Sound-producing mechanisms of Buenoa macrotibialis Hungerford (Hemiptera: Notonectidae)

In Buenoa macrotibialis, experimental results indicate that the stridulatory mechanism composed of the tibial combs and rostral prongs is involved in producing trills, chirps, and dart-chirps; the femoral ridges and coxal peg mechanism is involved in producing grasping-chirps and cleaning-chirps; and the forelegs probably stridulate in unison. Either half of the tibial comb can produce trills, chirps and dart-chirps, though these signals are usually altered from normal. Both combs are normally involved in signal production, but one tibial comb can produce these signals with only slight alterations. The frequency spectrum of acoustic signals of macrotibialis is generated by resonation, not by rate of stridulation. The body proper, or some part(s) thereof, apparently functions as the resonator. Vibrations created by stridulation of the tibial comb-rostral prong and femoral ridge-coxal peg mechanisms probably are transmitted to the resonator by the rostrum and/or coxae.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22083/1/0000507.pd

Exploitation of environmental noise by an araneophagic assassin bug

Predatory arthropods that specialize in invading webs and preying on the resident spiders ('araneophagic predators') face special challenges. As webs are exceedingly good at transmitting vibrations, it is difficult for a web invader to move through the web and remain undetected by the spider. An araneophagic predator that generates vibrations in the web may risk prey escaping or even counterattacking. To increase the chances of an undetected approach, predators may exploit episodes of environmental noise to approach, while their prey's ability to detect them is compromised ('opportunistic smokescreen behaviour'). Here we provide the first experimental evidence of convergent opportunistic smokescreen behaviour in an araneophagic insect, Stenolemus bituberus Stål (Reduviidae), which preys on web-building spiders. We tested how two common types of environmental noise, wind and localized vibrations in the web, influence the predatory behaviour and success of assassin bugs when hunting spiders. We found that assassin bugs were more likely to catch the spider in the presence of wind. During episodes of environmental noise, assassin bugs stepped more often and walked in a more continuous manner, apparently exploiting the opportunity to approach while the prey's sensory system is less able to detect the predator. Changes in predatory behaviour in the presence of environmental noise were not evident when S. bituberus was in an unoccupied spider web. This supports our hypothesis that noise-related timing of behaviour reflects decisions made as part of a predatory strategy, rather than responses to physical disturbance.6 page(s

Aggressive Mating as a Tragedy of the Commons in the Water Strider Aquarius remigis

The tragedy of the commons usually refers to the Overexploitation of resources such as food or water. Here, we show in a laboratory study that competition among males for females can also result in a tragedy of the commons\u27 situation. Male water striders (Aquarius remigis) vary widely in their aggressiveness toward pursuing females. The most aggressive males prevent females from feeding and cause them to leave the water surface, where they are unavailable to all males. Groups of nonaggressive males are collectively three times more fit than groups of hyperaggressive males, but hyperaggressive males are more successful than nonaggressive males within mixed groups. This is the classic tragedy of the commons\u27 situation, and it is likely to occur in many species that exhibit sexual conflict. We have also shown that individual differences in male aggression are stable across time and are not influenced by food or light regime, although all individuals become nonaggressive in the presence of fish predators

Zidovudine Adherence in Persons with AIDS: The Relation of Patient Beliefs About Medication to Self-Termination of Therapy

OBJECTIVE: To examine the relation of patient beliefs about medication usage and adherence to zidovudine (ZDV) therapy in persons with AIDS. DESIGN: Face-to-face interviews were used to determine attitudes of persons with AIDS toward ZDV and other prescribed medications, history of ZDV usage, and sociodemographics. SETTING: A public hospital infectious disease clinic, an AIDS day care program, and an inpatient unit in a voluntary hospital where care was provided cooperatively by staff and an informal–care partner. PATIENTS/PARTICIPANTS: One hundred forty-one people with the acquired immunodeficiency syndrome agreed to be reinterviewed as part of a longitudinal, New York City–based study examining outcomes related to quality of life. Initial recruitment procedures were to approach all active AIDS patients at each of the three sites between January and July of 1992; reinterviews, which were conducted an average of 6 months later, occurred from mid-1992 through May of 1993. MEASUREMENTS AND MAIN RESULTS: The Zidovudine Drug Attitude Inventory was used to assess subjective feelings and attitudes concerning ZDV and prescribed medications in general. Respondents were grouped into five categories on the basis of their ZDV usage history: (1) “short-term” users (i.e., those who had been taking ZDV for 25 months or less); (2) “long-term” users (i.e., those who had been taking ZDV for more than 25 months); (3) self-terminated users; (4) doctor-terminated users; and (5) never users. Long-term users were likely to view ZDV as an illness prophylactic. In contrast, self-terminated users and never users were most likely to believe that ZDV caused adverse side effects and that medicine need not be taken as prescribed. CONCLUSIONS: Patients’ beliefs about ZDV were significantly associated with adherence-related behavior. In particular, those who had self-terminated ZDV treatment believed that taking the drug was harmful, were skeptical of its ability to prevent illness, and felt that physicians’ directives about medication usage in general could be disregarded. These findings highlight the importance of educating patients about ZDV and of establishing regular patient-clinician exchanges concerning patients’ experiences with and beliefs concerning ZDV