Getting lost: the fungal hijacking of ant foraging behaviour in space and time

Many parasites have evolved strategies to exploit host behaviour for successful transmission. Ophiocordyceps manipulations of carpenter ant behaviour represent an evident example. Manipulated ants are coerced to ascend vegetation and clamp down their mandibles in a stereotypical ‘death-grip’ bite. The fungus then kills the ant, sprouts a stalk and releases infective spores. Research has focused on this final manipulation, leaving the subtler behavioural changes prebiting largely unexplored. Field and transcriptome studies found that the host circadian clock, olfaction and communication may be disrupted, which suggests that the fungus is affecting ant foraging activity and effectivity. To test this hypothesis, we investigated if the foraging behaviour of Camponotus floridanus ants is notably affected during early stage Ophiocordyceps infection. Specifically, we used a maze to quantify foraging patterns and trail optimization. Moreover, by comparing infected individuals to healthy ants and those infected with nonmanipulating Beauveria bassiana, we aimed to distinguish between nonmanipulator-specific and manipulator-specific changes. We found that Ophiocordyceps-infected ants became arrhythmic in their activity patterns, were less likely to participate in effective foraging efforts and seemed less able to communicate with their nestmates compared to healthy ants. We hypothesize that these changes in behaviours are adaptive to Ophiocordyceps transmission since they reduce the chance of aggressive interference by nestmates. Indeed, Beauveria-infected individuals remained rhythmic; however, they also seemed to lose their ability to forage optimally, suggesting that, in part, these changes in behaviour might be mere general behavioural side-effects of infection. Overall, this study informs future work on parasitic strategies underlying host manipulation, other parasite–host interactions and the behavioural ecology of infectious diseases in general

Learn To Meditate: Breath In Calm, Breath Out Stress

The high stress and anxiety levels reported by college students are a concern for many students pursuing a degree. Meditation is a research-supported method of reducing stress and anxiety. While many students would like to learn how to meditate, it is difficult to do so without some form of instruction. The present study uses behavioral fading procedures to gradually diminish the use of verbal and audio prompts in a guided meditation program to eventually transfer stimulus control from the prompts to the participants themselves to meditate successfully on their own. The goals of the present study were to increase the probability of maintaining a frequent practice of meditation, and to increase the participants’ success in meditating. Success in meditating was defined by the participants’ decrease in heart rate, along with the number of fidgeting behaviors they emitted in each session. The participants (n=6) were introduced to the fading procedures at different times, using a multiple baselines across participants (MBAP) design. Physically recorded measures indicate that the program decreased participants’ overall resting heart rate as well as their heart rate within sessions, fidgeting behaviors during meditation, and their self-reported anxiety levels. Further, some of the participants persisted with their meditation practice after the study was terminated. However, overall stress levels appeared to remain the same across the program. These results imply that a MBAP design that uses fading procedures for this limited amount of time is effective in decreasing heart rate and anxiety levels, but not stress levels

Getting lost: the fungal hijacking of ant foraging behaviour in space and time

Many parasites have evolved strategies to exploit host behaviour for successful transmission. Ophiocordyceps manipulations of carpenter ant behaviour represent an evident example. Manipulated ants are coerced to ascend vegetation and clamp down their mandibles in a stereotypical ‘death-grip’ bite. The fungus then kills the ant, sprouts a stalk and releases infective spores. Research has focused on this final manipulation, leaving the subtler behavioural changes prebiting largely unexplored. Field and transcriptome studies found that the host circadian clock, olfaction and communication may be disrupted, which suggests that the fungus is affecting ant foraging activity and effectivity. To test this hypothesis, we investigated if the foraging behaviour of Camponotus floridanus ants is notably affected during early stage Ophiocordyceps infection. Specifically, we used a maze to quantify foraging patterns and trail optimization. Moreover, by comparing infected individuals to healthy ants and those infected with nonmanipulating Beauveria bassiana, we aimed to distinguish between nonmanipulator-specific and manipulator-specific changes. We found that Ophiocordyceps-infected ants became arrhythmic in their activity patterns, were less likely to participate in effective foraging efforts and seemed less able to communicate with their nestmates compared to healthy ants. We hypothesize that these changes in behaviours are adaptive to Ophiocordyceps transmission since they reduce the chance of aggressive interference by nestmates. Indeed, Beauveria-infected individuals remained rhythmic; however, they also seemed to lose their ability to forage optimally, suggesting that, in part, these changes in behaviour might be mere general behavioural side-effects of infection. Overall, this study informs future work on parasitic strategies underlying host manipulation, other parasite–host interactions and the behavioural ecology of infectious diseases in general

Testosterone dose-response relationships in hysterectomized women with or without oophorectomy

ObjectiveThis study aims to determine the dose-dependent effects of testosterone on sexual function, body composition, muscle performance, and physical function in hysterectomized women with or without oophorectomy.MethodsSeventy-one postmenopausal women who previously underwent hysterectomy with or without oophorectomy and had total testosterone levels less than 31 ng/dL or free testosterone levels less than 3.5 pg/mL received a standardized transdermal estradiol regimen during the 12-week run-in period and were randomized to receive weekly intramuscular injections of placebo or 3, 6.25, 12.5, or 25 mg of testosterone enanthate for 24 weeks. Total and free testosterone levels were measured by liquid chromatography-tandem mass spectrometry and equilibrium dialysis, respectively. The primary outcome was change in sexual function measured by the Brief Index of Sexual Functioning for Women. Secondary outcomes included changes in sexual activity, sexual distress, Derogatis Interview for Sexual Functioning, lean body mass, fat mass, muscle strength and power, and physical function.ResultsSeventy-one women were randomized; five groups were similar at baseline. Sixty-two women with analyzable data for the primary outcome were included in the final analysis. The mean on-treatment total testosterone concentrations were 19, 78, 102, 128, and 210 ng/dL in the placebo, 3-mg, 6.25-mg, 12.5-mg, and 25-mg groups, respectively. Changes in composite Brief Index of Sexual Functioning for Women scores, thoughts/desire, arousal, frequency of sexual activity, lean body mass, chest-press power, and loaded stair-climb power were significantly related to increases in free testosterone concentrations; compared with placebo, changes were significantly greater in women assigned to the 25-mg group, but not in women in the lower-dose groups. Sexual activity increased by 2.7 encounters per week in the 25-mg group. The frequency of androgenic adverse events was low.ConclusionsTestosterone administration in hysterectomized women with or without oophorectomy for 24 weeks was associated with dose and concentration-dependent gains in several domains of sexual function, lean body mass, chest-press power, and loaded stair-climb power. Long-term trials are needed to weigh improvements in these outcomes against potential long-term adverse effects

Pathways From HIV-Related Stigma to Antiretroviral Therapy Measures in the HIV Care Cascade for Women Living With HIV in Canada

Associations between HIV-related stigma and reduced antiretroviral therapy (ART) adherence are widely established, yet the mechanisms accounting for this relationship are underexplored. There has been less attention to HIV-related stigma and its associations with ART initiation and current ART use. We examined pathways from HIV-related stigma to ART initiation, current ART use, and ART adherence among women living with HIV in Canada