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In this study we describe colony development, larval development, worker reproduction and mating frequency of the queen in laboratory colonies of Bombus impatiens Cresson. Comparison of our observations with data from B. terrestris -the best studied bumblebee -revealed both similarities and dissimilarities between the two. Colonies of B. impatiens have a high number of workers (374.5±108), but relatively low number of young queens (9.4 ± 20) and males (8.9 ± 20). As in B. terrestris, size differences between the castes in B. impatiens were pronounced and became conspicuous as differences in the molting weight of the larvae, starting at the second instar. Workers are able to lay eggs and about 9 % of the workers in old colonies had mature oocytes in their ovaries. Despite this, workers were almost never observed to lay eggs in the presence of the queen, and the "competition phase" which is known from B. terrestris was never observed. Mating frequency of the queen was examined using molecular techniques. Two out of ten queens had mated with 2 different males, suggesting some degree of polyandry in the population.

Insect microbiomes influence many fundamental host traits, including functions of practical significance such as their capacity as vectors to transmit parasites and pathogens. The knowledge on the diversity and development of the gut microbiomes in various blood feeding insects is thus crucial not only for theoretical purposes, but also for the development of better disease control strategies. In Triatominae (Heteroptera: Reduviidae), the blood feeding vectors of Chagas disease in South America and parts of North America, the investigation of the microbiomes is in its infancy. The few studies done on microbiomes of South American Triatominae species indicate a relatively low taxonomic diversity and a high host specificity. We designed a comparative survey to serve several purposes: (I) to obtain a better insight into the overall microbiome diversity in different species, (II) to check the long term stability of the interspecific differences, (III) to describe the ontogenetic changes of the microbiome, and (IV) to determine the potential correlation between microbiome composition and presence of Trypanosoma cruzi, the causative agent of Chagas disease. Using 16S amplicons of two abundant species from the southern US, and four laboratory reared colonies, we showed that the microbiome composition is determined by host species, rather than locality or environment. The OTUs (Operational Taxonomic Units) determination confirms a low microbiome diversity, with 12-17 main OTUs detected in wild populations of T. sanguisuga and T. protracta. Among the dominant bacterial taxa are Acinetobacter and Proteiniphilum but also the symbiotic bacterium Arsenophonus triatominarum, previously believed to only live intracellularly. The possibility of ontogenetic microbiome changes was evaluated in all six developmental stages and feces of the laboratory reared model Rhodnius prolixus. We detected considerable changes along the host's ontogeny, including clear trends in the abundance variation of the three dominant bacteria, namely Enterococcus, Acinetobacter, and Arsenophonus. Finally, we screened the samples for the presence of Trypanosoma cruzi. Comparing the parasite presence with the microbiome composition, we assessed the possible significance of the latter in the epidemiology of the disease. Particularly, we found a trend toward more diverse microbiomes in Trypanosoma cruzi positive T. protracta specimens.

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