Factors influencing nuisance blackfly (Diptera: Simuliidae) activity in the Scottish Highlands

Abstract. The nuisance activity of blackflies (Diptera: Simuliidae) was investigated in several habitats on Speyside, near Kincraig (57^o08'N, 3^o56'W), Invernesshire, in central Scotland during May-October 1987-89.
The main blackfly species caught landing/biting on humans were Simulium reptans, S. argyreatum, S. variegetum and the S. tuberosum complex, in order of prevalence. Blackfly biting activity occurred from mid-May to mid-September. Numbers of female blackflies attracted to volunteers were correlated with their body posture, habitat and the season. Overall, Simulium activity was greatest in mixed birch/juniper forest, least in spruce plantations and at intermediate levels on pasture, moorland and in Scots Pine forest.
Compared with an adult, a child experienced twice as many Simulium bites per hour (12.2 v 6.3) in the birch forest. On the child's body, 69% of blackfiies landed on the head, neck and back, whereas the majority landed on the legs (48%) and arms (28%) of adults. Bending over, especially during the exertion of gardening, was more attractive to anthropophilic blackfiies than standing or kneeling.     

A new branchipodid genus and species (Crustacea: Branchiopoda: Anostraca) from South Africa

Rhinobranchipus martensi gen. et sp. nov. (Anostraca: Branchipodidae) was collected from a shallow temporary pool in the surroundings of Grahamstown (Cape Province, South Africa) (33^o18'S, 26^o32'E). Rhinobranchipus shares partial fusion of the chitinized basal parts of the male antennae, the so-called clypeus, with other Branchipodidae. The new genus is distinguished from confamilial genera by the morphology of the basal part of the penes. The new species, known from its type locality only, should be considered endangered, if it has not already become extinct as a result of recent modifications of its habitat.     

The influence of environmental parameters on the bacterial populations of thermal springs in West Bengal, India

The physico-chemical characteristics and the bacterial populations of three thermal springs in West Bengal have been examined. The springs range in temperature from 42^o C (Saubhagya Kund) to 65^o C (Agni Kur.d). The levels of carbonate and bicarbonate alkalinity, total hardness and the ppm of chloride, phosphate and silicate as well of dissolved oxygen were measured at monthly intervals. Estimates of the bacterial populations were obtained from cultures. Water samples incubated at 37^oC for enumeration of mesophilic microbes, at 50^o C for thermo-tolerant bacteria and at 60^o for strict thermophiles. Tests for coliform organisms were carried out at 37^o C and at 50^o C.
All three springs show seasonal variation in their physico-chemical characteristics and in their bacterial populations. The cooler springs have large populations of mesophilic and thermotolerant bacteria but fewer thermophilic types. In the two hot springs (Saubhagya Kund and Swetganga), the differences of mean bacterial populations observed between 37^o and 50"C and between 50^o and 60^o C are highly significant ( P < 0.01), in the third (Agni Kund) the differences are also significant ( P < 0.01) but the population showed a rising trend with the temperature. Of the biotic and abiotic factors which could be involved in the observed seasonal variation in the bacterial populations, only the fluctuations in the phosphate levels were found to show a significant correlation (0.001 < P < 0.01).     

Thermoregulation in four Australian lizards of the genus Egernia (Sauria: Scincidae)

Mean thermal preferenda for the head and body were found to be similar in Egernia whitei, E. cunninghami, and E. bungana (range in T_H= 33.6^o -33.8^o C; range in T_B= 34.0^o-35.3^oC). However, those for E. majors were significantly lower (T_H= 31.1^o C, T_B=32.9^oC). Significant differences were found between mean head and body preferred temperatures in E. cunninghami and E. major. Higher temperatures were tolerated by the body than the head in all four species. Gaping was not observed to occur prior to cessation of respiration in any of the four species during radiant or solar heating. Based upon thermal preferenda and critical thermal maxima data, thermal safety margins for body temperature were calculated for E. whitei and E. cunninghami Postural orientation to the sun's rays increased and decreased heat gain. The seeking of shade was the most effective method employed by all four species for reducing head and body temperature.     

