Warming, but not infection with Borrelia burgdorferi, increases off-host winter activity in the ectoparasite, Ixodes scapularis.

Warming winters will change patterns of behaviour in temperate and polar arthropods, but we know little about the drivers of winter activity in animals such as ticks. Any changes in behaviour are likely to arise from a combination of both abiotic (e.g.

Manduca sexta caterpillars parasitized by the wasp Cotesia congregata stop chewing despite an intact motor system.

The parasitic wasp Cotesia congregata suppresses feeding in its host, the caterpillar Manduca sexta, during specific periods of wasp development. We examined both feeding behaviour and the neurophysiology of the mandibular closer muscle in parasitized and unparasitized control M. sexta to determine how the wasp may accomplish this.

Muscle in the caterpillar Manduca sexta responds to an immune challenge, but at a cost, suggesting a physiological trade-off.

Although skeletal muscle is a specialized tissue that provides the motor for movement, it also participates in other functions, including the immune response. However, little is known about the effects of this multitasking on muscle. We show that muscle loses some of its capacity while it is participating in the immune response.

Female ticks (Ixodes scapularis) infected with Borrelia burgdorferi have increased overwintering survival, with implications for tick population growth.

The tick, Ixodes scapularis, vectors pathogens such as Borrelia burgdorferi, the bacterium that causes Lyme disease. Over the last few decades I. scapularis has expanded its range, introducing a novel health threat into these areas.

From perplexing to predictive: are we ready to forecast insect disease susceptibility in a warming world?

Insects are critical to our ecosystems, but we do not fully understand their future in our warming world. Rising temperatures are affecting insect physiology in myriad ways, including changes to their immune systems and the ability to fight infection. Whether predicted changes in temperature will contribute to insect mortality or success, and the role of disease in their future survival, remains unclear.

Balsam fir (Abies balsamea) needles and their essential oil kill overwintering ticks (Ixodes scapularis) at cold temperatures.

The blacklegged tick, Ixodes scapularis, vectors Borrelia burgdorferi, a bacterium that causes Lyme Disease. Although synthetic pesticides can reduce tick numbers, there are concerns about their potential effects on beneficial insects, such as pollinators. Plant-based pest control agents such as essential oils could provide an alternative because they have low environmental persistency; however, these products struggle to provide effective control.

How insects protect themselves against combined starvation and pathogen challenges, and the implications for reductionism.

An explosion of data has provided detailed information about organisms at the molecular level. For some traits, this information can accurately predict phenotype. However, knowledge of the underlying molecular networks often cannot be used to accurately predict higher order phenomena, such as the response to multiple stressors.

High-Stakes Decision-Making by Female Crickets (): When to Trade In Wing Muscles for Eggs.

AbstractResource-intensive traits, such as dispersal and reproduction, can be difficult to express simultaneously because of resource limitations. One solution is to switch between resource-intensive behaviors. Such phenotypic plasticity is one strategy that organisms use to funnel resources from one expensive trait to another.

Friend or foe? Effects of host immune activation on the gut microbiome in the caterpillar .

For many animals, the gut microbiome plays an essential role in immunity and digestion. However, certain animals, such as the caterpillar , do not have a resident gut microbiome. Although these animals do have bacteria that pass through their gut from their natural environment, the absence of such bacteria does not reduce growth or survival.

Animals have a Plan B: how insects deal with the dual challenge of predators and pathogens.

When animals are faced with a life-threatening challenge, they mount an organism-wide response (i.e. Plan A).

Listening to your gut: immune challenge to the gut sensitizes body wall nociception in the caterpillar .

Immune-nociceptor connections are found in animals across phyla. Local inflammation and/or damage results in increased nociceptive sensitivity of the affected area. However, in mammals, immune responses far from peripheral nociceptors, such as immune responses in the gut, produce a general increase in peripheral nociceptive sensitivity.

Turning your victim into a collaborator: exploitation of insect behavioral control systems by parasitic manipulators.

Some parasites manipulate host behavior by exploiting the host's behavioral control networks. This review explores two examples of this approach using parasites from opposite ends of the size spectrum, that is, viruses and parasitic insects. The first example explores the use of the gene (egt) by some baculoviruses to deactivate the hormone 20-hydroxyecdysone.

