Extended hypoxia in the alfalfa leafcutting bee, Megachile rotundata, increases survival but causes sub-lethal effects.

Many insects are tolerant of hypoxic conditions, but survival may come at a cost to long-term health. The alfalfa leaf-cutting bee, Megachile rotundata, develops in brood cells inside natural cavities, and may be exposed to hypoxic conditions for extended periods of time. Whether M. rotundata is tolerant of hypoxia, and whether exposure results in sub-lethal effects, has never been investigated. Overwintering M. rotundata prepupae were exposed to 10%, 13%, 17%, 21% and 24% O2 for 11 months. Once adults emerged, five indicators of quality - emergence weight, body size, feeding activity, flight performance, and adult longevity, - were measured to determine whether adult bees that survived past exposure to hypoxia were competent pollinators. M. rotundata prepupae are tolerant of hypoxic condition and have higher survival rates in hypoxia, than in normoxia. Under hypoxia, adult emergence rates did not decrease over the 11 months of the experiment. In contrast, bees reared in normoxia had decreased emergence rates by 8 months, and were dead by 11 months. M. rotundata prepupae exposed to extended hypoxic conditions had similar emergence weight, head width, and cross-thorax distance compared to bees reared in standard 21% oxygen. Despite no significant morphological differences, hypoxia-exposed bees had lower feeding rates and shorter adult lifespans. Hypoxia may play a role in post-diapause physiology of M. rotundata, with prepupae showing better survival under hypoxic conditions. Extended exposure to hypoxia, while not fatal, causes sub-lethal effects in feeding rates and longevity in the adults, indicating that hypoxia tolerance comes at a cost.

Helping factors in a peer-developed support group for persons with head injury, Part 2: Survivor interview perspective.

OBJECTIVES: A follow-up study of the support group discussed in Schwartzberg's 1994 study was conducted to determine participants' perceptions of helping factors in the group. METHOD: Subjects were given a semistructured interview; follow-up interviews were held to ensure accuracy. RESULTS: Eleven helping factors were spontaneously generated from group members' data. These factors were socializing; finding out other people's perspectives and attitudes; expressing thoughts and feelings; receiving support; feeling something in common with other group members; gaining understanding, empathy, and acceptance through listening and sharing; getting perspective by learning about other people's limitations and strengths; helping others; getting help with problem solving; feeling hope, and learning information about brain injury. Members ranked expressing thoughts and feelings as the most helpful factor and finding out other people's perspectives and attitudes as the least helpful. CONCLUSIONS: These results support Schwartzberg's earlier findings, with some exceptions. The factor titles in this study have a broader scope than those in Schwartzberg's study, and not all of the factors determined in this study are completely comparable to Schwartzberg's factors. These findings may indicate that some differences in perspective exist between the participant observer and the survivors in the group studied.