Floristic composition, structure, and dynamics of an upper montane rain forest in Southern Ecuador

Two 1 ha plots of undisturbed upper montane rain forest in southern Ecuador were sampled for all trees with a dbh ≥ 5 cm. An extraordinarily high α-diversity for a forest near treeline is described. The "non-ridge forest" plot at 2900 m elevation has 75 species and 28 families ha^-1 and is believed to represent an advanced stage of succession whereas, the "ridge forest" plot at 2700 m elevation with 90 species and 38 families ha^-1 has a more rapid turn-over rate probably due to a more unstable environment. Downslope forces (soil creep) are discussed as a possible cause for 32–44% of all trees being inclined more than 30° in the moderately steep terrain (average slope 20° in both study plots). The plot of "non-ridge forest" is characterized by a much greater biomass whether expressed as basal area (44 m² versus 15 m²) or stem volume (214 m³ versus 52 m³), while the density is equally high (2310 versus 2090 trees ha^-1) in both plots. Families with Family Importance Value >25 / ha^-1 are Clusiaceae, Cunoniaceae, Melastomataceae, Myrsinaceae, and Ternstroemiaceae.     

THE CHARACTERS OF SOME COLIFORM BACTERIA ISOLATED FROM GRASS AND GRASS SILAGE

The species of coliform bacterium predominant on fresh grass was found to be a capsulated type growing well at 30^o C. but unable to grow at 37^o C. For this reason it will not be detected by the presumptive test in bile salt-lactose broth at 37^o C. The name Bacillus (Aerebacter) aerogenes graminis is proposed for this species.
It is possible that conforms of the above type contribute to a small extent to the initial fermentation of the silage. Those coliforms giving the presumptive test at 37^o C. were found in such small numbers in the silage investigated that their influence was concluded to be negligible.
This work forms part of some research carried out under grant from the Research Council of Imperial Chemical Industries, Ltd., to whom the authors wish to make due acknowledgement. Valuable help was also received from Dr S. J. Watson, who supplied samples of grass and silage-     

The optics of tsetse fly eyes in relation to their behaviour and ecology

Abstract The visual acuity of two species of tsetse flies, Glossina morsitans morsitans Westw. and Glossina pallidipes Aust., was investigated. Male G. morsitans eyes have an acute zone in the forward region, with large hexagonal lenses (mean minimum diameter, D=33, SE±0.7 μm), relatively small interommatidial angle (Δ(φ=1.08^o) and angular receptive field of individual ommatidia (Δp) of not less than 1.14^o. A narrow band of square lenses, with intermediate diameter and Δφ, merges with smaller hexagonal lenses in the periphery (24±0.7 μm), with relatively large interommatidial angle (Δφ=3.7^o) and small angular receptive field (Δp = c. 1.6^o). G.pallidipes eyes are similar, except that the lenses in the acute zone are larger than those of G.morsitans , in proportion to their larger body size. Female eyes are not significantly different from male eyes, except that they have a narrower region of binocular overlap (maximum for males = 24^o, for females = 18^o). The eye parameter (p=DΔφ) in the acute zone of male G.morsitans = 0.62, and in the peripheral zone = 1.56. These relatively high values are consistent with fast flight, visual detection of drift due to low wind speeds, mating chases and discrimination of cryptic host animals at high light intensities. The extended region of binocular overlap in males may serve as an early warning system of the approach of potential females. From our estimates, tsetse flies ought to be able to detect small objects against the sky c. 30 min before sunrise and after sunset, and to use their peripheral vision perhaps 15 min earlier and later than this.     

Factors affecting nest site selection and nesting success in the Common Eider Somateria mollissima

Nesting site selection and nesting success in Common Eiders Somateria mollissima were studied over a 3-year period (1991–1993) in the Mast River delta (58^o24'N, 94^o24'W), 40 km east of Churchill, Manitoba, Canada. Eiders preferentially nested on islands that had incubating Lesser Snow Geese Anser caerulescens caerulescens on them; this effect was also seen between years on the same islands. Eiders which nested on islands with geese had a reduced chance of having eggs taken by predators during egg-laying and had a greater chance of hatching once incubation had begun, independent of the number of other eiders nesting on the island. The distance to a goose nest was less in nests which did not lose eggs prior to incubation than in those which did, but there was no difference in the distance to a goose nest in eider clutches which did or did not hatch. Artificial eider eggs placed closer to goose nests had a lower probability of being predated than those placed farther away. Nests on islands farther up the river and farther from the mainland had higher nesting success, presumably because these nesting islands were inaccessible to Arctic Foxes Alopex lagopus.     

Initial checklist of fishes from Henderson Island, Pitcairn Group

Notes are given on the presence and distribution of reef fishes at Henderson Island (24^o21'S, 128^o19'W) from two separate visits in 1971 and 1991. Limited collections were made in 1971, whilst 1991 records are based on confirmed sightings and in situ photographs. 183 species from 49 families are listed, with museum numbers and lengths being given for collected specimens. This is thought to represent 80–90% of species present. The family with the greatest representation is the Labridae with 21 species. Only 31% of species appear to be shared with neighbouring Ducie Atoll, 390 km to the east, from where 138 species have been recorded, though this low percentage may simply reflect the greater recording effort undertaken at Henderson. Levels of endemism in the Pitcairn Group as a whole appear low (<2%).     

