Insecticide resistance in cotton aphid Aphis gossypii (Glov.) in the Sudan Gezira

The resistance to insecticides of three Sudanese strains of A. gossypii (Glov.) collected from cotton fields in the Sudan Gezira Scheme over three seasons (1988, 1989, 1990) and that of two French strains was studied in the laboratory. When compared with a known susceptible strain, the aphids were found to be resistant-to the eight insecticides tested. Evolution of resistance in Sudanese strains during the three crop seasons was observed. Assay of aphid homogcnate for carboxytesterase activity towards the substrates α-naphthyl acetate and β-naphthyl acetate showed that there was no enhancement of this class of enzyme and thus it was not a cause of resistance in this species. A study of interaction between the acetylcholinesterase (AchE) and pirimicarb established the kinetics of the inhibition process. I₅₀ values were found to be much higher for the Sudanese strains than for the susceptible strain. First-order inhibition kinetics revealed that resistance towards pirimicarb in Sudanese-strains was caused by a modified AchE which had a reduced affinity (higher K_a value) and poor carbamylation ability (lower K₂ value) for pirimicarb. The resistance mechanisms for the other insecticides remain to be studied.     

Chemical composition and biological activity of Salvia officinalis L. essential oil against Aphis fabae Scopoli (Hemiptera: Aphididae)

Journal of Plant Diseases and Protection - This study investigated chemical composition, repellent and biocidal activities of Salvia officinalis essential oil against Aphis fabae. In total, 19...     

Isolation of mycoplasmas from pneumonic sheep lungs in the Sudan

A cell type with properties similar to those of the brush cell was recognised in the bronchial epithelium of calves. It occurred in small numbers and was not found in airways distal to the small bronchi. The ultrastructural features are described, emphasising the two constant characteristics (i) a dense population of thick apical microvilli and (ii) cytoplasmic filament bundles which extent into the microvilli.     

Fishing and trade of devil rays (Mobula spp.) in the Bay of Bengal,Bangladesh: Insights from fishers’ knowledge

1. Devil rays (Mobula spp.) are globally threatened cartilaginous fishes that have attracted global conservation concern owing to their high extinction risk and lack of protection in many countries. Limited resources and data on threatened marine species, including devil rays, impede conservation actions, particularly in developing countries, many of which have high biodiversity.
2. Devil ray catch is a component of artisanal fisheries in Bangladesh, but data on their fisheries and trade are limited. To characterize devil ray fishing practices, fishers’ perception and trade, 230 fishers and traders were interviewed between 4 June 2018 and 22 June 2019, in four areas of south-east Bangladesh. Catch data were also opportunistically collected at landing sites.
3. Six devil ray species were documented, caught in an array of gill nets, set-bag nets and longlines. All interviewed fishers reported life-long devil ray bycatch in some numbers, and also noted a decline in catch over the last decade. Bottom trawling, increased bycatch levels, increased demand for devil ray products and, in some cases, ecosystem changes were identified by fishers as threats to devil ray populations.
4. Unregulated and undocumented trade and retained bycatch, especially by gill nets and set-bag nets, are fuelled by local consumption of devil ray meat and international trade in meat and gill rakers. Compliance with international trade control treaties for all Mobula spp. or the Bangladeshi law protecting Mobula mobular was low, with the majority of fishers (87%, n = 174) unaware of their existence.
5. To manage devil ray fisheries, and prevent possible population declines, we propose a combination of legally enforced gear modifications, and catch and trade control through community-owned implementation strategies. Additionally, we propose the simultaneous implementation of inclusive, community-based awareness and stewardship projects in conjunction with a coast-wide ray monitoring programme. Finally, we emphasize that more research and action rooted in a sustainable fishery model is urgently needed to protect Bangladeshi devil ray populations.

     

Determinants of adoption and adoption intensity of precision agriculture technologies: evidence from South Dakota

Precision Agriculture - Precision agriculture technologies (PATs) are promoted as part of both economically efficient and environmentally sustainable agriculture practices. Available PATs are...     

The serological reactions of Mycoplasma isolated from pneumonic sheep lungs in the Sudan.

Seven mycoplasma isolated from pneumonic sheep lungs were found to belong to two serologically unrelated groups. Isolates in one group reacted strongly with antisera to M arginini in the metabolic inhibition and growth inhibition tests. All isolates except one failed to react with antisera to M mycoides var capri or M mycoides var mycoides. The results of the present work support the previously reported division of the isolates into two groups on the basis of their biological properties.