carried out. The results showed that Acanthus montanus powder was the most potent with 65% adult mortality after 24 h of treatment. This is followed by Argyreia nervosa powder that evoked 52.5% weevil mortality. The least toxic to S. zeamais was Acanthospermum hispidum powder with 32.5% adult mortality. Extracts were more toxic than the powders of the tested plants. Acanthus montanus extract was the most toxic since it promoted 80% adult mortality after 24 h of treatment. Acanthus montanus, Alchornea laxiflora and Argyreia nervosa leaf powders and extracts completely prevented oviposition by adult insect, adult emergence, weight loss and seeds damaged. The phytochemicals present in Acanthus montanus were alkaloids (3.67 mg/g), saponin (3.33 mg/g), tannin (3.00 mg/g) and flavonoid (2.67 mg/g) contents. Acanthospermum hispidum had the least alkaloid (2.67 mg/g), saponin (1.67 mg/g), tannin (1.33 mg/g) and flavonoid (1.00 mg/g) contents. Acanthus montanus, Argyreia nervosa, Alchornea laxiflora and Acanthospermum hispidum were efficacious against S. zeamais instead of synthetic chemical insecticides that have environmental health hazards and they can be used in integrated pest management by farmers and foods merchants.
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BACKGROUND: Anopheles gambiae (Diptera: Culicidae) transmit malaria parasite that causes malaria fever in humans, causing millions of deaths every year among infants in tropical countries. This study was undertaken to assess the toxicity of Ocimum basilicum and Ocimum gratissimum against pre-adult stages and adult malaria vector, An. gambiae and non-targeted aquatic organism, fingerlings of Clarias garipienus. METHODS: Ethalonic extracts of O. basilicum and O. gratissimum were prepared according to the method described by WHO. The larvae and pupae of An. gambiae were exposed to plant extracts for 24h and their mortality was recorded. Toxicity of Ocimum species on non-targeted organism, fingerlings of C. garipienus was also investigated. RESULTS: Ocimum basilicum showed remarkably potency against pre-adult stages and adults An. gambiae causing 100% mortality at 0.4% concentration within 24h of treatment. The LC50 and LC90 of O. basilicum were lower than O. grattisimum in all stages of An. gambiae studied. Ocimum basilicum and O. gratissimum extracts significantly reduced the number of bites by the vector given a range of 72.25% to 81.75% protection. Ocimum species at the tested concentrations did not significantly reduce the number of fingerlings introduced. CONCLUSION: Ocimum species at the tested concentrations did not significantly reduce the numbers of non-targeted organisms, fingerlings introduced. Therefore, O. basilicum and O. gratissimum could be used to reduce malaria prevalence in the endemic areas of Nigeria as it poses no threat to aquatic organisms.