Spatial organization and population density of the fish community of the litter banks within a central Amazonian blackwater stream

Results of a study of the fish community of the leaf litter banks in the lower reaches of the Taruma-Mirim, a small central Amazonian stream is presented. The Taruma-Mirim is an acidic, blackwater, forest stream which flows through igapo forest and enters the Rio Negro close to Manaus. The commonly held view that these blackwaters hold an impoverished ichthyofauna is challenged. The studied litter banks hold about 20 species of fish, all of which were found to live within distinct subregions of the habitat. Average fish density was about 100 individuals m⁻². Absolute population sizes were found to be remarkably small; within a 200 m² area the most abundant species had a population size of about 10⁴ and the least abundant <10² individuals. It is argued that high species richness linked to specialized habitat requirements and small population size indicates considerable population stability. The factors leading to the evolution of such species richness are discussed.     

Calling behaviour in M.convecta females under different temperature and photoperiodic conditions

Abstract. . The effects of temperature and photoperiod on calling behaviour in females of the Australian common armyworm, Mythimna corwecta (Walker) (Lepidoptera: Noctuidae), were studied in the laboratory. Age at first calling was greater at 15 and 20^oC compared with 25^oC, but there were no significant differences between 25 and 30^oC. Females kept at 10^oC did not call, but if transferred at 10 days to 20^oC they called after a period similar to the pre-calling period at constant 20^oC. Onset time of calling was earlier at 15 and 20^oC compared with 25 and 30^oC, but there were no significant differences in calling duration. At 20^oC, age at first calling was increased by shorter day length (12h and 14h, compared with 16h), and there was an interaction between daylength and moth age affecting the duration of calling. Onset times advanced with longer daylength, but peak calling was later in relation to the lengtii of the scotophase. These results are discussed in connection with migration in M.convecta. Evidence for a circadian rhythm of calling was found in females entrained for 3 and 8 days after emergence under reverse-cycle conditions and then transferred to constant darkness. However, after 56 h and 80 h respectively of darkness, calling became de-synchronized. Subsequently, it appeared to re-synchronize to a different clock, which approximately correlated with the normal photoperiods the moths had experienced during larval development.     

The novel ‘tongue‐bite apparatus’ in the knifefish family Notopteridae (Teleostei: Osteoglossomorpha): are kinematic patterns conserved within a clade?

Osteoglossomorph fishes are unique in possessing a specialized feeding mechanism, the tongue-bite apparatus (TBA) involving the hyoid apparatus. The TBA is associated with two unique behaviour patterns - raking and open-mouth chewing - used to disable and macerate prey. The kinematics of these two behaviours was compared in two species of knifefishes (family Notopteridae): Xenomystus nigri (Gunther, 1868) and Chitala ornata (Gray, 1831) using high-speed video (250 frames s"¹). Both univariate and multivariate analyses indicated that there were significant interspecific differences in both raking and open-mouth chewing. Raking can be divided into three stages; the preparatory phase, power stroke, and recovery phase. During the power stroke posterior motion of the pectoral girdle and neurocranial elevation both appear to play a major role in prey reduction. In Xenomystus the power stroke involves significantly greater levels of neurocranial elevation (35^o) and pectoral girdle motion (38% of head length; 9.5^o) than that found in Chitala (neurocranial elevation 11^o; pectoral girdle motion 11% of head length and 5^o). Indeed, Xenomystus represents the most extreme raking behaviour of any osteoglossomorph thus far studied. Temporal displacement variables demonstrated that the power stroke in Xenomystus is significantly faster than in Chitala. Although some of the interspecific differences might be size related, these data suggest that a greater degree of difference exists in these highly specialized behaviours than previous work has demonstrated. These findings support the notion that biomechanical duplication (an additional ligament found in osteoglossomorphs) could be linked to increased functional versatility.     

