Dispersal of the lycaenid Plebejus argus in response to patches of its mutualist ant Lasius niger

We examined the movement rates of individuals of an obligate myrmecophilous butterfly, Plebejus argus (Lycaenidae: Lepidoptera), in relation to a patch of its mutualist ant, Lasius niger . Marked male and female P. argus from local (resident), fragmented and continuous populations were released into and away from (>100m) a patch of L. niger , and subsequently searched for in a 500×500 m area. Recaptures of males and females from all populations were strongly associated with the target patch of mutualist ants. First day recapture displacements were significantly higher for releases away from the target patch for males, but not for females. Mutualist ant presence was shown to be more important than nectar source density in determining persistence of P. argus in release squares. There was no significant difference in displacement distances or recapture frequencies (standardised for search effort) in the target patch of individuals from local (resident of target patch), fragmented and continuous populations. The recapture frequency in the target patch of males from the local population released outside the target patch was greater than expected from a null model of random straight line movement, suggesting non-random (systematic or orientated) search behaviour. The number of males remaining in the target patch following release into the target patch was greater than expected from a simple diffusion model, suggesting a behavioural response to patch boundaries or other cues related to the patch.     

Humidity‐terminated diapause in the tropical braconid parasitoid Microplitis demolitor

1. Microplitis demolitor, a solitary braconid parasitoid of Helicoverpa armigera and Helicoverpa punctigera, uses an increase in relative humidity to signal the end of diapause and the re‐establishment of direct development. 2. Photoperiod and temperature changes appear not to have a direct influence on the duration or termination of diapause in this species. 3. Once diapause termination is signalled, the adult parasitoids emerge approximately 38 days later. 4. The cue for diapause termination in M. demolitor is different from that used by its hosts and ensures that the parasitoid emerges to find a population of nonmigrating hosts. 5. It appears that the cocoon surrounding the diapausing parasitoid plays a role in diapause termination; parasitoids emerge earlier from diapause if the cocoon is removed but the weight of the intact cocoon does not appear to influence the length of time the parasitoid is in diapause.     

Long-term effects of gamma-irradiation on cultured human thyroid cells

When differentiated 15-day-old cultures of human thyroid glands were irradiated they exhibited a high degree of radiosensitivity, an absence of split-dose recovery, an increase in the number of non-senescent colonies observed over four passages, increased focus formation on the confluent postirradiation monolayer and a shift in the isozyme pattern of LDH towards the anaerobic form (LD 5). The effects are similar to those previously observed for irradiated sheep thyroid cultures, but occurred at lower radiation doses.