Acaricidal activities of extracts of Commiphora swynnertonii Burtt (Burseraceae), Melia volkensii Gürke, Turraea abyssinica Hochst., Turraea floribunda Hochst and Turraea cornucopia Styles & F. White (Meliaceae) against the brown ear tick Rhipicephalus ap

Acaricidal activities of extracts of Commiphora swynnertonii Burtt  (Burseraceae), Melia volkensii Gürke, Turraea abyssinica Hochst., Turraea floribunda Hochst and Turraea cornucopia Styles & F. White (Meliaceae) against the brown ear tick Rhipicephalus appendiculatus Neumann Extracts of the stem bark of Commiphora swynnertonii, the root bark ofTurraea abyssinica, T. cornucopia, T. floribunda and the ripened fruits of Melia volkensii were tested for acaricidal activities against nymphal and adult stages of Rhipicephalus appendiculatus in the laboratory. At a concentration of 10% (w/v), hexane and ethyl acetate extracts of C. swynertonii induced mean mortalities of 71% and 54% respectively, in two week old nymphs. A 10% (w/v) hexane extract was found to be as effective as the commercial acaricide Triatix against the twoweek- old nymphs. Extracts of T. cornucopia, T. abyssinica and M. volkensii induced no mortality in nymphs and adults, but suppressed oviposition capacity during the first day. On the other hand, 500µl of 10% (w/v) methanol extracts of T. cornucopia and T. floribunda delayed attachment by adult females of R. appendiculatus on the rabbit ears, engorgement and hatchability of their eggs.Keywords: acaricidal, activity, plant extracts, Burseraceae, Meliaceae,Rhipicephalus appendicullatus

Antifeedant activity of twenty six plant extracts and pure compounds from the root bark of Toddalia asiatica (L) (Rutaceae) against the anomalous emperor moth Nudaurelia belina (Saturnidae)

The antifeedant activity of petroleum ether (PE) (40-60%) extract of the root bark of T. asiatica and twenty five other plant extracts was investigated against the anomalous emperor moth N. belina. The petroleum ether extract of stem bark of Albizia anthelmintica, leaves of Cassia occidentalis, Balanites aegyptica, seeds of Cucumis sativaus, root bark of T. asiatica, root bark of Celtis durandii, B. aegyptica and whole plant of Cisus quadrangularis were found to be active against N. belina at a concentration of 1% w/v in a modified leaf disc method. Also, methanol extracts of the root bark of A. muricata and Eucalyptus spp were found to be active against N. belina at a concentration of 1% w/v. Three cumarius; dihydrotoddanol, toddanol and toddalactone and the alkaloid dihydrochelerynthrine isolated from the PE extract of the root bark of T. asiatica exhibited antifeedant activity at as low as 0.05% w/v. Toddaculine and toddanone which were also isolated from the P.E. extract had no activity at 0.05% w/v.Keywords: Antifeedants, Toddalia asiatica, Rutaceae, Nudaurelia belina, Saturnida

Aflatoxin contamination in Tanzania: quantifying the problem in maize and groundnuts from rural households

Published online: 28 Apr 2021Aflatoxins are toxic and carcinogenic secondary metabolites, produced by Aspergillus flavus and Aspergillus parasiticus, which contaminate food and feed and threaten human and animal health. To assess the prevalence of aflatoxins in Tanzania, 180 groundnut and 200 maize samples were collected from 9 and 10 districts, respectively. Aflatoxin contamination was quantified using high performance liquid chromatography. Aflatoxins were detected in samples collected from all districts and prevalence ranged from 92 to 100% for groundnuts and 10 to 80% for maize. The mean aflatoxin level for groundnuts was 6.37 μg/kg and the highly contaminated sample had 40.31 μg/kg. For maize, the mean aflatoxin level was 12.47 μg/kg and the highly contaminated sample had 162.40 μg/kg. The estimated average probable daily intake (APDI) of aflatoxin B1 (AFB1) from groundnuts consumption was 1.88 ng/kg body weight/day, while for maize, it ranged between 151.98-272.89 ng/kg body weight/day. The APDI for both groundnut and maize exceeded the provisional maximum tolerable daily intake (PMTDI) of AFB1 for adults (1 ng/kg body weight/day), bringing about health concerns for populations in Tanzania. Another alarming finding was that 75% of the farmers who provided samples for analysis were not aware of aflatoxins or the negative health impacts from consuming contaminated products. Results reported in this paper show that aflatoxin contaminated staple crops are widely distributed in Tanzania and that the risk of human exposure is high due to diet preferences. Awareness campaigns are required to inform and protect farmers and consumers

