Comparison of thin layer chromatography (TLC) and gas chromatograph determination of propoxur residues in a cocoa ecosystem

The fate of propoxur in a cocoa ecosystem has been studied using TLC and GC. Residues of propoxur as determined by both TLC and GC were not significantly different. TLC analysis of propoxur residues in soil, cocoa leaves and pods may not need any rigorous clean up since residues measured from cleaned and uncleaned extracts were not significantly different. The residue levels of propoxur in the soil were found to decrease rapidly and, by the 21st day, none was detected in the topsoil (0 – 15cm). Evidence of leaching of propoxur residues in the soil environment has also been demonstrated. The amount left in the top soil after the first seven days were 27%, 23% and 24% as determined by the TLC only, TLC with clean-up and GLC respectively. About 38% of pesticides detected on the cocoa pod on the day of treatment remained as residues on the pod seven days after treatment. The residue detected on the leaves on the day of treatment was higher than that for the soil. This decreased rapidly to 1.7% in 21 days compared to 16% for the soil and 23% for the pod. No propoxur residue was detected 21 days after spraying. African Journal of Science and Technology Vol.4(2) 2003: 24-2

Volatile compounds of maari, a fermented product from baobab (Adansonia digitata L.) seeds

The volatile compounds associated with baobab seeds fermentation for Maari production were extracted and analysed by Likens-Nickerson simultaneous steam distillation-extraction method and gas chromatography-mass spectrometry (GC-MS), respectively. Furthermore, the titratable acidity, tannin content and proximate composition were evaluated. A total of 96 compounds were identified with esters, acids, alcohols and ketones being quantitatively the major groups. Fermentation led to an increase in the concentration of total volatile compounds from 121.6 in unfermented cooked seeds to 809.1 mg kg-1 in the fermented product. Drying resulted in a significant loss of up to 80.7% of the total volatiles.Key words: Volatile compounds, maari, baobab, fermentation

Moving interdisciplinary science forward: integrating participatory modelling with mathematical modelling of zoonotic disease in Africa

This review outlines the benefits of using multiple approaches to improve model design and facilitate multidisciplinary research into infectious diseases, as well as showing and proposing practical examples of effective integration. It looks particularly at the benefits of using participatory research in conjunction with traditional modelling methods to potentially improve disease research, control and management. Integrated approaches can lead to more realistic mathematical models which in turn can assist with making policy decisions that reduce disease and benefit local people. The emergence, risk, spread and control of diseases are affected by many complex bio-physical, environmental and socio-economic factors. These include climate and environmental change, land-use variation, changes in population and people’s behaviour. The evidence base for this scoping review comes from the work of a consortium, with the aim of integrating modelling approaches traditionally used in epidemiological, ecological and development research. A total of five examples of the impacts of participatory research on the choice of model structure are presented. Example 1 focused on using participatory research as a tool to structure a model. Example 2 looks at identifying the most relevant parameters of the system. Example 3 concentrates on identifying the most relevant regime of the system (e.g., temporal stability or otherwise), Example 4 examines the feedbacks from mathematical models to guide participatory research and Example 5 goes beyond the so-far described two-way interplay between participatory and mathematical approaches to look at the integration of multiple methods and frameworks. This scoping review describes examples of best practice in the use of participatory methods, illustrating their potential to overcome disciplinary hurdles and promote multidisciplinary collaboration, with the aim of making models and their predictions more useful for decision-making and policy formulation

Pheromone attractants for the green mirid

A pheromone attractant composition for attracting the green mirid, 'Creontiades dilutus' (Stål), comprising as the component active in attracting green mirids an effective amount of an admixture of hexyl hexanoate and (E)-2-hexenyl hexanoate

Pheromone trapping for the green mirid, 'Creontiades dilutus'

With the reduction in the use of broad-spectrum insecticides, sucking bugs are becoming significant pests in transgenic cotton. One of these pests is the green mirid, 'Creontiades dilutus' (Stål) (Hemiptera: Miridae), which damages the terminals and fruiting bodies of cotton. The sex pheromone of 'C. dilutus' has been identified as a two-component blend in a 5:1 ratio of hexyl hexanoate and a female-specific compound, (E)-2-hexenyl hexanoate, respectively. We conducted pheromone trapping trials on cotton at various locations in NSW and Queensland to evaluate the potential of using pheromones as monitoring tools for 'C. dilutus'. Sampling for mirids was also done in these sites to establish any correlation between trap catches and mirid numbers in the field. Mirid samples were dissected to determine the sex ratio and mated status of females. Our data showed that the population dynamics of mirids were different between locations. Pheromone catches were significantly correlated with field mirids at some sites, whilst such correlation was not observed at other sites. Furthermore, in some cases, pheromone traps appeared to catch male mirids only when female mirids in the field were mostly mated, suggesting that the effectiveness of pheromone traps might be influenced by the "female competition" effect in the field

A sex attractant of the rough bollworm, 'Earias huegeliana' (Gaede) (Lepidoptera: Noctuidae)

The sex attractant of the rough bollworm was identified using gas chromatography and mass spectrometry (GC-MS) from female gland and air collections. Identified compounds were formulated into blends and tested in the field for attractiveness to males. The Gas chromatograph-mass spectrometry (GC-MS) analysis revealed 4 compounds, (E,E)-10,12-hexadecadienal, (E,E)-10,12-hexadecadienol, (Z)-11-hexadecenal and (Z)-11-octadecenal in a ratio of 4:1:1:1 in the gland extracts. (E,E)-10, 12-hexadecadienol was not detected in the air collections. Field bioassay showed the 2 components, (E,E)-10,12-hexadecadienal and (Z)-11-hexadecenal to be essential for activity of the blend. This blend was highly attractive to males only. 2 trap designs, the funnel and delta traps were tested and the delta trap was the better of the 2. Male response to attractant baited traps was found to be in the second half of the night, between 0200 and 0500 h. This was found to be synchronised to female calling time. Use of the attractant blend developed as part of the integrated pest management system in cotton is discussed

AGRICULTURE AND BIOLOGY JOURNAL OF NORTH AMERICA Analysis of some quality indicators in cured Cola nitida (Vent)

ABSTRACT Palatable and acceptable kola nuts for chewing are predominately obtained through curing. Curing involves the storage of fresh nuts in cane baskets lined with Musa sapientum (Linn) leaves or Mitragyna stipulosa (DC) leaves, with occasional turning and replacement of the leaves. The study explored how sensory attributes of kola nuts varied with curing duration (1 to 9 weeks) for phenolics and other biochemical compounds during the curing process of kola. The organoleptic assessment indicated that there are biochemical substances in the kola that influence the taste and the overall quality of the nuts. It was also clear that these biochemical substances are already present in the fresh nuts as precursors and are developed during the curing process. Total polyphenols could not be used wholly to account for astringency and bitterness in kola nuts. A subgroup, o-dihydric phenols could be better used to partly account for astringency and therefore as a marker