Local Enhancement Promotes Cockroach Feeding Aggregations

Communication and learning from each other are part of the success of animal societies. Social insects invest considerable effort into signalling to their nestmates the locations of the most profitable resources in their environment. Growing evidence also indicates that insects glean such information through cues inadvertently provided by their conspecifics. Here, we investigate social information use in the foraging decisions by gregarious cockroaches (Blattella germanica L.). Individual cockroaches given a simultaneous choice in a Y-olfactometer between the odour of feeding conspecifics and the mixed odour of food plus non-feeding conspecifics showed a preference for the arm scented with the odour of feeding conspecifics. Social information (the presence of feeding conspecifics) was produced by cockroaches of all age classes and perceived at short distance in the olfactometer arms, suggesting the use of inadvertently provided cues rather than signals. We discuss the nature of these cues and the role of local enhancement (the selection of a location based on cues associated with the presence of conspecifics) in the formation of feeding aggregations in B. germanica. Similar cue-mediated recruitments could underpin a wide range of collective behaviours in group-living insects

Mutual Mate Choice: When it Pays Both Sexes to Avoid Inbreeding

Theoretical models of sexual selection predict that both males and females of many species should benefit by selecting their mating partners. However, empirical evidence testing and validating this prediction is scarce. In particular, whereas inbreeding avoidance is expected to induce sexual conflicts, in some cases both partners could benefit by acting in concert and exerting mutual mate choice for non-assortative pairings. We tested this prediction with the gregarious cockroach Blattella germanica (L.). We demonstrated that males and females base their mate choice on different criteria and that choice occurs at different steps during the mating sequence. Males assess their relatedness to females through antennal contacts before deciding to court preferentially non-siblings. Conversely, females biased their choice towards the most vigorously courting males that happened to be non-siblings. This study is the first to demonstrate mutual mate choice leading to close inbreeding avoidance. The fact that outbred pairs were more fertile than inbred pairs strongly supports the adaptive value of this mating system, which includes no “best phenotype” as the quality of two mating partners is primarily linked to their relatedness. We discuss the implications of our results in the light of inbreeding conflict models

Enterobactin-Mediated Delivery of β-Lactam Antibiotics Enhances Antibacterial Activity against Pathogenic Escherichia coli

The design, synthesis, and characterization of enterobactin–antibiotic conjugates, hereafter Ent-Amp/Amx, where the β-lactam antibiotics ampicillin (Amp) and amoxicillin (Amx) are linked to a monofunctionalized enterobactin scaffold via a stable poly(ethylene glycol) linker are reported. Under conditions of iron limitation, these siderophore-modified antibiotics provide enhanced antibacterial activity against Escherichia coli strains, including uropathogenic E. coli CFT073 and UTI89, enterohemorrhagic E. coli O157:H7, and enterotoxigenic E. coli O78:H11, compared to the parent β-lactams. Studies with E. coli K-12 derivatives defective in ferric enterobactin transport reveal that the enhanced antibacterial activity observed for this strain requires the outer membrane ferric enterobactin transporter FepA. A remarkable 1000-fold decrease in minimum inhibitory concentration (MIC) value is observed for uropathogenic E. coli CFT073 relative to Amp/Amx, and time-kill kinetic studies demonstrate that Ent-Amp/Amx kill this strain more rapidly at 10-fold lower concentrations than the parent antibiotics. Moreover, Ent-Amp and Ent-Amx selectively kill E. coli CFT073 co-cultured with other bacterial species such as Staphylococcus aureus, and Ent-Amp exhibits low cytotoxicity against human T84 intestinal cells in both the apo and iron-bound forms. These studies demonstrate that the native enterobactin platform provides a means to effectively deliver antibacterial cargo across the outer membrane permeability barrier of Gram-negative pathogens utilizing enterobactin for iron acquisition.Pacific Southwest Regional Center of Excellence for Biodefense and Emerging Infectious DiseaseKinship Foundation. Searle Scholars ProgramMassachusetts Institute of Technology. Department of Chemistr

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

Microbial organisms carried by brown-banded cockroaches in relation to their spatial distribution in a hospital.

A simultaneous study of cockroach (Supella supellectilium) distribution and of associated carried bacterial flora has been made in the main hospital in Rennes (France). Wild cockroaches carry a high number of bacterial species that can be related to the normal environmental flora and a contaminant flora acquired from particular environments. The diversity of carried bacterial species reveals a proximity factor between continguous floors of the building which leads us to suppose that cockroaches are able to forage from one floor to the other

Bacterial load of cockroaches in relation to urban environment.

Sanitation is an important problem in relation to the control of pests in urban environments. This investigation analysed the potential risk related to the presence of cockroaches and their capacity for disseminating bacteria in six different types of buildings: hospital nursing area and out-patient area, swimming-pool pool-side and toilet area, low-income flats and food-handling places. Fifty-six species of bacteria were identified from 157 samples, 14 of these have previously been reported as potentially pathogenic for man and vertebrates. Similarities were found between samples collected in (a) the hospital out-patient area and food-handling establishments and (b) the hospital nursing area and flats. Pool-sides possessed a poorer bacterial flora. There was a greater bacterial specific diversity in food-handling establishments, flats and swimming-bath toilet area. Enterobacter cloacae. Klebsiella pneumoniae and Klebsiella oxytoca were dominant species in flats and the hospital nursing area. Therefore, cockroaches can play a role in disseminating bacteria, which they can carry passively on their cuticle

Perception of cuticular hydrocarbons by the olfactory organs in Periplaneta americana (L.) (Insecta : Dictyoptera)

WOS:000233791800013International audienceDespite the importance of cuticular hydrocarbons (CHs) in insect chemical communication, direct proof that they ire delected and recognized by insects by contact or by olfactory receptors are rare. In Periplaneta americana, CHs induce aggregation The aim of our study was to investigate how CHs are detected by P. americana antennae. Using solid phase microextraction and gas chromatography, the three main CHs of the species profile were identified in the volatiles entitled by these insects. Gas chromatography coupled to electroantennography recordings demonstrated that the antennae responded to these three CHs. Furthermore. CHs had an attraction effect in Y-olfactometer bioassays when presented at high concentrations, As CHs can be perceived by A americana. at least from a short distance, they could play it role in attracting conspecifics during aggregation processes. in addition to inducing aggregation when direct contact is possible. (c) 2005 Elsevier Ltd. All rights reserved