Plague: past, present and future

[Introduction] Recent experience with SARS (severe acute respiratory syndrome) [1] and avian flu shows that the public and political response to threats from new anthropozoonoses can be near-hysteria. This can readily make us forget more classical animal-borne diseases, such as plague (Box 1). Three recent international meetings on plague (Box 2) concluded that: (1) it should be re-emphasised that the plague bacillus (Yersinia pestis) still causes several thousand human cases per year [2,3] (Figure 1); (2) locally perceived risks far outstrip the objective risk based purely on the number of cases [2]; (3) climate change might increase the risk of plague outbreaks where plague is currently endemic and new plague areas might arise [2,4]; (4) remarkably little is known about the dynamics of plague in its natural reservoirs and hence about changing risks for humans [5]; and, therefore, (5) plague should be taken much more seriously by the international community than appears to be the case

Do diatomaceous earths have potential as grain protectants for small-holder farmers in sub-Saharan Africa? The case of Tanzania

Participatory on-farm field trials were set up over three storage seasons, from 2002 to 2005, in different agroecological zones of Tanzania to compare the efficacy of the enhanced diatomaceous earths (DEs) Protect-Its and Dryacides alone or combined with the pyrethroid permethrin. Other treatments included three commercially available synthetic chemical dilute dusts, containing 1.6% pirimiphos-methyl and 0.3% permethrin (Actellic Super and Stocal Super from different manufacturers) and 1% fenitrothion and 0.13% deltamethrin (Shumba Super); traditional protectants; and a locally available DE collected from Kagera in north-west Tanzania. Treatments were applied to maize and sorghum grain and dried beans. Insect pests are the main threat during storage, which in Tanzania includes the devastating larger grain borer, Prostephanus truncatus. All the grain protectants, except the traditional ones, kept damage incidence well below that of the untreated controls, and usually below 10% for periods of 40 weeks of storage. Exceptions occurred when grain was badly infested prior to treatment, in which case Actellic Super dust was more effective than the DEs. Very little difference in damage was observed between the DE treatments until 40 weeks of storage. In addition to the commercially available synthetic grain protectants, Protect-Its 0.25% w/w or Protect-Its 0.1% w/w plus permethrin at 2 mg/kg can be recommended to protect dry un-infested, winnowed maize and sorghum grain that is to be stored on-farm in sacks or woven granary baskets for periods of 4 months or more in Tanzania. Beans can be protected with lower application rates of Protect-Its 0.05% w/w or Dryacides 0.1% w/w. The study also demonstrated that Actellic Super dust obtained from an approved source and applied according to the manufacturer’s recommendations is effective in protecting stored maize, sorghum and beans for periods of at least 40 weeks—contrary to many of the suggestions that this product is no longer effective in Tanzania

Iron Production in North Pare, Tanzania : Archaeometallurgical and Geoarchaeological Perspectives on Landscape Change

Archaeology, archaeometallurgy and geoarchaeology are combined in this research to examine the chronology and development of iron metallurgy and its environmental repercussions in North Pare, Tanzania. Pare was a prominent centre for iron production from at least the second half of the first millennium AD, and it has been assumed that this technologywith its demand for wood charcoalhad a significant and detrimental effect on local forest cover. This research sought to examine this claim by exploring the spatial, chronological and technological characteristics of iron production in Pare in conjunction with geoarchaeological evidence. Contrary to older assumptions, our results demonstrate that erosion processes were well established in North Pare before the documented intensification of smelting and smithing activity, and that iron production continued despite environmental changes. We suggest that although iron production may well have contributed to deforestation and erosion in Pare, it is unlikely to be the sole causal factor