More Like this

1. Mating and starvation modulate feeding and host-seeking responses in female bed bugs, Cimex lectularius

   https://doi.org/10.1038/s41598-021-81271-y  

   Saveer, Ahmed M. ; DeVries, Zachary C. ; Santangelo, Richard G. ; Schal, Coby ( January 2021 , Scientific Reports)

   Reproductive fitness and survival are enhanced by adaptive behaviors that are modulated by internal physiological states and external social contexts. The common bed bug,Cimex lectularius, is an obligate hematophagous ectoparasite that requires host blood for growth, development, and reproduction. We investigated how mating, starvation and social interactions affect host-seeking, blood feeding, oviposition, and survival of female bed bugs. The percentage of females that fed and the amount of blood they ingested were greater in mated females (90–100%) than in unmated females (48–60%). Mating state also modulated the female’s orientation towards human skin odor in an olfactometer; more mated (69%) than unmated (23%) females responded to human odors. The response rate of unmated females (60%) to skin odor increased with longer starvation period, while the opposite pattern was observed in mated females (20%). Although fecundity after a single blood meal was unaffected by long or short residence and interaction with males, females subjected to frequent copulation attempts had lower survivorship and lifespan than females housed with males for only 24 h. Taken together, these results indicate that by adaptively and coordinately expressing behaviors based on the internal physiological state, females maximize their survival and reproductive fitness.
2. Persistent symbiont colonization leads to a maturation of hemocyte response in the Euprymna scolopes / Vibrio fischeri symbiosis

   https://doi.org/10.1002/mbo3.858  

   Rader, Bethany ; McAnulty, Sarah J. ; Nyholm, Spencer V. ( June 2019 , MicrobiologyOpen)

   The binary association between the squid,Euprymna scolopes, and its symbiont,Vibrio fischeri, serves as a model system to study interactions between beneficial bacteria and the innate immune system. Previous research demonstrated that binding of the squid's immune cells, hemocytes, toV. fischeriis altered if the symbiont is removed from the light organ, suggesting that host colonization alters hemocyte recognition ofV. fischeri. To investigate the influence of symbiosis on immune maturation during development, we characterized hemocyte binding and phagocytosis ofV. fischeriand nonsymbioticVibrio harveyifrom symbiotic (sym) and aposymbiotic (apo) juveniles, and wild‐caught and laboratory‐raised sym and apo adults. Our results demonstrate that while light organ colonization byV. fischeridid not alter juvenile hemocyte response, these cells bound a similar number ofV. fischeriandV. harveyiyet phagocytosed onlyV. harveyi. Our results also indicate that long‐term colonization altered the adult hemocyte response toV. fischeribut notV. harveyi. All hemocytes from adult squid, regardless of apo or sym state, both bound and phagocytosed a similar number ofV. harveyiwhile hemocytes from both wild‐caught and sym‐raised adults bound significantly fewerV. fischeri, although moreV. fischeriwere phagocytosed by hemocytes from wild‐caught animals. In contrast, hemocytes from apo‐raised squid bound similar numbers of bothV. fischeriandV. harveyi, although moreV. harveyicells were engulfed, suggesting that blood cellsmore »from apo‐raised adults behaved similarly to juvenile hosts. Taken together, these data suggest that persistent colonization by the light organ symbiont is required for hemocytes to differentially bind and phagocytoseV. fischeri. The cellular immune system ofE. scolopeslikely possesses multiple mechanisms at different developmental stages to promote a specific and life‐long interaction with the symbiont.

   « less
3. Bed Bug (Hemiptera: Cimicidae) Attraction to Human Odors: Validation of a Two-Choice Olfactometer

   https://doi.org/10.1093/jme/tjy202  

   DeVries, Zachary C ; Saveer, Ahmed M ; Mick, Russell ; Schal, Coby ( November 2018 , Journal of Medical Entomology)

   Abstract Bed bugs (Cimex lectularius L.) (Hemiptera: Cimicidae) are obligate hematophagous ectoparasites, and, therefore, must locate suitable hosts to ensure survival and reproduction. Their largely nocturnal activity suggests that chemosensory and thermosensory cues would play critical roles in host location. Yet, the importance of olfaction in host attraction of bed bugs remains unclear. We developed and validated a Y-tube, two-choice olfactometer and tested its suitability for investigating attraction to human odors (from skin swabs). Olfactometer orientation significantly affected the percentage of bed bugs that were activated by human odors, with significantly more bed bugs responding when the olfactometer was oriented vertically (bug introduced at bottom of the olfactometer) compared with all other orientations. Starved (7–10 d) adult males, mated females, and nymphs responded (47–77% moved up the olfactometer and made a choice) when human odors were present in the olfactometer, while starved, unmated females did not respond. Skin swabs from all five human participants elicited high response rates (65–82%), and bed bugs from four different populations responded to skin swabs (40–82% response rate). However, in all assays including those resulting in relatively low response rates, bed bugs exhibited >90% preference for human odors over blank controls. These results provide strongmore »evidence that bed bugs can respond and orient towards human odors, independently of all other host cues. Furthermore, the validated olfactometer should enable rapid and efficient evaluations of bed bug behavioral responses to semiochemicals.« less
4. Symbiont Genomic Features and Localization in the Bean Beetle Callosobruchus maculatus

