The evolution of female-biased genital diversity in bedbugs (Cimicidae).

Rapid genitalia evolution is believed to be mainly driven by sexual selection. Recently, noncopulatory genital functions have been suggested to exert stronger selection pressure on female genitalia than copulatory functions. In bedbugs (Cimicidae), the impact of the copulatory function can be isolated from the noncopulatory impact.

Female bed bugs ( L) anticipate the immunological consequences of traumatic insemination via feeding cues.

Not all encounters with pathogens are stochastic and insects can adjust their immune management in relation to cues associated with the likelihood of infection within a life cycle as well as across generations. In this study we show that female insects (bed bugs) up-regulate immune function in their copulatory organ in anticipation of mating by using feeding cues. Male bed bugs only mate with recently fed females and do so by traumatic insemination (TI).

Bedbugs Evolved before Their Bat Hosts and Did Not Co-speciate with Ancient Humans.

All 100+ bedbug species (Cimicidae) are obligate blood-sucking parasites [1, 2]. In general, blood sucking (hematophagy) is thought to have evolved in generalist feeders adventitiously taking blood meals [3, 4], but those cimicid taxa currently considered ancestral are putative host specialists [1, 5]. Bats are believed to be the ancestral hosts of cimicids [1], but a cimicid fossil [6] predates the oldest known bat fossil [7] by >30 million years (Ma).

Social cues trigger differential immune investment strategies in a non-social insect, .

Social immunization (SI) is a horizontal transfer of immunity that protects naive hosts against infection following exposure to infected nestmates. While mainly documented in eusocial insects, non-social species also share similar ecological features which favour the development of group-level immunity. Here, we investigate SI in by pairing naive females with a pathogen-challenged conspecific for 72 h before measuring a series of immune and fitness traits.

Bed bug aggregation on dirty laundry: a mechanism for passive dispersal.

Bed bugs have shown a recent and rapid global expansion that has been suggested to be caused by cheap air travel. How a small, flightless and anachoretic insect that hides within its host's sleeping area manages to travel long distances is not yet clear. Bed bugs are attracted to the odour of sleeping humans and we suggest that soiled clothing may present a similarly attractive cue, allowing bed bugs to 'hitch-hike' around the world after aggregating in the laundry bags of travellers.

Cuticular colour reflects underlying architecture and is affected by a limiting resource.

Central to the basis of ecological immunology are the ideas of costs and trade-offs between immunity and life history traits. As a physical barrier, the insect cuticle provides a key resistance trait, and Tenebrio molitor shows phenotypic variation in cuticular colour that correlates with resistance to the entomopathogenic fungus Metarhizium anisopliae. Here we first examined whether there is a relationship between cuticular colour variation and two aspects of cuticular architecture that we hypothesised may influence resistance to fungal invasion through the cuticle: its thickness and its porosity.

Traumatic insemination in terrestrial arthropods.

Traumatic insemination is a bizarre form of mating practiced by some invertebrates in which males use hypodermic genitalia to penetrate their partner's body wall during copulation, frequently bypassing the female genital tract and ejaculating into their blood system. The requirements for traumatic insemination to evolve are stringent, yet surprisingly it has arisen multiple times within invertebrates. In terrestrial arthropods traumatic insemination is most prevalent in the true bug infraorder Cimicomorpha, where it has evolved independently at least three times.

Human fine body hair enhances ectoparasite detection.

Although we are relatively naked in comparison with other primates, the human body is covered in a layer of fine hair (vellus and terminal hair) at a relatively high follicular density. There are relatively few explanations for the evolutionary maintenance of this type of human hair. Here, we experimentally test the hypothesis that human fine body hair plays a defensive function against ectoparasites (bed bugs).

Male mating rate is constrained by seminal fluid availability in bedbugs, Cimex lectularius.

Sexual selection, differences in reproductive success between individuals, continues beyond acquiring a mating partner and affects ejaculate size and composition (sperm competition). Sperm and seminal fluid have very different roles in sperm competition but both components encompass production costs for the male. Theoretical models predict that males should spend ejaculate components prudently and differently for sperm and seminal fluid but empirical evidence for independent variation of sperm number and seminal fluid volume is scarce.

The ontogeny of immunity in the honey bee, Apis mellifera L. following an immune challenge.

The honey bee, Apis mellifera, is an ideal system for investigating ontogenetic changes in the immune system, because it combines holometabolous development within a eusocial caste system. As adults, male and female bees are subject to differing selective pressures: worker bees (females) exhibit temporal polyethism, while the male drones invest in mating. They are further influenced by changes in the threat of pathogen infection at different life stages.

Ejaculate components delay reproductive senescence while elevating female reproductive rate in an insect.

Increased female reproductive rates usually result in accelerated senescence. This correlation provides a link between the evolutionary conflict of the sexes and aging when ejaculate components elevate female reproductive rates at the cost of future reproduction. It is not clear whether this female cost is manifest as shorter lifespan or an earlier onset or a steeper rate of reproductive senescence.

Bacteriolytic activity in the ejaculate of an insect.

