Olfactory attractiveness of mixtures of some host plant and conspecific semiochemicals to the banana weevil Cosmopolites sordidus (Germar, 1824)

A simple "Y" shaped olfactometer was used in laboratory studies on the olfactory attractiveness of mixtures in various proportions of industrial analogues of some host plant and conspecific-based semiochemicals, or their combinations with banana rhizome, to the banana weevil. The aim was to identify factors that influence their attractiveness to the weevil, and consider the possibility for their use as lures for trapping the weevil in the field. Cosmopolites sordidus was attracted to the mixtures at specific concentrations and proportions of constituent chemicals. 6-methylhept-5-en-2-one was only attractive on its own at 1 µl/100 ml and in mixture with 4- mercaptophenol, but not at 10 µl, 0.01 µl, or in combination with banana rhizome. 4-mercaptohpenol and 2-n-butylfuran, which were compatible with most host plant-based chemicals and were attractive as a mixture, were perceived to be key elements in the composition of attractants to the weevil. It was concluded that in addition to the composition, other factors that may determine the attractiveness or otherwise of a mixture to C. sordidus are the proportions and concentrations of the constituent chemicals.

The effects of non-host plant essential oil volatiles on the behaviour of the pollen beetle Meligethes aeneus

The use of semiochemicals for manipulation of the pollen beetle Meligethes aeneus (Fabricius) (Coleoptera: Nitidulidae) is being investigated for potential incorporation into a push-pull control strategy for this pest, which damages oilseed rape, Brassica napus L. (Brassicaceae), throughout Europe. The response of M. aeneus to non-host plant volatiles was investigated in laboratory assays to establish whether they have any effect on host plant location behaviour. Two approaches were used. First a novel, moving-air bioassay using air funnels was developed to compare the response of M. aeneus to several non-host plant essential oils. The beetles avoided the host plant flowers in the presence of non-host volatiles, suggesting that M. aeneus uses olfactory cues in host location and/or acceptance. The results were expressed as 'repellency values' in order to compare the effects of the different oils tested. Lavender (Lavendula angustifolia Miller) (Lamiaceae) essential oil gave the highest repellency value. In addition, a four-arm olfactometer was used to investigate olfactory responses, as this technique eliminated the influence of host plant visual and contact cues. The attraction to host plant volatiles was reduced by the addition of non-host plant volatiles, but in addition to masking the host plant volatiles, the non-host volatiles were avoided when these were presented alone. This is encouraging for the potential use of non-host plants within a push-pull strategy to reduce the pest colonisation of crops. Further testing in more realistic semi-field and field trials is underway.

Evolutionary history of vegetative reproduction in Porpidia s. l. (lichen-forming ascomycota)

The evolutionary history of gains and losses of vegetative reproductive propagules (soredia) in Porpidia s.l., a group of lichen-forming ascomycetes, was clarified using Bayesian Markov chain Monte Carlo (MCMC) approaches to monophyly tests and a combined MCMC and maximum likelihood approach to ancestral character state reconstructions. The MCMC framework provided confidence estimates for the reconstructions of relationships and ancestral character states, which formed the basis for tests of evolutionary hypotheses. Monophyly tests rejected all hypotheses that predicted any clustering of reproductive modes in extant taxa. In addition, a nearest-neighbor statistic could not reject the hypothesis that the vegetative reproductive mode is randomly distributed throughout the group. These results show that transitions between presence and absence of the vegetative reproductive mode within Porpidia s.l. occurred several times and independently of each other. Likelihood reconstructions of ancestral character states at selected nodes suggest that - contrary to previous thought - the ancestor to Porpidia s.l. already possessed the vegetative reproductive mode. Furthermore, transition rates are reconstructed asymmetrically with the vegetative reproductive mode being gained at a much lower rate than it is lost. A cautious note has to be added, because a simulation study showed that the ancestral character state reconstructions were highly dependent on taxon sampling. However, our central conclusions, particularly the higher rate of change from vegetative reproductive mode present to absent than vice versa within Porpidia s.l., were found to be broadly independent of taxon sampling. [Ancestral character state reconstructions; Ascomycota, Bayesian inference; hypothesis testing; likelihood; MCMC; Porpidia; reproductive systems]

NSAIDs: GI risk with a past history of peptic ulceration

In this Drug points article the author describes a case of osteoarthritic pain where prescribing diclofenac resulted in gastrointestinal ulceration and comments on the issues it raises.