   https://doi.org/10.1128/AEM.00212-21  

   Berasategui, Aileen ; Moller, Abraham G. ; Weiss, Benjamin ; Beck, Christopher W. ; Bauchiero, Caroline ; Read, Timothy D. ; Gerardo, Nicole M. ; Salem, Hassan ( May 2021 , Applied and Environmental Microbiology)

   Johnson, Karyn N. (Ed.)

   ABSTRACT A pervasive pest of stored leguminous products, the bean beetle Callosobruchus maculatus (Coleoptera: Chrysomelidae) associates with a simple bacterial community during adulthood. Despite its economic importance, little is known about the compositional stability, heritability, localization, and metabolic potential of the bacterial symbionts of C. maculatus . In this study, we applied community profiling using 16S rRNA gene sequencing to reveal a highly conserved bacterial assembly shared between larvae and adults. Dominated by Firmicutes and Proteobacteria , this community is localized extracellularly along the epithelial lining of the bean beetle’s digestive tract. Our analysis revealed that only one species, Staphylococcus gallinarum (phylum Firmicutes ), is shared across all developmental stages. Isolation and whole-genome sequencing of S. gallinarum from the beetle gut yielded a circular chromosome (2.8 Mb) and one plasmid (45 kb). The strain encodes complete biosynthetic pathways for the production of B vitamins and amino acids, including tyrosine, which is increasingly recognized as an important symbiont-supplemented precursor for cuticle biosynthesis in beetles. A carbohydrate-active enzyme search revealed that the genome codes for a number of digestive enzymes, reflecting the nutritional ecology of C. maculatus . The ontogenic conservation of the gut microbiota in the bean beetle, featuring a “core” community composedmore »of S. gallinarum , may be indicative of an adaptive role for the host. In clarifying symbiont localization and metabolic potential, we further our understanding and study of a costly pest of stored products. IMPORTANCE From supplementing essential nutrients to detoxifying plant secondary metabolites and insecticides, bacterial symbionts are a key source of adaptations for herbivorous insect pests. Despite the pervasiveness and geographical range of the bean beetle Callosobruchus maculatus , the role of microbial symbioses in its natural history remains understudied. Here, we demonstrate that the bean beetle harbors a simple gut bacterial community that is stable throughout development. This community localizes along the insect’s digestive tract and is largely dominated by Staphylococcus gallinarum . In elucidating symbiont metabolic potential, we highlight its possible adaptive significance for a widespread agricultural pest.« less
5. The Role of Antennae in Heat Detection and Feeding Behavior in the Bed Bug (Hemiptera: Cimicidae)

   https://doi.org/10.1093/jee/toaa250  

   Gaire, Sudip ; Schal, Coby ; Mick, Russell ; DeVries, Zachary ( October 2020 , Journal of Economic Entomology)

   Appel, Arthur (Ed.)

   Abstract The common bed bug (Cimex lectularius L.) is an obligate hematophagous ectoparasite that has significant impacts on human health and well-being. All life stages of bed bugs (except eggs) feed solely on blood, which is required to molt and reproduce. Bed bugs use multiple cues to locate their hosts, including heat, CO2, and body odors. Of these cues, detection of heat appears limited to a short distance of <3 cm. However, it remains unclear if bed bugs can detect radiant heat, what structure(s) are responsible for heat detection, and if heat detection via the antennae is required for feeding. In this study, bed bug response to radiant heat was evaluated using the two-choice T-maze assay with the heat source either in contact with the surface (i.e., conduction) or not in contact (i.e., radiation) in nonantennectomized bed bugs. Further, we systematically ablated the bed bug’s antennal segments (distal tip, first segment, and all four segments) and assessed their responses to heat and feeding in a unique two-choice T-maze assay and individual feeding assays, respectively. Our two-choice assays with contact to or no contact with the surface indicated that bed bugs cannot detect radiant heat. Later, we found that the distalmore »tip of the terminal antennal segment is responsible for orientation toward a heat source. However, >50% of the bed bugs fed even when the entire antenna was removed, suggesting redundancy in sensory cues that drive feeding. These results will be used to better understand the role heat plays in bed bug host attraction and design of traps.« less