Immunity for nothing and the eggs for free: Apparent lack of both physiological trade-offs and terminal reproductive investment in female crickets (Gryllus texensis).

Should females alter their reproductive strategy when attacked by pathogens? Two hypotheses provide opposite predictions. Terminal reproductive investment theory predicts that reproduction should increase when the risk of death increases. However, physiological trade-offs between reproduction and immune function might be expected to produce a decrease in reproduction during a robust immune response.

Eating when ill is risky: immune defense impairs food detoxification in the caterpillar .

Mounting an immune response consumes resources, which should lead to increased feeding. However, activating the immune system reduces feeding (i.e.

Predator exposure-induced immunosuppression: trade-off, immune redistribution or immune reconfiguration?

Although predator exposure increases the risk of wound infections, it typically induces immunosuppression. A number of non-mutually exclusive hypotheses have been put forward to explain this immunosuppression, including: trade-offs between the immune system and other systems required for anti-predator behaviour, redistribution of immune resources towards mechanisms needed to defend against wound infections, and reconfiguration of the immune system to optimize defence under the physiological state of fight-or-flight readiness. We tested the ability of each hypothesis to explain the effects of chronic predator stress on the immune system of the caterpillar Predator exposure induced defensive behaviours, reduced mass gain, increased development time and increased the concentration of the stress neurohormone octopamine.

The stress response and immune system share, borrow, and reconfigure their physiological network elements: Evidence from the insects.

The classic biomedical view is that stress hormone effects on the immune system are largely pathological, especially if the stress is chronic. However, more recent interpretations have focused on the potential adaptive function of these effects. This paper examines stress response-immune system interactions from a physiological network perspective, using insects because of their simpler physiology.

The parasitic wasp Cotesia congregata uses multiple mechanisms to control host (Manduca sexta) behaviour.

Some parasites alter the behaviour of their hosts. The larvae of the parasitic wasp Cotesia congregata develop within the body of the caterpillar Manduca sexta During the initial phase of wasp development, the host's behaviour remains unchanged. However, once the wasps begin to scrape their way out of the caterpillar, the caterpillar host stops feeding and moving spontaneously.

Stress responses sculpt the insect immune system, optimizing defense in an ever-changing world.

A whole organism, network approach can help explain the adaptive purpose of stress-induced changes in immune function. In insects, mediators of the stress response (e.g.

Sickness behaviour in the cricket Gryllus texensis: Comparison with animals across phyla.

Immune activation alters behaviour (i.e. sickness behaviour) in animals across phyla and is thought to aid recovery from infection.

Reconfiguration of the immune system network during food limitation in the caterpillar Manduca sexta.

Dwindling resources might be expected to induce a gradual decline in immune function. However, food limitation has complex and seemingly paradoxical effects on the immune system. Examining these changes from an immune system network perspective may help illuminate the purpose of these fluctuations.

Parasitic aphrodisiacs: manipulation of the hosts' behavioral defenses by sexually transmitted parasites.

Animals have a number of behavioral defenses against infection. For example, they typically avoid sick conspecifics, especially during mating. Most animals also alter their behavior after infection and thereby promote recovery (i.

The effects of stress hormones on immune function may be vital for the adaptive reconfiguration of the immune system during fight-or-flight behavior.

Intense, short-term stress (i.e., robust activation of the fight-or-flight response) typically produces a transient decline in resistance to disease in animals across phyla.

A viral aphrodisiac in the cricket Gryllus texensis.

We identified the insect iridovirus IIV-6/CrIV as a pathogen of the cricket Gryllus texensis using electron microscopy (EM) and polymerase chain reaction (PCR) analysis. EM showed that the virus attacks the fat body, an organ important for protein production, immune function and lipid storage. During infection the fat body hypertrophied, but egg production withered, leaving the lateral oviducts empty of eggs; the females were effectively sterile.

The behavioural effects of predator-induced stress responses in the cricket (Gryllus texensis): the upside of the stress response.

Predator-induced stress responses are thought to reduce an animal's risk of being eaten. Therefore, these stress responses should enhance anti-predator behaviour. We found that individual insects (the cricket Gryllus texensis) show reliable behavioural responses (i.