Flying and walking of small insects (Musca domestica) recorded differentially with a standing-wave radar actograph

ABSTRACT. An actograph is described for recording the behaviour of small insects, by using a standing-wave radar system in an enclosed metal cabinet. Experiments show that the system produces an output frequency dependent only on the speed of movement of the subject. By filtering the signal electrically into components below and above 5 Hz, walking and flying of adult Musca domestica could be separately recorded. Each filter is followed by a level-comparator with hysteresis. Activity causing signal to cross the hysteresis-band is recorded as an event on a digital counter, and also integrated or summed to be displayed as a stepped-integral or bar-chart of total distance covered by the subject in each counting period. The energy-density of the radar can be kept very low, so that possible influence on the subject is minimal. The detector is remote from the box containing the subject, giving great flexibility in container design, so that the apparatus is ideally suited to the study of environmental factors.     

Further studies on the occurrence of freshwater Microturbellaria in the British Isles

Five new British records of freshwater Microturbellaria are illustrated: Gieysztoria infundibuliformis, Castrada lanceola, Castrada neocomensis, Castrada viridis and Strongylostoma elongatum. These species together with a new species, Macrostomum johni described by Young (1972), are woven into the fabric of the existing key for the group (Young, 1970). All six species were recorded from the littoral zone of lakes in Caernarvonshire, N. Wales. The times of the recordings are indicated.     

Incubation temperature in the Australasian Gannet Moms senator

Gannets (Sulidae) and some other pelecaniforms incubate their eggs under the webs of their totipalmate feet. These species have a wide latitudinal distribution from tropics to subarctic, but little is known of the incubation temperatures attained. I measured egg temperatures of the Australasian Gannet Morns serrator at Cape Kidnappers, New Zealand, employing a data logger to obtain records every 15 min for day-long sample periods at undisturbed nests. Egg surface temperatures were relatively stable and little affected by ambient temperature. Mean surface temperature of natural eggs was 34.9^oC for samples taken during the first 4 days of incubation, but this then increased and stabilized at 36.5^oC. Internal temperature of pipped eggs was about 1^oC higher, attributable to embryonic heat production. Upper surface temperature of eggs kept in a fixed position was about 2^oC below deep adult body temperature (40.3^oC), suggesting heat is transferred directly from the body through the feet. Clutch size does not appear to be limited by an inability to warm two eggs. These results are in general agreement with measurements from other web incubators and are well within the range for species with conventional brood patch incubation.     

Molecular Characterization of a Barley Gene Induced by Cold Treatment

A cDNA library was made from low positive temperature (6 ?C/2?C) grown barley shoot meristems. Several genes which are differentiallyexpressed, as measured by mRNA abundance, were selected fromthe library using a differential screen. This paper reportsan analysis of in vivo expression in several cultivars, theDNA sequence, copy number and chromosomal location of one gene(BLT14). In addition, genomic restriction fragment length polymorphismfor this gene in the 10 most widely UK-grown spring and 9 mostwidely UK-grown winter barley cultivars is analysed. Key words: Hordeum vulgare, low temperature, RFLP, differential expression, cDNA sequence     

Sexual swarms in Daphnia magna, a cyclic parthenogen

SUMMARY. Dense swarms were observed in a population of Daphnia magna (Crustacea: Cladocera). The swarms appeared during a sexual period in which females were abundant but males were rare. Each swarm contained several males and large numbers of 'imminently sexual' females, a class of females that was rare except in the swarms. This implies that both sexes respond to attractant stimuli, and that the female response occurs only during a brief critical phase in the ovarian cycle.     

Morphometric analysis of interspecific and microgeographic variation of crayfish from a Mexican cave

Two undescribed species of Procambarus crayfish (Crustacea, Decapoda) inhabit the subterranean stream running in the recently explored Cueva de Los Camarones, Chiapas, Mexico. Individuals ranging from dark, robust, large-eyed forms with an epigean mien to pale, comparatively slender, microphthalmic ones resembling related troglobites were found, but only the extremes could be distinguished visually. Evolutionary relationships among individuals were investigated morphometrically by means of multivariate analysis'on 14 body dimensions. These analyses revealed a significant discontinuity between the two species, mainly determined by the shape of the rostrum, chelae and telson. The occurrence of a few aberrant phenotypes may indicate the existence of some gene flow between the two species.
Microgeographic variation was demonstrated within the less cavernicolous species. The characters involved were the same as those that discriminate between the two species. These results are compared with allozymic data presented in a parallel paper and the role of genie introgression and environmental induction are discussed.     

The effect of heat treatment and meristem-tip culture on June Yellows in strawberry

Because there is some evidence that June Yellows (JY) of strawberry may be caused by a pathogenic agent, combinations of heat treatment and meristem-tip culture that are known to eliminate some viruses from tissues were used in attempts to cure affected Cambridge Favourite strawberry plants from JY. None of 397 propagants derived from JY-affected plants subjected to various combinations of these treatments were freed from JY. Indeed, all propagants showed more obvious JY symptoms than the parent plants from which they were derived, suggesting that such treatments may be useful for detecting incipient JY in symptomless strawberry stocks.