Contrasting Responses of Wing Morphology of Three Blowfly (Diptera: Calliphoridae) Species to Competition.

Competition influences the expression of morphological, physiological, and behavioral traits and also regulates ecological and evolutionary dynamics. This study aims to identify and characterize changes in wing morphology in response to intra- and interspecific competition in three necrophagous blowfly species. Using geometric morphometry, we analyzed 3,238 wings from Lucilia sericata (Meigen, 1826), Calliphora vicina Robineau-Desvoidy, 1830, and C. vomitoria (Linnaeus, 1758) raised under cloistered and pairwise conditions. The three species reacted similarly to intraspecific competition-reducing wing size with increased competition-but displayed contrasting patterns of response to interspecific competition. Lucilia sericata displayed a directional change in wing shape in response to an interspecific competitor, while C. vicina increased the scattering of individuals across the morphospace, and C. vomitoria displayed no significant change in response to the same stimulus. Our results show that the same stimulus yields distinctive responses; thus, different competition-related strategies are expected to occur in the three species.

Mannose-resistant haemagglutination (MRHA) and haemolysin (Hly) production of strains of Escherichia coli isolated from children with diarrhoea: effect of breastfeeding.

Haemolysin production (Hly) and mannose-resistant haemagglutination induction (MRHA) of human (H), bovine (B), and both (HB) erythrocytes was investigated in strains of E. coli isolated from 142 cases of children with diarrhoea aged 0-36 months. Haemolysin production was more frequent in strains isolated from children under 1 year and this characteristic was strongly associated with HB+ haemagglutination (P < 0.005). Isolation frequency of MRHA strains was compared in 53 breastfed and 50 non-breastfed children under 1 year of age. HB+ strains were significantly more frequent in non-breastfed infants (P < 0.025). Severity of diarrhoea evaluated by the number of watery stools per day, was significantly reduced in the breastfed group (P < 0.05). The results suggests that breastfeeding may protect infants against the establishment of HB+ strains which might be acting either as a main pathogen or as an opportunistic strain.