Multiple and frequent trypanosomatid co-infections of insects: the Cuban case study.

Trypanosomatids are obligate parasites of animals, predominantly insects and vertebrates, and flowering plants. Monoxenous species, representing the vast majority of trypanosomatid diversity, develop in a single host, whereas dixenous species cycle between two hosts, of which primarily insect serves as a vector. To explore in-depth the diversity of insect trypanosomatids including their co-infections, sequence profiling of their 18S rRNA gene was used for true bugs (Hemiptera; 18% infection rate) and flies (Diptera; 10%) in Cuba. Out of 48 species (molecular operational taxonomic units) belonging to the genera Vickermania (16 spp.), Blastocrithidia (7), Obscuromonas (4), Phytomonas (5), Leptomonas/Crithidia (5), Herpetomonas (5), Wallacemonas (2), Kentomonas (1), Angomonas (1) and two unnamed genera (1 + 1), 38 species have been encountered for the first time. The detected Wallacemonas and Angomonas species constitute the most basal lineages of their respective genera, while Vickermania emerged as the most diverse group. The finding of Leptomonas seymouri, which is known to rarely infect humans, confirms that Dysdercus bugs are its natural hosts. A clear association of Phytomonas with the heteropteran family Pentatomidae hints at its narrow host association with the insect rather than plant hosts. With a focus on multiple infections of a single fly host, using deep Nanopore sequencing of 18S rRNA, we have identified co-infections with up to 8 trypanosomatid species. The fly midgut was usually occupied by several Vickermania species, while Herpetomonas and/or Kentomonas species prevailed in the hindgut. Metabarcoding was instrumental for analysing extensive co-infections and also allowed the identification of trypanosomatid lineages and genera.

Only mothers feed mature offspring in European Ceratina bees.

Parental care directed to adult offspring is uncommon in animals. Such parental care has been documented in Xylocopinae bees (Hymenoptera: Apidae). Moreover, some Ceratina bees (Xylocopinae) are known to feed mature siblings, and feeding of mature siblings is achieved by dwarf eldest daughters when mothers died. These daughters are intentionally malnourished by mothers and usually originate from the first brood cell. Here, we examined the pattern of care provided to young adults in three small European carpenter bees: Ceratina (Ceratina) cucurbitina, C. (Euceratina) chalybea, and C. (E.) nigrolabiata. Observations of nest departures and arrivals were performed to study foraging behavior. We detected intensive foraging behavior of mothers in all three studied species. However, we did not observe regular foraging behavior of daughters in any species. The experimental removal of mothers in C. cucurbitina led to the emigration of young adults and did not initiate foraging activity in daughters. We conclude that the feeding of siblings does not occur in these species unlike in the American species C. calcarata. We detected female-biased sex ratios in the first brood cell in C. cucurbitina and C. chalybea. Female offspring in the first brood cell was smaller than other female offspring only in C. cucurbitina. Our results show that a female-biased sex ratio and the small size of daughters in the first brood cell do not provide sufficient evidence for demonstrating the existence of an altruistic daughter and also that the pattern of maternal investment is not exclusively shaped by social interactions.