Protein and amino acid composition of the tergal gland secretions ofBlatta orientalis andEurycotis floridana (Dictyoptera: Blattidae)

Summary Nymphs and adult females ofBlatta orientalis and nymphs ofEurycotis floridana produce a proteinaceous sticky secretion which accumulates on the last abdominal tergites. The proteic patterns do not differ between individuals of the same species. HPLC analyses show that all the common amino acids are found in both species, aspartic and glutamic acids representing 24 to 37% of the total amount of amino acids. InB. orientalis, glutamic acid is the more abundant amino acid whereas inE. floridana it is the aspartic acid. The secretion appears and accumulates rapidly on isolated insects. Behavioural assays revealed that these secretions have a defensive role.     

Pheromones inBlattella germanica andBlaberus craniifer (Blaberoidea): Glandular source,morphology and analyses of pheromonally released behaviours

Females ofBlattella germanica andBlaberus craniifer produce a volatile sex pheromone attractive at a distance for conspecific males. During the emission of the pheromone, females ofB. craniifer adopt a typical calling posture; we never observe such a stance inB. germanica females. For both species, the glandular structures responsible for pheromonal production are located on the female pygidium. InB. germanica, the thickness of the glandular epithelium is clearly correlated with the attractiveness of females, being maximum for 13 day old females. The functions of the pygidial glands are discussed in both species.     

Social organisation of thornbill-dominated mixed-species flocks using social network analysis

Mixed-species associations are a widespread phenomenon, comprising interacting heterospecific individuals which gain predator, foraging or social benefits. Avian flocks have traditionally been classified as monolithic species units, with species-wide functional roles, such as nuclear, active, passive, or follower. It has also been suggested that flocks are mutualistic interactions, where niches of participating species converge. However the species-level perspective has limited previous studies, because both interactions and benefits occur at the level of the individual. Social network analysis provides a set of tools for quantitative assessment of individual participation. We used mark-resighting methods to develop networks of nodes (colour-marked individuals) and edges (their interactions within flocks). We found that variation in flock participation across individuals within species, especially in the buff-rumped thornbill, encompassed virtually the entire range of variation across all individuals in the entire set of species. For example, female, but not male, buff-rumped thornbills had high network betweenness, indicating that they interact with multiple flocks, likely as part of a female-specific dispersal strategy. Finally, we provide new evidence that mixed-species flocking is mutualistic, by quantifying an active shift in individual foraging niches towards those of their individual associates, with implications for trade-off between costs and benefits to individuals derived from participating in mixed-species flocks. This study is, to our knowledge, the first instance of a heterospecific social network built on pairwise interactions.