Influence of habitat characteristics on small mammals in a Mexican high-altitude grassland

Small mammals in a high-altitude grassland area close to Mexico City were studied. Populations of 10 species were censused using live traps in 48 sample quadrats. Within each quadrat, vegetation characterization, including complete floristic listings, cover values for species and layers and values of habitat modification, were assessed. Habitats were described according to plant communities identified using ordination and classification methods. Nine different plant communities were obtained. Densities and abundance of all small mammal species were calculated for each of the habitats classified. Peromyscus alsloni was the most abundant species in all habitats, reaching maximum densities of 55 ha⁻¹ in pine forest with dense ground and herb layer. Peromyscus melanotis also occurred in all habitats but at lower densities (maximum 29 ha⁻¹). Reithrodontomys megalotis was found in all habitats except in tall dense grassland. Densities for this species were generally low (1-9 ha⁻¹) but reached 19 ha⁻¹ in short dense grassland. All other species were largely absent from 4–8 habitats and showed very low densities (0.75–4 ha⁻¹). The densities of the more abundant species were largely correlated with more open habitats and higher indices of habitat modification. Lower altitude grassland habitats have a greater abundance of small mammals and a higher species richness than the medium and higher altitude, physiognomically more complex habitats. Species richness was highest in tall pine-alder forest with a species-rich, dense herb layer and lowest in pine forest with dense ground and herb layers. Species richness was positively correlated with overall small mammal density.     

Bird fauna of northeast Asia: a summary of the unique biodiversity and the priorities for conservation

The subcontinent of northeast Asia, defined as the region east of the Lena River between 58^o and 72^oN (and excluding the Kamchatka peninsula), is 3500 km × 1500 km in area (Fig. 1). Influenced by ice-covered seas, low air temperatures and permafrost, it has a complicated mosaic of habitats, supporting a diverse and unique bird fauna with a number of endemic species and populations.
East of the Verkhoyansk range, the northern limit of continuous coniferous forest retreats southwards and is replaced by two vegetation types unique to northeast Siberia: Larch tundra-forest ( sparse Larix cajanderi ) and tall bush tundra ecotone (dominated by the Shrub Pine Pinuspumila and Bush Alder Alnus fruticosa). Shrub Pine dominates sub-alpine altitudes throughout the interior and coastal ranges, descending in places to sea level.
Coastal habitats include river deltas, brackish water bays, offshore drift ice fields and leads, lagoons, sand spits, marshes, intertidal mudflats, cliffs. offshore islands, upwellings and surface currents. Warmed by the ground water, the permafrost-free interior valleys support lush deciduous woods of Poplar Popubs suaveolens and Korean Willow Chosenia macrolepis . Higher in the mountains, dry lichen tundra and rocky deserts occur.     

Discharge patterns of locust visual interneurones

The spike discharges of the descending contralateral movement detector (DCMD) neurone, and of some smaller visual interneurones (S-units), were recorded in the ventral nerve cord of adult Schistocerca gregaria Forsk., in response to a stationary disc (25^o) or a small spot (0.2^o) stimulus. The discharge rate of each neurone was plotted over a period of 5 s exposure; the total number of spikes in this period was also noted. The DCMD response to the 25^o disc was a high-frequency burst falling off quickly to a low rate; the 0.2^o spot evoked a prolonged discharge with an early peak in rate. In S-units the discharge was prolonged with both targets; the rate rose to an early peak in each case, with a much higher rate for the larger disc. For the DCMD the total number of spikes per stimulus (5 s) was greater for the 0.2^o spot; for S-units it was greater for the 25^o disc. Thus an increase of about 30-fold in the number of ommatidia stimulated resulted in a fall in the total DCMD response to about one-quarter; a similar increase evoked a rise of about 6-fold in the S-unit response. When the 25^o disc was presented at progressively reduced intensities the total spike response of the DCMD rose steadily to a maximum at about 2.9 μ W m^-2; using the same procedure the spike output of S-units, initially high, declined monotonically. The role of inhibition in these results is discussed.     

Development rates of some pre-adult stages in blowflies with reference to low temperatures

Abstract. Duration of some pre-adult stages of Calliphora vicina Robineau-Desvoidy, C.alpina Zett., C.vomitoria Linn., Phormia terraenovae R.-D. and Lucilia sericata Meig. were determined at 3.5–26^oC, in the context of use of these insects in forensic estimates of post-mortem intervals. Egg development in C. vicina occurs down to at least 3.5^oC, larval growth to 4^oC and puparial formation, development and perfect adult emergence to 5^oC. Growth curves by successive weighing of individual larvae showed specific differences in rates of development of the above species at constant temperatures. Alternating temperatures for 12 h periods (such as 10^oC and 20^oC) to simulate diurnal changes, usually, but not at all temperature pairs tested, caused acceleration of growth relative to the corresponding constant temperature (15^oC in the above case), in C.vomitoria, P.terraenovae and L.sericata , but usually caused retardation of larval growth in C.vicina. In this species, larvae as single individuals on beef liver in small tubes grew on average at the same rates as those (50–100 larvae) growing communally. All species showed variation in larval growth between individuals, more marked in C.vicina , and slower-growing larvae showed increased unexplained mortality. Because of this and to avoid complication by fast-growing larvae from later laid egg batches on a carcass, growth curves given are those of mean weights of the heaviest 25% (upper quartile) of groups of 40–90 feeding larvae. Variation in growth rates, and acceleration or retardation of growth in different species under alternating temperatures, thus affect suggested procedures in obtaining estimates of post-mortem intervals using these insects.     

