Personality in the Cockroach (Diploptera punctate): Evidence for Stability Across Developmental Stages Despite Age Effects on Boldness

Despite a recent surge in the popularity of animal personality studies and their wide-ranging associations with various aspects of behavioural ecology, our understanding of the development of personality over ontogeny remains poorly understood. Stability over time is a central tenet of personality; ecological pressures experienced by an individual at different life stages may, however, vary considerably, which may have a significant effect on behavioural traits. Invertebrates often go through numerous discrete developmental stages and therefore provide a useful model for such research. Here we test for both differential consistency and age effects upon behavioural traits in the gregarious cockroach Diploptera punctata by testing the same behavioural traits in both juveniles and adults. In our sample, we find consistency in boldness, exploration and sociality within adults whilst only boldness was consistent in juveniles. Both boldness and exploration measures, representative of risk-taking behaviour, show significant consistency across discrete juvenile and adult stages. Age effects are, however, apparent in our data; juveniles are significantly bolder than adults, most likely due to differences in the ecological requirements of these life stages. Size also affects risk-taking behaviour since smaller adults are both bolder and more highly explorative. Whilst a behavioural syndrome linking boldness and exploration is evident in nymphs, this disappears by the adult stage, where links between other behavioural traits become apparent. Our results therefore indicate that differential consistency in personality can be maintained across life stages despite age effects on its magnitude, with links between some personality traits changing over ontogeny, demonstrating plasticity in behavioural syndromes

Do non-steroidal anti-inflammatory drugs or smoking predispose to Helicobacter pylori infection?

Susceptibility to Helicobacter pylori infection is a poorly understood phenomenon. This study was undertaken to establish whether either smoking or chronic non-steroidal anti-inflammatory drug (NSAID) consumption might in some way predispose to H. pylori infection and hence lead to peptic ulceration. Serological evidence of H. pylori infection was assessed in 100 consecutive subjects receiving NSAIDs without any evidence of gastrointestinal upset and 100 matched controls. All subjects had a full assessment of their smoking habits. Sixty-three per cent of patients taking NSAIDs compared to 51% of controls had evidence of H. pylori infection (NS). Smoking habit also had no effect on H. pylori colonization. The ulcerogenic potential of NSAIDs and smoking does not appear to be mediated via a prediposition to H. pylori infection