Reproductive fitness and survival are enhanced by adaptive behaviors that are modulated by internal physiological states and external social contexts. The common bed bug,
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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 »
Insect societies vary greatly in their social structure, mating biology, and life history. Polygyny, the presence of multiple reproductive queens in a single colony, and polyandry, multiple mating by females, both increase the genetic variability in colonies of eusocial organisms, resulting in potential reproductive conflicts. The co-occurrence of polygyny and polyandry in a single species is rarely observed across eusocial insects, and these traits have been found to be negatively correlated in ants.
Acromyrmexleaf-cutting ants are well-suited for investigating the evolution of complex mating strategies because both polygyny and polyandry co-occur in this genus. We used microsatellite markers and parentage inference in five South American Acromyrmexspecies to study how different selective pressures influence the evolution of polygyny and polyandry. We show that Acromyrmexspecies exhibit independent variation in mating biology and social structure, and polygyny and polyandry are not necessarily negatively correlated within genera. One species, Acromyrmex lobicornis, displays a significantly lower mating frequency compared to others, while another species, A. lundii, appears to have reverted to obligate monogyny. These variations appear to have a small impact on average intra-colonial relatedness, although the biological significance of such a small effect size is unclear. All species show significant reproductive skew between patrilines, but there was no significantmore » Significance statement
Many species of eusocial insects have colonies with multiple queens (polygyny), or queens mating with multiple males (polyandry). Both behaviors generate potentially beneficial genetic diversity in ant colonies as well as reproductive conflict. The co-occurrence of both polygyny and polyandry in a single species is only known from few ant species. Leaf-cutting ants have both multi-queen colonies and multiply mated queens, providing a well-suited system for studying the co-evolutionary dynamics between mating behavior and genetic diversity in colonies of eusocial insects. We used microsatellite markers to infer the socio-reproductive behavior in five South American leaf-cutter ant species. We found that variation in genetic diversity in colonies was directly associated with the mating frequencies of queens, but not with the number of queens in a colony. We suggest that multi-queen nesting and mating frequency evolve independently of one another, indicating that behavioral and ecological factors other than genetic diversity contribute to the evolution of complex mating behaviors in leaf-cutting ants.
Synopsis Intra- and inter-sexual communications are vital to the survival and reproductive success of animals. In species that cycle in and out of breeding or other physiological condition, sensory function can be modulated to optimize communication at crucial times. Little is known, however, about how widespread this sensory plasticity is across taxa, whether it occurs in multiple senses or both sexes within a species, and what potential modulatory substances and substrates are involved. Thus, studying modulation of sensory communication in a single species can provide valuable insights for understanding how sensory abilities can be altered to optimize detection of salient signals in different sensory channels and social contexts. The African cichlid fish Astatotilapia burtoni uses multimodal communication in social contexts such as courtship, territoriality, and parental care and shows plasticity in sensory abilities. In this review, we synthesize what is known about how visual, acoustic, and chemosensory communication is used in A. burtoni in inter- and intra-specific social contexts, how sensory funtion is modulated by an individual’s reproductive, metabolic, and social state, and discuss evidence for plasticity in potential modulators that may contribute to changes in sensory abilities and behaviors. Sensory plasticity in females is primarily associated with the naturalmore »
Ever since Darwin, evolutionary biologists have studied sexual selection driving differences in appearance and behaviour between males and females. An unchallenged paradigm in such studies is that one sex (usually the male) signals its quality as a mate to the other sex (usually the female), who is choosy in accepting a partner. Here, we hypothesize that in polygamous species these roles change dynamically with the mating status of males and females, depending on direct reproductive costs and benefits of multiple matings, and on sperm competition. We test this hypothesis by assessing fitness costs and benefits of multiple matings in both males and females in a polygamous moth species, as in moths not males but females are the signalers and males are the responders.
We found that multiple matings confer fitness costs and benefits for both sexes. Specifically, the number of matings did not affect the longevity of males or females, but only 67% of the males and 14% of the females mated successfully in all five nights. In addition, the female’s reproductive output increased with multiple matings, although when paired with a new virgin male every night, more than 3 matings decreased her reproductive output, so that the Batemanmore »
Our results suggest that choosiness in moths may well change throughout the mating season, with males being more choosy early in the season and females being more choosy after having mated at least three times. This life-history perspective on the costs and benefits of multiple matings for both sexes sheds new light on sexual selection forces acting on sexual signals and responses.
The ability to identify odors in the environment is crucial for survival and reproduction. However, whether olfactory processing in higher-order brain centers is influenced by an animal’s physiological condition is unknown. We used
in vivoneuron and local field potential (LFP) recordings from the ventral telencephalon of dominant and subordinate male cichlids to test the hypothesis that response properties of olfactory neurons differ with social status. Dominant males had a high percentage of neurons that responded to several odor types, suggesting broad tuning or differential sensitivity when males are reproductively active and defending a territory. A greater percentage of neurons in dominant males also responded to sex- and food-related odors, while a greater percentage of neurons in subordinate males responded to complex odors collected from behaving dominant males, possibly as a mechanism to mediate social suppression and allow subordinates to identify opportunities to rise in rank. Odor-evoked LFP spectral densities, indicative of synaptic inputs, were also 2–3-fold greater in dominant males, demonstrating status-dependent differences in processing possibly linking olfactory and other neural inputs to goal-directed behaviors. For the first time we reveal social and reproductive-state plasticity in olfactory processing neurons in the vertebrate forebrain that are associated with status-specific lifestyles.