Spatial and seasonal distribution of Culicoides imicola in Iberia in relation to the transmission of African horse sickness virus

Abstract. Collections of biting midges were made over 24 months from sixty sites spread across Iberia. Information on the distribution of the vector of African horse sickness virus, Culicoides imicola , from these 3119 samples showed that this species was annually present across south-western Spain as far as 3^o53'W and throughout most of Portugal, up to 41^o5'N. C.imicola was found in all areas where African horse sickness epizootics had occurred in 1987-90 and also in areas outside the epizootic zones.
Seasonal patterns of capture success of C.imicola , from seventeen frequently sampled sites where the vector was present, usually showed a late summer-early autumn peak. At the sites furthest south there was a discrete peak, mostly in September or October, before and after which the numbers captured increased or decreased steadily. At higher latitudes peak abundances occurred as early as May or as late as November, population build up was less uniform and numbers often declined rapidly after the peak was reached. Both the distribution and seasonal abundance patterns closely matched transmission patterns of African horse sickness virus, which rose during late summer and caused most cases during the autumn months.     

Aspects of the ecology of the coral-eating starfish Acanthaster planci

In the central region of the Great Barrier Reef, Acanthaster planci eats its own disk area of coral each day. At the southern end of the reef lagoon populations of A. planci eat substantially less than this amount of coral per day. Branching and plate corals are preferred food species and massive and encrusting forms are rejected while the preferred food species are available. Only when branching and plate forms on a reef have been consumed will A. planci attack massive and encrusting species. On Australian reefs preferred food species form between 70–99% of the coral cover.
On the Great Barrier Reef A. planci spawns in January and juveniles settle in the top 3 m of water on the windward edge of reefs or on isolated patch reefs behind the main reef. Intolerance of wave attack forces the growing starfish to migrate into deeper water. Lateral movements, probably induced by shortage of living coral in deep water, bring the starfish around the ends of the reef to the leeward side. Here they destroy most of the living coral.
It is suggested that the visual impact of A. planci on reefs of the Indo-Pacific region is related to the composition of the coral fauna. Reefs with a high proportion of preferred food species will be severely damaged while those with faunas composed mainly of massive and encrusting forms will not be altered greatly by starfish predation.
Work on larval development of A. planci carried out by Henderson & Lucas, 1971 showed that metamorphosis took place only at water temperatures of 28^o -29^o C. This suggests that the A. planci plague on the Great Barrier Reef will not spread south of latitude 20^o S (29^o C isotherm in January).     

Gene flow and hybridization following introduction of Mus domesticus into an established population

Seventy-seven house mice ( Mus domesticus ) from Eday, Orkney were released into a long-established population on the Isle of May (56^o 12'N) in 1982. Introduced allozymes, mt and Y-chromosome DNA, and Robertsonian chromosomes spread rapidly, reaching approximate stability c . 3 years later at frequencies different to those in both parental populations. The hybrid population was morphometrically intermediate between the two parents. This is a preliminary summary only; full details will be published elsewhere.     

The status of Phaiophleps lyckholmi (Dusen) R. G. Foster (Iridaceae)

An examination of the south Patagonian and Fuegian plant, Phaiophleps lyckholmi (Dusén) R. C. Foster, shows that it can be distinguished from the more widespread P. biflora (Thunb.) R. C. Foster by its leaf anatomy and perianth colour; these taxa can also be separated on the lengths of the peduncle and filament-tube, and on the shape of the perianth tube, although there is some overlap in these features. Because of the intermediates it is proposed that the two taxa be recognized as subspecies– P. biflora subsp. biflora , occupying grassland and dwarf-shrub communities at altitudes below 700 (-1000) m, reaches north to c. 46^o S latitude in Patagonia, while P. biflora subsp. lyckholmi (Dusén) D. M. Moore Stat. nov., is restricted to open habitats above (150-) 1050 m in Tierra del Fuego and Patagonia south of 48^o 50's latitude.