The rapid evolution of ejaculate components is considered to be largely driven by sexual selection. Less attention has been paid to the fact that sperm and microorganisms frequently meet; we consequently predict selection for substances that protect a male's ejaculate. We report, for the first time, bacteriolytic activity (lysozyme-like immune activity [LLA]) in the ejaculate of an animal, the common bedbug Cimex lectularius.

Antimicrobial defense and persistent infection in insects.

During 400 million years of existence, insects have rarely succumbed to the evolution of microbial resistance against their potent antimicrobial immune defenses. We found that microbial clearance after infection is extremely fast and that induced antimicrobial activity starts to increase only when most of the bacteria (99.5%) have been removed.

Introduction. Ecological immunology.

An organism's fitness is critically reliant on its immune system to provide protection against parasites and pathogens. The structure of even simple immune systems is surprisingly complex and clearly will have been moulded by the organism's ecology. The aim of this review and the theme issue is to examine the role of different ecological factors on the evolution of immunity.

Situation exploitation: higher male mating success when female resistance is reduced by feeding.

Optimal male and female mating rates rarely coincide. Males often shift the rate in their favor by either increased signaling and by overcoming female resistance to copulation. The concept of sensory exploitation posits that males produce signals that mimic naturally selected benefits and so deceitfully attract females.

Temporal patterns in immune responses to a range of microbial insults (Tenebrio molitor).

Much work has elucidated the pathways and mechanisms involved in the production of insect immune effector systems. However, the temporal nature of these responses with respect to different immune insults is less well understood. This study investigated the magnitude and temporal variation in phenoloxidase and antimicrobial activity in the mealworm beetle Tenebrio molitor in response to a number of different synthetic and real immune elicitors.

Female-limited polymorphism in the copulatory organ of a traumatically inseminating insect.

Sexual conflict can produce several evolutionary outcomes, one of which is female-limited trait polymorphism. We examine the African bat bug Afrocimex constrictus (Cimicidae), a species where both sexes are subjected to traumatic intromission from males. We show that males possess female genital structures that in related species ameliorate the costs of traumatic insemination.

Estimating the mean abundance and feeding rate of a temporal ectoparasite in the wild: Afrocimex constrictus (Heteroptera: Cimicidae).

The feeding frequency of blood-feeding invertebrates in the wild is largely unknown but is an important predictor for the potential of disease transmission and for estimating the effects blood feeding may have on the host population. We present a method to estimate the mean feeding frequency per individual parasite from the frequency distribution of fed and unfed individuals in the wild. We used three populations of the cimicid species, Afrocimex constrictus, that parasitises the fruit bat Rousettus aegyptiacus.

Functional consequences of blood clotting in insects.

Recent in vitro studies have revealed several important aspects of the biochemical and cellular processes involved in insect blood clotting. However, in vivo empirical studies of the functional consequences of clotting are lacking, despite the role of coagulation in wound-healing, preventing infection, and its homology with vertebrate wound repair. Here we present results of the in vivo effects of haemolymph coagulation and its consequences on the spatial disposition of immune activity, in the American cockroach Periplaneta americana.

Biology of the bed bugs (Cimicidae).

The cimicids, or bed bugs, belong to a highly specialized hematophagous taxon that parasitizes primarily humans, birds, and bats. Their best-known member is the bed bug, Cimex lectularius. This group demonstrates some bizarre but evolutionarily important biology.

Self-harm caused by an insect's innate immunity.

It has been a long-held assumption that the innate immune system of insects causes self-harm when used to combat an immune insult. We show empirically that this assumption is correct. Invertebrate innate immunity relies heavily on effector systems which, on activation, produce cytotoxins that kill pathogens.

Immune function and parasite resistance in male and polymorphic female Coenagrion puella.

Background: Colour polymorphisms are widespread and one of the prime examples is the colour polymorphism in female coenagrionid damselflies: one female morph resembles the male colour (andromorph) while one, or more, female morphs are described as typically female (gynomorph). However, the selective pressures leading to the evolution and maintenance of this polymorphism are not clear. Here, based on the hypothesis that coloration and especially black patterning can be related to resistance against pathogens, we investigated the differences in immune function and parasite resistance between the different female morphs and males.

An advantage for young sperm in the house cricket Acheta domesticus.

We show that males of the house cricket Acheta domesticus regularly expel sperm packages (spermatophores) independently of copulation and at a rate that is not affected by the presence of females. We then show for the first time that the age of sperm affects their likelihood of being stored by females after copulation; younger sperm were overrepresented in the female sperm storage organ and therefore in the sperm population used for fertilization. Our results suggest that the reproductive success of males may increase if they deliver ejaculates with young sperm, and the results may explain why the males of several species are regularly observed to discard ejaculates.

Selection on insect immunity in the wild.

The strength of selection on immune function in wild populations has only been examined in a few vertebrate species. We report the results from a study measuring selection on a key insect immune enzyme, phenoloxidase (PO), in a wild population of the damselfly Calopteryx xanthostoma. We followed individually marked males from the pre-reproductive adult phase and recorded their lifetime mating success.

Dietary glycerol and adult access to water: effects on fecundity and longevity in the almond moth.

The quality of food eaten by larval insects will affect traits such as gamete production, fat reserves, muscle bulk and body size in the adult. Moreover, larvae also depend on high moisture content in the diet for survival. The almond moth (Ephestia cautella) (W.